THD Flexi 50 Head

No idea what year this amp was made, bought new however.
1-channel, but the boost & master features make it seem like 2.
FX loop is eries: quiet & effective.
Biasing is really something, and the ability to use various /different tubes is great. 50/20 watt adjustability makes it great for studio, rehearsal, or stage. It morphs most amp sounds plus has it's own dynamic & touch-sensitive abilities.

Works well with single coils or HB's, and any style of playing.
Absolutely quiet, but if you load the front end with pedals or chains of stuff, you will hear anything unless you buffer them.
From twang to smooth to bluesy to screwam: it covers the gamut.
Also chimes quite nicely!

Like a tank it is - bottom line.

Have felt the need to contact them, but they have a superb rep and also have a great rating with the BBB in Seattle. Just wrote them about the warranty. Their website is EZ to navigate , and they have new products to morph this unit into a combo or in a head cab.

After 40 years, I think this will take the place of all my big stuff. Feature-packed, compact, and "flexi"-ble. Just what I was looking for. The YouTube videos, reviews here at HC, and magazine reviews do not lie. Have Bogner, Fuchs, Mesa, Vox and more in my stable. This piece just moved up to the front of the line-up.

Don't know what year but serial is 0491.
Amp is crazy versatile. I play everything from Country, Church, Rock, Blues, Metal. Depending on your tube choice you can get anything out of it. A very cool feature on this amp is you can bias the amp right on the back. No jacking with taking the cover off or anything. It is even printed right on the back what the settings should be. Makes switching tubes a breze. All you need is a voltmeter.
Not quite 2 channel, but a footswitchable boost and master volume. You can control the amout of gain boosted, and the boost has a tone adjustment. Super effective. Has one effects loop which is very clean. I use this amp in church and in a rock/country cover band. The power is fantastic. 50/20 watt switch only adds to the tone choices.

I play a les paul, strat, and a early '90s yamaha pacifica. All sound amazing. I have never owned an amp this sensitive to dynamics. I have owned Peavey 5150 head, Mesa Reto-verb head, Mesa MarkIV, and Mesa f-30. This amp kills them all. When you know what you are doing with real tube amps like this one, you can dial up any sound with it. Each and every knob makes a huge difference in tone. You can hear the difference between all your pedals, and guitars. Finally I can hear all the mods in my Keeley pedals, and in my Fulltone pedals.

Seems like a tank. I would totally rely on this amp.

Have never had to use them, but have only heard great things about them.

Love this amp. Will NEVER get rid of, or sell. Have been playing for 15 years, and have never come across something this amazing. If lost I would shoot myself for being so incompetent. If stolen my 9mm will be looking for your tail. I compared it to all the boutique amps made. Picked this one because it is by far the most versatile.

purchased amp 4 mo. ago tube swaping is endless old lion kt66---beautiful bell basman sound eh kt 88 lots of headroom valve art el34s my personal favorite pre amp tubes make a bi diff too.. i tried mullards jan phillips chinese tung sol believe me they all make a diff it all depends on the use of application and you tweakin abilities

sound quality is where this amp shines its by far the best ive played ive owned a 63 bassman a black face twin 73 super lead 75 master volume sound city peavey heritage jcm 800 and more.. vintage marshalls have always been my favorite until the flexi 50 came along ..i have a custom shop strat a classic les paul js1000 and i just purchase a jackson rr5 each guitar takes on its own personality through this amp like none ive ever heard.. the key to the sound is in the tweakin of the amp..with the jackson i have to completely re eq the amp relative to the strat which the pick ups arent nearly as hot.. but when u find that sweat spot its amazing..

looks like a tank.. feels like a tank... i really dont know though ..like i said ive only owned this amp for 4 months hope it lasts like my marshalls

havent needed it yet ....

ive been playing for a long time..25+ seen aa lot of crazy stuff over the years heard a lot of good and not so good equiptment played many a club marshalls have been by far my best experience over the years old ones too... not the new ones although i havent payed the hand wired.. this thd is a keeper and is my presant amp i use to gig with ...wouldnt change a thang,,,

Amp was made in 2003. I primarily use the amp to play with friends and out occaisionally. Lots of tone shaping possibilities which could possibly be the reason some find it difficult to dial in a sound - extrememly sensitive to small changes. Love the fact that you can swap tubes - I can get chimey Fender to classic marshall no problem - metal requires a foot pedal to get close. To me the 20/50 watt setting has a lot more to with the quality of sound than the "amount" of sound. No reverb is bothersome.

I primarily is my JET Earlewood with this amp which has the ability to switch to humbucker of single coil. I have a ton of pedals, but mainly use analogman tube screamer, Anlgmn Boss DS-1, Angmn Chorus and HK reverb/echo. My band plays a huge spectrum of music - so, I find myself missing a channel switching amp at times. However, when I dial the sound in I am looking for this amp is as sweet or brutal as I want. I can see where others may have difficulty getting "a sound" from this amp - several times I questioned whether I liked this amp or not because I was spending time trying to recreate a particular sound. When I decided to find my sound is when I really began appreciating this amp.

My experience is this amp is built pretty solid. I move it around a lot and have never had any issues. Never needed to call THD.

No experience.

I've been playing off and on for 20 years - moreso in the past 5 years. If stolen, I might consider a channel switching amp, but in the end I would probably replace the THD. I might even consider a second THD and set it up differently. I receive many compliments on my sound and I happen to like it too.

Everybody knows the features, I'm not going to list them here. Lots of "candy" and things that seem great in theory, but ultimately are useless in practice!

Well, this is the MAJOR stumbling block for this amp. It just plain sounds awful on anything other than totally clean settings. Tried with a multitude of different tubes and a plethora of guitars, it always sounds like a piece of sh*t. A damned smelly piece, too! Just how the hell THD has created those wonderful soundclips in uses to promote this woeful amp is beyond my understanding. Must involve tons of outboard gear and studio trickery to create those tomes, because they just don't exists inside this sucker.

Seems reliable, but sounds like sh*t.

No idea, never bothered with them.

Compared to almost anything on the market, this amp sucks big time. It is incredibly bad sounding! And incredibly non-versatile. From all the frothy, rapturous write-ups it has had, I can't help but wonder if the reviewers were testing a different amp to the one that THD sell to the general public. Seriously deficient in every category, even the FX loop is a useless primitive piece of sh*t. Awful amp! Fortunately I was able to unload it on Ebay and get my money back. Shame, THD, shame!

Yowza, where to begin? This amp has a plethora of unusual options including footswitchable boost (with it's own gain and tone) and master volume (I find this particularly useless)as well as an input hi/low switch, and the ability to use almost any tube in existance to tweak your sound with. Another feature, in my eyes anyway, is the ability to carry a fifty watt amp around like it ain't no thing. It's about fifty pounds and appears to be about the size of a loaf of bread on steriods. Very useful in my opinion.

Let me start by saying I didn't love the overdriven sound it makes, although I did find a lot of good sounds in it. It just didn't give me a useable version of the Marshall sound I assumed it was going to create. The majority of everyone else posting here says otherwise, so I'll take their word for it, as they own it and I merely auditioned it, using a GE Smith Tele and a Gibson ES 339, as well as two Jetter pedals (red and blue) and my Landgraff Dynamic Overdrive. I also ran a Lee Jackson Mr. Springy reverb pedal, a Diaz Texas Tremadillo, and a Mad Professor Deep Blue Delay through the loop. The distortion pedals all sounded fantastic, better than any other amp I've tried them on. The pedals ran through the loop sounded reasonable, but I think they'd sound better run through the front, making the fx loop more of a feature to list on a brochure than a functional aspect of the amp. Regardless, I think that this little beast is great. I may end up buying it if I can find a better sounding reverb unit to run into it, but this is a small beef. It seems to be the perfect pedal player amp, and I can only imagine switching tubes will only further add to tonal variations.

No idea. The general consensus is that they're tough little bastards, and I'd be pretty comfortable gigging without a backup, maybe bring some spare tubes along just in case.

I called THD after my experience and asked them a few questions and they were more than happy to talk about their products with me.

I really liked it because it made my pedals sound pretty damned excellent. As a stand alone amp I think it'd be somewhat limited, but that's not much of a consideration for me as I'm basically looking for a small and awesome amp to run a bunch of pedals into. This would definitely fit the bill. A little spendy, yes, but an intriguing concept for an amp, and I'd be comfortable assuming that it'd be an investment that I'd have around for a long time.

The Flexi has a lot of features you expect (FX loop, eq), some less common (cut and tone knobs) and some features NO other amp has (tube swapping, easy re-biasing). I gig consistently with it in a rock/variety band. The master/boost foot switching capability makes the amp versatile enough to play in a band that handles a lot of different genres, but, being truly one channel, if you've got the amp tubed for a great dirty sound, it never gets really clean via a click of the "boost" switch and vice versa. I've found that it's close enough for my tastes, and the sweet tones you can dial in override this slight shortcoming.

My other beef is that, unlike the Univalve, the Flexi does not have an attenuator built in, presumably because of the complication of heat dissipation in a higher power amp. So, to get the full benefit of hearing different types of power tube saturation, you have to buy a Hotplate, or practice at full, ear-shattering volume.

The feature feature is the tube-swapping capability. Owning this amp is like a history lesson in tube amplification and provides countless hours of tinkering.

I run no effects and use both humbucker and single coil guitars. The whole point of the Flexi is that it has multiple personalities. And the different personalities the amp take on are based on the unique characteristics of different tube combinations rather than shallow modeling effects. Different tube types not only vary in distortion and tonality, but in sustain and response.

When I first got the Flexi, with it's stock tubes, it sounded kind of stunted to me, but the brilliance is in the capability to experiment. Right now, I am hooked on 6L6's for a present, more saturated sound. Last week, I ran El34's for what was nearly spot on old-school Van Halen "brown." KT88's are sweet for clean-ish jazz and Chicago blues. I use JJ Tesla tubes almost exclusively.

You can get anything from clean to SRV to ACDC to Malmsteen with some trial and error.

I have yet to have any concerns with any THD equipment. It turns out, you can even drop it.

This is easily my favorite amp. It takes time--you have to experiment for days, maybe weeks, with different tubes to find that sweet spot. But when you do, you do. I get guitarists at set break at every gig that compliment my tone and want to see my rig.

Also, this amp doesn't hide mistakes well. You have to be a good guitarist or willing to work your technique, or you'll hate it. But who wants to listen to a sloppy guitar player behind a wall of gain and effects anyway?

All of them are usfull

This is my favorite amp. Nothing I have played comes close. The harmonic are unreal

I never had a problem with it.

Ed and Andy and the rest of the THD family have always been good to me.

I have been playing 37 years at this time. Do I need to say more than this is the best amp I have ever played.

The Flexi 50???s features have been well stated by previous contributors. The Line- Out is fantastic. THD is one of the few manufacturers that have this area figured out. The tube swapping ability allows you to tailor the gain range and feel to suit your needs. I do not feel that this amp is a chameleon that can replicate the sound of the best vintage amplifiers. The Flexi has its own sound. The tube-swapping does affect the character, and how the amp reacts in a very audible and useful way. The Flexi is not a true channel-switcher, but you can set it up so that the Boost acts as your dirty channel. I wish that you could use the footswitch to toggle the lo/high input and the boost function independently. I still give it a 10 because the design is well thought out with many useful features that do not detract from the tone.

To start, let me say that I have found most of the reviews on this product to be exceedingly accurate. I have owned the Univalve, the Bivalve, and now I have settled on the Flexi. I play many styles of music including rock, blues, hip-hop, jazz, funk, r & b as well as some of the hard stuff. I play a Les Paul and a Tele and I use a Dr. Z Airbrake attenuator. Just as a base of reference, my favorite amplifiers aside from the THD line include: Marshall JCM 800 (good ones are very hard to find), Fender Super Reverb, Fender Vibro-King, Matchless DC-30, and Vox AC-30. The Flexi brings out the best in both guitars and brings out the differences in pickups and wood. It does clean tones, driven clean, and distortion equally well. The low end presence is excellent and you can achieve that percussive low end snap heard in Marshalls and Fenders. There is plenty of bass on tap, without any muddiness. Others have described the Flexi as a cross between a Marshall and a Fender with some AC-30 thrown in. I agree. The THD amps definitely have their own sound though.
The Flexi is extremely touch-sensitive and is a joy to play. In fact, the THD line has ruined most other amps for me. They feel sluggish in comparison. I can no longer stand to use overdrive/distortion boxes. I find that the Flexi, with its great sustain, allows me to connect notes easily and thus makes it a very forgiving amp to play in that respect. Sound characteristics are very difficult to describe, but I will do my best. The tone is 3-dimensional, meaning there is harmonic activity after a note is struck. Notes bloom. The bottom end is very tight. Even at high gain settings, you can hear each individual note in a chord. The Flexi is plenty bright, though not nearly as bright as a Marshall Plexi. It has a unique midrange that sits a bit lower in the frequency spectrum than that of a Marshall, and cuts well in a live situation.
I had the chance to a/b the Flexi with a Marshall Plexi Reissue. It is my opinion that the Flexi can do just about everything that the Marshall can do, and a million other things. I found the Plexi RI to be much looser and sloppier animal while the Flexi has a much tighter, more refined sound. The Marshall is way brighter which some players may prefer, especially those who are trying to accurately copy the Jimmy Page thing. It???s a very cool amp, but to my ears the Flexi blows it out of the water.

