THD Bi-Valve Head

I bought this amp in October of 2008 to take the place of my 1966 Fender Bassman that was going in for a much needed filter cap job and I wanted something that was capable of the California clean sound that I have had forever with my Bassman.
If you are reading this you already know what features it has and does not have.
As far as the features I use, I would have to say evrything BUT the attenuator. I have never cared much for attenuators since I have so many great distortion pedals that I can get my tones at a whisper quiet volume at home.
Now as far as "does it have enough power?" Yes!!! Please realize I have played through a 40 watt Bassman forever to get my clean and slightly overdriven tones and when I want "The Nasty" I stomp the A/B
to kick in my Soldano Hot Rod 50."another amazing amp IF you load it with KT 88's!"
A lot of you may think 30,40 or 50 watt heads are not loud enough and all I can say is "mike your cabs and put it through the P.A. if you have a sound man with good ears!"

Now onto why it took me 6 months to post this review.
When I took possession of this head it came to me with 2 Tung Sol 12AX7's (think ECC 83 if you are from over there). Tung Sols are great tubes and I have no problems with them-- BUT-- it was what was in the power amp section that made me say " What in the heck was I thinking when I paid $1500.00 for this thing!!!"
It came loaded with Valley Art's made in China El 34's that were totally devoid of any personality. One would think that if it had 34's in it that it should have a little bit of the Plexi vibe to it but these tubes had the vibe of a belt sander.
I tweaked the amp for hours with the 34's in it and found no redeeming quality in the sound so it was time to dig into my box of tubes (new and NOS)and start experimenting.
I first tried a pair of Grooves, (Hardness 4) 6l6's and it was sooo much better that I played with them in there for weeks but they still didn't nail my Bassmans tone so I tried some Svetlana 6l6's that I had taken out of my Bassman after about three or four years of service.
Well that got me very close to my Bassman tone but not quite yet but I still lived with them for some time after I installed them.
Now these Svets were old when I put them in and one night I could tell that they were on their way out and becoming microphonic so it was back to my box of tubes.
The next set in there were a matched pair of Peavey Super Sixes that I had in the original plastic from when I bought them circa 1981
still with the price tag on them ($9.79--I wish I had bought a thousand of them at that price!).
And that is where the story ends for now because these tubes nail the Bassman tone,chime and richness that I have been used to for over 40 years.
I am not however done with the experimentation since this is a self biasing amp and I am going to order the THD YJUNI adaptors to try EL 84's and see if it gets the AC 30 sound and after that KT 66's and 77's for the old JTM 45 sound.
Thats the beauty of this head since all it takes is tube swapping to get an infinite array of tones out of it. I have not even messed with the pre-amp tubes yet because the Tung's sound so right in there.
Oh Yeah, this thing works very well with pedals too just as long as you know how to place them in them in the amp. I have some in the effects send and return and some thru the front end but I won't bore you with which is which.

So far so good as far as reliability. I am still a weekend warrior and rarely a day goes by that I don't practice or play for several hours and outside of the Svetlana's going microphonic on me no problems . The amp is super quiet until you get it past 4 o'clock and it gets a little hissy at that point but i rarely play it past 2 o'clock and that is always on the "More" setting.
I guess this rates as a 10 also

I have never had to call them but in reading other reviews everyone says they are very helpful if you have questions so I guess I will coat-tail them and give it another 10.

I have been playing since 1965 so I think I have a pretty good knowledge of what amps should sound like since I have owned (and still own) so many of the great ones.
If it were stolen I would first try to find another AA 165 circuitry Bassman like mine for a backup but still probably buy anther THD since the tube swapping factor is so much fun!
I love almost everything about it for the exception of the attenuator since I don't use it at all and the few times I did it sounded not so good to my ears.

One channel with a few knobs. Its got a cut switch, noise reduction circuit, and a built in attenuator, but all these features take away from the tone, which is why I don't use them. I do think the voltage switch is cool in that it changes the feel of the amp. A master volume and a mid knob would have made this amp complete, but the ability to swap tubes and change the output is priceless in its own right. This amp is all about cooking the power tubes, so I bring a box of different tubes with me when I gig to get that power amp distortion at the volume I need it.

HINT: you can use the attenuator to knock the volume down to bedroom volumes, but it seriously squashes the tone. Get some 6G6 tubes from eBay to knock the output down to about 1 watt (use the Low Voltage setting or you'll fry the tube). From there you can use lighter attenuation if you need to reduce the volume further. This is way better for practicing than using heavy attenuation with a more powerful tube.

My rig goes like this: Carvin CT6--> Peterson Strobo Stomp--> Bivalve--> Earcandy Buzzbomb loaded with their Green Machine speakers. This rig sounds so good that I just want to hear the amp, I don't want a bunch of pedals getting in the way.

At first, I didn't like this amp. The highs were dull and the mids weren't much better. I played around with different tubes and found that I liked various JJ tubes much better than the Electro Harmonix tubes it came with. I have another amp that came with EHs and I can honestly say that I just don't like them. That amp sounded way better with the tube swap too.

After I upgraded the tubes, I still wasn't where I wanted to be. I tried the amp through a couple Marshall cabs and I could never dial out the mud I was hearing. This amp doesn't like Marshall cabs, its just that simple. My friend turned me on to Ear Candy cabs and I ordered one. From the first time I plugged into it, I knew my cab search was over.

Now that I've got the tube and speaker thing nailed down, I can tell you what this amp really sounds like. Simply put, the cleans rival a good Fender and the overdrives rival a good Marshall, but it doesn't sound like either. It sounds like a THD. You can tube swap to your hearts content and change the character of the amp, but it will sound like a THD no matter what. For me this is a good thing in that this amp works for lots of different styles and I don't end up sounding like everybody else. Different tubes and settings yield lots of cool flavors, so its hard to decide sometimes which one to use!

The cleans are crisp and chimey, the overdrives are rich and detailed. The really great thing about this amp is that you can use the entire spectrum of your guitar's volume control and the tone cleans up without ever getting muddy. Sparkling cleans and screaming leads are just a knob twist away. You don't need channel switching or distortion pedals with this amp, just a little practice turning the volume knob quickly. I play rock, country, and jazz and it covers all of them really well.

Overall, if you're willing to spend time tweaking tubes and settings, trying different speakers, and are willing to let the amp be itself instead of trying to make it copy something else, your efforts will be well rewarded. If you're looking for something different that will fit the bill for lots of different styles, this amp may be your ticket.

I've had this amp for about a year and a half and used it on lots of gigs. Its worked just fine. So far, so good. I bring extra tubes and fuses with me when I gig, after all it is a tube amp.

I've never had to contact THD, but lots of people on the Univalve forum have posted good things about their customer support.

I've been playing about 20 years, professionally for the last 6. I've played lots of different amps in my day and I would put this amp up against anything else out there. Its got a personality all its own and its a great sound. This amp will turn heads and inspire you to keep playing, which is what a great amp should do.

The ability to swap in any combination of preamp and power amp tubes is amazing, obviously. However, I find the attenuator and noise reduction completely useless. The attenuator dulls the output sound to the point of sterility, and using the noise reduction circuit sounds akin to running your guitar through a badly buffered, non-true bypass effects pedal. This isn't exclusive to my Bi-Valve... every one I've heard has the same "problem". I'm not sure how this hasn't been picked up on and mentioned yet. Fortunately I use the amp for clean or mildly overdriven sound and the attenuator isn't needed, even in my apartment (my neighbors haven't complained yet, somehow).
I wish it had a mid control.

