THD Bi-Valve Head

Just as described below. My only real gripe is having to use a reverb pedal when playing at home. My Princeton has spoilt me. The single channel is no problem for me, as it's pretty easy to manipulate the overdrive level with the guitar volume. I play mostly Blues with some Jazz and Rock here and there and the BiValve gives me exactly what I want. Now, you do have to spend some time figuring out what tubes sound the best in what combinations, but that's all part of the fun. I'm a constant tweaker of tone, so I never settle on one setup and it just seems to get better.

I play a Lonestar Strat in open G for slide, a new American Deluxe QMT SSH, and a '72 Telecaster. All sound very good through the BV, but the Tele is a little weak in comparison to the Strats in most every way. The singles and Humbuckers sound equally good on the Strats, and the new S1 switching is even more useful with the BV than any other amp I've got. Giving really smooth and full tones that sound nothing like a normal Fender. My Deville and JCM900 don't seem to fair as well with the S1 options. The clean tones are rich and smooth, and the overdrive can be anywhere from a very slight creamy breakup on chords to full blown saturation that's way too much for me. However, it's all very dependant upon the tube selection and amp settings. There are several ways to alter the tone, but it's not hard at all to find great sounds in the BiValve. I'm giving it a 10 since it nearly equals my '68 Princeton Reverb (which is one, if not the, best sounding amp I've ever heard) in clean tones, and blows it away in the distortion and versatility catagories. It really does sound awesome!

Haven't had it too long, but it seems to be built like a tank. Spare tubes and fuses are always a good idea at a gig though.

Never dealt with THD, but I bought mine online from Steve's Music up in NY. Wonderful customer service from Steve, and a truely outstanding price!

I'm a full time musician and guitar instructor with about 10 years experience. I currently have a mod'ed Hot Rod Deville, a 100w JCM900 w/1960a cab with two Vintage 30's and two G12T75's, and my beloved '68 Princeton Reverb which I play through the Marshall cab most of the time. The BiValve covers all that ground with superior tone and much more flexablilty. If I need to play a big outdoor gig, I've got the Marshall. For everything else the BiValve does a better job than any amp I've played through.

The bottom line is that the BiValve is truely a superior tone machine that allows you to sculpt your own personal sound with relative ease. It's also an INCREDIBLE deal and just super fun to play with!

The BiValve has some very nice features such as a built in hotplate, a hi/lo voltage switch an efx loop and and a variable line out. It also has the ability to change tube types on the fly with no rebiasing. Since it is only a single channel amp, it does have some limitations for live use. For this reason I give it an 8.

I am currently using the BiValve to drive a Bogner 4x12 cabinet. My main guitar is a PRS McCarty. Tubes are 2 EL34 with 2 12ax7's. Because I have been primarily a Marshall player my whole life, I am in love with the 70's classic rock sound(tone). The BiValve can nail those sounds perfectly. Whats better, it can get them at a much lower volume thanks to the built in hot plate and Hi/Lo voltage switch. It also has the ability to get some fairly high gain sounds. Not metal,but more of a hot rodded plexi sound. My favorite setting for the amp is the "More" channel on Lo-V with the hot plate engaged. I dial it in for a good crunch tone and then use a FullDrive 2 for my leads. It sounds killer.
Even though the BiValve is single channel it is not a one trick pony amp. Using the "less" input, you can dial in some great clean tones. Actually the more I use the BiValve the more I discover its versatility. It is a very fun amp to play.

So far no issues. The amp is built extremely well. Of course being a tube amp you always want to bring spare tubes to a gig.

I have not had a need to contact THD.

Overall I give the BiValve a big thumbs up. For home and studio use it is very versatile. The tone is awesome for both clean and distorted sounds. For live use it has some limitations if you need to switch between a clean sound and distorted sound on the fly. It can do both very well but it requires some knob tweeking. I will say this, the 30 watts is plenty loud so dont worry about it being under powered. Also, I think they are a great value in the used amp market.

Pretty versatile amp for studio use. Live it is more of a one tone at a time type of deal, since the two inputs differ drastically in volume. The features are simple, but very useful. Definately much more flexible than the Univalve. You can use one tube in this amp and it sounds about 85-90% like a UniValve which is great for quieter recording, yet pop in two El34s and you are gig ready. I do wish you could switch between cleaner and dirty tones on the fly, other than that there is nothing I'd really add to this amp.

Great sounds are available in abundance with this amp. I do find that it can be sensitive to what guitar you use as well as speakers. To me, the preamp tubes make more of a tonal difference than the power tubes. Certain guitars seem to like certain tubes and settings, while other guitars may not, so I would say this is not a plug and play amp even though it is a simple layout. Some people may get great tones right off the bat, others may need to tweak a while, but they are in there. Great for blues, country, rock and hard-rock, maybe even lighter metal. Not a ton of clean headroom, I find it breaks up just a hair when set clean for gigs, but this also depends on your speaker setup. I had a Univalve for about a year and loved it, but sold it and bought the BiValve to get a more gig friendly amp. If you can afford the step up, the BiValve is a better amp to get, since it is so much more flexible than the UniValve.

Never had a problem. THD amps are built like tanks so I have gigged without a backup. Even when I use other amps, this is in the car as a backup, since I am confident it will always deliver.

Best customer support I have ever seen, bar none. Ed Degenaro is around on many internet forums, answers lots of questions and seems to have the patience of a saint.

I've been playing over twenty years. I got this amp mainly to use in home recording, but I wanted more power than the UniValve if I ever needed it. I don't know if I would replace it, since I also have a Flexi-50, but I would be very upset if it were stolen. It doesn't do everything, but what it does do is enough for me. If you want a solid, reliable great sounding amp without a lot of bells and whistles, check one of these out.

Has every feature I could think of ...exept the possibility to switch between "more" or "less" channels and effect-loop on the fly.

I use this amp as a practice amp. Play mostly `60. `70 and `80 rock and hard rock. This amp sounds right for me and it is just powerful enough so that you can play it wide open most of the time to get the pushed, saturated sound. Pure Tone !