I have gigged extensively with both the Bivalve and the Flexi and I have never had an issue with either. One of the great benefits of the tube-swapping capability is that there is no need to see a tech. These things are built exceptionally well. I would feel confident buying one on the used market.

I have never had an issue with any of the THD products.

The THD Flexi represents one of the best values on the instrument market today. I have gone through over a dozen amplifiers in the last few years trying to find my sound: JCM-800, Marshall Slash Signature (Jubilee), Fender Super Reverb RI, Mesa Boogie DC-5, Fender Deville ???among many others. Being a career musician, I have had the opportunity to test out much of the high end gear out there as well: Bogner, Budda, Egnator, VHT, Dr. Z, Gibson, Top Hat, Victoria, Vox, Matchless??? So far, the Flexi is my hands down favorite.

see my prior review

Just wanted to update my prior review. I have now had this amp a couple of months, and the honeymoon is still not over! I am now running GTEL34M power tubes, v1 GT12AX7R, v2 GT12AX7M, v3 12AX7C preamp tubes into a 16ohm THD Hot Plate into a custom 4x12 cabinet loaded with Celestion 70/80's. My guitar is a Fender MIM Fat Strat with a Floyd Rose, loaded with a Seymour Duncan Custom Custom trembucker. I still have NO complaints with this amp, it sounds killer. The classic brit style crunch is incredible, I still feel like I got one helluva deal.

Still works perfect, very solid build.

I have spoken with Ed, about a Hot Plate issue, awesome guy, very helpful. THD really gets an 11 here!!

Absolutely no buyers remorse, I only wish I had bought this amp first and saved all the money I spent on other inferior heads. If you like classic Judas Priest, Iron Maiden or even early Van Halen with some tube experimentation this amp will nail that tone, But where it really excels is at giving you YOUR tone. One other thing that still irritates me is the guy who reviewed this amp in Guitar World put down as a CON "no high gain option". Duh! This was designed to produce classic rock tones in the style of the jcm-800 and plexi, not Nu-metal tones. That is like saying a Mesa Dual Rectumfrier has "no Vox AC15 option" Apples to Oranges dude!

I've played 40 years and owned a dozen amps. This is what I've been looking for my whole life. The best Marshal tone I've ever wanted with lower lows, higher highs, and a low midrange with mind blowing complexity and harmonic content.

Simply breath taking. Tons of headroom. Id NEVER give this up. THe clean boost is the best I've heard. Really exposes the flaws in my pedals.....Its like a science lab.

Built like a tank. best build Ive ever seen.

The best. I called three times about tube choices and they were totally helpful!

I play, rock.blues, jazz, funk. It does it all. Totally dynamic and responsive to my guitars volume control.

THD Electronics Flexi 50 head. #214, Extremely versatile controls, volume, treble, midrange, bass, bright switch, input hi/lo switch, boost switch with gain and global tone, master volume with bypass switch, cut (presence) control, effects loop, line out with level switch and control knob, two speaker jacks, impeadence switch, external bias check points with adjustment controls, switch input to high with boost switch, footswitch jacks for the master volume and boost circuit, and the designer, Andy Marshall's signature with plexiglas cover right on the back, cool huh? the external bias contrrols alone make this one woth a 10. How much would you save a year on trips to the amp tech, just for new tubes and a bias?

I installed (2) Groove Tubes GTEL34M's for the power section and the pre amp now consists of V1 GT12AX7C, V2 GT12AX7R-2, driver is a GT12AX7R, all new. With the boost engaged this combination delivers a better than authentic JCM800 tone. Turn off the boost and there is that sought after Plexi tone. Putting a 12AT7 in V2 as recommended by the manufacturer yields a chilling early rock tone anyone would fall in love with. Very responsive amp, will make you a cleaner player. No where to hide sloppy chops, this thing is as articulate as any amp out there, note clarity is hands down the finest I have heard. Truly a quiet amp, even at extreme settings, it hums just enough to let you know it is ready to erupt at your command. All of the various controls and switches are dead silent, and very usable. Nothing here you would look at and say "why?".

I have only had the amp for a week now, so I am going to be honest and say no opinion. But I will say it seems to be built to survive. Everything is seems to be of the highest quality, it looks, feels and sounds very solid. I really expect years of trouble free service, how many used amps can you feel that confident about.

Here's one you never heard before. I purchased this amp used from an online auction site(yes, the E word), and thought it was not going to include the manual. I emailed customer support telling them my dilema, and requested a manual. Les than three hours later , I had the file sitting in my in box with friendly reply. Wow, fast you say, huh? Now, this was on SUNDAY afternoon. Customer support, on sunday? It is true, cross my heart! The manual was included with the amp, just to give Music Go Round in Novi thier credit, thier customer support is also top notch. Thanks again guys!

I went through the disappointment of trying to get my sound from large company produced budget tube amps, Crate(bv60h), Peavey(windsor,valveking), Epiphone(socal50h), Marshall(avt50h). The one thing they all share in common, when really pushed to loud volumes the sound just goes to mush. Why make a 50 or 100 watt head that only sounds good a quarter of the way up and then just starts a downward spiral in the muddy mess the louder you go. Then I decided to get the amp I originally wanted but Thought was too much money to spend. Well, I spent triple the new price of a Flexi trying all the others. After playing this amp for a week, I realize how expensive this lesson really was. This amp is by far the most versatile amp on the market.

All this info has been covered elsewhere in these reviews. This amp tries to cover lots of ground, but most of it I consider a waste. For all intents and purposes I consider it a 2 channel amp, but I was happiest when I treated it as a non-master volume single channel amp running on full power. The clean settings give you wonderfully sparkley tones, but I don't care for the overdrive at all. Obviously many of the reviewers like the overdrive, and it's there if you want it. One thing nice about this amp is it's LIGHT. That's important when you get tired of lugging 70 lb. combos around.

Like I said, the clean tones are great. Set it for full power, non master volume, and you get glassy, chimey, and harmonically rich tones. Very pretty. Sounds great both with my Strat or my Les Paul. But that's where it ends for me. All the other bells and whistles are just a waste. The over drive (boost)is harsh and not musical at all, in my opinion. Very uninspiring. Use a good pedal if you want gain. The master volume settings were equally unimpressive, since I don't care for the amp's overdrive sounds. I tried all sorts of different tubes and the results were always the same. That's too bad, because I bought this amp hoping I'd be able to achieve nice tube overdrive at a lower volume. The overdrive tones on this amp never sound good. I like the clean tones, but I have to knock it because the overdrive sucks.

I owned this amp for about a year before selling it. It seems to be made very well, and THD has a great rep. I never had a problem, and never had to get it serviced. Never gig without a back up. You may have the best amp in the world, but tubes fail and soldered wires can disconnect and nothing lasts forever.

THD has a great rep, but I never dealt with them.

I've been playing 20 years and have been through all sorts of amps. My current keeper amps are a Fender Vibro King, Whitney MV34, Bassman Reissue, '73 Princeton Reverb, and a Musicman 130-212. I was very disappointed in the Flexi-50, especially after reading all the glowing reviews.

You can find a better description of the features else where
But here are some things you should note:
Tube bias system- use any power tubes you like
Tone controls- more like a 3-band eq, makes it so much easier to dal in a specific sound
Master control-gives you four fot switchable sounds:
1. clean rhythm
2. clean lead
3. rhythm overdrive
4. lead overdrive

Wish it had:
2 independent channels
Reverb
No Cut control

I'm not going to compare this amp to any other amp, because the majority of us, like myself, have never played a vintage marshall, vox, or fender. Those amps are for collectors, not players.
i am using an '81 les Paul studio straight into the amp, and have a 2x12 Avatar cabinet w/ celestion lead 80's.
This has an outrageously clean tone. I prefer the ton controls set to a mid scoop which gives it a bell like, even acoustic qualities. 6L6's and 6V6's have the best clean tones. Use 6L6's if you need more head room.
EL34's and 7581's are better for overdrive.
The boost control is not another channel, its a volume increase.
so if you want a nice crunch tone, you have to peg the boost and switch in the master to control the volume. to get more distortion, all you have to do is turn up the volume and turn down the master. If you have the volume past three, it will start to compress which is distracting when you try to play fast.
Your speaker choice will be crucial to your sound. if plan to focus in on a overdrive setting, you may want a greenback or a V30. The lead 80's are very clean and very articulate, so they match with the flexi because it has the same qualities. My favorite over drive setting w/ the lead 80's is "smooth upper mids" setting in the manual, basically a mid boost.

Built like a tank, weighs a ton
everything is well thoughtout on this amp
becareful of liquids because the chassi is exposed to this due to the holes in the role cage.

Great.
talk like humans to you
respond quickly on emails

Cleans, cleans and more awesome cleans make this amp a winner in my book.
If you want footswitchable distortion, get a Mesa. dont bother with this amp.
If clean is what want, go wih amp, you will not be disappointed.
it really says want it to say when your playing.
Check out Avatar cabs if want a decent cab with nice speakers.
the flexi is a truely awesome and revolutionary amp.

Footswitchable Master volume & Overdrive boost. Bias controls on back mean you never have to buy tubes in matched sets again. Speaking of tubes, put pretty much whatever you want in this sucker! I've tried EL-34, 6L6, and one of each and it sounds great with all of them. Can't wait to try some EL-84's with my new Yellow Jacket converters! 50 watts of sweet, totaly configurable tube power. Half power switch drops it to 20W for even more FLEXIbility. Use a wide selection of cabinets too. I really miss not having reverb, but the other features of this amp almost make up for that.

Marshall Plexi tones to die for. Distortion totally controllable with master vol & boost. Sky's the limit for sounds and tones on this baby...Marshall, Fender, Vox and more are all there with a quick tube swap and re-bias.

A sherman tank should be built this tough!

Ed Genaro and his supports staff are the best I've ever dealt with...barre none! Nead a manual, PDF emailed to me. Problems with some yellow jackets, replaced no questions asked. Questions to be asked...answered promptly. I can honestly find no fault with the customer support...a few other companies should take notes here!

I'm normally fairly critical, so hats off to these guys for making the best amp I could find at a really fair price (not cheap, but very fair).

All knobs and switches offer considerable tone and dB shaping. LOVE the individual bias feature. The only change I'd make would be to make the input gain footswitchable.

This amp has a unique voice, which is probably more reminiscent of Marshall in it's hey-day, but more refined. I've owned Marshalls from the '60s, '70s and '80s, as well as a handful of Fenders, a couple of Boogies, a rack rig with an ADA MP-1, and a few "boutiques." Currently, I have 7 amps, including a handwired Marshall, Vox, Fargen, Fender, etc., and I have to say that the Flexi is the one I grab for EVERY gig, week after week, regardless of whether it's to play classic rock, funk, blues, or jazz.

I have a Les Paul Standard, a Strat, a Tele, and a couple of other guitars and use a mix of Duncans, Texas Specials, and Fralin pickups. I'm a bit of a pedal nerd with a decent collection of overdrives, treble boosters, and distortions built by Keeley, Fulltone, and other "boutique" brands. I also have used a wide variety of tubes in this amp, both new and NOS. The point to all of this, is that despite the subtle variations created by all of these things, this amp always sounds great. Does that mean that it will, or that it should, be perfect for everyone? Of course not, however, if you understand it's niche and then spend some time with it, you'll be rewarded. It took me a while to understand the preamp design, the unconventional controls, and so forth, but once I did it went from a nice sounding amp to "the sound in my head."

To me, these are the tricks to this amp:
1. It sounds best with the "boost" section on all the time, and thus I don't use the footswitch. I'd imagine that gain freaks peg the boost control, but I find that it works best if you back off of it just a bit.
2. You have to use the volume control above 12:00...I prefer it at 3:00-ish. Above that you may find it to break up and compress sort of like a fuzz tone, so again, pegging this control doesn't work for me. This amp is very much about smacking the output, so cranking the volume (within it's "sweet spot") is crucial...thus it's best to use an attenuator for reducing volume (except where 20 watt mode and subtle reduction of master, boost, and cut controls can sound great to reduce volume by, say about 4dB).
3. Keep the bass control down.
4. Most room eq-ing is done with the cut control.
5. The master thins it out too much for me...a hotplate is better (however subtle master settings are nice to add some bite).
6. This amp is capable of a fair amount of high end...thus I don't like it as much with Celestion 75s or V30s...better with H30s and Classic Lead 80s.
7. Like any amp, this front end likes some pedals more than others. Likewise, it may require different settings on pedals and guitars. It is highly sensitive, thus very dynamic, but it will also reveal some things you probably didn't hear with other amps.