I use a wide variety of guitars and effects. Fender Jazzmaster, Danelectro U2, a 60's Fender Duosonic, a Fender Telecaster, a Les Paul Junior, and an Agile Cool Cat with Gibson 57 Classics. Tons of fuzz boxes: Zvex, Fulltone, MI Audio, etc. Tons of overdrives: Subdecay, Catalinbread, Lovepedal, etc. A Keely Compressor, modded Ibanez Analog Delay, Moog stuff, Electro Harmonix 16 Second Digital Delay, blah blah blah blah and a clean boost out front so my signal doesn't weep in agony from being run through so much cable and true bypass stuff. Usually, I run the head into a closed back Avatar 2x12 with G12H's. Sometimes it goes into a 4x12 with Celestion V30's, depending on the application.

This amp handles every pedal flawlessly. Fuzz pedals are no problem whatsoever. Perhaps the people complaining about the amp's inability to handle fuzz are running the treble too high, and thus getting a harsh, shrill tone when they kick in the fuzz. Its a common mistake that nearly everybody makes. Guitars and guitar amps really don't need more treble than they natively provide, and in general they need less, so cut that **** back. If you don't, I wonder how you can run fuzz on any amp without sounding even worse. I run the treble cut switch active at all times unless I'm playing funk or ska, which I don't do.

As far as my style goes, I play avant-garde jazz, electroacoustic, noise, drone, ambient, free jazz, fusion, country, blues, shoegaze, 60's pop, pre-punk, post-punk, and probably some other things that aren't coming to mind. I use this amp for everything. Currently I have it equipped with a 6L6GC and an EL34. Perfect amount of clarity, definition, note separation, punch, harmonic content, etc.. When switching playing styles or guitars I generally only need to make slight adjustments to treble, bass and attitude.

I only have 2 complaints for this category:
1) Out of the box, the head comes with 12ax7's in both positions. With this setup, the "more" input was incredibly harsh and useless to me. "Less" was not loud enough and wouldn't break up enough even with volume dimed. Fortunately, this problem is easily solved. I replaced the input tube with a 12au7 and the driver tube with a 12at7. Now, the "more" input has the perfect amount of volume and natural break-up at around 3 o'clock. Also, swapping to lower-gain tubes warmed up the sound and tamed the highs a bit, which takes us to the next issue...
2) Too much high end. But, THD had the foresight to add a handy "treble cut" switch for those of discerning taste. Ideally, one wouldn't have to cut treble so dramatically on a moderately expensive amp such as this one, but that seems to be the modern trend. I suppose that in order to compete with other manufacturers who are making far overly top heavy amps (Fender, Marshall, and nearly every boutique manufacturer), THD had to respond in kind. But hey, at least they have a "treble cut" switch.

Reading over my complaints, they seem petty since they are easily rectified, and they are both merely symptoms of the unfortunate tastes of modern guitarists. I give this head a "9" in this category because though it isn't the best amp I've heard, it is pretty damn close and half the price.

Though I have babied this thing, it does seem fairly fragile. Somehow, at some point, the 2nd power tube socket stopped functioning. I'm incredibly careful when it comes to handling the amp and swapping tubes, so I'm not sure how this happened. Perhaps I received a faulty one, or it was handled roughly in shipping.

Without exaggeration, I can say THD is the best company I've ever dealt with. Ed authorized my amp repair, did it for free and shipped it back at THD's expense... all in one week. I had thought companies with this degree of integrity were extinct, but Ed proved me wrong and restored my faith in modern commercial industry (well, as much as any single company could).

I've been playing for about 10 years. I own and have owned a lot of vintage tube amps and their modern equivalents. This is the most flexible and best sounding amp I have personally owned. If it were stolen (how would I lose it?), I would most likely buy something less expensive, as I couldn't afford another one of these at the moment. Money permitting, it would be a toss-up between this and a Marshall JTM45, though I would probably settle on the Bi-Valve.

Okay, I'll try not to repeat what the others have said. Yes, it is awesome that you can put nearly any tube in the preamp and power stages. But it's got a lot of personality on its own. If you hear a fender twin you know what you're hearing. This amp is best when you mix things up a bit. I've played with a 6V6 and EL84 (with adapter) this is where few other amps can tread.

One major caveat is that this amp works poorly with most fuzz pedals. This is fine if you play high distortion levels all the time. I like clean sounds too. And I collect fuzz boxes. So stop thinking this is the amp to end all: it ain't. 8.5 cause it does sound great.

I play alternative classic rock/punk. I like it because it has a thick rock feel. I can get a mid-overdrive that is all vox like with chiming lushness. It fits my style. I own modified strats. One of the strats has a high gain pup that boosts the imput of the amp.

Okay, with my intro you likely think I'm going to thrash it some more. Nope. With a celestion in a big or ADA stackable 1x12 cab it sounds awesome. You can run the spread from mid to high gain. I use a hot rails pup in the bridge and this thing screams. When you punch a boost pedal, wow. This amp loves to be pushed.

My fave tube combo is a low gain affair with 12AU7 and 12AT7 in the preamp and 6V6 pair in the power amp. It sounds close to a deluxe when I plug it into a second 1x12 cab with a Jenson. This thing has tons of personality but you have to coax it.

Even when you keep the amp and pedal volume consistent that amp is very touch sensitive which mean you can get a variety of sounds by changing pick attack. If you think 30 watts isn't enough, it is. This amp is LOUD.

It looks to be very tough. Massive transformers are shielded by fuses at each stage. I've dropped it and it still works. Get the gig bag. This thing needs a home.

THD is awesome. You call and they answer. No call center. Straight forward talk. Good people.

I'm a 20 year vetren of punk n blues. I would buy this again. I'm no amp builder but I think I would have liked a master volume. But this is a different kind of amp. I'd like it to take any fuzz box like a fender or crate does. Don't buy this thing for clean. I didn't and I'm not disapointed. It's pure tone, Man. It's expensive but when you put the price up against other boutique makes it's moderately priced.

c'mon you guys know already. 30 watts, swap tubes without biasing, single channel class A tube head

guitars- garbage strats with gibson pickups- classic 57' 498t. Danelctro 59 dc.
I play rock and it totally fits the bill. It has just enough gain for heavy rock( I have el34's , and JJ 12ax7's runnin), but it isn;t over the top. It doesn't hide your playing like a peavey 5150, or a mesa boogie, and thats why I like it. I love single channel amps, and thats why I got it about 5 years ago, when they came out. The only thing I feel it lacks Is the lower midrange thump of a Marshall, but I guess thats what you get with a class A amp. I love the fact that I can clean it up by rollin off the volume. The distortion isn't brutal, but musical ,and the feedback is musical, as if the amp knows what key youre playin in. It is loud , but not as loud as I need all the time. Sometimes I play halls and the midrange just gets eaten up by the room, and the drums. In a club setting it's great, and it records like a dream.

I gigged this amp for 5 years in a rock punk band. I have never had a blown fuse during a show. it has been rode hard and never failed me at a gig.