Les Paul Custom with stock pickups works best for me. This amp is never noisy, it just sound better the more you crank it !

The amp can do many sounds from early saturated buttery thick sounds (6V6) to more chunky crunch (E34L, EL34) to less power distorted more headroomish (6550, 6L6).

It also has a complexity and warmth to its sound rarely seen.

I have never made a 4X12 cab scream with this amp (a scream for help, maybe.) A more suitable combination is a 2X12" or 1X12" G12H 30W or alnicos will work fine !

The clean channel can go muddy on high volumes depending on the power-tubes, but it always sound great.

You will not have a tight bottom end at higher volumes as the bottom end always is a difficult load for the amp that demands wattage.

I believe most people will discover many enjoyable sounds in this amp.

Never had any trouble.

Don`t know

Been playing for 12 years. If it were stolen I would consider a flexi 50 because of the additional power, nothing else. If the flexi 50 were down on tone or general sound quality, I would still go with the Bivalve.
There is just something I love about this amp, probably its ability to add something of a feeling or state which helps get across your musical message and feel.

This tube amp is Class A, single channel, and very versatile. It's self biasing, so you can use a wide array of power tubes without having to make your amp tech rich. The other reviewers cover the "features" of this amp pretty well, so I won't waste your time. I will say it's got some very useful extras (effects loop, line out) that don't rob your tone. The built-in Hotplate attenuator works well when used lightly. If you attenuate too much, you lose tone. Like all tube amps, this one sounds best pushed. This amp is listed as 30 watts (varies according to tubes used), but don't let that fool you. This amp can make a 4X12 scream.

My main guitar is a Wolfgang, but I play a bunch of different guitars through this amp and they all sound good. It really brings out the character of each guitar. This amp can do anything from Jazz to heavy Rock depending on the tubes and guitar you choose. It has a huge amount of gain, but I wouldn't use it for 7-string or baritone nu-metal.
I think the single most important thing you can do when you first get this amp is start with a lower gain pre-amp tube in the driver position (I really like a JAN GE 5751. Mullard 12AT7 is good too). After you play a bunch of different tubes through this amp, you really get to know the flavor of each tube and how to mix and match specific tubes for any sound you're looking for. Even though Vintage tubes do tend to sound a little better (and last longer), this amp still sounds great with modern production tubes. I love this amp in the studio. Why settle for one of those "modeling amps", when you can have the REAL thing?!

All THD products are extremely well built. I've had my THD Hotplate for years and never had any problems. I expect to get the same performance from my BiValve.

Never dealt with them, but after doing a lot of digging on the web, I haven't heard any complaints. You can't say that about most companies.

I've been playing for 25 years and used/owned a lot of gear. My main rig is a Soldano Decatone. I've been salvaging Vintage tubes for years, so the self biasing feature of the BiValve is what first drew my attention. I liked the idea of putting all my mismatched tubes to use. After hearing the wide range of tones this amp will produce (with vintage OR modern tubes), I realized you don't have to be a tube monger to love this amp.
I do wish this amp could be switched between the "less" and "more" input. That would make it a little more versatile for live use. If you want REAL tube tone in lots of different flavors, this is your amp.

Enough said. Great stand alone amp or using as a preamp for other amps. Basic and versatile. Not too complicated but you can make it work for a ton of different needs that come up. My favorite feature is the fact you can go from 30W to 15W by pulling an output tube. The hotplate is useful but I never use it b/c my ears hear a difference when it is on. Channel switching would be nice but I would not likely use it with my current setup.
My tech knows more about tubes and the specifics than I, so when we are in some city, he stops and somehow finds great hard to find tubes. So we have a nice collection. I give him the ability to change at will. So we do a lot experimenting and we actually keep getting more specialized and better results as we go along which makes it exciting for he and I. That is a feature in other amps that would be a pain in the ass, but with these amps you just pop the top off and have at it. So for me it is a ten.

I play in a semi-national band, touring 3-5 days a week. We play anywhere from 100 person clubs in NYC to larger theatre-sized venues in our markets. Our style from what I am told falls between Our Lady Peace/Counting Crows/Catherine Wheel. This is simply one of the best amps I own. I use this in conjunction with the univalve (as a preamp/dummy load) using a GCX switcher to place the univalve in and out of line. An Axess Electronics BS2 splits the Univalve feed into the Bivalve and a Vox AC30. It is running a Mesa 4x12 w/ Vintage 30's. The great thing about the Bivalve is the ability to roll the volume off of your guitar and get very complex crunch/clean overtones. I am playing on Les Pauls and SGs w/Fralin pickups and it really adds something special to the overdone Marshall/Mesa thing. I run this amp slightly distorted allowing me to have a clean sound when I play soft and a crunch when I attack harder.

The amp sounds are complex and broad. It can sound like whatever amp you have played on, trust me. I get a overdriven Vox Top Boost sound out of it. Could be the tubes and the way I use it, but when I run the Univalve through it, is straight power amp distorion. Cuts through the mix and has very defined frequencies. It makes me play better b/c there is no moosh to hide behind. It is a very articulate sounding amp. I have done the Marshall/Mesa/Fender thing for years, but wanted a new direction for my band and my sound in particular. Well I am glad I found the Univalve 3 years ago, b/c it pointed me to this amp. For real touring musicians it is great b/c when we play smaller club dates I switch to 15W and when we play our theatre dates I can just crank it.

Reacts great with any array of pedals. I have used the effects loop and it is good. I just prefer to run everything in line. I give it a 9 for the many useful sounds you can achieve with it at the turn of a knob. Very reactive tone knobs.

Here is the best part of the amp. Great company, great personal skills, and great designs. I have a backup to everything just in case. But with this and the univalve I bring extra tubes on the road and I really never have to worry about anything. I can not honestly say that about any amp I have ever played used. When we go out and are not coming to home base for another 3-4 months reliability is more important than anything. Yes I use a Vox AC30 too, but we have to bring two others AC30s to get us through one of those 3-4 month tours. That is a pain in the neck and was in our pocketbook.

Great! These guys are class acts. When you find a company like this you stick to their products. For me they are up there with the Robert Keeley's of the world.

