THD UniValve Head

If you're reading this then you're probably aware of the Uni's features. The big selling points for me were the self biasing and the built in Hotplate. The only thing I really wish it had is a mid control.

I'm currently using an Avatar 2x12 open back cab with a Celestion Alnico Blue and a G12H Anniversary. Guitars: Tom Anderson Cobra, Suhr Classic, G&L ASAT Z-3. It's tough to rate the sound of the Uni because it will accept almost any tube. I bought this amp without ever playing through it knowing(hoping) I could find my sound through experimenting with different tubes. Seemed like sound logic at the time. The Uni is very sensitive to tube changes so be prepared to do some experimenting of your own before you find the sound you're looking for. I have 2 or 3 tube combinations that I really like and I pretty much stick to those now. So, the sound...the Uni sounds wonderful from clean to mild overdrive, no problem there. If you don't normally play with a lot of overdrive this is a gorgeous amp, definitely lives up to the hype in this context, BUT...when you crank up the volume to the point were you start getting some power tube saturation things get a bit fizzy IMO. I've been searching for a good tube combination for heavy overdrive and I've had some success, but the fizz is always there. If I try to dial it out with the tone controls it ends up too dark. I suppose it could just be the nature of a class A amp. Whatever the case, I just don't care for the way this amp sounds overdriven, regardless of the tubes being used. I'm not the only one who's experinced this, visit Univalve.net and you'll find a lot of threads on this topic. My solution has been to use overdrive/boost pedals with a low/medium volume setting on the amp and it works nicely, but only after buying some pretty expensive pedals; Xotic RC and AC Booster, Xotic BB Preamp to name a few. I'd also like to mention the Hotplate because this is a feature that I had high hopes for. While it does a great job of allowing power tube overdrive at bedroom levels the tone is pretty far from what the amp sounds like with little or no attenuation, a bit of a let-down. I can't blame THD for this though. It's my understanding that it's the nature of the beast when using an attenuator. Bottom line is this: From clean to mild overdrive I give the Uni a solid 8. Crank up the volume and I give it a 6.

It rarely leaves my studio so I can't comment on it's road-worthyness, but it appears to be nicely overbuilt. Very sturdy metal chassis and cover. Feels very solid.

Never dealt with THD.

Ideally you'll want to grab a few different tubes and take the Uni for a test drive before you buy. Unfortunately that's not always possible. Again, IMO the Uni sounds great from clean to mild overdrive, especially with single coils. If you need more overdrive for hard rock/metal sounds the Uni may not be for you. The ability to use just about any tube is the Uni's big selling point and for just under $1K it's a good deal. It's very nicely constructed and one of the best looking amps I've ever seen.

This amp was manufactured in 2001. The serial is I belive #308. It is extremely well-built, although light enough to carry around in the NYC subway!

It has two channels, but no channel switching, no effect loop, no headphone jack, but it does not need any of that.

As it is known all around the world by now, this amp has the ability to take any octal-based power tubes (it has only one power tube socket) without re-biasing and it also takes any type of pre-amp tubes (two pre-amp tube sockets).

This amp is for experimenting and playing around with tube combinations til you find what you like. And you will like more than one combination for sure!

If you get 'tired' of one sound, go and switch all the tubes, or switch one tube, or two or all, and you will have something completely different coming out of the amp.

The amp has -in addition to two inputs (Rock and Roll), a volume knob, treble, bass, and attitude (it changes the edginess of the sound and your attack against the strings), it has a built-in attenuator, a built in and very hip-looking noise-reduction system, and a voltage switch to use with the different power tubes. The eq (treble and bass) are highly interactive, meaning that the more you turn them up the less middle you will have, the more you turn them down the more middle you will find. So the middle frequencies are managed through the tactful interaction between treble and bass.

I would like to change nothing in this amp, nothing at all. It is just what I wanted and needed. Nothing more, but nothing less.

I play/record/produce experimental Latin Rock mostly, though I usually gig backing up other artists. The amp suits everything that I play and more.

The rock channel is for louder, edgier, noisier applications. The roll channel is for the quieter, cleaner, chimmier stuff. Both channels are ideal for recording.

