THD Flexi 50 Head

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.