Awesome! My amp died during a rehearsal, and I brought it to a local repair shop. He sussed out the problem, called THD, and in a few days he had the parts and fixed free of charge. THD hooked him up with a bunch of yellowjackets as payment. I had my amp back in less than a week, and I live in New Jersey,THD is in Cali.

Had it for 5 or 6 years. I also have a peavey classic 30. I will never sell it because itis so unique and would like to keep it in my tone arsenal. I just wish it was real loud, and had more midrange crunch, so I guess I better get a marshall. It could use a midrange control knob.

Single channel hi/lo input. Effects loop. Built-in Hot Plate Attenuator. Noise Reduction. A little more than I usually like in an amp (The more stripped down, the better!) but EXTREMELY easy to dial in. Instructional pamphlet also very helpful! TWO features absolutely blow my mind. FIRST, you can run up to a 2 OHM load! Awesome. But secondly, and MOST importantly, the amp is automatically biased, which means you can plug almost any tube you like into it, in any combination! This amp has a maximum output power of 30 Watts Class A, and can out-perform almost any 50 watt Class AB amp in my opinion. I usually use it paired up with a Marshall 1960A Lead 4x12 cabinet, in conjunction with a SOVTEK Mig 50 paired with a Marshall 1960B Lead cabinet. The SOVTEK takes care of the lows and mids, but the THD adds to the lows, and cuts through with the highs. Well done!

I play a Gibson Les Paul special, loaded with an active EMG 81 & 85. This guitar paired up with aforementioned configuration produces what I call the 'bikini effect'. A great hi-lo blend. Very 80's metal. However, I also use a 1972 reissue Fender Telecaster Deluxe, which uses 'wide-range' pickups, which give me all the mids, lo's or hi's I need, depending on the pickup selector. This amp is exactly what I needed for my sound. Very little noise, depending on which tubes you are using. The lo input gives you creamy, smooth bluesy tone. The hi input gives you an edgier, more aggressive tone, and breaks up around 5 or 6. I love the natural overdriven sound of this amp, and use no overdrive or distortion pedals to achieve a very heavy, crunchy overdrive. If you want to hide all your mistakes with this amp, don't count on it. This overdrive is very 'true' and will let you know when you screw up, but will tear the faces off your audience when you nail that solo. Just to lgive you an idea of what kind of music I play, I'll give you a hint: I'm tuned B standard, dropped to A. If you love heavy strings, but can't achieve a bright tone, this is your amp.

This baby comes equipped with a full steel chassis. It's a little heavy, but there's a good chance it would survive a fire or a 20 foot drop. Heavy duty. As far as electronics, I have not had a single problem yet. Because the amp is auto-biased and can handle a variety of different tubes, there is also a hi/lo voltage setting. So if you're going through a lot of tubes, you're probably the one to blame. I've had a pair of Valve Art EL-34 power tubes, and a TUNG-SOL A12X7 input and drive tube in since day one, which was 6 months ago. They both sizzle like the day I put em in, and remember, I like it loud and heavy!

Haven't had a reason to contact customer support.

I've been playing since I was 12 (10 Years) and I've played Marshall 2061X, Orange AD 30, Dr. Z-28, Hi-Watt Custom 20 etc. and the only other amp that compares in tone is a Bad Cat 30 watt class A. But if you'd like to pay about $1000 less for the same quality, go THD. The only thing I may be frustrated by is the fact that this is the Pandora's Box of amps. I may go 30 years before finding the right configuration of tubes, but it's the last Class A amp I'll ever buy!

Single channel hi/lo input. Effects loop. Built-in Hot Plate Attenuator. Noise Reduction. A little more than I usually like in an amp (The more stripped down, the better!) but EXTREMELY easy to dial in. Instructional pamphlet also very helpful! TWO features absolutely blow my mind. FIRST, you can run up to a 2 OHM load! Awesome. But secondly, and MOST importantly, the amp is automatically biased, which means you can plug almost any tube you like into it, in any combination! This amp has a maximum output power of 30 Watts Class A, and can out-perform almost any 50 watt Class AB amp in my opinion. I usually use it paired up with a Marshall 1960A Lead 4x12 cabinet, in conjunction with a SOVTEK Mig 50 paired with a Marshall 1960B Lead cabinet. The SOVTEK takes care of the lows and mids, but the THD adds to the lows, and cuts through with the highs. Well done!

I play a Gibson Les Paul special, loaded with an active EMG 81 & 85. This guitar paired up with aforementioned configuration produces what I call the 'bikini effect'. A great hi-lo blend. Very 80's metal. However, I also use a 1972 reissue Fender Telecaster Deluxe, which uses 'wide-range' pickups, which give me all the mids, lo's or hi's I need, depending on the pickup selector. This amp is exactly what I needed for my sound. Very little noise, depending on which tubes you are using. The lo input gives you creamy, smooth bluesy tone. The hi input gives you an edgier, more aggressive tone, and breaks up around 5 or 6. I love the natural overdriven sound of this amp, and use no overdrive or distortion pedals to achieve a very heavy, crunchy overdrive. If you want to hide all your mistakes with this amp, don't count on it. This overdrive is very 'true' and will let you know when you screw up, but will tear the faces off your audience when you nail that solo. Just to lgive you an idea of what kind of music I play, I'll give you a hint: I'm tuned B standard, dropped to A. If you love heavy strings, but can't achieve a bright tone, this is your amp.

This baby comes equipped with a full steel chassis. It's a little heavy, but there's a good chance it would survive a fire or a 20 foot drop. Heavy duty. As far as electronics, I have not had a single problem yet. Because the amp is auto-biased and can handle a variety of different tubes, there is also a hi/lo voltage setting. So if you're going through a lot of tubes, you're probably the one to blame. I've had a pair of Valve Art EL-34 power tubes, and a TUNG-SOL A12X7 input and drive tube in since day one, which was 6 months ago. They both sizzle like the day I put em in, and remember, I like it loud and heavy!

Haven't had a reason to contact customer support.

I've been playing since I was 12 (10 Years) and I've played Marshall 2061X, Orange AD 30, Dr. Z-28, Hi-Watt Custom 20 etc. and the only other amp that compares in tone is a Bad Cat 30 watt class A. But if you'd like to pay about $1000 less for the same quality, go THD. The only thing I may be frustrated by is the fact that this is the Pandora's Box of amps. I may go 30 years before finding the right configuration of tubes, but it's the last Class A amp I'll ever buy!

Single Channel, 2 preamp tubes, 2 power tubes in any combination. Volume, Treble, Bass controls, hi-cut switch, low and high gain inputs (using one or both sides of the first preamp tube)Multi-tap output transformer, effects loop, line out, Hi-low power switch, and built-in speaker attenuator. Actually alot of features!

This amp is very sensitive to different guitars, pickups, and speakers, to say nothing of tube types. You can vary the sound any way you like and it will always be musical due to its class A configuration. I've found my best signal path to be Barden pickups in a strat with a Warmoth Boat neck and Callaham bridge block and saddles, using a KT-88 and KT-77 power tubes, with 5751 and 12at7 preamp tubes with the high gain input. The amp goes into a 1x15 mojo cabinet with a EVM-15L. This amp goes from clean to driven with the turn of your volume knob, with the ability to get all shades in between. Getting musical even-harmonic feedback at will with the guitar volume knob on 4 and the sound relatively clean is unattainable with any other amp i've tried.