Excellent! Really heavy duty. No problems.

Superb...really nice and helpful people. In addition, the users forum

http://www.univalve.net/forums_new/

has been very helpful in tweaking it to taste.

I've been playing about 30 years, and for the last two, this has been just about the only amp I've used. The Flexi-50 is appropriately named...I play a wide variety of gigs and venues, from weddings to outdoor festivals, and have never had a problem dialing it in. Simply an excellent value.

My Flexi is an 05. I play a number of styles, from heavy space-rock to jazz, to blues on occasion, to straight up STP style rock. This thing covers them all. The ability to use any kind of power tubes with this thing is incredible. It's amazing how the character of this amp changes with tubes. I use this head in small to medium size clubs, and I've used it on an outdoor gig once. It handles every situation just fine. I have to say that I always use my tone for every type of style I play. My pick attack, my guitar, and other factors in the way I play change according to the needs of the moment. This amp doesn't have a ton of knobs, channels, or options on its own (unless you count being able to use any type of power tube or preamp tube and completely change the character of the amp), but it is the perfect amp to use as a starting point to add your stompboxes and other accoutrements.

The ability to rebias in a matter of minutes yourself will save you a TON of money, and make your tubes last much longer.

I use a PRS Custom 22, a Hamer USA Studio Goldtop, and a USA Hamer Artist. I also occasionally use a Japanese strat and tele. It handles all guitars equally well. You know how they say that tone is in the fingers? Well, I believe that's true, but I think your equipment can either let your tone come through, or squash it and hinder your creativity. This amp is one of those that lets your tone come through. It's incredibly sensitive to the subtleties and nuances of your pick attack, your touch, and the type of pickups you have. In addition to all that, it sounds like freakin' BUTTER. Rich, complex, and a depth that I've not heard in an amp at this price.

It has plenty of clean headroom, though you can change that with a set of power tubes and a different driver tube. I've been able to get very convincing Fender tones, Marshall tones, Vox, Tweed Fender, and a bunch of others just through changing the tubes and resetting some of the switches. If you want to hear the difference between a NOS tube and a current one, this amp will REALLY let you hear the difference. Here's the thing- this amp, in and of itself, doesn't do the channel switching, clean to blistering distortion at the touch of a switch thing. It is more geared toward those who like to turn an amp up all the way and use the guitar volume knob, or those who like to run the amp clean and add pedals. I am one of the latter.

The tone controls are unique in that adjusting one doesn't affect the others. They are incredibly responsive, and you can get a wide variety of tones with a bit of twiddling. The one downside is that the amp is very, very bright. So much so that I actually run it with the treble nearly off. It doesn't matter, I still get the tone I need from it.

The amp is incredibly quiet. Even in my house, where I don't have a single grounded outlet, it remains quiet.

I would gig without a backup with no hesitation. Nice to see a well constructed circuit board amp. The chassis is incredibly tough, and it's obvious that a lot of love and care was put into the construction of this amp. I have never had a problem with it, it has never so much as crackled. Considering the quality, I expect that it won't require service anytime soon. I got to meet the designer of the amp, and he told me that he hopes this amp is the amp that people consider a classic 25 years from now. He hopes it'll be the workhorse that people continue to gig with for years. You know, it says something when other amp companies have postings on their website touting the quality of THD amps.

Every email I've sent has been met with extreme courtesy, and quick response. Ed DeGenaro even called me at home to discuss a concern that I had, which turned out to be nothing. This is a company I'm happy to support. It's good to know that they not only appreciate your business, but work to make some of the best amps money can buy.

I've been playing for 17 years. I researched buying my final amp for 2 years. I've owned Carvin, Mesa Boogie, and Ampeg, among others, I tried some other great amps- Bogner, Rivera, Carr, Victoria, Soldano, Bad Cat, Orange, and others. I was seriously impressed with all of the above, and it was a tough decision, but I'm happy with the one I've made. I got this because of its simplicity combined with its versatility and just all around great tone. The one thing I wish it had was an option for reverb, but I don't miss it enough to let it bother me.

If it were stolen, I'd definitely buy another one. I couldn't be happier with a purchase. I hate to give such a glowing review, but I seriously have nothing negative to say about the amp.

You can read about the features in the manual. I play in a classic rock band that gigs every week. This is a basic two (channel switching amp) with an effects loop, which i dont need or use, a direct out jack for going straight into the snake or board, again i prefer a microphone so i dont really need this.(i have gotten great results with a Blue Ball Mic. it seems to sound better that my sm57) It has an interesting tone stack that makes use of a tone control in addition to the regular treb, mid, lows, and presence controlls, also a hi or low input gain switch, and a treble or normal boost switch, giving a variety of options in setting up your sound. It comes with a heavily constructed footswitch to activate the gain and master on/off setting. This amp sounds great in the master volume mode, using the master volume tone stack to shape differing gain structure but to my ears it excells in the normal position with the master volume off. Thats where you can really hear the character of this amp. But it so hard to decide, both modes sound so good and on any given day i may choose either option (depending on the size of the room). The flexi has a 20 watt and a 50 watt option, where the 50 watt setting applies more current to the circuit whereby the tone is altered to a stronger, slightly louder, less compressed sound. I tend to not use boost pedals or overdrives,for the most part and use my volume controll to alter volume. Unles you are using a super clean amp with loads of headroom boost pedals seem to saturate the tone too much for my liking and actually cause it to lose projection. Many times on many amps i have set up a overdrive to sound really great only to find that when PLAYING WITH THE BAND the sound and projection of it sucks. My ideal of an overdrive is to work on the POWER section NOT the preamp section. After i set up my rythem tone and i need a boost for a lead part I WANT THE SAME SOUND.....ONLY LOUDER. A pedal cannot deliver this, so i must make the trade off and just use my volume knob to project solo's . (back in the day i used 2 amps, but i choose not to do this anymore) Every now and then i may use a chorus and in some songs a wah, but thats it. I find it more pleasing to concentrate on the focus of playing and the sound of the guitar rather than an effect. I bought this amp because i heard a player using 1 in his band. He was really stoked about the amp and was very helpfull allowing me to come to their practice to try it out. This amp needs to be tried out at practice with the rest of the band playing. That way you can get an idea of how its going to sound live, rather than sitting in a small room at the music store. Shoot, you can get anything to sound good at a low volume with tons of saturated gain. Its when you're paired up with a pumped up drummer and a angry rythem guitar player and a string poppin bassmaniac, and you really have to open it up is where you can hear the projection and tone and presence of this amp.

I use this amp with les paul customs, standards, and a few different strats a 71 and a newer swampcaster. I play in a classic rock band that plays every week. My current main guitar is a stock 1979 lp custom (custom shop gold top). I have been playing over 35 years, my dad was a recorded opera singer and played 6 different instruments. Sooo..i have been around music and musicians a lot. If you enjoy the tone of the masters (page, beck,clapton,kossoff, etc.), you will enjoy this amp. There are a variety of tones possible with this amp as i will get to later. The whole trick of this amp (and finding your own voice) as a guitar player involves the total sum of the parts ( guitar, strings, pickups,cord, amp, tubes, speakers) This amp does not seem to be noisy and has a variety of fenderish clean to modded marshall tones, but with a lot more bandwith in all areas. I wouldnt classify this amp as a high gain amp, but...with the preamp buried is can get really fat and greasy...ala Leslie West. At 50 watts(w el34's or 6550's) this amp can get louder tha a 50 watt JMP. (my other guitarist uses 1). Or using the 20 watt setting it can replicate marshall high gain tones at a respectable volume. As i grow older i find that false security of having the gain knob buried has left and i find myself seeking tone and sustain rather than gain. This is a great amp for blues, or classic rock IMHO.

This amp seems to be built like a tank. I quit hauling my 50 watt smallbox around as a backup amp. I just take a couple of extra tubes.

Customer support is great. I bought the amp at Indoor Storm used, as a trade in (a young player took it home for a few months, and didnt like it). And i was pleased to find out that Ed said we can start your warranty the day i called, obviously THD is not worrying about this amp breaking down. I have had a few conversations with Ed Degenaro about different aspects of this amp, and was always treated kindly and courteously...and...promptly. One time i e-mailed a question to THD and i didnt even have time to sign off the computer before they replied....Now thats the kind of service i like. BTW the folks at indoor storm are absolutely great to deal with also. KUDOS....

I waited months before submitting a review on this amp. I wanted to test it in live playing situations. So many times i have tried an amp out in the store only to take it on a gig and be disappointed. Now a couple basic things..POWER TUBES.. NOS Mullards(not the re-issues) NOS Siemens, NOS Tesla's, NOS 6550's GE or Tung Sol. Dont even mess with the others you are wasting your time and money. Just get the real shit. Pre amp tubes... I like mullards, telefunkin, amperex, Brimar's, GE's, NOS phillips, tungstrams. I saw 1 telefunkin 12ax7 on this tube dealers site for $425.00...Crazy world we live in..... Q: why do you think they want so much $$$ for these old tubes?????...ANS: because they ROCK. and tube dealers know that some tone fanatic is going to shell out the cash to get that sound. Let me add that the ElectroHarmonix 12ax7 isnt a bad tube, or are the jj ecc803's..nor are the new GT 12ax7 Mullard clone. But each tube has its strong and weak points depending on what you like. But across the board the mullard and telefunkin, and amperex seem to sound the best to me. Now we move on to speakers. The safest speaker to start out with are the V30's i guess. Depending on your tastes there can be many different choices. I have tried G75M's, greenbacks (which dont sound anything like original greenbacks), Weber thames (a nice chime speaker)JBL greybacks (nice clean sound, but dont try and clip them blaaaach)and V 30's. Of all the V 30's sound the best (to me). All mentioned in a 4X12 metal handle old (with J.Marshall's signiture in it ) Marshall cab @16 ohm. Get a good instrument cord. You playin a 2k guitar in a 2k amp and using a $6.95 cord. haaaa... Well that about all i have to offer......good luck....and God Bless.....

20-50 watts, effects loop, boost, self biasing for different tubes. I can't think of more you would need in an amp like this. Very single channel old-school, but extremely versatile.

I should start out by saying I have never felt strongly enough about any product to submit a review like this. I have been in the market for a low wattage tube combo to use at home. I was recently lucky enough to test drive one of these at a Guitar Center with a Les Paul through a Marshall 4x12 cab. I am not crazy into effects, but I do like a little reverb or delay to fatten up my sound normally. I typically walk away unimpressed by most dry amps without some reverb at least. All I can say about this amp is I have never played an amp that actually made me smile while playing it. I am talking about a smile that wouldn't go away for several hours after the experience. I even woke up in the middle of the night a few times thinking about the amp. I won't say it was perfect, but, it came closer to the tone i've heard in my head all these years than anything else i've tried. With the 20 watt switch it was easy to get a cranked Marshall vibe at low volume. The only flaw i could find was it was a little more muddy for rhythym than I would like. I feel confident with a little more time with the amp, it could be dialed out to near perfection. It wasn't the combo i was looking for, but I still can't stop thinking about it.

Seemed very well built. Very heavy for it's size.

I have been searching for the tone in this amp for the past 17 years i've been playing. I didn't buy it because it wasn't a combo, and was a little more money than I wanted to spend. It could very well be the perfect amp tonally for my needs. I just purchased a slightly used Soldano Astroverb 1x12 combo off of ebay based on my experience with this amp and the reviews from this site. If it delivers what reviews claim it could be my last amp purchase. If not I may have to start saving for a Flexi 50.

2005 Flexi-50, very versitile, single channel, boost and master, series effect loop. It has enough power and a very complimentary set of features. I have used this amp gigging, and in my home studio, I am highly satisfied with the features.

This is one of the best sounding amps I have ever heard or owned. You really have to understand how various guitars, pick ups, and tubes work together to get fantastic sounds. I have tried it with the stock EL-34s it came with (excellent), GT-KT66-HPs, and Yellow Jackets with Tesla EL-84s. I have used it with an Anderson Drop Top Classic, Stratocaster Deluxe, Les Paul Standard, PRS Custom-24 and Ibanez RG-520QS with DiMarzio Tone Zone in the Bridge. You can come very close to the Bluesbreaker (KT66 with Les Paul or PRS), Marshall JMP (EL34 with any) Vox AC-30 (EL84 with Anderson or Strat). Certain things don't work as well (Anderson or Strat with KT-66) in my opinion. Also, very nice Fenderish cleans. The amp really shines when played loud with output distortion and no master. Boost for leads is very effective when used in this way, I don't experience the compression others have noted. Really superb harmonics, highly noticable tube characteristics. Again, you must understand how the various factors work together but truly unbelievable sounds when you plan and tweak it. Not for super high gain modern rock as others have noted. Outstanding, phenomenal sounds and gives you the opportunity to learn about tube characteristics.