Been playing for about 10 years. I have honestly had a lot of amps and gear (Marshall DSL-50, Marshall Master Head, Marshall Super Lead, Laney VC-50, Orange Combo, Fender Dual Showman, Fender Bassman Heads, Mesa Boogie Maverick, Mesa Tremoverb Head, Matchless DC-30 (stolen), Mesa Triaxis, Marshall JMP-1...etc) This is the one amp that I will always use on stage and in the studio. I will always have another flavor of amp with me to add to the sound, but this is a must for me. I am fortunately in a position to influence some people and I always point them towards this and the Univalve.

Its hard to rate this catagory. I play vintage-type amps exclusively. Compared to most vintage-type amps this thing is packed with features but for someone who's used to channel switching its not that flexable. Yet if thats your complaint I think your missing the point of amps like this. I wish it had a preamp circuit closer to the classic british design (normal and bright volumes, Bass, Mid, Treb) but it has its own thing and honestly I cant knock this amp in any way in the feature dept. Its crazy but I think more then anything else I love its size. Just my marshall heads alone take up so much space. Plexi's are huge. HiWatts are huge. If I set the THD cab Vertically (on its side) and set the BV on it I have a little mini stack like those old Sovtek Midget stacks. But this rig has huge tone. The tube flexability is obviously a big deal. Prepare to spend some $$$ on tubes if you dont have a collection. That can be fun though. Tweakage and trials. If you like that sort of thing.

Ill say more then anything else I like the features of this amp. A 10 in this catagory says versatile. In a modern sense I guess its not but to the vintage/boutique world it really is.

I like Les Pauls. I like PAF type pickups.

For people reading here trying to figure out what the sound is of the BV Ill say it sounds closest to early marshall sounds. Its hard to pinpoint it as one thing but it seems to really be in that early marshall heritage. Not Vox or fender as much as marshall. Youll find an accurate ACDC and Rush way before youll find Brian May or SRV. Not to say they cant be found but its easy to dial in those sounds right away, especially with the stock EL34's. Its like a Metal Panel Plexi with a little bit of Vox and Bassman thrown in. Its definitly got a high bite to it like a 70s plexi. An accentuated higher range that can seem shrill or can be on certain settings. Theres ways to defeat that and get real warm or even brown tones with this amp.

Vintage style amps like this just have such a unique and amazing tone. They chime. You can hear all kinds of overtones when you hit an open E. It makes all modern amps and distortion pedals and all that stuff sound and feel the same. The amp's unforgiving. If you have bad technique youll sound bad with this amp. On the other hand if you have good technique youll find this amp very rewarding.

Heres a few things I found with the tone. Im a huge marshall fan so I tried the hardest to nail those tones. Ive gotten very good Vox at times as well. Ive had a harder time getting fender but Ill admit I havent tried much at all. I also focus more in the crunch tones then clean tones.

One thing with old marshalls is that its very common, when trying to get a tight, high-gain tone, to dime the treble and mid and leave the bass at like 2 or 0. The tone controls of old amps seem to interact more with the tone of the amp. Modern amps eq's seem like stereo eq's. They only adjust the loudness of the frequencies. Setting the bass on 0 and the treble on 10 would make a modern amp sound like its inside a tin can. On old marshalls, and the BV, the tone controls seem to alter the frequency responce more. Their a bit more interactive. When the bass is up high the gain is very loose and tubby. When its low the gain is tight and chunky. I think with the BV if you want a cleaner or bluesier tone you can have the bass higher but for a little more gain and a tighter tone you want to dime the treble, or at least set it to 12o'clock or higher, and turn the bass off. It doesnt make the amp sound suddenly like it hass no bass. Or make the treble suddenly tear your head off. It just makes the overall bass responce tighter and thicker actually. Its very common with old amps to run the tone controls in that way. For a brown sound with this amp I think its a necesity. I can get a very warm and soft yet tight, EVH-like sound were you really get a nice thick "chunk" when playing those mutes low strings.

The Attitude is a weird control. I like to keep it at 10 to get the most "plexi" out of it. It also tightens up the gain and makes the amp seem to have more gain when its up. I usually only turn it down when Im going for a cleaner tone.

One thing about getting more gain with the BV. Using a 12ax7 in the driver only makes life harder. With 2 12ax7's in this amp and the volume dimed its a very loose, out of control gain. Fuzzy and feedbacky. I like to use a 6189 (12DW7) in the driver to tame that gain and I can get a tighter, higher, smoother and warmer gain as a result. The 6189 also tames the harsh top inherent in this amp. a 6189 may be a lower gain tube but its more useable gain. So I can actually turn the volume up to 10 and know the gain will be smoother, chunkier and tight.

With these few things I can get a really nice, ballsy crunch. I can also get a great brown sound. Obviously to get more of a classic plexi crunch sound it should be on HiV and to approximate the EVH sound it should be LoV. Or better yet. Leave it on high and use an actual variac.

I want to stress another thing Ive learned. Moreso with this amp then with others Ive played, the speakers make a

All I can say is they answer emails in 1 to 2 days.

This is a review I have been meaning to contribute for a while. I've had this BiValve for almost a year now, but I wanted to wait until I recorded with it and had planty of time to test it out to give a fair honest review. My bivalve is 2002, #141. All the features have been previously listed but I will say that the controls are very simple, intuitive and musical. Every knob and switch (of which there are not many) is very useful, and the only thing I wish it had is a midrange control. Although I love the midrange content in it's natural tone, I would like to be able to dial in more midrangey crunch for some things. overall, though I'd say the amp is very well designed and versatile. Although I do also wish (really wish) it had the ability to use an ABY box to switch between low and high gain inputs. This would make a live situation much easier as the amp only has one tone instantly accessible. and I can't exactly afford to have two of them.