Built very solid, parts are outsourced to the same firms that make parts for Boeing I hear. I carry extra tubes but that's all. So far so good

extremely friendly, helpful, and best of all, AVAILABLE!

I've played 22 years, used all kinds of old and new amps. This amp is in a class truly by itself. The purity of sounds has almost eliminated my need for any pedals. The only drive pedal that doesn't take anything away from the amp's tone is the Klon Centaur, so I still occasionally use that.

Single Channel, 2 preamp tubes, 2 power tubes in any combination. Volume, Treble, Bass controls, hi-cut switch, low and high gain inputs (using one or both sides of the first preamp tube)Multi-tap output transformer, effects loop, line out, Hi-low power switch, and built-in speaker attenuator. Actually alot of features!

This amp is very sensitive to different guitars, pickups, and speakers, to say nothing of tube types. You can vary the sound any way you like and it will always be musical due to its class A configuration. I've found my best signal path to be Barden pickups in a strat with a Warmoth Boat neck and Callaham bridge block and saddles, using a KT-88 and KT-77 power tubes, with 5751 and 12at7 preamp tubes with the high gain input. The amp goes into a 1x15 mojo cabinet with a EVM-15L. This amp goes from clean to driven with the turn of your volume knob, with the ability to get all shades in between. Getting musical even-harmonic feedback at will with the guitar volume knob on 4 and the sound relatively clean is unattainable with any other amp i've tried.

Built very solid, parts are outsourced to the same firms that make parts for Boeing I hear. I carry extra tubes but that's all. So far so good

extremely friendly, helpful, and best of all, AVAILABLE!

I've played 22 years, used all kinds of old and new amps. This amp is in a class truly by itself. The purity of sounds has almost eliminated my need for any pedals. The only drive pedal that doesn't take anything away from the amp's tone is the Klon Centaur, so I still occasionally use that.

The SN is 220, I bought it new from Corner Music in Nashville, TN but it looked like it had been there for some time. I play heavy praise and worship music and also am a closet 80's shred fan,kind of shows my age. Because of the music I play I have to have an amp that goes from pristine clean to grinding metal. I have been on an amp quest for some time, I was really wanting to buy a multi-channel amp, which this one is not. But when I tried it out in the store I was hooked on the tone and versitility of tube swapping. When I got it home where I could really strech it out I was amazed by how loud it was, Class A amps are deceaving with their power ratings. I have a Marshall 4X12 cabinet loaded with Celestion V30's. I loaded the head with 2- 12AX7C9 Chinese preamp tubes and JJ KT88 power tubes and MAN! what a tone. This was a harmonic rich, air pushing low, beautiful singing tone that was breathtaking. Be advised though that this was power amp distortion and not buzzy preamp distortion and every little nuance of your playing will be heard. As you roll off the guitar volume knob the beast settles into a purring kitten. I wish I was quick enough with the volume knob to use this as channel switching because the tone is so sweet I hate using any other head! Well I'm sure going to practice try and find a way, I've even been thinking about buying another head and setting up for just a clean sound even though I can't afford to. Sounds like every other tone junkie I'm sure!

Man, this is where this head shines. I've tried so many different heads and there was always something about the tone I didn't like. It seens like no matter what tube combination you use, the sound is cool, but there are some that I like more than others. Of course as stated above the KT88's were my favorite sound followed closely by Tung-Sol 5881's. That's the beauty of this amp with just a few simple tube swaps you can dial in your own custom tone. I have several different guitars I play through the amp : Gibson Les Paul Classic w/burstbucker pro pickups, Jackson Dinky w/ Seymore Duncan 59, Ibanez RG550 and RG560 both with Seymore Duncan 59's. Even thouht the last 3 guitars have the same pickups and Floyd Rose Tremelos they still all sound a little different because of the different type of wood used in the body and neck of the guitars. Be advised that some people are not going to like class A amps, They are very much in your face. If you like the sound of a buzzy Mesa type preamp distortion you may not like the sound of this amp. If you like power amp distortion dripping with harmonic overtones this is the amp for you.

It's new and I haven't had the chance to gig it yet, however, by looking at the quality of construction I would be confident to only bring some extra tubes. The head will even continue to play if one power amp tube blows and it has lights on the back that shows you which tube is bad.

Here is another reason I am so excited about this amp, The amp had been sitting in the store for so long the original shipping box, owners manual, and warrenty card, had been lost. I got their number off the website and called to register the amp. I contacted Ed De Genaro of THD and told him I had just bought a THD amp and before I could tell him why I called, He thanked me for buying one of their products! How many times has that happened when dealing with customer service anywhere? He answered all my questions and treated me like a rock star, I wish all companies were like this!

For the price I payed this amp is an increadible value. Like I stated above I was looking for a multi-channel tube head and played several in the store that sounded good but I kept coming back the one head that sounded GREAT! No channel switching, no MIDI, no reverb (except for the natural reverb it makes with voume!)But tons of pure addictive tone!

Save your money, sell your car, get a loan. Do anything you can to get one of these amps. They are special.

I am blown away with the sound of this amp. I have a couple of vintage Fender tube amps that sound good but doubt if I play them much anymore.

Just bought it. We will see.

Just bought it. We will see.

Buy one.

The previous reviews set forth accurately the cool features of this amp. I received my first Bi-Valve three weeks ago and liked it so much I had Musicians Friend ship me a second one. A second channel would be nice, but one can't have everything in a Class "A" amp. I like blues and hard rock which this amp can more than deliver.This amp is very quiet with good cables. Because of the mix and match possibilities she gets a 10.

The Bi-Valve is a tone monster and can be used for almost any style of music. Could probably be used for metal with the right trash in front of the pre-amp. I decided to get the second amp to use as a channel two. I'm using a Keeley/Framptone amp switcher which works like a dream. The Framptone is quiet and does not color the sound. My first amp is loaded with Groove tube GE 6L6's while the second has Groove Tube EL34M's. Im getting the best that each tube has to offer. Im running these amps through a Mesa Road King 2x12. I get an airy and open tone (6L6s) with the "open back" side, and a tight and responsive tone(EL34's) on the "closed back" side. The attenuator allows for some great power tube distortion. The choice of inputs (more/less), power level( hi/low),attitude control,tubes (preamp/power),and attenuator settings open up a new world of tinkering for tone. My Gibsons sound great as do my Fenders. The amp is quit powerful and has no trouble pushing a four ohm Road King 4x12 cabinet. With the full power settings the B/V can get quite loud.

Just got-em so I have no real basis to evaluate. Seem to be built like the proverbial brick !!!!house. I would run-em without a back-up.

My first amp came on a Friday and was missing the power cord. I immediately called THD and advised of the situation and they mailed me a cable the following Monday. They only asked me for the amp's serial #. I Received the cord on Wednesday. The warranty is two year, transferable. I have E-Mailed questions on three occasions and received responses from Ed DeGenaro w/i two or three hours.

Been playing on and off for fifteen years. I own some Boogie gear
(Road King, Stiletto, Lone Star Special) and a Marshall JCM 900.Have various Gibson and Fender guitars. The Bi-Valve has its special place in the collection and cannot be duplicated by my other amps except, possibly, in some areas, the L.S.Special. This amp is too cool. On its face the price may seem high but you wont mind once you try it. If I got ripped off I would damn sure replace the Bi-Valve.