Build like a tank, small problem with bias diode out of the shop, fixed me up immediately.

Very good. Spoke to Andy Marshall about a small diode problem, dealt with immediately.

Playing for 30 years, definately replace if lost of stole, really unique amp. Many excellent amps out there but the Flexi-50 does perform as advertised once you understand the factors related the the sound coming out of the amp. Could use a true parallel tube driven effects loop but not a real issue.

This is an incredibly versatile amp. You can read the features below ... Plenty of power, depending on the tubes you choose. Paired with the THD cabinet and a power brake, this thing is unbelievable!

I have mine set up as a blues amp...with a little bit of edge. I use my guitar's volume control to push it into distortion. I like the stock tubes ... but swapped the V1 preamp tube for a NOS RCA AT7. Great sound.

Only had it for a short while, but tubes are easy to replace ... looks solid!

Great web site... check below for a great forum...

http://www.univalve.net/forums_new/

By far the best amp I've ever owned or used for that matter.

Single channel
Volume, Treble, Mid, Bass and Presence controls
Switchable Master Volume
Switchable Boost function with gain and tone controls
Bright switch
High / Low input switch
Effect loop
Impedance switch for 2,4 and 4, 8 and16 ohm cabinets
Allows for substitution of virtually any power tube
Easy to adjust power tube bias. Individual bias pots for both power tubes with outputs for a multi-meter.

I have used this amp with: An '89 Strat with stock pickups and a Seymour Duncan ? pounder at the bridge.
A Squire Tele Deluxe loaded with Seymour Duncan JB and Jazz pickups and coil-taps.
An Ibanez S470 with stock pickups
A parker P-38

My musical style is primarily classic rock with occasional, semi-competent safaris into blues and jazz.

I too wanted to love this amp but I think we are still just friends at this point. Here is why:
It all started when I bought a 70-something Traynor YBA-1. It sounds great, I don?t need to use any pedals. But I know the Traynor is going to catch fire any day now so I bought the tank-like THD Flexi in hopes that I could replace my beloved Traynor with a modern and ostensibly more reliable amp.

First off, the Flexi-50 really responds differently with different power tubes so I will treat each individually:

EL34s: Clean, low volume / low boost sounds pretty good. Playing Jazz with a loud drummer is damn near impossible. At high volumes there is very little headroom before serious power amp distortion, nasty compression and clipping take place ? at least for single notes. It did sound REALLY cool playing rhythm in open G on a bunch of Stones tunes. However, on single note runs at high volume / high gain it basically sucks a** (in my humble opinion)

6L6s: At clean or slightly overdriven settings it sounds great -- the amp has a wonderful clean / slightly dirty tone. Think Stevie Ray or maybe Ronnie Earl without reverb. Switch on the neck pickup on a Strat with the boost and volume set at reasonable levels and you should be able to nail a pretty cool blues tone.
It also sounded pretty good at high volume / high gain with the 6L6s but not as good as my Traynor YBA-1.

6V6s: Sounded pretty cool in my bedroom in both clean and high gain modes but there wasn?t enough volume to compete with a spirited drummer. The only time the master volume feature seemed even remotely useful was with the 6V6s loaded

Summary:
* I agree with others that the overdrive can definitely be ?farty? sounding and over-compress. 6L6s seem to help.
* I also agree with others that technique does seem to count for something with this amp.
* The amp has a cool clean tone and good crunch tone for classic rock rhythm guitar. Forget about nu-metal.
* The amp will cut through a loud mix
* The amp seems to sounds cool with an overdrive pedal (I have a Boss SD-1)
* With its boutique price tag, the Flexi-50 should have a much better overdriven lead tone.

I have only owned it for two months. I appears to be very sturdy.

N/A

I have been playing for 30+ years.
I have owned or played several Mesas (no thanks), A silver face twin, a Peavey Classic 30 (great amp) and a vintage Traynor YBA-1 (near nirvana)
I would probably buy something else if this was stolen.

I purchased this amp new in the beginning of 2005. My intention was to find something a little more flexible that my Marshall JCM2000, which I have been playing for the last few years. There was not a dealer in my area at the time, so I bought this over the internet based on the rave reviews this amp has been getting. This is a single channel amplifer, but with quite a bit of control over that one channel: including foot-switchable Master Volume and Boost features, along with the usual EQ controls. This is an all-tube amplifier designed to allow the user to try different combinations of input and power tubes. I was particularly drawn to this amp because of this ability: to try out different tubes in order to fine tune my sound. This amp also has a feature which makes it easy for the user to adjust the bias of the power tubes. As for the single channel feature, the THD website describes using only the guitar volume for "cleaning up," the guitar signal. I did not find that practice to work particularly well for me. In retrospect, the THD statement about the different channels on multi-channel amps sounding "more or less the same" may be a bit self-serving, as THD only makes single channel amps at this time.

I play in a classic rock band. My primary guitars are a stock Les Paul Standard with "Burst-bucker" pickups, a Strat with Dimarzio "stacked" single-coils, and another Strat with Lace Holy Grail pickups. I would say that the lead guitar sound I shoot for the most runs along the lines of Journy/Boston/Santana/Mana, etc. It is in this capacity for lead guitar sounds that, in my opinion, this amps falls sadly short. I hate to say this. I really WANTED to love this amplifier -- after all, the reviews are great, so the amp must be awesome, right? Right out of the box, plugged into an Avatar Speakers 2X12 with vintage Celestians, this thing sounded horrible. I was trying to get a sweet, over-driven, boutique amp sound, but this amp was not about to give it. The distortion sounded fuzzy and synthetic, like cheap transistors. It seemed to have a lot of buzz to it, like a Marshall with the presence control pegged to maximum. Strangely, the initial pick attack to the strings was very loud and percussive, but the signal seemed to drop off faster than expected, as though a compressor was engaged at the time of sounding the initial note, but then disconnected as the string begins to vibrate. Reducing the "CUT" control helps minimize this, but not enough. I called the folks at THD; they felt that I would have much better performance if I incorporated a Hot Plate into the set-up. One 8-Ohm Hot Plate and $279.00 later, I tried it again, but the amp was not any better. The Hot Plate seemed to increase the hiss. Another phone call to THD, and I was swapping out the EL34s for 6L6's. Actually, this smoothed things out a bit, reducing some of the hiss when the Gain and Input Volume were at 3:00 O'Clock or better, but I still didn't think it sounded very good at all. If fact, my cheap practice amp, a VOX ADT30, sounded much, much better. More phone calls to THD resulted in Ed giving me some recommended control settings over the phone: while I very much appreciated his time, the amp still sounds very strange to my ears: a percussive intitial string signal, lack of sustain, and a tone rife with hiss (or should I say lack of tone?). I have now tried the amp through a different speaker cabinet, but this does nothing to improve the performance. There is now, since the time of my purchase, a THD dealer in my region. This dealer says that "this isn't a high-gain amplifier;" he recommends running the amp clean, and putting a high-quality overdrive pedal on the front end for that "harmonic distortion" lead guitar sound. That would probably work to some extent, but at this much money, I would expect this amp to sound a lot better without any effects. The best sound I have gotten out of it is a fairly clean blues sound (think SRV's clean stuff). By itself, I have not gotten this amp to give me the harmonic-distortion, violin-like sustain that I was hoping for. Maybe I got the lemon. I cannot account for the fabulous reviews this amp gets, unless these folks are just playing clean blues and jazz?

This amp has not broken on me. It appears to be very well made. I would gig with it if I liked the way it sounded.

The customer support, despite my problems with getting this amp to sound decent, has been wonderful. I have spoken directly with Ed and Andy up at THD, and I do very much appreciate their time even if the amp isn't working for me. On my last conversation with THD, however, they were kind of pushing me to try this thing through the THD speaker cabinet, and I have to say that I felt frustrated that the solution to the sound quality problem kept being to buy something else (tubes, Hot Plate, etc.) Still, these folks have been very generous and patient with me over the phone. I can't imagine being able to talk to an engineer over at Marshall, for instance!

My overall rating for this amp is very low because, fundamentally, I never got really good guitar sounds out of it. The name and description of this amp implied something much more versatile than it actually was, at least withn respect to the one I bought. I would like to close this review with some advice to others that may be thinking about buying one of these: First: buy it from somewhere that you can return it (Musiciansfriend, etc.). That way, if it really doesn't work for you, you can return it. Second: really assess your performance styles and determine if a single-channel amp is going to work for you. I think that a lot of rock music is far better suited to a channel switching amp. Third: forget the hype. Forget the reviews. Forget what I write here, and forget what the other guys wrote. Plug in your guitar find your sounds and play it. Close your eyes and listen, really listen. If it really works for you, then great! If not, then return it, and don't worry about being judged as a lesser player if you can't convince yourself to feel the same way as previous reviewers may have. After all, art is subjective. As for myself, I have found a much better solution with a Mesa Lonestar, but that will be a different review......

Visually the amp looks terrific -- watch those valves glow --E34's on this come as standard. It is pricey but offers a tonal pallete that sounds good to my ears. I was wary about gigging with this though as only a plastic cover is offered -- I'm sure some manufacturer will have a flightcase for it. I opted to buy the THD speaker enclosure as it's about the best reference monitor I've heard (I tried it with other heads). All the controls work well together but do take time to find that sweet spot. I like the idea of a single channel -- I've always found that most amp manufacturers compromise somewhere on their multi-channels -- either the clean or the dirty suffers. The ease to change valves makes this a good choice for the recording guitarist -- go brit or yank armed only with a multimeter. The provision of 20w or 50w is good too as this is seriously loud. It'd be nice to have a footswitich to bring in pedals in the loop -- too much footstomping for me.

The sound. First try in the shop, I sounded really messy. This amp takes no prisoners when it comes to sloppy technique. I immediately slowed down and tried to interact with it. This amp really does raise the bar --although I have found it needs an overdrive/distortion pedal to take it into this millenium's style of heavy tones. That's not a criticism -- it's just that it's hard to go from crystal clean to crunch to squeal. This amp does it all -- but it does require careful setting up and thinking ahead. I've found a Boss DS1 works well and a hotcake. This needs to be heard in a band environment because that's where it really cuts through like no other amp I've had. However, if you play sloppy -- this will exaggerate those errors. It might just help your technique!
I use a Fender Strat with duckbuckers and a JB along with a custom built guitar made many years ago by Ian Watt. For the first time I can really distinguish between the pickups.

Tubes look easy to replace and so far it's not broken down on me. I always take along a Boss GT6 I can plug into a PA if it fails -- doesn't supply the sound of the Flexi -- but it's a safe back up.

Before I bought this I harrangued the customer support people about availability of parts and servicing and they were very helpful.
I really must say they've responded each time to any queries -- no matter how stupid sounding.

I'd buy another if this was nicked (stolen) I love it's apparent simplicity -- it's about the guitar and how it interacts with the amp. For example my guitar sounded poor plugged into a Peavey Joe Satriani model -- but the Ibanez Satriani guitar sounded very good.
With the THD all the guitars sounded good. I tried Mesa Boogies -- Peaveys -- Marshalls and settled for this.

Taking into consideration that it is a single channel amp, it does have a good amount of features, but some of the features aren't really as useable as it first seems. For example, the footswitchable boost looks good on paper, but in reality, the volume difference is to great to be of any use. I would have liked to see the ability to switch only the input gain switch via foot (now, you can only switch it and the boost simultaniously). The amount of gain that the input gain switch adds is just the right ammount for lead boost.

This can be an incredible sounding amp, or nails on a black board, depending on the player and playing style. For those used to modeling amps, or all in one FX boxes, this amp may not suit your needs. It can sound immensly better than the modelers, but it takes more work to play (as with any real tube amp). Where on a modeler, you can pretty much hit the strings any way you want and still get the same sound, with the Flexi, dynamics play such a big part of it's tone that you actually have to play your instrument.

This is the third THD I've owned, and I've never had a problem with any of them.

I've heard great things about their support, but I haven't seen it first hand. I've tried e-mailing, and never got a response. I see that they are now selling to Musicians Friend. Perhaps the company is getting a little big for their employee base?

If you use real tube amps, and are looking for a single channel amp that sounds like what you think the best hot rodded plexi SHOULD sound like (but never does), then you'll be happy.