This amp has some incredible sounds and is extremely versatile. Much more than I thought when I bought it. When reading the glowing review, I doubted this amp could do all that previous reviews said it could, but upon hearing it I was sold. The true test is that when I bought it, my musical style was different, and having changed styles, the amp had adapted itself perfectly to my new playing.
OKay, well if anyone cares, my rig consists of a stock lefty G&L asat special semi-hollow w/ soapbar style pickups, or a heavily modified lefty Gibson SG special w/ seymour duncan pickups (which btw will soon be changed to joe bardens). My pedalboard is simple, I run either guitar into a VHT valvulator line driver (a buffer that converts your signal to low inpedance to save your signal from tone suck caused by long cables and pedals), a snarling dogs blues bawls wah, a fulltone fat boost, and a boss tuner and noise reduction pedal. I run the bivalve into a THD 2x12 cabinet which also sounds great.
As I mentioned earlier when I bought this amp I played a different style of music. I played Heavy Rock along the lines of Tool and Soundgarden. The belavle sounded great for this and thats initially why I bought it, for the massive overdrive sounds. I put of pair of 5881's in it along with some high gain 12az7's and I could get big massive grind. Now, my style has changed to a more Rock/Pop/Blues/Spacey kind of thing that way more vintage sounding. I can use an EL34/6L6 combination for clean dirty, or a pair of EL34's for crunch and it has great clarity and punch. With different combinations of power tubes (EL34, 5881, 6L6gc, KT66) and a few different variations of 12ax7 and 12at7 preamp tubes I can dial in everything from really clean, to egde of dirt on the low gain input and blues rock to ballsy crunch to singing lead to massive distrortion on the high gain input. I really am quite impress with the versatiity. I wouldnt really call this amp truly high gain, but thats good for me because i don't want rectifier tone. it also doens't have as much clean headroom as a fender but I have a fender amp for that.
This amp records really well and cuts through the mix great. it's versatility is welcome in the studio and it isn't noisy at all. I rarely use the noise reduction because the light bulb tends to burn out fairly quickly and it has a slightly negative effect on the tone. Oh, and in case you think 30 watts isn't loud enough, try running this thing without the attenuator on, it'll rip your head off! More than loud enough to keep up with a band practice. I'm sure you could use it live and it would be more thanloud enough as well, but any club you play at with a decent seating size will mic the amp anyways and tell you to turn down. I think 30 watts is plenty and more than that is just silly unless you need crazy clean headroom.
The hot plate attenuator does a great job of reducing the volume without affecting the tone, but be forewarned: don't expect to be able to run this amp at bedroom volumes and have massive sounding tone. The reason for this is the speakers, not the amp. When a speaker (especially an 80 watt celestion like what comes in the thd cab) is not given a lot of power, it won't sound good. All the distortion in the world won't sound huge without good speaker break up. For this reason I almost prefer to run the amp with the attenuator off at low volumes. It has way more harmonic content that way and a bit more treble as well. So, in my opinion, the attenuator is great, but you can't create cranked amp unless you crank an amp.
When I play this amp live, I am probably going to run the amp at full power on the high gain input with the volume at abot 1/4 (which is still plenty lound and decently distorted) and use a good tube distortion pedal (like an SIB varidrive) to get my overdrive sounds at a reasonable volume. Although the distortion on the amp is incredible, I need to versatility of switching between clean/dirty

Okay, check this out. This amp is extremely well built and is very dependable. But after having mine for about 8 months, it just uyp and died one day. Just suddently in the middle of my playing, the sound just cut out and was reduced to a mild fizle. I thought it might be a tube or a fuse but it wasn't. I called THD and Ed Gegenero (very nice guy) told me he thought it was a cold solder joint that had come loose and I should send it in for servicing. I was nervous about this because I needed to record with it in less than a month and I've heard how long some companies take to service thier equipment. But I sent it in and had it back in well less than 2 weeks. Ed kept in contact with me via phone and was very helpful. They even sent it back to me with a brand new set of power amp tubes at no charge! The amp has worked perfectly since. one time I though it had died again (this problem turned out to be a George L's cable that I had improperly connected and subsequently came loose cutting in and out) and I called and spoke to Ed again. He said to check everything including the tubes and if the amp had a true problem that I could send it back and he would send me a brand new one. SO it's clear that they really stand behind their product. I would gig this amp without a backup, although not without some spare tubes and fuses just in case. Although I've never personally blown a fuse, some other reviewers indicate this does happen.

As mentioned before THD is great to deal with. They are super helpful and nice and they really take time to tlak to you and answer all your questions. All of my many stupid e-mails to them have been answered withon 2 days. They really stand behind their products and with good reason. They are the best. Did I mention that they were willing to replace my amp for free if it broke down a second time?!?!

I have been playing about 5 years. I have gone through many changes in stlye and gear over this time. I started with a small combo then moved to a marshall half stack. Then I moved to a rack system tpe preamp/poweramp setup. That being too complicated to use all the time I went to a large fender Blues deville combo amp, and then to this bivalve setup. It's small enough to lug around for practice (although heavy as hell!) and it sund amazing without having 6 channels and 37 knobs and switches. It's simple and fun and inspiring to play. Before buying this amp I tested a few other amps as well as researched lots of other "boutique" amps. This one had the best features for the best price as well as a solid company standing behind it. a rare find. The only other amp I've tested that sounds this good is the bad cat hotcat at about twice the price. I still may buy the hotcat because of the ease of switching inputs between clean and dirty for ease of use live, but for the price I paid the bivalve can't be beat.
Would I buy it again? Yeah I think so. I am always experimenting with tone so I think I will always be trying new amps, but I have become very attached to the tone I get from this amp. Everytime I play it I feel inspired to create, and I think thats what a great amp does. It not only sounds good, but it feels good too.
If this amp had a midrange control and on the fly switching it would get a 10.

My BiValve is a 2003 and it suits my style of music perfectly. I play Blues, Classic Rock, Rock, Hard Rock, Alternative Rock and a little metal. This is a 30 watt single channel class A amp. It does have an effects loop (unlike the Univalve). Don't think a 30 watt is loud ? Go try one ! I really thought that I would try some tubes and settle into a particular combination and I would stick with it....but nooooooooooo....I actually change tubes all the time based on my mood.

My favorite tubes in it are EL34 types and my favorite preamp tubes in it are NOS mullard 12AT7's and NOS baldwin 12AT7's ( I snagged some of these Baldwins for $5.00 a piece...talk about a good value...extremely low noice / microphonics).