Rock-On!!

THD BiValve 30 Watt Head Single channel amp, hi and lo inputs with a significant difference in volume between them, bass, mid and high frequency eq controls and attitude control to adjust the tightness of the sound being fed to your speaker cab.

The amp also has a high and low voltage plate switch that works great to allow for different tones from the same tube combinations and a built-in hot plate attenuator, which, for me, is a fantastic feature, since it allows me to use the amp for low volume/high tone practice at home. FInally, there is a light bulb feature for noise reduction, which also works really well.

But the one thing that sets this amp way apart from the rest is the fact that it's 100% self biased and allows you to use any power/preamp tube combination under the sun! All these features provide you with a real tone lab and, most importantly, a W I D E road to finally find your tone! Two big thumbs up on features!!!

All in all this amp is built like a tank and constructed very well. I bought mine used on ebay and had it shipped from the US to Italy, where it got "lost" in customs for a couple of weeks - no problems whatsoever - the amp sounded great from the day I got it and it just gets better and better everytime I play it.

In just two words - SIMPLY AMAZING!!! There is apparently no limitation to the variations of sounds you can get out of this amp, except for metal, which requires you to plug into a boost or distortion pedal in front of it. Aside from this, this amp can deliver just about any sound you want.

This amp is extremely touch sensitive. Any change in attack is noticed immediately. It is also very transparent and, no matter how hard you drive the tubes, your guitar's and playing style come through it clearly.

SInce it's a single channel amp, one of the things I had to get used to was to control the tones from my guitar's volume knob, but after about a week of playing, I cannot imagine going back to channel switching.

The amp is extremely quiet, even at full volume on high input, thanks to the light bulb. Without it there is a little hum, as well as when using single coil pick-ups, even if they're hum-cancelling.

I play mostly blues and classic rock, but go to hard rock and some modern metal once in a while. For the latter tones, I'm currently using a Fulltone Fat Boost in combination with the boost feature on the Radial Loopbone and it works really well for me. The tubes are JJKT77 and JJ EL84 in the power section and JJ ECC803S and JJ ECC83S in the preamp section. I use the low voltage switch and it works just fine for me.

Built like a tank. No problems whatsoever!

Ed De Genaro is the greatest guy when it comes to your questions. I've e-mailed him several times to ask questions before I bought the amp (when I was reviewing it here) and after to ask questions about the amp itself and other products to go with it. He always answers the e-mails, usually from one day to the next and he's a great guy to talk to.

Together with Tom Anderson (Roy and Co.), other companies should take note of how customer service should be done!

Fantastic value! It isn't cheap by any means, but it's worth every penny and all the wait to get it. If it was stolen, I'd get another one.

One word of caution and, actually, confirmation of a few of the reviews I've read here: be prepared to spend some bucks on tubes, as you will go nuts experimenting with them. I'm still buying tubes and I'm sure I will be for a while still...but it's a great and rewarding experience, since everytime you get a new type/brand and put it in, it's like getting a new amp or for sure a new variation.

Have fun!

I'm sure you've read in the other reviews the greatest feature this amp hold. The ability to put in almost any tube combination you want without having to rebias the amp. Just plug and play.

On top of this the amp has a very cool and modern look about it.

It's a 30 watt one channel monster. Many people might be put off by the fact that it doesn't have the ability to switch between two channels. I would suggest getting a pedal or if you are crazy like me, get another head and ABY them. Currently I am running the THD through a Hartke 410 cab with a VHT 212 cab. I have a Fender Prosonic head that I am running through an old Hartke 412 cab with celestions. With the ABY I have the ability to switch between the amps or play both of them at the same time. This on top of the tube switching capabilities allows me to have a multitude of sonic abilities. Let me tell you, when I run both together, oh my god, pure molten lava comes out.

Another cool thing about this amp is the hot plate power attenuator. This allows you to squash the signal and get the right amount of saturation on your distortion at whatever volume you play at. Many people say it affects the sound in a bad way, but I don't think so. To me it sounds great.

Even though this thing has only one channel, you can switch the tubes, cabs, and guitars to get ANY sound you want if you only take the time to experiment. This baby is a sound scientist's dream amp. Currently I have tried only one tube combination: 2 Groove Tube 6l6 and 2 Groove Tube 12ax7 tubes. It sounds fantastic. The distortion sounds great and is not too saturated allowing all of the notes to ring through. This amp will surely show you the flaws in your playing as you cannot hide behind saturation.

This baby will get plenty loud. Without using the hot plate I cannot get it over about 3 when I am practicing with the band, so I find it difficult to get a lot of distortion without using the hot plate, although I'm sure if I did some tube experimentation I could.

The guitars I use include the following:

1970s Gibson double customized Les Paul Custom with three pickups
1990s Gibson Nighthawk Special with three pickups
1970s Gibson Marauder
1994 Epiphone Les Paul standard (soon to be customized)
Early 90s Wayne's World Ltd. Edition Squier Stratocaster
2004 Dean Exotica Accoustic

All of these guitars sound great through this amp.

This thing is like a tank and very heavy. I have yet to gig out with it so I can't say how reliable it will be when I start. So far I have had no problems.

This is where THD really shines. If I could give them a 20 in this department I would. I emailed Ed Deganero multiple times about the amp a I received a response every time within a couple of hours. I needed some cleaning tips and the manual(which he promptly emailed). One time he even called me at my contact number no more than 5 minutes after I sent an email so he could talk to me directly. I asked him some questions on speaker impedance and how it relates to the amp. Technically I wouldn't think it is his responsibility to explain this to me, but he did so in such an efficient and personable manner that I nearly couldn't believe it was actually happening. I have NEVER received customer support of this level ANYWHERE! These guys are great and will do anything in their ability to make sure you are fully satisfied with their amp...and trust me, you will be.

I have been playing seriously now for about a year or two and I can't say enough about this amp. If it was ever stolen I would certainly buy another one without any amount of hesitation. To anyone who is looking to get a $2500 head, do yourself a favor and pick up one of these instead. You will be glad you did.

The only thing about this amp is the fact that it's hard to find in a music store unless you live in California. I took the word of these reviews and bought this amp without ever having listened to it in person. There are some sound samples on www.thdelectronics.com that are good, but depending on your speakers it is nothing like hearing this baby in person. I am so happy I took the chance, it was well worth it.

2004 - Versitile Yes with able to change tubes without re-bias, single channel class A, the amp is extremely loud for 30watts. Excellent for rock. Takes to good foot pedals with the best. Features are covered in other reviews.

Guitars - PRS McCarty; Swamp and fender american strat. The amp has the cut-through in a multi-guitar band that you need. It does require a cabinet loaded with good speakers. (vin30 and g12h30) If not it will sound thin and harsh. I use a boss noise supp., so noise is never a problem. The amp does not have a great deal of gain, even at full throtle. I use a H & G Tube Factor for more gain. However it will kick your ear-in-the-butt at max vol. Think of a Marshall Plexi with class A attack. Your chops better be up to power.

I've owned the amp for 2 years with no problem. No backup. However I own or have owned over 30 amps in my 20+ years of playing this one rates with the best.(TopHat,VoxHW,Hughes ect...)
uilt like an anvil.

Andy was great to deal with. I highly recommend if this is your kind of Tone...