15 watts of pure Class-A tube power is pretty loud! Don't be fooled by the wattage. 15 watts is not quiet at all.

I wish it had a volume/master volume setup to drive the pre tubes for more variety. I wish it had a effects loop, you would think a kinda techy, frilly amp like this would. The amp is light and quite nice looking, The hotplate works well at reasonable attenuation.

The roll or clean channel is nice and likes pedals a lot but it only achieves about half the volume of the rock or gain channel. I would have probably liked this amp much more if the roll channel had more headroom. The rock side is slow and spongey with not much headroom or articulation. Not at all plexi like. It's closer to a cranked tweed deluxe sound. I have owned many near top shelf amps in this price range, Marshall DSL 100, Fender Prosonic, Mesa MK3, 70's twin Reverbs, Traynor YBA1 Bassmaster. The Univalve is not worth any rave in the sound category for the price.

Honestly, if you want a great low to medium volume plexi rock tone at an affordable price, get the cleanest sounding, loud and punchy old {70's Twin Reverb, 60's Sunn, 70's Traynor, or 70's Ampeg) tube amp you can find. Then get a Tech21 Sansamp (original or classic only). Many guys also swear by the Roland JC120 with the Sansamp because it's a loud, clean and indestructable (solid state) amp. This is the best affordable plexi tone I have found and I've tried a lot of 700 dollar amps in the quest. Plus it's easy to put effects between. A plexi clone? no, but way, WAY better cranked plexi tone than the Univalve. No noise because high power is clean power, the powerful amp is barely even trying. The Univalve is sweating it's ass off thus noisy. The Sansamp will provide better articulation and rich harmonic tone, loud or at TRUE, whisper quiet bedroom levels. Just try it, SAVE YOUR CASH, you'll see.

Did not have any problems.

I will never buy another THD amp. I tried it, it's nothing special for the price.

single-ended EL34 amp with built in attenuator

I hear lots of people saying that the Univalve sounds like an old Marhall plexi. Crap. These people did not own a plexi....the Univalve sounds nothing like a marhall. A Marshall will give you an outstanding overdrive as soon as you start cracking up the master volume (a different thing than having lots of distortion in the preamp....the one I am talking about is power amp distortion,which is what a plexi is all about).
The Univalve sounded sterile and too clean to me ,with it's master volume fully up.
It has none of the dynamics of a plexi.
The people that say that this amp will 'reveal' your sloppy playing (if you play sloppy) probably did not own a good tube amp before,and were too busy with their Boss Metal Master pedal crap.

Something else that I did not like about the Univalve: when it's cranked up and the attenuator is engaged.the sound was sort of coming and going....sounded unstable to me.
Overall,the Univalve sounds a little too cold for my taste. There are other good amps around. I will get a cheap pignose g40-v and will pay a tech to have it converted to EL34 valves instead of 6l6.
As this amp is based on an old Bassman,(old Marshalls were based on that too,they say) it should be interesting.

The Pignose costs a lot less than the Univalve. I am getting it as soon as I can

seems well built,but then again,at the price it should be.

as I said,it is too clinical in the power amp distortion area,for me,too cold

You can use virtually any tube you know off and adjust a degree of gain treble, bass and attack as you please ...

It depends on your valves: 10 if they are outstanding, or 6 if they are bad or old or 1 if they are dead.

WARNING: THIS IS NOT AN AMP FOR BEGINNERS or sloppy players as it is like a superb hi-fi systema nd does not pardon sloppy playing or less than perfect gear.

Some people rated it poorly as they have bad guitars or bad cables or (very critical) used cheapo tubes or (almost as bad) low-rate speakers.

This amp revals THE Truth about your gear, sound and playing so make sure you have everything on par.

Sloppy players and beginners stay out - or buy Line 6 or Roland gear.

3 years no problem

Great people - great community.

I use it mostly as my tone pre-shaping unit and plug it into one of my numerous other amps. Still, Univalve is THE best and most versatile.

If you have $850 and you are a SERIOUS about your SOUND and if you have some GREAT guitars and CAN play well - then simply - buy one !

I purchased my UniValve new in 2006.