I also like so far the 6V6's / 6L6GC's / NOS 6L6's / 6550's. Each yield a different sound or attribute which the BiValve can capitalize on. It is so easy to swap tubes...Why not put in some 6550's when you need some clean head room or some loud tight compressed distortion with crisp highs. Why not slap it some EL34's to get a thick low end and one of my favorite 'power tube' distortions.

I like this amp just the way it is. Some people complain that the unit doesnt have built in reverb. This thing sounds so good, I don't miss reverb. The tone is so thick and true.

I am a Gibson Double humbucker kind of guy. I mainly play a Les Paul Standard, Gibson SG and a 1970 Guild S-100 thru the amp. The Les Paul sounds the best thru the amp as far as 'Tone'. This Amp with a my Les Paul makes for a really thick sound. If you like a truly overdriven sound (not that fuzzy stuff they call overdrive)this is the amp ! The amp has built in noice suppression that you can turn on or off. The amp has a bulit in hotplate so you can crank up the tubes but turn down the volume ! This is a really great feature, however, the more volume you soak up with the hotplate the less you will like the sound. Cut the volume half-way even 2/3's and it still sounds good....start going lower and the tone loses it's luster. You can't expect to get that thickness if you rob 90% of the volume. There is also a low-v / high-v switch for controlling the plate voltage on the tube to get increased volume...I personally prefer the low-v setting. There are two input jacks labeled 'more' or 'less'. The less is better for clean sound and the more is better for overdriven sounds. I could go on and on about this amp.

Check out http://www.univalve.net/forums/ for univalve / bivalve info / thoughts / opinions provided by other users.

Yes I feel I can depend on it. Backup tubes and fuses are probably all that one needs. A backup is always a good thing just in case something happened to the BiValve that was outside THD's control....like the bouncer smashed it several times with a baseball bat because you were hitting on his girlfriend !...I dont think the unit would fail on it's own accord. Any Questions ?

Doesnt get any better.

I have called asking questions a couple of times and THD's staff has always been helpful and courteous. Ed pointed me to a helpful forum:

http://www.univalve.net/forums/

Ed and Andy have posted alot of info about the amp on this forum and it appears they try to help all that need it. I have tried getting support from Fender and Crate and I would not call it support !

These guys are fantastic !

I don't know what the warranty is for this amp, but it is the most solid piece of equipment I own. It is built like a tank. If I ever have a problem with the amp, I am pretty sure THD will exceed my expectations.

I have been playing guitar for 15 years. I have a small home studio and some other amps, but nothing that compares to the BiValve. The BiValve is my first expensive amp and it is worth every penny. Expensive is a relative term. It is expensive compared to my Peavey Classic 30 or Crate VC50 2x12 combo. It is not that expensive when you compare it to some of the other makes & models on the market. If it was stolen, State Farm better Damn well buy me another one !

Why did I chose a BiValve over other amps in this price range ?

Besides the fact that it sounds fantastic !

1) The tube flexibility
2) The built in attenuator
3) The built in dummy load & variable line out
4) Attention to detail
5) Small footprint (nice for my cramped home studio)


It will probably take me years to explore all of the possible sounds that I can get from this amp...but I love it already.

This is an update to an earlier post. Have obtained 2 Mullard EL34-XF1 tubes along with 2 Mullard 12AX7 tubes. What a sound. You have to experience it to believe it. I use a Sparkle Drive or my TS9 to push the front end a little and it just sings. I am after a Blackmore/Schenker/Roth type of sound. The natural harmonics are incredible. Also have started using a set of KT66's I was able to dig up. Cleaner tone. Great "punch". Fairly loud. Very sensitive to attack.

Still experimenting. A word of caution though...Those with G.A.S. may aquire a new weaknes...T.A.S. tube aquisition syndrome!

Bought new in June 2002, ser#0069. On the surface, this may seem to be a simple, single channel tube amp. However, this is probably the most flexible amp I've used. Details are included in posts below...I can only say that every knob and switch is really useful.

Right now I'm using this with a '60s reissue Strat, and it sounds great. I'm using it in the more channel with Philips 5814A and Magnavox 12DW7 preamp tubes, and Philips 7581 and GE 6550 output tubes, for a cleaner sound with more headroom. With the volume pushing about 3/4 this moves from a more Fender clean to more of a Vox feel. With two 12AX7s and output tubes that clip faster (ex. EL34), it's got a lot of really toneful gain. Personally, I love the tone of this amp, and think that most will agree, although I don't hear it suiting a scooped metal lover. As others have said, this amp has the complexity and tone in a class with amps costing 2 and 3 times more.

I've been using this regularly without backup and have had no problems.

Excellent! Quick, courteous, knowledgeable.

It sounds and "feels" phenomenal, is very portable (but a little heavy), incredibly flexible, and very dependable.

Had the amp about 6 months - #125. Features noted below. I can't overstate the utility of the line out - you can use it to drive an effects processor/slave amp for a stunning wet/dry setup, or while recording, you can record the line-out in addition to miking the cab and mix the tracks to taste. Channel-switching and on-board reverb are about the only things I can think to add. I don't miss the reverb (I prefer studio-quality digital 'verbs to springs anyway), but the ability to switch between clean and dirty sounds on the fly would be useful for live situations.

Rig is thus: Fender American Deluxe Tele/Fender American Strat Plus/Paul Reed Smith Custom-24 -> BJFE Baby Pink Boost -> Fulltone Clyde Deluxe Wah -> SIB Varidrive -> Maxon OD808 -> BiValve Head -> THD 2x12 Cabinet. I run the line-out of the BiValve into a t.c. electronic G-Major, then into a slave amp for a wet/dry setup. I primarily use the BiValve for recording, and playing at home and in small venues.

The BiValve is simply the best-sounding amp I've ever played through. Certain amps may have an edge in one area or another, but the overall tone of the BiValve, coupled with the tonal flexibility of different tubes, control settings, and overall volume (with the built-in attenuator) makes this a studio dream machine. Wonderful clean tones, great high-gain Marshall-esque tones, and the best in-between crunch tones I've ever heard. This amp wasn't really made with ultra-gain metal tones in mind - you can get pretty close, but you might find you need some sort of overdrive pedal to get you there. Thirty Class-A watts is plenty loud for most venues.