If you're playing a Pod or digital stomp box, move on. You won't like the amp, because it sounds and feels like a real life tube amp.

the features are fine.... did'nt want a modeling amp tried them all.... the master vol. on /off, boost/gain,bright,
hi/low all are real usable

the amp sounded great at home...but on stage WONDERFULL.....It cut throughthe mix with some of the best tones' I've played in 40 years...... (oops I dated myself) Im using a marshall 2061xc w/ 2-12 celestion gh speakers...Thanks ED, for the advice (it's Greg from Flag)I play rock n blues it's great for my styles

My amp had a faulty bridge rectifier crct...THD took care of it pronto....so I did'nt miss a gig....and this was during the NAMM
show week prep...Thanks again ED

Customer Support is fantastic readusual last remark

I've been Playing for 40 years... I own 1774x LE Marshall 18 watter
Custom shop LP,Custom shop 336 Gibsons , a Don Grosh Strat, and a Vox tonelab SE for effecs. Tryed most everthing over the years.... Davoody too..Frank Gambale was my instuctor (LAMA 96')...If it was ripped off I would get another...This AMP ROCKS

Nice. It is basically a one channel amp with two different footswitchable flavours but I regard this as a two channel amp for easier reference. There are two gain structures that can also have two different volume levels. You can either have a clean sound and a dirty rhythm then switch to a pedal for solos. Or you can have two rhythm sounds + use a pedal for solos. Or you can dial one channel for rhythm and the boost channel for solos... And it works. You can dial in a darker solo tone or a brighter one... Go and see the description on the THD website.
The best feature after the sound quality is the bias possibility. I can use various tubes, even if not matched and bias the amp all by myself and I am no technician. Would never dare doing so on other amps. Then you can also disengage the master volume circuit and have a non-master volume amp ! Having enjoyed several non-master volume amps in the past this was a very important factor for me. For now I use the Master Volume as it is a very well executed design that doesn't take away from the good sound of this amp. Switch the Master Volume out of the circuit and the amp shines. You can also use the footswitchable master volume as a volume boost for solos.

Awesome. Use it mainly with Strats (single coils and HB in the bridge). Works wonderfully in a band context. You are never too loud and always cut through. Has the right frequencies tuned in. Great for classic Rock, Blues or Blues-Rock. Even for Hardrock. For Nu-metal, I would use it as a good foundation and add some pedals in front. You can use it with various cabs and speakers as I did with good results. Don't judge this amp solely by playing it in a store or at home. Take it on a gig and you will be surprised as to how well it responds to your playing dynamics and the sound of the other instruments in a band context. You have to turn it up to get best results.

Built like a tank. FAA approved technology it seems! Not point to point, but a very thick PCB well supported and well built with thick copper traces. Tube sockets and pots are chassis-mounted. I don't expect any probs in the near future. Should last a lifetime. I bought the amp only 2 months ago, but used it on a few gigs with no problems.
I had many Marshalls new and old break down on me. Never use without backup though. You never know. There are tubes inside. But you can easily change them and rebias and off you go.

They seem very nice and responsive. I emailed them a few times directly with questions and got quick answers that were to the point.

Tens everywhere ? Well for me it is the best amp I ever had. Because I have many variables to take into account: sound, built quality, size, bias, tubes etc. The Flexi with a 1x12 cab, a Strat or a Paul, plus my collection of pedals is the ticket to go. Sounds huge and cuts through. 3D tone and dynamics. What else do I need ?
I have had the following amps and always had a complaint: Budda Superdrive combo (best sound but bulky and not flexible enough), Soldano Caswell (great sound but not my cup of tea), various Marshalls (classics but not reliable enough and needed the 4x12 to sound right), various rack gear, combos and heads... I feel like I will not look any further for amps. I can concentrate on my playing and maybe add some pedals to get different flavours now that I have the right foundation.

What they said

Using mostly strat type guitars.This am is very touch sensitive (maybe too much for some judging by some reviews)and dynamic .It has the best cleans of any amp I have ever owned,and also the sweetest and fattest lead tone!!This is a very good amp for old school (do it all with the volume knob)kinda guys perfect for blues,classic rock ,country and jazz(when not to much head room is needed)
The huge lead tone is great for the shreader solo kinda thing,But

This amp will not do Nu metal,or would not be first choice for old metal.
I give this amp a 11,and if I could I would give it a 37 to make up for all the guys who couldnt handel it.

Built like a tank

The best

I have had alot of amps including 5 Fenders,6 Boogies and 11 Marshalls and the FLEXI has a feel and touch that seperates it from all other amps in the price range.
Not for beginners or Nu metal.

I won't go through the trouble explaining all the features, but there are lots of 'em. I bought it brand new mid 2004 and still have it but will try to sell it after the christmas season when people have money.

I really don't understand all the great ratings this amp has gotten here and on other forums. The flexi is absolutely horrible. When driven hard at gig levels, the distortion is harsh. The boost then compresses the hell out of the amp and squishes the notes too much. The master volume is also not very good. by the way, I'm not the only one with this opinion-the others who have played this amp feel the same about the amp. The amp excells at mid gain levels, but other than that it sounds like *hit.

looks dependable.

never talked with them. One of the employees is on the forums all the time and I suspect that's why people aren't cutting this amp too pieces the way it should.

I've been playing for over 25 years and play in 2 cover bands (classic rock and contemporary pop) here in California. I have many guitars but usually play my prs mccarty and custom22 at gigs. I have 3 old Marshall heads, a VHT CLX (great amp!!), and a rack set up which I normally use for gigging. After I got the thd, I tried using it at rehearsals for my classic rock band along with a avatar 2x12 and I hated it. I should have tried this amp out before buying it as this amp is not very good. I gave up with it and put the amp in my closet. It's harsh and just doesn't sound very good. It sounds nothing like a Marshall (I have a 72 and 74 superlead, and a 78 100 watt masterlead to compare to the thd). I have also played a Univalve and Bivalve-both amps are way better than the Flexi. I just can't recommend this amp.

My amp has not arrived yet, it is on order but I have had a number of these cross my bench and have spent many hours with them.

Most if the features have been mentioned here in other reviews. I will take a moment to approach things from a bit of a different angle.

The late 1980s saw some great amp builders come on the scene. Matchless, Dr. Z and THD were a few of them.

THD came to my attention though a friend, Aspen Pittman, founder of Groove Tubes. Now you may love or hate GT but the point here is that Aspen has one of the most extensive amp collections around and he does have a great ear. When THD came out with their tweed bassman reproduction Aspen commented that is was perhaps the best sounding and playing tweed bassman he had ever heard.

Years later I saw an amp called a Univalve. I am involved with tubes in my line of work and this amp seemed to be just the thing to actually compare tubes easily. Too often we rely on tests, traces and specs where these things differ more in the actual tone aspects of the tube. I bought a Univalve from The Amp Shop in So. Cal.

My UV was one of the earliest. I met with Andy Marshall from THD to perform a change to make the amp more reliable. The amp had been 100% reliable for months and this change was something that would fix something "that could happen" but rarely did. It never happened to me. In the process of making the change an etch had to be cut. This opened my eyes quite a bit. You cannot tell all that easily the thickness of etches visually. Once you try to cut one of these THD traces and realize you need a power grinder you realize how thick the etches and substrate are. The construction of these amps is about as perfect as it gets. THD uses proper technology to it's best advantage where it is best applied. Chassis mount sockets with flying hand wired leads to the board. Modern resistors rather than carbon comps which are not as stable and are more noisy.

The Univalve became a primary studio tool. One feature overlooked by far too many folks was the great transformer isolated line out. I use the UV as a preamp quite often. Get the gain and tone from the UV and take it's line out to a Fender Twin Reverb and you can have a pretty amazing rig.

The Flexi 50 - No surprises here. I first saw and heard this amp at the 2003 NAMM. I was very impressed. I told the THD folks I wanted to get on the list for one. They were not going to be shipping for a while as the tone stack was not finalized. Andy and Ed at THD don't let things out until they are completely satistied with the end result.

The amps has the features most people would want and that most folks would find useful. I am a big fan of the THD line outs. They are one of the few folks that seem to know how to do this in a way where it works for the applications I need. I have used the UV in very large live environments. Mic the cab and run to one channel and take the line out to a second channel and you can cover a lot of arena area.

The dual voltage is a great feature for 6V6 use.

The amplifier is fully featured yet not messy or complex.

I have used the Flexi 50 amps in a number of environments - live work, studio work, etc.

This amps is not trying to replicate a specific amp. I guess when folks hear Flexi they think Plexi. This is sort of a yes and no. This amp covers the tones and bases of the early era Marshall amps really nicely. BUT >>>> it can also cover bases other than just the "Marshall" tones. With a 12AY7 in V1 and a nice set of 6L6 output tubes and a 4x10 cab you can hear tweed bassman tones and character. With a 12AX7 in V1 and V2 and 12AT7 in V3 with those same 6L6 tubes and an open back 2x12 you can cover Fender tones pretty darn nicely.

This amp does not "copy" other amps. It is a very versitile amp that lets you move to the character of other amp types due to it's design and architecture, tube change ability, etc.

On cabinets by the way, I have used these amps with 1x12, 2x12, 2x10, 4x10, ported, open backed and closed back cabs. Some of you know the other amps and cabs I have and most of those cabs have been used. I have strong personal preferences, and I think Ed at THD has made comments that I am more a "Fender guy" than a high gain guy. Yup, I grew up on Fender, Marshall, Vox in the 60s and have sort of stayed that way but I work with a lot of folks that are quite "over the top" when it comes to gain or walls of cabs. These days the walls of cabinets are going away due to the "Nashville backline" where control and tone are important in live performances. Now one needs a great cab that may be out of sight. I want to just take a second here to say that my two favorite cabinets in the universe are the Dr. Z Z-Best and THD 2x12 cabs.

This amp is very versitle in the "sound" area and covers more bases due to it's tube swappage ability than most any other amp. Many folks think that you can switch 6L6 to EL34 in other amps with a rebias. Well, sort of yes and no. Technically yes, but the amp's output transformer was generally optimized for a specific tube and these two tubes are different. So how can this be done by THD? They have their own design transformers and these are quite different than convention iron. When you move a convention speaker tap from the 4-8-16 ohm positions, you are using a smaller portion of the transformer and the winding setup is not the same. THD transformers use the full core at any setting. Perhaps this should be mentioned as a "feature" but it does affect the sound.

THD also makes transformers that you can buy for your non THD amp. They also make something called the reactive rectifier which is a very cool piece of gear that many folks do not know about. Their Hot Plate and Yellow Jackets are already well known.

If you do want over the top metal sounds just grab an Extreme III pedal and have at it. The amp is very pedal friendly.

I expect this amp to give the same reliability as my Univalve. My UV goes to many gigs, concerts, and studio sessions. The UV has been used from day one many times per week, has been flown over most of this planet, used as a stand alone amp and as a preamp. It has injested more "suspect" tubes as a test device without propblems. It has never had a single problem - EVER.

If there are folks thinking that only a PTP amp can be reliable think about a Navy F-18 pilot crashing onto a carrier flight deck every day. These pilots are surrounded with PCBs that are lighter surface mount technology with micro etch work. Basically, a well built amp is a well built amp and a badly executed PTP amp or PCB amp is going to be a nightmare.

THD support is legendary. Ed at THD is also a killer player and is more than happy to offer his advice on just about anything even if it is not a THD product. Ed is also pretty terrific on recording techniques and live rigs. Andy Marshall is a super fellow too and seems to surround himself with great folks from the receptionist outward in their staff.

I have been playing since I was eight. I am now 55. On my other gear it is basically Fender, Marshall, GT, THD, Victoria, Mesa, Dr. Z, and more. A lot of this is on my business website at Guitar Amplifier Blueprinting. When I am not at GAB I am at GT (Groove Tubes) where I run the SAG (special applications group). I see a lot of amps cross my path, maybe a bit more than the average fellow out there.

For a 1 channel head, this amp is loaded with features:
-Boost with its own gain level and tone control (on footswitch too)
-Defeatable master Volume (on footswitch too)
-High and Low gain inputs, which can be assigned to the boost switch so that boost on activates high gain input, boost off turns it off.
-Accepts most power tubes, so mixing a 6L6 with an El34 can be done to finally get that wider range response with the screaming more compressed mids of the El34.
-Accepts a bunch of preamp tubes for changing the gain structure.
-Full boat of tone shaping controls
-Effects loop
-INCLUDES footswitch
-Well vented design, does not need fan, and is easy to carry.
-Huge transformers for getting those harmonic tones out of your guitar.

If you can't sound good through this, then you really, really need to figure out which side of the guitar those strings go on. This amp has the best slight overdrive sound of ANY amp out there, and I mean any of them. Bad Cats through Bogners, none of them get this rich sound that works with your pick attack and vomue control. But crank up the gain and turn the volume up/master down a bit, and you have heavy Marshallesque crunch with so a huge wall of sound around it. Tremendous amp, the best thing to come out of THD yet.

Don't know yet ... built like a little Sherman Tank. Big trannies in this one ... but two side handles make it sturdy and easy to carry.

NA

Been playing for 30 years, made very good bucks playing and teaching, and tried every freakin amp that exists at least once, and owned a bunch of them to boot. This is a tone monster ... it beats the living snot out of those expensive Plexi clones from Fargen, Reeves and Mojave .... it is really Andy Marshall's greatest achievement. It drips tone ... and the price is SOOOOO reasonable on these. Get one before it wins a Guitar Player award and the price doubles! If you don't believe me, check out the price jump on the Budda Superdrive II 80 watters!