Cool features: Line out: use it in the "Power Amp In" of a Fender Blues Deluxe. Increases the volume and accesses the Fender's reverb. I've also used this feature direcly into my 1964 Bandmaster head: very sweet sounds!!! Attenuator: seems to compress the signal a bit and drops out some of the highs, this is actually a good thing and I often use it on it's highest setting (e.g. highest volume) just to tweak the tone.

Bummers: No channel switching: I like to roll the volume back on my guitar to get the clean sound, but the hi-gain input just doesn't clean up as much as I would like. Being able to switch between the two would be great. However, with a 6l6GC tube there is more clean headroom.

No reverb: I have an analog spring reverb unit, but the Univalve's hi-gain input blows the sound up so much that it sounds like I'm playing in the Grand Canyon, and yes, I did turn the reverb all the way down. It's either off or Canyon city. However, it works beautifully for the low gain channel. Shame on me for not dragging the reverb unit into the store to check it out. Is this the deal breaker? No way!!!

I'm using a 2002 Gibson Special Faded Les Paul with Humbuckers played through a custom made 2X12 cabinet with Celestion G12L 35 watt speakers. I play mostly blues influenced rock. I was looking for the Allman Brother's sound. It took me about a week of noodling to find it...well actually what I have is a lot nicer in my humble opinion. It's smooth and creamy, lots of sustain, a very musical sound: no harsh ear piercing sounds. I set the amp volume at about 10:00 (1/3 volume) and the guitar between 7 and 10. The high is set very low (between 8:00 and 9:00) and the low is mid-way up. When I set everything at 12:00 (that would be 5 on normal amps) it was just way to bright and harsh sounding. The "Hi" nob is very sensitive between 0 and 3 and less so between 5 and 10.

This amp gets some amazing clean tones as well. However, with the EL34 stock tube a good clean Jazz sound is tough to get at stage volume. In a crowded club the vocal noise will be louder. With the volume all the way up, the amp distorts slightly bassed on how aggressive one plays. This sound is amazing, and wonderful for playing blues.

The reverb thing is hardly noticable until you stop playing or play staccato single note riffs. Pulled a blind test with the guys in the band. None of them picked up on the lack of reverb and were stunned when I clued them in. Don't really know why this is the case, but I like the sound. My Bandmaster has a similar effect but a more elastic / spongy feel.

The easiest sounds to dial up are the 70's-80's metal tones. AC/DC, Zepplin, The Darkness. Right out of the box my wife's jaw dropped and she said, "Oh, my God, that sounds exactly like AC/DC." Very fun to play, and if you've been trying to get this sound with any amp that doesn't have EL34s, then you will be stoked.

Warning: use your ear protection with this amp, don't be fooled by the wattage. Even on the 5 watt setting this amp gets very loud through the high gain input. If you play metal with a drummer that likes to play hard, this amp will not cut the mustard. On the other hand, every time I turn my Blues Deluxe up enough to get that nice power tube distortion going, the club owners run over pissing and moaning that the bartenders can't hear the drink orders: not so with the UniValve!!!!!

Overall I am delighted. I am planning on purchasing a KT-66 tube, but beyond that I'm not sure I would want many more sounds than what I already have. When David Geffen comes crawling back and begs us to accept his offer, I will buy a Flexi-50...and a BiValve...and a....

I've owned the amp for a few months...so far so good. It's built like a tank.

Haven't had any contact and haven't needed any.

I've been playing for... let's see 37 minus 10, ouch 27 years, what a cruel question to ask!!
I also own a late 1980s PRS Custom 24 and a Mexican Strat, however, I play the Les Paul most of the time. The best thing about this amp is that it get's the most amazing sounds at volume levels that are more reasonable. I practice in the basement of our house at night on the 5 watt setting and the kids on the second floor never wake up. Mom can watch the inane reality TV shows and chat on the phone during the commercials. Everyone is happy. This is not the case with my other amps. Fortunately, I play with some very tallented musicians who are all well schooled in the Jazz and Blues genres. Listening to each other is highly valued. As a result, I really do have enough volume. We played one gig in a medium sized theater. I ran the THD through the Blues Deluxe for a little extra stage volume, but the mic was in front of the 2X12. I could hear myself through the monitors no problem...kudos to the sound guys. It doesn't always work out that way. Finally, I tried out some very expensive "boutique" amps prior to this purchase. Bang for the buck this amp is untouchable!!