Construction is top-notch. THD has a stellar reputation. That being said, I haven't had it long enough for my comment to have weight. I don't expect any problems, and I expect any problems I do have to be handled well (see below...) Would gig without a backup, although I would bring some spare tubes and fuses.

Absolutely top-notch. THD's reputation is well-earned in this area. If you want other opinions, visit www.univalve.net and read...

Been playing 16 years, mix of jazz, rock, blues, etc. Have owned a fair amount of gear and played through a lot of other stuff. I would replace this amp in a heartbeat. It's so easy to lose yourself when playing through this amp - the sound is that good. There are a lot of boutique amps out there, many of them outstanding products, most of them focused on one tonal area or another. The BiValve is a chameleon, able to adapt itself to almost any situation. I have not encountered any other product with the tonal quality and flexibility of the BiValve. I'm sold...

Class A all tube amp with built in attenuator as described by others ... it is very heavy ...

Probably the best sounding amp at any price anywhere: sounds very 3 dimensional and rich and basically beyond words ... after hearing this baby you will never touch digital toys :-)

It was brand new when I tested :-)

Nice guys at THD.

In the end I didn't buy it as it is very heavy and if I sclepp that and also a cabinet that's too much ... instead I bought the THD HOTPLATE attenuator that I use with my LIGHT combo (35lbs) Divine sounding class A 3 channel all tube $650 Ashdown Peacemaker 40 - Ashdown now sings and as it is class A the sound is almost as good as the THD BiValve and I have several channels etc ...

If I were younger and wanted THE TONE I would buy either this head or Peacemaker 50 head or Cornford Hellcat; the latter is ost expensive ($1499) ... but under $1k my Peacemaker rules ...

This is a "follow-up" review to my earlier post. I made a mistake in
calling the two inputs on the Bivalve "Rock" & "Roll." On the Bivalve, the two inputs are "More" & "Less." Other than that, I enjoy this amp more & more every time I play it!!

The amp is serial number 108. I play a mixture of blues, R&B and 1960's-70's rock and this amp does them all well. I've owned/played just about every "cool" amp out there over the years (including Marshall, vintage Fenders, Orange, etc) and the BiValve has the richest/fattest tone of them all! I don't really miss the reverb that much, but if Andy added it, he'd have a real winner! The 30 watts is plenty of power, in fact I am currently using two "JAN" 6V6GTs in it (to reduce power for practice sessions). Will run 2 RCA 6L6GTs for gig situations. Am running the amp thru a single 12" Celestion G12T-75 in a closed back cab...would love to have one of the 2X12 THD cabs but can't currently afford it! May also run the amp thru a 4X10 Slant Front Marshall Cab I can purchase for cheap!

Using mainly a Gibson '59 Reissue Les Paul Sunburst Standard with the "Burstbucker" pickups and lightweight stop tailpiece...sounds great with many of the old classic overtones that made the '59 Burst so famous...amp is very quiet and can generate a load of different sounds including the "full-tilt" boogie (ZZ Top sound). It also generates a nice crunchy rhythm sound on the "more" channel w/ the volume at about 9 or 10 o'clock...I use various OD pedals for taking solos...

no problems and don't expect any...this thing is built like a battleship!

responses from THD have been very timely!

I love this amp...it is a little heavy to lug around (but not as bad as a Marshall Super Lead 100! I think it is a wonderful addition to any "tone-hound's arsenal!"

The Bivalve gives the player so much flexibility: between changing tube types(and not worrying about biasing), and the two channels "Rock" & "Roll," & the built in attenuator, the player has a full pallette of tonal colors to "paint/play" with.

Also, the effects loop is a benefit, I run my tube reverb through it.

My Bilve is #54, and I've had it about a month. I play mostly blues and slide, and the Bivalve has enough power for me to gig with.

I use all P90 pickup style guitars, and they sound great. Between using the "Rock" or "Roll" channels, using the attenuator, and then trying different power tube and preamp tube combinations, if one can't get the tone they're looking for I'd be quite suprised!!

Moreover, the Bivalve has allowed me to delete two pedals from my pedal board. I have no need for my Analog Man Compressor or my TS9. I can get the tone I need from the Bivalve ITSELF!

Also, this is a quiet amp. I've only played it throught my THD 2x12 cab, but it is quiet. If I'm not playing, there's no noise coming out of the amp!

Built like a ROCK! Looks solid.

I've contacted THD by phone and email, and they've been quite helpful and friendly.

I've been playing 30 years now, mostly acoustic country blues and slide.
So when I play electric, I'm looking for a good fat, clear, slide tone.
I had a Victoria 20112 that I sold for the BiValve. The BiValve gives me more clean headroom, and like I've stated previously, the amp gives the player so mucjh flexibility in shaping a tone it's hard for me to imagine not being satisfied with it. My tone quest for amplification has ended, and if my BiValve was lost or stolen I'd be pissed and replace it ASAP!

I purchased this amp new in September of 2002. This is a class A two input channel amp (More) for just amazing crunch to high gain lead, and (Less) for pristine clean. However this is not a channel switching amp. This amp is extremley versatile for finding great tones and lots of them with the tube swaping feature plus the cut switch, noise reduction, power output, and hotplate features. I have found numerous fantastic tones using all. It does come with an effects loop which works very well though I do not use it and a line out/instrument feature on the back of the amp. I am using this feature for my wet cab setup going to a GT-6 effects processor then into a Mesa 50/50 power amp into a stereo 2X12. This is used in conjuction with the THD speaker output to another 2x12 cabinet for a nice Dry signal which sounds exceptional by itself. I love this amp so much that I want another just so I can A/B between both the Pristine clean and Lead inputs. I use this amp for live work and recording and has more then enough power to run by itself in any live application.