20+ years of R & R, I don't think you could go wrong with the THD-Bivalve. Solid in all areas.

Got to start by saying univalve.net is a fantastic site for THD users, don't talk to THD before you visit this dedicated web site for THD heads. A great bunch of players and answers to every imaginable question THD and more...

Features, everything I need.... took some getting used to the unique THD features such as Hotplate, Attitude & unique EQ response. But very versatile and sounds that are everythign they've been described as.

I am posting this review after 16 months of ownership... so I think I am across what it can do now... : )

Using '92 Les Paul & Custom Tele with SD STK1 & Lil'59,
Good for country & western music.. lol.. Rock, roll, not a high gain monster... pure pedigree with attitude...

It's a brick... all quality here people, streets ahead of the pack on this aspect.

THD are second to none in service... irrespective of what a stray comment on this site may say. Go to univalve.net to get an idea of what I am talking about.

Yes I have had an email that they did not answer on day 1, but they are busy, busy. I rang 'em and persisted and they went out of their way to help me.

I ordered a 240v conversion kit - unreal support.... direct from Ed DeGenaro (serious pro by all measures - helping lil' ol' me get sorted - what a guy!). Too easy!

Killer...

I am not sure of the year, this is a single channel tube amp. I love it. It has everything and more than I need in an amp to play in a band situation. It isn't a fancy amp other than how versatile 1 channel is. The tweakability is where it is at.

Thinking that most amps with 2 channels lose something on the way, I am giving this amp a 10.

I am playing a Peavey Generation Series 1 guitar with a duncan distortion in the bridge and a classic strat pickup in the rear. I run this through a wah, and I run a DOD bifet preamp in the loop for solo boosts. The amp is quiet so far, I swapped one of the 12 ax7 out for an at 7. It sounds less preampy. I am runnin this through a Z best cabinet which more than beats the competition.

The amp gets a nice distortion that can be cleaned up nicely with the tweak of a volume knob (on your guitar). This is of course if you are like me and prefer a less preamp gainy tone.

Otherwise you can use whatever tubes float your boat. I am fairly new to this and haven't experimented too much, but my bet is that BRUTAL DISTORTION is available depending on your tube selections. Like 2 12 AX7 and some KT 88's!!. I think this amp can get most tones pretty close. EVEN brutal!! It has USABLE distortion not muddy. Keep in mind your speaker cab plays into this as well.

I have no opinion YET!!

I emailed Ed Degenero and he was nice and helpful.

I have been playing 25 years. If it were stolen or lost I would get another one. I love that this amp is completely your own beast. You can do with it whatever you want tube wise. This gives it major appeal. But not to be forgotten, this amp sounds great. It is hard to make it sound bad actually. The tonal controls are very usable and very sensitive. I have stopped looking for tone after finding this amp. This amp gives me so much satisfaction I cannot explain in this box!! Anyone spending $3000 on a boutique amp should be looking at buying 2 of these!! The distortion is so usable and musical sounding. Even at brutal distortion levels (which isn't my thing) this amp sounds very clear sounding with the right tubes.

As listed already, but basically:
30-Watt Class-A, Single Channel Amplifier head
Built in THD Hot Plate
Effects Loop, Line Out w/Level Control
Hi-V/Lo-V Voltage selection
2 Inputs More and Less (only 1 can be used at a time and you can't A/B them)
Best Feature: Change Pre- and Power-Amp tubes endlessly to hone in your sound.

This amp pretty much suits my needs perfectly. Most off the shelf amps have some good tones, but none of them really are "me." While,
I'm still experimenting with different tube combinations I'm getting much closer to the sound I want.

The only feature I wish this amp had would be the ability to A/B the Hi and Lo inputs, making it a quasi-channel switching amp.

Sound is very subjective, but this amp is getting me closer to the tone I am seeking. The ability to change the tubes to almost any type made is one of the best features and the primary reason I purchased this amp.

I play just about every style of music from Classical to Jazz and Country to Rock. This amp is very touch sensitive and dynamic. If you play sloppy through this amp, you'll get a sloppy sound, but play with some feel and good technique, and this amp will sing. If I have one beef with the amp, it would be when the Hotplate attenuation is active. If you crank the amp and play with some force, there is a noticeable, albeit brief, "sag" and dropoff in the sound. I've only experienced this with the HotPlate active, but I guess it wouldn't be an attenuator if it didn't attenuate the volume.

Playing through the More input will give you an edgy clean to a nice, smooth distortion. I'm not sure if you'll get metal sounds from this amp, but hard rock sounds are abundant. Again, depending on the tubes you use, you can get more or less distortion. The Less input is clean throughout the whole volume range, with maybe a slight edge at peak volume.

I use the THD 2x12 cabinet with this head and get some great low end with this amp. My guitars are a Van Halen Music Man, Fender Lite Ash Strat, PRS Rosewood McCarty, and a custom Tele with Seymour Duncan Phat Cats. All of these guitars sound great through the amp and each add their own character to the amp. One thing to note...my volume knobs on the guitars actually work! With a channel to switch to for leads, I've found this amp to be very dynamic in responding to volume settings on the guitar.

I'll give it a 10 because it's been rock solid, although I've only had it about 1.5 months.

I sent an email to THD regarding tube specs and performance with the amp, but never got a response. Not a huge issue, I was just looking for some extra resources on tubes.

I've been playing for 17 years and gone through my fair share of gear. This amp is one of my all-time favorites. I really feel like this amp allows my personality and style to show through. So far, I've only used EL-34's in the power section (I swapped the stock ones, which weren't as "alive" as the Groove Tubes), but will eventually try some other styles of tubes. Also, I put a 12AU7 in the Driver position and it really cleaned the preamp section up (I favor Power amp overdrive more than Preamp distortion).

I looked at the Mesa Boogie Lone Star and Dual Rectifier, some Traynor amps, B-52, Vox, and Dr Z before choosing this amp. I think the allure of tube swapping really grabbed my attention as the other amps did not allow customization of the tones as much.

Really simple...No boost, no reverb... More and less inputs, high-cut switch, 2 speaker outs with selectable impedance switch, effects loops w/ effect out level control, bass, treble (no mid), volume, attitude (shapes the distortion character), high/low voltage switch, built in hot-plate attenuator, noise-cancelling circuit w/ a really cool red bulb reminiscent of old Fender amps...and the best part...complete tube swapping freedom without ever having to bias! I give it an 8 for versatility just because no mid, no channel select, no boost, no reverb, etc.

I've owned this amp for about 4 months and I've played Strats, teles, 'Pauls, an Ibanez semi-hollow, even my acoustic guitar. This amp sounds sweet no matter where it's set at and is perfect for just about everything you could think of. It doesn't do the Mesa thing though...But it does give you amazing tones. Lots of harmonics...My favorite settings so far are an EL34 and a Mesa 6L6 together and a 6550 and an EL34 together. The 6550 gives it a slightly darker sound that compliments my Tele AWESOME! I run the volume all the way up, the attitude about 2 o'clock, bass at 2 o'clock and treble at around 10 o'clock. It gives a sweet, complex, dark and rich sound.