THD Univalve, manufacturing year unknown, but the serial number is #1336. Rock/Roll inputs, volume, treble, bass, attitude standby, Hi/Lo voltage selector, noise reduction, and power attenuator controls are on the front face; line out, speaker out, speaker ohm switch, and fuses are on the back. Most notable feature is removing the heavy-steel cage and trading out tubes to your hearts content. Very hearty construction, but you won't throw your back out moving it around. 2 pre-amp tubes and 1 power tube controls your tone. I presently have an unmarked 12ax7, an old Mullard 12au7, and vintage RCA 6L6 in the power slot. Rock, blues, country, jazz, and everything in between sounds wonderful through this head.

Given the ability to re-tube without biasing your amp as well as very touch sensitive controls, this amp is fantastic. Ideal for direct recording and live use, but not necessarily a road warrior amp.

I play a stock '04 Fender American Deluxe Strat, an '89 Les Paul Custom updated with Duncan 'buckers, and a Gretsch Electromatic Hollowbody with DeArmond 2000k single coils. All of them have subtle nuances that the THD embraces and amplifies. No more "everything sounding the same" when I play!! So far, I've been very pleased dialing in clean tones with the Roll as well as plugging into the Rock input and cranking the attitude knob. While you can get very loud with this amp, the controls allow you to use the tone and volumbe knobs on your guitar (remember those?) to achieve a smooth, compact tone that is very enjoyable at bedroom volume. I am also completely in love with the built-in Hot Plate attenuator to play with overdriven tones without disturbing the peace. If you're into metal, you'll probably want to check out the Bivalve or Flexi to boost your wattage. Otherwise, if you can't find a tone you like with the Uni, nothing is going to make you happy.

My Uni was brought in from a local recording studio when they decided to downsize their inventory, but it was used to good effect while they had it. Based on the research I carried out before, everything THD puts into the amp is designed to be more durable than any other manufacturer; this covers the wiring, the body material, fuses, and the overall amp to ensure that it'll last. I haven't gigged with this, but you'd have to throw it from a moving car to even dent it. As long as you have tubes (Heheheheheh) and fuses in your toolbox, this amp should last you for years.

After I bought my Uni, I wanted to build my own 2x12 cabinet and thought about calling to ask if they recommended series over parallel wiring. Called THD, and while the tech guy wasn't immediately available, the guy I spoke with twice offered to call me back or have me e-mail him directly and he would pass it on. I managed to get the info I wanted, but if I needed THD support, I'm fairly confident they would back up whatever I needed. There is also a dedicated group of THD users who post at univalve.net that can guide you through everything THD-related. Worth checking out if you're thinking of buying one of these.

I've been playing for about 15 years now, and I think that this may be the only amplified head I will ever need again. My new addiction? Tubes! Seriously, I went from a hybrid combo and an all-tube Epiphone Valve Junior to a tube machine that makes me realize what I've been missing. Although my ears aren't as trained as they should be and my playing skills are a little lackluster, you can really appreciate the difference in dropping a 12au7 in the driver position. See? Three months ago, I would have had no clue what that meant.

I was looking for this amp for a long time, and never saw one around. By chance I wandered into a local store one day and saw it used for a good price. At first, I kept trying to talk myself out of it by telling myself it didn't have reverb, that I'd have to buy a cabinet, surely something better must be out there. After three weeks of mulling it over, I couldn't get the sounds out of my head. I even brought my own guitars with me to the store, and it was the best sound they had ever made. Suddenly, the doubts became strengths: build your own cabinet, choose your speakers and be in charge of your own sound. Reverb? Playing in a room generates it's own reverb, no? A great-sounding 15 watt, hand-built, all tube, American guitar amp head for a reasonable price? Why was I trying to talk myself out of that?!?