THD Flexi 50 #0210. hand built in seattle. it has a hi/lo input switch, volume, treble, middle, bass, a bright switch, a footswitchable boost circuit (NOT a second channel) w/ gain and tone controls, a master volume also defeatable via footswitch or the switch on the front panel, a cut knob (which is NOT a presence control, it controls the overall brightness, but not the gain), the amp can be run at either 20 watts, or 50 watts, it has an impedance selector, a line out, an effects loop, an option to switch the hi input with the boost when it is engaged, AND if that is not enough, there are external bias points because you can use almost any kind of power tubes ( as well as many kinds of preamp tubes, which can be swapped without biasing). i never use the footswitch, because i always have the boost on, and control the breakup with a volume pedal. it is capable of wonderful cleans as well as ferocious overdrive.

i use humbucker equipped guitars and no effects pedals - only the aforementioned volume pedal. this amp is perfectly suited to my playing style, which is very dynamic. the amp is very touch sensitive, so i can go from soft and clean to a raging distortion very quickly and smoothly. it's been said that the flexi has Fender blackface cleans, Vox chime, and Marshall overdrive all in one amp. well, it does. sort of. the overall voicing is sort of a combination of all of those things. it's not like a modeling amp where you can switch from "marshall" to "vox"...or whatever...the option to use many different types of tubes makes the flexi very user tweakable. i personally prefer it with NOS GE 6550A's, and mullard 12ax7's.

the amp has never broken down, and i don't expect it to. the build quality is absolutely great. i've heard that thd uses FAA approved techs to do it's circuit boards, they have higher standards than the military...so i guess it's build like a plane, not a tank. i will only give it a nine, because i've only had it for five months, so i can't be POSITIVE it will never have problems....

ed @ thd is great. best customer service around.

i've been playing for twelve years. i'm not a big gear whore. once i find something that works, i stick to it. i had my previous amp (a HIWATT) for ten years before i decided i was ready for something new. after much research, i found out about the flexi and i knew it was the amp for me. if it were lost or stolen, i would replace it immediately!

My Flexi #102 was hand-crafted in '03 and, outside of my former '65 Fender blackface Twin, is the first tube-amp I've owned in nearly 40 years. After "experiencing" the tone-shaping opportunities of this one-channel amp, I'll never settle for solid-state again! I use no special effects, as the Flexi's boost/master pedal meets my needs for tonal & gain effects.

I play a modified '94 Les Paul ClassicPlus w/ '57 Classics, and tend to play classic rock/blues/tad-o'-jazz-type style. I admit to being a better rhythm than lead player, and this amp fits the bill! I always liked the "cleans" of the Fenders, but have been lured by the "crunch/overdrive" of the Marshalls, and the THD Flexi affords the best of both (IMO)!

My Gawd!...it's built like a tank, and I have experienced NO PROBLEMS in more than 6 months. From what others have shared, I think I can honestly expect total reliability.

I've conversed with a few folks at THD, and they are ALL TOP KNOTCH! Very responsive to my inquiries, and I forsee no problems.

10-In nearly 40 years of off-n-on playing, from '60's rock through country and jazz-fusion experimenting, I really think that this amp "covers them all!" I really can't find anything "wrong" with this amp. And complementing it with a fine Avatar G212H special cab has made this purchase all the more sweeter!

2004, #166. Plenty versatile with the switchable boost and master functions for my needs. To me, it seems to work as if you are playing a single channel amp and the boost functions like a really good overdrive pedal. It's not as complex to dial in as a two channel amp.

I'm using this with several guitars, a Les Paul, Tele, Strat and 335. I have yet to be able to get a bad tone from this amp. Definately a Marshally sounding amp, but not dead on. Mine seems a little sweeter than most Marshalls I have played, kind of like a Marshall with a touch of Dumble thrown in. I play classic rock and blues and am able to get all the tones I need straight into the amp. I have used a clean boost with it to equalize the volume difference between single coils and humbuckers. I also have found that I prefer a 12ax7 in the second preamp slot instead of the stock 12at7, this change made the amp a little more versatile for me. I wouldn't say this is an extremely loud amp. It is certainly loud enough for gigs, but I am using it with out an attenuator in the 50 watt setting and have had no complaints about excessive volume. Of course, if you turn everything up to ten, that may change.

I've had it for a month with no problems and I don't expect any. This company has a good repuation and for very good reason. I've owned a UniValve and still have a BiValve and have had no problems with any THD product

Again, this is one place that I can't see anyone having a problem with. Tone may be subjective, but these guys really care about their customers and go the extra mile to try and make them happy. Ed Degenaro has the patience of a saint

I've been playing for over 20 years and since I bought this amp, it is the first time in a while I've stopped looking for new gear. All my guitars sound better, so I would have to replace it if it were ever stolen. I was looking at Germino, Aiken and Demeter, but the features and price point on the Flexi won out. Plus, these amps are really small and easy to carry around.

Mine's an early model, probably early '04 with red lettering. It's my 3rd THD amp having gone through the Univalve > Bivalve > Flexi path and each one is better than the last (and they're all good). The Flexi suits me best as I can get huge clean sounds with master and boost off, but dirty them up with the boost/master combination, then get into serious overdrive with a pedal. Or of course put lower power tubes in and overdrive the amp more, and just use the footswitch and the guitar's volume control. Or anything in-between, and that's the key to this amp; as you can reconfigure the pre-amp and power stages totally you can turn it into absolutely anything you want! In 50w mode with 6550s it is *very* loud even when running crystal clean. With 6L6s pushed hard in 20w mode it is loud and beautifully dirty. The fx loop is great with some units, not so great with others - parallel would be better than series. It's only the fx loop that makes me give it 9 rather than 10 here.

I play in a rock covers band that gigs 1-2 times per week. I use mostly Les Pauls. The Flexi is great as a sonic canvas on which to "paint" all the different sounds I need with various fx pedals, and has plenty of headroom for all the venues I play. I also occasionally play in blues outfits and it's equally good for that without any fx pedals, given the right tube choices - anyone who doesn't like this amp just hasn't put the right tubes in to suit them.

I've never had a problem with a THD amp. Built to last.

Whenever I've needed missing parts or whatever they've sent them without hesitation. They are an outstanding company for customer support and advice.

I've been playing since the early 70s and have owned pretty much everything, and the Flexi is the best to date. If it were stolen I'd buy another like a shot. Because of the ability to reconfigure it and alter its sound there's really nothing to equal it - it's as good as you make it. The only thing I really wish it had is a parallel fx loop.

This is a brand spankin? new Flxi-50. I assume it was built in ?04, as they do sell well, from what I understand.

I have, by virtue and many thousand dollars worth of trial and error, and serious leaps of faith of buying amps based on reviews, or word of mouth that one amp cannot be all things to all people. I have an original ?64 Fender Super Reverb, and a Dr. Z Maz 18 jr. I have gone through probably 10 amps before this is nearly 20 years of playing guitar; however NONE of them was a Marshall, or an amp with a Marshall vibe (go figure!).

I was pleased to find an effects loop, along with a lot of other features with this amp. Some of them are pretty subtle, but they really add to the ability to shape the tone, as well as, to a great extent compensate for different rooms when playing live.

This amp is LOUD, particularly when you play this without the master engaged (which I greatly prefer). Of course my Dr. Z, at 18 watts is damn loud too. How much volume do you need? I imagine that, for me, the Univalve would be plenty loud, and mic it if you have to!

The only thing that I really miss is a reverb. If you call Ed at THD he will tell you that they reason a reverb was not added was that they prefer reverb to be added in the mix, as opposed to at the amp. He also asserts that reverb is generally more beneficial to a clean tone than a dirty/distorted tone. I don?t know about this, as all but one of my previous amps had reverb and I use it nearly all the time ? except during recording, where I agree that you should record as dry as possible.

Beyond this, what more do you want?

Tone. After a week, my initial impression has been: WOW! This amp is fantastic. This amp just drips tone. It really has so many faces! The clean is, well, not too clean (which I generally dig?). This amp absolutely NAILS the semi-dirty Hendrixy tone that I grew up loving. This is, in my opinion, one of the most difficult sounds to get out of an amp. It is probably the best tone out of the Flexi.

The distortion is pretty thick. Not a hard core grind like a Mesa (duh! It is not a Fesa Boogie!), but sweet and singing. I am generally skeptical of any ?boost? mode in an amp or pedal, as they generally disappoint, however this one is fantastic. The separate tone control for the boost really makes this a 2 channel amp ? but it isn?t, get it? Me either, but suffice it to say that the boost gives you all of the distortion you will need unless you are a shredder, in which case you would (should?) never consider this amp in the first place. (If you ARE a shredder, stop reading here and nav to the Boss Metal Zone reviews?). I have a Fulltone Fulldrive II as my overdrive pedal, and, in the past I have really liked it, however, it does not, in my opinion, mesh well with this amp. The Fulldrive sounds kind of ?transistory? with this amp, which is ironic, because I thought it was the most transparent overdrive pedal that I had heard. Good deal! More stuff to buy?

One other thing I have noticed about this amp is the unbelievable dynamics I get out of my pickups. Single coils, P-90?s, HB?s all are awesome. And all totally different. I thought this would be an HB amp (it is?), but I TOTALLY dig the single coils out of this amp as well. Really really nice, and not at all noisy. Then, there are the greatest pickups on the planet (P-90?s). STUNNING! Try a Guild Blues 90 with this amp for rhythm guitar, with boost off and mild distortion and you will cream!

The additional switches really allow you to shape the tone. The 50 watt/20 watt switch does alter the tone a lot! The 20 watt is nice, but smoother than the 50 watt. The 50 watt is ballsier, though, and more fun! The master volume is defeatable, and this is a FANTASTIC option ? one of the best of the amp. This amp (and most amps) behaves totally differently with a Master than without one. If you have never tried a NON- master volume amp, do yourself a favor and try one TODAY! The touch sensitivity is wonderful.

The other caveat about this amp is that it NEEDS to be turned up. This really is not (to my disappointment) a bedroom amp. It is like having a Ferrari (for $1500?). It HAS to be driven fast, and will never be satisfied going slow. I have a Hot Plate, and this does help, but it EATS the sensitivity of the amp. The tone is good, but the feel is lost. It is a sacrifice we have to make?.damn it!

I have no idea. It is new. But is weighs a TON! And looks cool!

I am really pissed at Harmony Central for only having a 1 ? 10 here. There are a few manufacturers that are unreal in their service, and THD really is one of them. When I was considering this amp I called THD, and talked to Ed DeGenarro. We chatted for nearly an hour about all sorts of things about their amps, the design decisions they had made, caveats about their products, and traffic in Seattle. All sorts of stuff! To think that you can call a company and have a receptionist (a human, non-computer, non-recorded receptionist) answer the phone, and transfer you to the guy that designs the stuff is ridiculous. You cannot ask for more. I have not had to deal with them when things have gone wrong, but, based on my conversation, I have no doubt that they stand behind their product 100% and truly want to help (what a novelty! Try calling Mike Fuller at Fulltone sometime! OUCH!).

The only other person that has support to this level that I have encountered is Mike Zaite (Dr. Z). If you call him, he will talk to you all day! To the point that you will actually have to get HIM off the phone! Go figure!

So far, this amp rocks! Of course it is the new kid on the block, and we are still in the honeymoon stage?but I think that this is a marriage that will last. This is not a 1 trick pony, appears to be rock solid, sounds fantastic, and is a BLAST to play. Seriously, what more could you want????

Well let me tell you! You can try different tubes,. Not just different EL-34?s but 6L6, KT-88 (these are really cool, BTW?.), 6550?s, 6V6. Nearly anythin you can think of! You can even MIX AND MATCH. An EL-34 and a 6L6 AT THE SAME TIME, for example. You can even bias the amp yourself ? in about 3 minutes! So if you are bored and feel the need to change your setup, you can pop a few tubes (pre and/or power) and see where it takes you rather than getting a totally new amp!

Talk about FLEXIble! This amp is cool! There is enough to keep you busy for years with this amp. Complex tone, great vibe, extensibility. Get one and feel the power!

I believe this amp was made in '04. I've had it for about 3 months now. Features-wise, it's not too bad, but has just the basic stuff. The tube-biasing feature is cool, but nothing all that special.

I've spent 3 months trying to dial in a sound I could love, but have not been able to succeed. I have an old 70's Les Paul and an '89 American Fender Strat, both which are fine guitars, but neither really seems to shine with this amp. I play mostly classic rock and bluesy oriented stuff and thought this amp could cover those grounds, but I've decided that this amp just doesn't have it. It's rather flat and two dimensional and kind of harsh on the highs. I went by the hype of what I read on the Internet and now I know how foolish I've been going by that. To me, it's a pretty flat-sounding amp, certainly not what I had in mind. I plan to ebay it pretty soon.