Built like a tank, I've gigged with it quite a bit and it never gave me any trouble. I've heard you can even use this thing to test good and bad power tubes (I wouldn't recommend it...but it's possible)

Dave at Avatar is an amazing guy to do business with. He sells awesome products and backs up everything he puts out the door. I know he along with Ed and Andy at THD would rapidly take care of any situations should they arise. Ed promptly answered every question I had about this amp.

I've been playing guitar for about ten years now and I'm by no means a master, but I know good quality and good sound when I find it, and this is it. If you are a cheese-head who's idea of good tone is the volume and gain pushed past 11, this ain't your amp. But if you are looking for an amp that will let you find your sound, this is it. I played Vox AC30s, high end Marshalls, high end Fenders, Mesas, etc., and could not find the "sound" I had in my head, until I took a chance on the BiValve. I would replace it with 2 more if it were ever lost or stolen!

Serial #0665...not sure what year that equates to, but purchased new from Dave at Avatar Speakers in July 05. Check out http://avatarspeakers.com/ for some great prices on THD & Avatar Speaker combinations. Regarding features, this amp could not be simpler...single ended, class A, treble, bass, no boost, no reverb, not even a midrange eq. The beauty however is the engineering on the inside with the ability to mismatch power tubes...even run on a single power tube. The built in THD Hotplate is a plus when set at 12:00 or higher but tends to over-compress & choke the tone when set at quieter volumes. The full-power switch bypasses the Hotplate entirely for the best no-compromises tone. A Hi/Lo voltage switch lowers the voltage from 450-470 plate voltage to 300-320. Lower voltage produces warmer and more spongy character...and, maybe even more importantly, to use the great old 6v6, 6k6, etc tubes from yesteryear that can't tolerate high voltage of most amps. The "light bulb" feature reduces hum somewhat but I find that I rarely use it...at least not at reasonable volumes because it seems to take a little of the shimmer off the tone...but this could just be in my head. The "attitude" control operates like a subtle drive control, making the overall tone more aggressive. Two inputs "more" and "less", as the name implies offers the choise of a hotter vs lower gain input. I find myself using the "more" input exclusively and using the attitude control to put some "hair" on the tone. A dummy load allows you to unhook the speakers for direct recording, but you'll need a cab simulator or you'lll get some pretty funky tone. All things being equal, this design is a thing of beauty!

I'm primarily a single coil guy...my primary guitar is a Warmoth VW set up like a strat w/ a killer Rio Grande Muy Macho set (Stelly, Muy Grande, Muy Grande)and flame maple top & maple neck. The combination of the beefy Rios and the bright flame maple top & neck make for a very balanced tone and sounds incredibly "3D" thru this amp. Right now, I'm experimenting with a Boss VF-1 multi-effects in the EFX loop with great results, but even without the VF-1, and plugged straight into the "more" channel, the #2 & #4 positions it give off an almost "chorus-like" high-end chime...very satisfying.

I've not gigged with this amp yet, but I'm pretty OC about stuff breaking...I'd bring fuses, tubes and a Digitech modeling pedal to plug into the PA if all else fails. That said,it appears that Andy Marshall and his crew are also OC about building a bulletproof amp...I have no doubt that this amp will survive whatever I can dish out.

Ed DeGenaro at THD is a guitar player's guitar player and the nicest guy you'll ever email. THD's has a reputation as a company that spends the $ to make the very best over-engineered product out there and then stand by it religiously. It was the tie-breaker in my decision to buy this amp sight unseen, based soley on the MP3s and the Harmony Central reviews. They exemplify the saying, "...if you don't take care of the customer, somebody else will".

I've been playing 35 years blues/rock, roots, and stright up rock...and is influenced by guys like Jimmy Thackery, Bugs Henderson, Johnny Winter, David Grissom, Gary Moore, etc, and this, IMHO, is the perfect amp. I've no doubt that, with the right distortion pedal and a closed back cabinet, you could go for any modern tone. The bottom line is that I can not say enough about this amp, other than this is the most satisfying purchase I've made in 35 years...it's simply the best amp I've ever owned. I'll still pick up a stomp box here or there, but my search for basic tone is over.

Read features below. The only 2 I cared about when buying it were

1) Class A
2) Self Biasing

The built in Hotplate is Ok, but I seriously doubt it will get used much. I thik the THD Hotplates are inferior to other attenuators, including the Dr. Z Air Brake. But that does not detract from the amp being exactly what I was after.

I always thought the Bogner XTC in the blue channel with the Class A option engaged was the best tone I had ever heard. Tight and punchy, with tons of sweet crunch tone that was like ear candy. Well, this amp with a tube change sounds as close as you can come at less than 1/3 the price. I like Plexis, but I also love the harmonics of a Class A amp. The BV gives you both, but be prepared to work a bit with the amp. In the LV (low Voltage) mode the amp is thicker sounding, but not as quick off the fretboard. The brown sound is found here, and the volume is lower. I like the higher voltage sound, as it is punchy and quick and much more suited for the classic rock I play. Big crunchy chords and stinging Zep type leads. Great stuff.

You will end up swapping tubes until you go mad, unless you first take a step back and see that the EL34s it comes with sound excellent themselves. A tweak here and there, and they will do any Marshall sound in the book except metal. Power tube distortion is what it is all about. The BV sounds great.

Not much to go wrong, but stuff does happen. THD is as good as any amp builder.

They always answer Emails ...

Just what I was looking for. I will go down the tube swapping route, just to see what is out there, but I got excellent tone right out of the box. I love a huge plexi crunch sound, and this amp delivers that with lots of Class A overtones thrown in. Leads are easier in the Low Voltage (Van Halenesque) setting, and 80s metal players will like playing in that territory. The built in Hot Plate is cool, but I will never use it. This is a great amp for the money.

Features have been rehashed ad-naseum in the many reviews below; all tube class A single channel head. Classic, straightforward design with a few twists. Used at home for practice and some recording. Plenty loud!

I use this amp mainly with my Strats. Cab is an Avatar 2x12 with Eminence Private Jacks (Greenback clones). I play bluesy rock, heavily influenced by Deep Purple, Jimi, Robin Trower, etc. Perfect for what I like to play. Just for fun I plugged my Jackson with EMG's in last night - it was just plain creamy! This amp will take a wide variety of tubes, so it is a tone tweakers dream come true. I am currently using a 12ax7 in the pre, a 12at7 in the driver, and an EL34 with 6L6 combo in the power section. This tube combo delivers what I'm looking for; the guitar just sings, and this is with the volume at 1:00 using the attenuator. Harmonic overtones galore, natural tube compression. Roll your Strat back to 7 on the volume, and you will nail Blackmore's tone on Machine Head. I've never played through an amp that was so sensitive to the guitar's volume knob. That's one of my favorite things about it. Works well with my pedal collection. I don't use the effects loop (call me old school). Clean input (called "Less") I don't use too much. Nicely balanced tone, no icepick highs, punchy, articulate, touch sensitive. Best amp I've every played through, and I've been playing since 1975. I bought this amp without having played through one first based on the reviews here at HC, as well as the cult-like following on the THD online forum. I was not dissapointed in the least. Fantastic sounding amplifier.

I've only had it for a couple of weeks, so can't comment too heavily on reliability. However, it is built like a tank. Loads of steel, weighs a ton. I don't anticipate any problems.

I've emailed THD a couple of times with questions, they answered me promptly. I only live about 40 minutes away from their shop, so they gave me an open invitation to bring the amp down anytime for any reason. How cool is that?