I am playing a Godin LXGT, and Fender American Deluxe Fat Strat. I mostly play rock which is of 70's style genere. As far as tones, it is hard to beat. You can custom tailor (your) tone very easily just by using the features of the amp plus switching tubes which by the way is self biasing and a very easy to do. I am currently using two Amperx 6550's for the power output section and a 5751 in the input section and a AT7 for a drive tube. Just Amazing sounding. The stock set up is also great but more apt for overdriven tones. I mostly play clean with chorus and reverb to cruch and Plexi when needed. I again would love to have two amps just to punch between those two tones. I have been mainly using the (Less) section of the amp wide open for the prestine full clean tone. If you play mostly crunch to plexi lead you will love this amp. Run the amp in the More input at 3:00 to 4:00 and use your volume nob for switching. This amp does this perfectly. The hot plate feature is great for controling the output volume for practice without sacrificing tone.

This amp is built like a Rock though not too heavy and extremly attractive with both the cover on or off for that vintage look. As far as servicing just carry a couple of spare tubes and plug in if needed.

The support from this company is outstanding I have contacted both prior to sale and after sale and was able to get answers to my questions immediatly.

I have been playing for over 20 years and have owned Fender, Ampeg, Legend, and Mesa Boogie. All which were good in their own way. However I really love this amp over them all. I wish it could channel switch, but that isn't much of a big deal I am just going to get another one to do that. To have an amp of this quality and features would cost as much as two amps anyway.

THD's reputation for quality is number 1! Andy Marshall is on the forefront of amp design. The hotplate and hi/lo voltage selector are 2 more reasons I went for this head. I've always used a hotplate and variac with my Marshalls and have always been very satisfied with the tone created.

Loaded with Electro Harmonix EL34EH's, EH 12AX7 input and a JAN GE 12AX7 driver I really felt I had found the holy grail! I mainly play early Strats and more recent Les Pauls. The tone is just incredible considering it is not a Marshall. Currently I am running it through a Marshall 1960AX cab. A true plexi sound. The power tube compression on 10 is very warm and smooth with an almost harmonic sound. This head really nails what I've been after without spending 4 or 5 grand!

I agree with a prior post recommending spare tubes and fuses if you are going to gig on 10 and hi power for extended periods of time. The construction is rock solid. I can't forsee any problems based on prior experience with THD products.

The support people are very into what they do. They reply to any questions in no time at all. I have dealt with them in the past for questions with my hotplates and heads. I've never had a THD product fail.

Always been a Marshall player. I currently have a '69 50W and a '74 50W MKII. I have an 8 and 16 ohm hotplate,a sparco variac, a TS808 and a KLON.That's it except for delay and reverb pedals. I've been playing on and off for 20+ years. What do I love about this head? TONE,TONE,TONE! I am amazed at the early Marshall tone I can get. Or You can create your own tone with the many tube variations. If stolen I would buy another hands down.

Accepts a wide variety of pre- and power amp tubes. Power tubes can be mismatched (different brands, or even different types, ie 6L6 and EL 34) or you can use only one of the two sockets! The front panel starts with two inputs: "Less" (lower gain) and "More" (you can't A/B between these...when you plug into "Less," "More" is disabled. Next is a High cut switch, volume, treble, bass, attitude (varies the driver tube's effect on output tubes...this is a sort of midrange and texture control...very cool), noise reduction, hotplate attenuator, hotplate on/off, hi/lo voltage to output tubes, standby, power. Back panel includes AC in, fuses with indicators, fx loop, line/inst level out, level control for line/inst out, output impedance selector (two positions: 2/4 ohm and 8/16 ohm), parallel speaker outs. It should also be mentioned that the output has a "dummy" load so you can operate the amp with no speaker connected (ie for running the line/inst level for silent recording or for slaving into a power amp or the front end of a bigger guitar amp).

This is the ultimate club amp--once you get a feel for how to alter it with different tube combinations, it becomes a chameleon that is perfectly matched to every room and situation.

I traded a Univalve for the BiValve. While I really loved my Univalve, it was never enough power...even for rehearsals. However, there's a sonic difference between the two as well. To my ears, the Uni is spongier and brighter. I could coax both "British" and "American" sounds out of it, but I felt it leaned more toward the latter. The BiValve, TO ME, really leans more toward the British side, although it can certainly be made more American.

I mainly use the "Less" channel, as I play funk and R&B. I use an NOS Philips 12AT7 in the input and an Ei gold 12AX7 in the driver. I have generally settled into three basic power tube combinations: 1) Hi power, using two 6550s. 2) Mid power (this is used about 90% of the time), Svetlana 6L6 and an EH EL34. 3) Low power: Two Visseaux 6V6's are great for rehearsals...sometimes I replace one with an EL84 (requires Univalve Yellowjacket adaptor). The "Less" channel has a fantastic clean tone/texture, even at full volume. Cranked, you can get the clarity of clean and unbelievable sustain...

Beyond tube choice, the trick to this amp for me is balancing the volume control with the hotplate (if it's needed) and reducing bass at higher volume settings to keep low end tight. Very quickly , I've learned to do this in an instant...it's easy once you understand the way the controls interact...8 months' experience with the Univalve came in handy here!

It works great with both Gibson/humbucker type guitars and Fender/single coil types. My Strats are HSS, so I'm certainly not an authority (on anything, but especially not on) bridge position single coils.

Although I gig with this in the "less" channel, I love to crank the "more" channel at home. I love to blast out AC/DC, Van Halen, and other very Marshall-esque tones....this amp delivers them in spades! Although I often don't get into a full on tube change, a 12DW7 in the input and a 12AU7 in the driver seem to be the trick for this higher gain channel. I guess it stands to reason that the "more" channel is more susceptible to microphonic tubes...the set I have in the amp now is dead quiet in "less," but unbearably microphonic in "more."

Bottom line: With the right sets of tubes and a good overdrive pedal, you can get just about any sound you can imagine. It's THAT good. Buy one, you won't be sorry!

I had the Univalve for 8 months, and traded it on this about a month ago...Both look and feel solid...I have no reason to expect anything but great dependability.