Didn't have any problems with it, but I baby all of my amps. Seems that it's a pretty reliable amp.

Haven't had to deal with the company as I haven't had any problems with it in the 3 months I've had it. Just doesn't have the tone as far as I'm concerned.

I been playing for 20 years and have owned various Marshalls, Fenders and Boogies. Thought that this could cover them alll but I was mistaken. Not a bad amp, but certainly didn't live up to the hype and the expectations. The master volume on this amp is useless. Doesn't work well at all. I live in Montana and bought this amp based on all the hype I read on the net. Guess that's what I get for living out here and just reading stuff on the net. Could never get this amp to sound warm and lively. It's just flat and not really happening compared to my Fender Deluxe and Marshall JCM2000 Dual Reverb. I'll be ebaying it pretty soon. After 3 months, I've done all I could to make it sound good and just couldn't do it. A disappointing experience but I know that I can't win 'em all.

This has been covered pretty well, but here goes: Basically a simple amp that has some neat features. Two channels, like on a Bivalve, but they are switchable, along with a switchable boost and master volume. This is handy, because you can switch the master volume on when you go to the boost channel and avoid having a huge jump in volume. Makes it like a two channel amp.

I am using it with a THD 2x12 cab and various guitars. I have yet to find a bad tone out of the amp and I found it very easy to dial in. The amp is quiet and does have a nice clean tone, not quite as lush as my Fender pro reverb, but definately very nice. Of course, the overdriven tones is flat out awesome. This amp likes to be turned up! Not an all out metal amp, this amp definately sounds more like a Vintage Marshall when cranked up. Great for classic rock sounds and heavy blues. If you like those classic Marshall tones, you owe it to yourself to check this amp out. If you are into Nu-Metal, look elsewhere.

Hasn't had any problems yet, but I haven't had it for very long. I have a lot of faith in THD products. Their amps are very well constructed.

THD has the best customer support I've ever seen. Ed Degenaro is easy to get a hold of and seems to be happy to help out customers.

This amp is the one for me. Finally an amp that gives me classic Marshall but also has a good clean tone when I need it. If it were stolen it would be replaced

Features: see the THD home page. I wanted to play with this amp a few months before I commented on it. It has an extraordinarily "flexible" set of features for delivering great vintage tones.

My main guitars are the basic food groups: Strat (Custom Shop '60 with Joe Barden PU's; LP (Historic '57 with Seymour Duncan Antiqity PAFs); and Tele (Muddy Waters Tribute Telecaster). When I bought the head, I thought I was buying a Plexi clone. To my ears, I bought the best Fender clean/overdrive amp I have ever heard. Back in the day (late '60s and early '70s), I had a mid-60s SuperReverb that I "dimed" to get the best tone I ever heard. This amp exceeds ny recollection and is controllable in volume.

"Built like a tank" is such a cliche. Let me say: I have owned THD amps for more than a decade without any problems.

It's been a while since I've spoken with Andy and/or Ed, but I think they are top flight and very accessible.

I've have been playing loud rock'nroll for a long time. I have owned a lot of amps. I wish there were a 4x12 cabinet to go with this head. (I have THD's 2x12, which sounds really good.)

Mine is #234. I have found this amp to be very versitile great full clean tone with gain for days. It is a one channel amp with Boost and Master volume on off switch. I use this as my main gigging amp. This amp has more then enough power to handle any live show situation. More details can be found at the THD web site or Univalve.net

I am using a Godin LGXT and Fender American Deluxe Fat Strat. The tone suits my style just right. I love the clean and gain and other tones in between I can dial in. This amp is very quite and has great headroom when used Clean up to 1:00 with no Master Volume. It then goes into a beautiful distortion and combined with the right twist of the knobs and on and off switches this amp will provide a fantastic lead tone which doesn't get mushy when strummed.

This Amp is a THD, like all there products first rate with great build and design. I would feel fine with out a back up.

First Rate all the way. Ed DeGenaro helped me get mine. I live in Utah where there are no dealers he helped get me this one to demo which I compared it to a Bogner Shiva and a Bad Cat Hot Cat. I ended up keeping the Flexi which I thought sounded as good and better for less money.

I have been playing for over 20 years and owned a THD BiValve, and a Mesa Boogie Rack, before I purchsed this fine amp. I was looking for a nice open clean tone and fantastic gain out of one amp under $2000.00. My gain needed to go from just to the edge of break up, to spongy, to tight lead tones with out a ton of tweaking. The Flexi does all this even with stock tubes. I haven't even thought of swapping tubes in this amp because it sound so good out of the box. As stated earlier I was comparing it to the Bad Cat Hot Cat and Bogner Shiva. I found this amp to be as equal or more in all catagories. The Hot Cat seemed to have a more full sounding Clean tone and can switch from Clean to Gain using a ABY switch which I liked over the Flexi however was $650.00 more. The Bogner Shiva was a true two channel amp which also sounded great but I found the Flexi tone more to my liking both in clean and gain. I also demoed a Mesa Boogie Lonestar and the all three blew that thing away. I don't know what is going on with the people who have been slamming this fine amp. I just ignored there reviews and tried one my self. Now I am a happy owner.

Go the THD.com and you will learn all you need to know.
I have serial #25.

I mainly use G&L's ASAT Classic Hollowbody,ASAT,and a Strat w G&L S500 pickups. I have played Don Grosh and Baker Guitars through it and they sounded fantastic.
The amp is quiet and pristine, you can control it very well with your guitar. Nice clean sound then attack the strings and it really starts to sing. I have played about every amp known to man,Bogner,Marshall,Fender and others. When I heard the Flexi50 at the NAMM I knew it was the Amp that had everything I could want.

Solid as a rock. No problems ever...WHo needs a backup.

I have contacted the company. They got back to me the same day, and answered my question and more.

I have been playing for 20+ years and have owned boatloads of guitars, amps, and gear. But the Flexi50 is one of the best things I ever got. If this amp was stolen I would replace it yesterday.

This is a semi "retraction" since I gave it a 2 rating in sound a while back.

I must've had a flop. I went to indoorstorm.com and listened to the sound files. The one i had and returned sounded NOTHING like the sound clips. I'm wondering if the tubes or some other part was defective. The tone I had was farty, hard, cold, and not dynamic what-so-ever. Fellow reviewers, go to those sound clips and tell me if thats the sound you get. I might reconsider my purchase then.

Won't list all the features; they're clearly covered elsewhere below. One feature that does distinguish this product is clearly the ability to use virtually every tube type to signficantly alter the amp's responsiveness and tonal characteristics. Since this has not been stressed in prior reviews will focus more on that below. Only comment here will be to say that this actually does make the Flexi more versatile than most of the reviews would suggest. It makes a world of difference and experimentation is heartily recommended. More below

Have been playing pro and now pro-am for over 25 yrs and have owned at one point or another virtually every type of amp and axe. Current axes used with this are HB and single coils: a Gibson 59 LP RI with PAFs, a vintage 57 LP Special with P-90's and an early Fender 'Cunetto' 50's Nocaster RI.
Was a dedicated Marshall user until I heard the THD Flexi sound samples and sold my [much loved] TSL 100 to buy one. The Guitarist Mag review said I 'wouldn't look back" - and I haven't. This IS the sound I've loved - and heard in my head - for the past 25 years . I play blues, rock and jazz and the Flexi shines in all three - at least for me. FWIW, for blues/rock, my personal fav are the vintage Marshall sounds of Rory Gallagher, SRV, early Clapton and Hendrix. Short of a time machine, this is about as close as one can get.
As mentioned above, tube change can make a world of difference. 'Out of the box' with the tubes it came with my Flexi sounded very good , but a bit too bright and not quite as rich , expansive or 3 dimensional as I'd hoped for - especially at less than high volume (esp with no hotplate. But a simple swap of the pre-amp tubes it came with to some vintage ones just opened up the tonal range, eq, responsiveness and soundstage opened thing up beyond belief.[Vintage 12ax7s and a 6201]. A change of its shipped with output tubes did even more to make this tone heaven - especially for nailing vintage tone and grind. Using a Mullard EL34 and GEC KT 66 combo I can summon up either vintage Plexi or JTM 45 Bluesbreaker on demand. Switching to straight EL34's gives me the pure later vintage Marshall sound. Cleaned up the amp is as good as it gets for jazz; boosted and driven, it is pure blues and rock heaven.
Bottom line: I've never played an amp that was this responsive or gave me this much tonal control & flexibility (using its T,M,B eq control, its boost & boost tone controls, trebel boost, hi/lo inputs, Master vol/defeat and 50/25 watt settings). If you love - and would love to nail - the sounds of the players named above, then this is your time machine and amp. I feel certain that this is the last amp I will ever buy.
Don't use pedals, don't need to - though this amp seems to really love them [tried a Fulltone Full Drive 2 and never head it sound sooo good. - but do use an EH Holy Grail through the effects loop and both I and the Flexi love it.
Bottom line: Whatever your personal 'sound' is - short of death metal - with a little experimentation and perhaps a few tube swaps, you ought to be able to nail like nothing else you've tried before.

Don't know of ANY amp built more robustly so hard to imagine anything going wrong.

Hope I don't lose credibility with all these 10's - am really trying to be as objective as I can, but unless you've dealt with THD, you've never really experienced 'customer service'.

As noted above been playing pro and now pro-am for over 25 yrs . Have owned at one point or another virtually every type of amp and axe. Current axes used are HB and single coils: a Gibson 59 LP RI with PAFs, a vintage 57 LP Special with P-90's and an early Fender 'Cunetto' 50's Nocaster RI.
If lost or stolen would do whatever I could to get another one. It totally nails THE sound of blues, R&R [and jazz] for _me_ so I wouldn't even bother to look elsewhere. If I had Paul Allen's $$$, I'd still play a Flexi.

n/a

As a follow-up to my previous review. Swapping the stock pre-amp tubes out for some NOS Mullards really warmed this amp up. I'm playing it with a JTM-45 using split signal and it definitely has its' own vintage sound. Much tighter, focused and less creamy. The combination of the two make a great sound and I'm often find myself checking to see if I've got delay on or not because of all the natural phase-shifting between the two. Really a 60's-70's psychedelic sound...

I agree with the reviewer below about the fickleness of the effect loop after running my Foxrox TZF flanger thru-it. On the other hand, it loves EH's Holy Grail. Curiously, using the TZF on front-end and feeding the split-signal to my JTM yielded great Hendrix jet-planes.

Still wish this amp had two inputs with independent gain controls like my JTM. Just makes things a bit more flexiable.

I tried this out in the store, kind of a cool amp with the tube swapping features, but not my type of tone.

The amp, to me, just sounded too vintage, which isn't a bad thing. For the money that these things go for, I would hope for more variety, but I guess the tube swapping feature is a cool thing to nail a specific tone. I also tried it with different pedals up front, some sounded good

Ok, I've been playing for a long, LONG time now. Both professionally and as a hobby (currently). I've owned WHAT I THOUGHT were some of the best and worst amps out there. This review site on this amp is becoming a juvenille joke !! Who cares if the amp is being judged out side of its intended use..if you like something or don't...that's just it, nothing else..its a matter of personal taste. That's such a moronic statement to say that a person doesn't know what he's talking about because it was used / reviewed out of its "element"!! That's like saying that $hit doesn't stink if its smelled in its proper context !! If someone doesn't like the amp, why say, "oh, what did you expect, its a vintage amp, its not supposed to do this or that, what are you dumb?". I tried this amp after reading all the hype and how people are so enamoured with it thinking it must be the end all be all of amps. I don't think it does the vintage vibe all that well, having played a friends Marshall Plexi for some time now and other assorted vintage amps (Vox, Fender, etc.). I agree that its not a "warm" sounding amp....but then again, it wasn't fully broken in so maybe thats why it was a bit stiff.

Cmon people, read your words carefully and stop trying to justify things by saying something was not used in its proper context. Reviews are that...REVIEWS. If you like it great, if not cool. Stop with the attacks, justifications, personal issues, or what EVER !! Let it go already and stop taking it personally. Now go home and hug your THD's, tell it that all is ok, and that you'll see to it that no harm comes to it ;-)

I don?t want to get into a war of words over this amp because this is not the forum for such discussions. However, I feel compelled to make a few points about the previous two poor reviews for the amp.

1). Not that I advocate anybody calling something else an ?idiot? based on their opinions but the first reviewer to give the amp a bad review does say some pretty weird things. First he criticises the amp for sounding like a vintage Marshall ? did he not read the blurb? I mean it?s pretty obvious that the amp is aiming for those kind of tones (albeit an individual THD take on them).