I bought this amp on Ebay and got a smokin'deal, as it was brand new in the box. It was part of a music stores overstock sale, and they goofed and put it in the wrong category, so nobody was bidding on it. I was expecting to drop over a grand for one. I've been playing since 1975. I mainly play Strats, however I do have a couple of humbucker equipped guitars when I get into that mood. Pedalboard with the classics, wah, fuzz, OD, Univibe, etc. Love the tones of Blackmore, Hendrix, Trower, Schenker. With this amp and my pedals I can do all of those and more. If it were stolen or lost I would replace it with the same amp. I was considering a Dr. Z, but the ability to swap out tubes in the THD was too good to be true. I can't imagine anyone owning one of these and not being able to nail their dream tone after some experimentation. The only thing I wish you could do is A/B between the two inputs. I've owned many amps (Fender, Marshall, Peavey, Roland) and none have come close to this one. Even tried one of those modeling jobs for a couple of years.... nope! There is nothing like being able to control the gain with just the guitar's volume knob. It's like having 5 different overdrive pedals under your little finger. Kick on the fuzz, and it will nail Jimi's tone on Spanish Castle Magic. I could go on and on. Just buy one, dammit!

What can you say about features? It is a one channel amp, kind of old school and has to be driven from the guitar. These are definitely not bad things we just arent used to doing things this way anymore with all these new multi-channel amps.

I play a Gibson Les Paul Elegant. I use this amp for kind of a southern/classic rock/ blues sound but just a little more modern sounding. this amp is as quiet as a mouse, I had a fender hot rod deluxe and it was pretty quiet but I have never played through and amp that was this quiet. I had trouble dialing in the right tone when I first got this amp but after playing with a lot of different tube combinations and learning that if you sit right in front of the speaker cab with the volume cranked any amp will sound harsh I think I found my tone. this amp can go from country brite and clean (with the right tubes- 6L6's or a 6L6 and an EL34)to super hard rock overdriven to bluesy kind of Stevie Ray tone just by changing pickup selection and volume knob on the guitar. If you have been using an amp with a drive channel or a clean amp and distortion pedal you should be prepared to have to get used to this amp and spend a lot of time experimenting with it because you wont use this amp the same way that you used your other amp (I know this from experience)this amp is the most touch sensitive amp that Ive ever played Ive even put a compressor in front of it just in case I get a little heavy handed on accident (the les paul pickups are really hot)

So far ive only used this amp around the house and through one long cranked brutal recording session, will be gigging soon and do not expect any problems. Holds up wonderfully.

I wish that I could go better than a 10 in this category because these guys are top notch. I have contacted them on numerous occasions before and after buying this amp to ask questions and they are wonderful, they respond quickly and give helpful answers. This is definitely one of the best pars of owning this amp.

This amp is wonderful, I also have a 2x12 cabinet and I am totally impressed with THD stuff. I love the versatility and customer service. I really must stress that even though this amp is a simple one channel amp that you really do have to find its sweet spot and experiment with it. Also just like any other amp before you make a decision on its tone consider the room that you are playing in. I had trouble with tone in my living room (acoustics like a cardboard box) but when I played it in just a little more lively room it was awesome, now I am hooked. Feel free to email any questions about this amp.

Pure Class A Head. Can mix and match just about any combination of pre and power tubes. Built in Hotplate.effects loop line out etc. Just about everything that you'll ever need its right here. The ability to alter the gains of the pre tubes and changing between any combination of KT66/6L6/EL34/6V6/EL84(with a univalve yellowjacket)will help you uncover just about any amp tone I can think of. Its great fun too.

Listen up. This is without any shadow of a doubt, the best amp I have ever ever owned. If like me you have spent your time frustratingly searching out your the perfect tone and find that even with the big name amps and guitars and expensive boutique pedals that tone is just slightly out of reach, this amp will take you there and probably beyond. Its a strange feeling when you realise the search is over!! I also have a mesa tremoverb and heartbreaker, 2 old Marshall heads and a old vox AC30, but all don't quite give you the sheer excitement and feel of this amp. With my band, the Bivalve has revolutionised our recordings and our live sound.I use selection of stock 1990s gibsons and US fenders. Nothing vintage!
The touch sensitivity and way the guitar volume effects it is a revelation. Clean sounds are chiming and slightly compressed kinda like gilmour on shine on you crazy diamond, while the high gain settings well outstrip my marshalls and mesas with breath to spare. W(ith the occasional keeley pedal in front) It cuts through the band mix in a way that marshalls and mesas often dont. They sound good played alone, but add the band and they kinda get lost. The THD kills the dual recs hand down if you wind it up with a java boost or a fuzz head in front!

My first one developed a gradual sonic fault after about a year. The difficulty with such a perfect amp like this is that the slightest niggle is immediately audible. They said it could be a transformer issue. But get this...THD UK (Synergy) immediately sorted me out a brand new replacement and even had Andy Marshall contact me from the US to sort out what could be wrong as it is such a rare occurence.

My replacement needless to say is a stunning bit of kit

See above..Truly exceptional

THD (and Robert keeley and Z Vex) should give all other music companies lessons in customer care. They are the genuine article. I guess its because they are as proud of their products when they build em as we are when we play em.

I now have a THD univalve, bivalve, 2 hotplates, 6 yellowjackets. THD really do help me play my music and get that real sonic thrill that we all spend our lives and money trying to find. If you can play well and care about tone, I defy you not to sound and play even better through a Bivalve or univalve.
I know I sound like a THD rep, but I have genuinely stopped looking for pedals and amps in shops now the THDs and Robert keeley pedals are are here to stay...now as for guitars....

i bought this amp on ebay. i play in an original melodic rock band. amp does a decent plexi sound but is not as convincing as my cage amp. the features are decent. the thd atten. is a nice feature for some, but i hate the way it affects the tone. too many artifical sounding eq bumps for me. just a single channel amp. wish you could have the ability to a/b less and more features or combine both like an AC-30. plenty enough power. easy access to change tubes, but i like to retube and get on with it.

I play mostly solidbodies(les paul, guild, anderson cobra) with duncan jb's. the amp sounds are just not happening for me. not enough clean headroom just sounded very harsh and clacky on less. it was running through a bogner 4x12 with vintage 30's. the more channel was a little buzzy. i switched to lower gain preamp tubes and got better results but still the sound was not tight enough. i was trying to retire my jcm800 for a lower watt amp. i guess i have been spoiled. but with all the positive things i have heard about the amp i gave it a try. i love to dial in eq and i just could not get this amp to blow my socks off like everyone else.

was very reliable. you can definitely count on this amp in this department. never broke down on me and i played out with it 3 nights a week for 8 months, before i sold it on ebay.

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i have been playing for 23 years. i own a smf 30 watter, cage 18/00 series, marshall jcm800. used to own a mesa heartbreaker, ac-30, various fender combos, marshall heads. i would not say this amp is close to the amps i currently have especially considering the high price. my smf was $850 used on ebay and it's variety kills. the bv is a well made amp. reliability was never a problem, i just think people are so jacked that you can change tubes on the fly that they are wigging out. the atten. was worthless for me just did not like how it compressed the sound and re-eq'd my speakers natural sound. my overall rating is considering price tag and other amps in the price range.