By email or telephone, THD's customer service is TOP NOTCH! Not only are they personable and quick to return customers' calls, but they are very knowledgeable. I am so impressed that I have effectively become an unpaid sales rep (I'm pressuring my local dealer to pick up the line). Furthermore, when it came time to replace a transformer in my JTM45 reissue, I chose THD over other more authentic repro trannies, because I figure their way of doing business needs to be rewarded...I plan to buy a 2-12 cab and a hotplate (for my other amps) as well...

I've had no problems with my BiValve, nor did I ever have any with the Uni.

In 30 years of playing, the only amp I had that rivaled this in tone was an original '60s plexi (that would be WAY to loud for what I do now). In terms of flexibility, I've seen nothing that compares. I could easily sell everything else...There are only a very few situations where this might not be enough power (outside, big stage?), but you also have the ability to slave this into a power amp! If lost or stolen, I'd be crushed until I bought another...

Straight ahead Class A tube amplifier.Since I was reviewing this product at a Namm show in Nashville, I couldn't get as much time inhand as I would have liked. Best feature over other Class A amps at the show was versatility at the Power output tube stage. Just carry a hotplate mitt and switch on the fly. Super sound at low volume levels and the harmonics were glissening. No onboard reverb that I saw. Too dry at low attack levels.

Best sounding amp in it's class. Clean distortion to play jazz or minor scale/chording. Fat and smooth.

I am looking for one in my area today. I want a used one for under 1k.

This amp is the real deal. Plenty of kick for gigs. It's a dual channel Class A amp (although you cannot switch channels with a footswitch). It has a series FX loop. Volume, Bass, Treble, Attitude (thickens overall sound), and High Cut switch, plus a built in Hotplate that acts like a Master Volume control. There is also a noise reduction circuit that works very well, but does slightly effect the sound.
Of course the main feature of this amp is that you can put different tubes in the preamp, driver, and power tube section, and even use two different model power tubes at the same time, as well as a single power tube for lower volume levels. There is a hi/lo switch that allows the use of tubes that cannot handle high plate voltages.
One other thing, there is a line/instrument out. You can use it for direct recording, to slave a second amp, or even to use the BiValve as a preamp in a larger rig.

Well, at first, it sounded very good. This was with the stock tubes. A Russian EL34 and 6L6 for power, an EH 12AX7 for the preamp, and an El Yugo 12AX7 in the driver. I was not satisfied with very good, so I started swapping tubes. I have settled into two Russian KT88 tubes for power, a JAN GE 12AX7 for preamp, and a Sylvania 12AU7 for the driver. I keep it on the lo voltage setting.
I found that the biggest difference was with the 12AU7 in the driver, which is a very low gain tube. Although it renders the low gain channel basically useless, the high gain channel now SMOKES! It also totally cleans up with the guitar volume knob. I also noticed that the lower gain driver tube made the FX loop more useable for delay, which can get overly compressed when it comes before heavy power tube gain.
I found this amp to be very virsitile as far as styles. You can go from pristine clean, to just breaking up blues, to chunky rock, to searing lead guitar. It's just a matter of matching the tube combination to your particular style. The stock tube setup will cover all these bases, but tube experimentation can allow you to really zero in on the exact tone you're looking for.
The cabinet and speaker is also a big factor. I used both the THD 2x12 w/ classic leads, and an openback 1x12 with a vintage 30. TOTALLY different sounds. The tube compliment I mentioned before worked great with the 2x12, but was way to bright for the V30. Replacing a phillips 12AT7 for the preamp, and putting JAN Phillips 6V6s in the power amp really warmed the 1x12 V30 up.

I went ahead and opened the amp up. The internal design is just amazing. All components are top notch, and the soldering job is near perfect. If you have a habit of really cooking tubes in hi voltage mode, I would bring some spare tubes and fuses to a gig.

This is where THD really shines. I've emailed Ed quite a few times with questions about the amp (the first run didn't include a manual). He got back to me within 24 hours, and many times within only a few hours. They will bend over backwards to accomidate. They really take pride in there work.

This amp is not cheap, but it may well be the last one you every buy. There are many good boutique amps out there, but with most, you're pretty much stuck with the tone they offer. The BiValve allows you to really find your own tone through use of different tubes.
I love the amp. I'd be real pissed if it were stolen. I'd buy a replacement in a second. In fact I may buy a second one anyway.

The Bi-valve has all the features of the Uni-Valve, with the addition of a second power tube socket (The amp came with a 6L6 and a El34, which can be used simultaniously). It adds an effect loop, a high cut switch, the line out is now balanced TRS, it has an additional speaker out, and LEDs to indicate a bad fuse or tube for each socket.

I bought this amp without even hearing it, as I am the owner of a Uni-Valve. My expectations were exceeded. The ability to mix two different tubes opens up many new tone posibilities.
I play modern rock, with a "vintage" edge to it. More of a 60's-70's vibe then the distortion you hear alot today. I am using G&L guitars with Fralin single coils. I go from guitar to a wah, to overdrive pedal into the amp and 2x12 cab, then out the instrument level output of the amp into a analog chorus and delay, and into a Fender Deluxe reverb. I have a dry and wet mic'd cabinet, and let the soundman mix to taste. The line/instrument out sounds very good in this configuration. Where most line outs sound thin due to impedence mismatching, this output sounds great. For true line level use, switch to "line".

I will not rate this, as only time can attest to this catagory, and this amp just came out. I can say, these amps, as anything else from THD, are built like bricks. Aside from the tubes, you could drop it off a moving truck, and still make the gig. I have been touring lightly with the Uni-Valve with no problems.

I've e-mailed with questions several times and always received a prompt and helpful answer. They seem to be one of those rare companies who are very concerned with customer satisfaction.

I've been playing more than half my life, and have been in constant search for the "ultimate" tone. I went from a transistor combo, to a marshall stack, to a full on rack system, to a vintage fender combo, and have finally, aquiring the uni-valve, ended my search. The bi-valve sounds just as good, if not better, and adds some needed features. When I first got this amp, I couldn't stop playing it. For several weeks, I played 4-5 hours a day. It's just that good. You don't want to eat. You don't want to sleep. You just want to be attached to this amp.