2). Then he criticises the lack of a hotplate. When did THD say that this amp came with a Hotplate? There?s no conspiracy theory ? if you need a hotplate either buy one separately or buy a Uni or Bivalve. More to the point, why did it not occur to you during slapping $1400 on the counter that the lack of a built-in hotplate would compromise your enjoyment of the amp?

3). Then the guy says that he thinks the Fuchs Overdrive Special smokes the Flexi-50! I expect if you are after the Dumble/Fuchs tone then it probably does smoke the Flexi-50 but then why the hell are you buying a Flexi anyway?!

4). Finally he says ?Don?t get me wrong, if you like classic Marshall sounds, then this is the amp for you?. So what are we concluding here? That the Flexi-50 is very good at what it claims to do? In which case, why bother giving it a low score based on your misinformation? All it achieves is the misleading of others.

5). As for the reviewer below complaining about H-C vetting and then proceeding to do everything he complains about ? seems like a bit of a waste of time to me. Then saying that because the amp cost a certain amount it should have more than one channel doesn?t really add up, particularly looking at the competition. Perhaps if he had persevered longer he would have found the Flexi as useful as I do ? using the boost and master functions turns it into the most useful three channel amp I?ve ever used.

6). As a final point, I hope he enjoys his Hot Cat ? I tried one and thought it was Bad Cats worst offering (and I would take a Matchless over a Bad Cat) so there you go, each to his own!

The key point is that both the poor reviews are slating the Flexi-50 because it doesn?t do things that it never promised to. Bottom line, if you do your research and, most importantly, try out the thing and know what you are buying, I fail to see how you can be disappointed. I agree that people are going to have different views on amps which is fine. But if you are going to slate an amp at least be informed and be descriptive about what you didn?t like ? you owe it to the manufacturer (particularly those who are affected by internet reputation) to be responsible in you reviewing.

To get back on topic for a second, the amp has all the features I would personally need or want...I guess that's all I can judge it on.

I'm using the amp with a 52 reissue Tele loaded with Fralins and an Ernie Ball Musicman Silhouette Special. There's a switch at the back of the amp that allows you to go from 'lo-input' for the un-boosted channel to hi-input for the boost channel. This is how I am running it at the moment. Therefore I can go from pseudo-Fender tone on channel 1 (softer attack, warmer) to the myriad of tones channel 2 offers which are in a JMP vein but with far more versatility.

The boost mode is to my mind quite different to the unboosted tone. To view it just as a boost doesn't do it justice. It obviously has a lot more gain, but it also has more bass and treble with a harder attack making it more percussive than with the boost not engaged.

I find it cleans up extremely well using the guitars volume ? better than any other amp I?ve played or owned. Not just from vaguely clean to crunch either. The guitars volume can take this channel from absolute clean to crunch to scream without any dip in volume or treble or bass.

The Flexi is very clear sounding and will expose your weaknesses but will also force you to be a better player. I'm selling my Cornford which has been redundant since getting the Flexi. I plugged into the Cornford to give it one last play before packaging it up and my playing sounded better than it ever has before. The fact that the Flexi has been pushing me to play that much better has meant that when I plugged into a less 'articulate' amp, my technique sounded great...bit of a catch 22 situation!!

Just to give this review some balance I have found that the Flexi can be picky about which pedals it likes. My Keeley SD-1 (modded to be more like a Tubescreamer) sounded awful. Also, although I don?t tend to use an effects loop, my brief experimentations with the loop on the Flexi have not been that successful resulting in a dip in volume (although I?m assured by other users that experimentation is the key). Finally, if you are thinking of getting a Flexi-50 you should factor in the cost of a THD cabinet. I was running mine through a 2x12 V30 cab which sounded great until I got the THD cab ? enough said!

I would gig without backup. The amp seems fullproof. I feel more confident with THD's PCB design than many high-end manufacturers PTP amps.

They seem very nice and helpful. I bought one of the first Flexi-50s in the UK after Andy Marshall himself demoed the amp at the Music Live show in Birmingham, UK. He was a really good bloke and took the time to answer my questions. Also, Ed DeGenaro frequents some of the discussion boards on the net and always seems open and friendly.

I think it is a great amp. If it were lost or stolen I would definately by another with the insurance. There's nothing I hate about it. I guess reverb would have been cool but I definately don't miss it due to the 3-D tone of the amp.

I considered other amps such as the Bogner Shiva and the various Marshall clones (Blockhead, Cornell, Germino etc). Living in the UK these other options would have cost a lot more and given me less flexibility apart from maybe the Shiva which I found too compressed sounding. Also, I like giving my custom to companies that take chances, try to push boundaries and stand out from the crowd. I think THD and there amps do this above all the others I was looking at.

Just purchased one, kept it for about a month and traded it in for a Hot Cat 15. I don't think its worth the price of admission.

Here's why I sold it...no feel or a character of its own. It reminds me of an old vintage Marshall, but without the warmth. I have to agree with "anonoymous" who gave it a 2. I won't go that low, possibley a 4 since its does the old school sound well. I also think its uncalled for when a person, lets call him P-Rick, calls a reviewer and "idiot" just because he didn't like an amplifier that is considering getting. Harmony Central should better police these issues. It becomes a "my toy is better than your toy" battleground...or should I say Playground. C'mon kids, lets grow up and agree to disagree.

Built like a tank. I wouldn't expect any issues.

Don't know, didn't keep the amp long enough to use them.

Again, I think for the money spent I should be getting more amp for my money. Cmon, no channel switching? My Hot Cat allows "psuedo" switching via an A/B switch, killer overdrive, crystal cleans, and all with bounce, feel, and vibe. This amp is very sterile.

Brand new amp with a really simple circuit from what I understand. The features are as described below and the Flexi was purchased to replace my Marshall 2554 Silver Jubilee, which was just to noisey for my music style of Jimmy Page meets Billy Corgan. I had my amp repair friend, who I obtained the unit from, replace the stock EL-34's with EH KT-88's for me. My other amps are a JTM-45 with KT-88's, THD Univalve with a KT-88 and a Marshall DSL 201. Amp is very versatile for my needs, although I'd really be happy if it had separate inputs/gain controls like my JTM-45. The 20-50 watt power switch is really handy for playing in a San Francisco Victorian and being kind to my neighbors.

I've finally found the sound I was looking for, especially the natural vibrato in it's timbre! Makes me think of Big Brother one minute, Jimmy Page the next and Jimi Hendrix the next. The guitars I'm playing it with are a Heritage CM-150 with stock Schallers and a 1974 Strat with humbuckers in all positions. Both guitars are wired for series/parallel and phase-reversal and I usually split my signal to feed two amps. I also play exclusively in a dropped-D tuning and this amp has no problem dealing with my low-d string and is really sensitive to my various pick-up settings.

I've played this amp thru a basic Marshall 1960A cab, a THD 2x12 with Longhorn and Vintage drivers, a VHT 2x12 and a Marshall 4x10 cab. I've settled on the Marshall 4x10 for the moment because the punch I get out of combination, although the 1960A had really tight bass and I can see driving both cabs with this amp at somepoint. The THD cab sounded a bit too brittle to me and seems much happier with the JTM-45.

This amp really shows off the differences in all of those settings and its' distortion ranges from a hint to major crunch with incredible clarity and pick response. It really likes to be opened up, but sounds great thru a hot plate. I get all the distortion I need by feeding my split signal to it with the Marshall 4x10 and JTM-45 driving the THD and VHT cabs. If I need really major metal distortion, I'm thinking I could drive very nicely with my Univalve for a bit of maxed-out KT-88 crunch.

I plugged an EH Holy Grail into the effect loop and was surprised at how much my volume dropped. On the other hand, the Holy Grail has never sounded so quiet or clear.

The unit is built like a tank, although initially the gain-switch didn't work (see below). Fortunately, from what I understand, THD amps are almost never seen in amp repair shops and my Univalve hasn't had any problems in 2-years.

I called Ed about the faulty gain-switch after first receving the unit. He thought it was a shorting pin on the foot-switch input jack not contacting correctly and advised I could take it back to the amp-repair friend who I obtained it thru for a quick fix. I was glad that I was able to get a local repair rather then send it back to THD. Unfortunately, they didn't offer to pay my amp-repair friend for the quick fix so I need to drop them down a few points here.

I've been playing off and on for about 30 years. I started playing in earnest a few years ago and have been finding my tone. This amp is definitely a great addition to my amps and finally rounds out my sound. I don't think I need any other amps, although I'd seriously consider purchasing a THD "plexi" amp if they ever offer one again. I'd replace it with any second thoughts if lost or stolen.

This amp is based off a vitage circuit READ: simplicity, with a modern twist.

(foot)switchable master, (foot)switchable boost with separate tone control, switchable lo/hi input, 20w/50w switch, can use any octal pinned power tube and any 12??? preamp tube. Bright switch, 3 band eq plus "cut" knob.

PROS: switchable boost, 20w/50w switch, biasing this amp seriously takes about 10 seconds.
CONS: well, it's based on a Plexi, so you wouldn't expect alot of features, you would expect TONE, so that is why I am not going to give a low score in this category. Modern channel switching amps compared to the Flexi are like apples and oranges....

I have played guitar for ~20 years, and play a little of everything from blues /classic rock/metal to acoustic bluegrass, classical and jazz.
My guitars are Les Pauls with SD '59s, and PAFs, Strats and modern "shred" guitars w/ high output buckers.

I played this through Marshall cabs with Celestion Vintage 30s, as well as various 2x12 cabs...

The gain characteristics of this amp are vintage (of course) and there is certainly no diode clipping going on in this amp :-)

This is not a bedroom or apartment amp. The gain is a little weak at bedroom volumes w/ or w/o an attenuator. Also at low volumes w/o the master, the amp tends to be a tad bright. The tone controls were definitely effective in taming the treble, so no problem.

It is once you open this amp up volume wise that the Flexi begins to really sing. It loses its bright edge and sounds vintage "Marshall like" all the way. I have played it both with the master volume on, as well as master off, and master off through a Weber Mass attenuator, and they all compare pretty darn closely! Very smooth vintage valve tone, I was going to say "creamy balls" but eeew that could be taken the wrong way ;-)

One characteristic I noticed is there is a sort of THD signature mid frequency present in all of their amps including the Flexi...you also hear it in the Univalve and Bivalve. It is different sounding than anything I have heard, and it is the thing that differentiates this amp from being a Marshall clone. READ: This doesn't sound exactly like a Marshall, it sounds like a THD Flexi-50!

The gain structure changes (as stated in THD's literature) with the type of axe, pickup and cab. To really do metal, I need high output pickups and an overdrive pedal, but this is a VINTAGE sounding amp, not a HIGH GAIN amp (JMP or DSL), so even if you boost your signal it will be smooooth and buttery like Jimi playing a Plexi.

The guitar cleans up into overdriven clean Fender territory with hi input and the guitar volume rolled back, and very clean Fender on the lo input ....a very nice clean sound.

So just like the previous reviewer said, it just was not for me with my playing style. This amp does sound awesome, but for my playing only a MArshall super lead or JMP will do the trick!

However for the tones it is supposed to do , a won't give it a 2, because hey it is not meant to do hi gain, and it is a great sounding amp!

THD is well known for the "industrial strength" of their products. Much of there manufaturing is done by professionals in the aircraft industry, so I doubt there will be problems here.

There packaging is kind of flimsy however....

Just check out univalve.net. Ed DeGenaro is always on this board helping out people with any issues, settings etc. A very friendly guy.

For the price point, this is a great amp and you can't go wrong.

Go to THDelectronics.com for the features.

Ugh, I was hoping to like this amp. I didn't like it what-so-ever. I like an amp that can go from a spanky clean to an all out thrasher and anywhere in between. This amp is more of a vintage sounding Marshall, very crunchy and loose. Sure you could throw a pedal up front for more gain as people say, but then what's the use of the amp then? I want an amp that can suit all my desires - from jazzy clean, to silky blues, to crisp rock, to chunking metal. I have varied interests and I want an amp that can cover lots of ground. This amp is cool that you can swap tubes, but I think that's a neat feature. I beleive an amps quality is in its preamp. The nice thing about the UNI and Bivalves were the ability to overdrive the power amp via the built in hot plate. This amp doesn't have than option and the preamp gain is weak on its own. Sorry, I didn't care for it. I have a FUCH's overdrive supreme that I just got and it really smokes this amp...but it was over $1000 more so it should! Don't get me wrong, if you like classic Marshall sounds, then its the amp for you. Throw in the tube changing option and you have a winner. Just wasn't for me.

THD's are built like tanks. I had a Univalve, I know.

I spoke with Andy Marshall and Ed Genero numerous times when I had my Univalve. THD shines in customer support in my book.

Its a cool amp, but I think its over shadowed by numerous amps out there. For $1000, the Rocktron Vendetta smokes this amp in tone and versatility. Its basically the same as the Egnater TOL (Bruce Egnater designed the Vendetta). I also think lots of Mesa's and Marshall's sound better than this amp.