Like a British sound? Thrown in a EL84 and slap it on Hi voltage. Love your old Fender? Swap in a 6V6 and keep it on Lo. Want your own sound? Load up on some old tubes from eBay, send the kids to camp, put the dog in the yard and tell the misses that she really should treat herself to some new shoes and spend the day putting your own mark on your Univalve with your favorite guitar; I think you'll like it.

i tried it in my local shop, but bought used. i like it's simplicity on the front, and i also appreciate what it has on the back. i find it very versatile for what i like to do. mostly i keep it at about 2-5 o'clock and it crunches nicely on it's own, but absolutely comes alive with my pedal setup. i haven't owned many amps, and only 1 other all-tube but this is an extremely responsive amp. it responds to everything from the slightest knob adjustment on your guitar to any variation in technique. it's awesome, with some obvious limitations that are easy to get around if you need to.

i've got a stock 93 gibson sg std. i play fuzzy stoner rock type of sounds, and with my pedal rig it's amazing. on it's own it wouldn't cut it for everything i want to play, but that's what pedals are for. my cabinet clearly can't keep up with this thing sonically, so i'm working on getting the goods in that area as well. i have a 500watt stereo power amp to beef up the volume that will be a consideration when getting my new cabs, but even with my crappy 2x12 this thing with my rig has me in acid guitar bliss everytime i plug in. it can handle a huge variety of sounds, depending on your speakers. i go from high end painful screech to superbassy sludge mainly thanks to my main pedal, an EH Micro Synthesizer. This pedal is insane. I also use an EH deluxe memory man and for massive sustain and feedback possibilites i have a little t.c. electronic preamp pedal. this amp rocks.

it always works for me

no experience here, but from what i read it sounds good

I've played guitar for almost 20 years now. I'd get another one if i needed to, unless i decded to buy the bigger one. i love it.

Wow. Pretty simple amp. Only 15 watts :( Are you kidding me. This thing is LOUD. I can not immagine you running out of volume. The 3 tubes are self bias-ing. Great head room. The amp really cuts through. Sounds like a truck. Everything is clear....even with alot of gain.

Gibson Les Paul Custom '1975 and an ESP Vintage Plus with EMG's. This amp does not care. It makes whatever you have sound like it's supposed to.

Haven't had it long enough.

I love it. I bought it from Avatar speakers for $600 and also purchased a 112 cabinet with a Celestion Vintage 60 (Hellatone) speaker for a total of $812 delivered. Smokin' deal. Geat gear

This is 1-yea follow up review of this amp. The features have not changed, and I still love what it has.

I have purchased a veritable cornucopia of fine tubes, NOS GE's Sylvania, you name it, I know own them. I always run back to the stock GT6l6B. Although I do love many of the other tubes, the sound is VERY subjective. If you get one, you need to experiment with not only different power tubes but also the Input and the Driver tubes as they may a world of difference even with the same power tube. None the less, whatever tube I've run in it had it's bright spots with every guitar and on just about every setting. The only disappointment I had was a Telsa JJ6l6 (which I bought off ebay and it simply could be a bad tube). BUT...the sound....my god, clean and soft to dirty and wild. there is NOT ONE BAD AREA in this amp. I will say you may find the Hotplate to be a tad too compressive with bigger output tubes, 6550's and such. Solution, run 6k6 or 6v6's, turn the plate voltage to low, and don't run the hotplate...WOW!

I have not been abusive, but I have also not treated it like a baby. It's my work amp...I need to play it....I play it...I pack it...i play it..i pack it. It's NEVER failed. NOT ONCE! It's forgiving and doesn't complain. Good tubes on hand, I wouldn't worry a bit. I never take a second amp (Call me stupid-but i don't feel i need one).

Well as I predicted, THD customer support has been OUTSTANDING at answering EVERY one of my stupid questions. ED is like my long lost brother keeping me in line, helping me not make stupid mistakes with my Univalve and giving me extraordinary guidance and suggestions. AND GET THIS......My amp is not under warrenty since i bought it used, but I still get treated like I bought a 1000 of them! Good luck getting ahold of fender or marshall...Mesa Does return your calls and helpful, but not like THD. i get consise info from ED within hours of sending him an email. I'm Saving my money for the flexi 50 to add to my collection just so i have something else to bug ED about for another year! THANKS GUYS!

This is an awesome amp. I would not have it for my ONLY amp because sometimes you just need the AB push/pull thing or that old fender recto sound. BUT....it is MY MAIN AMP. MOST TIMES MY ONLY amp, and IF i was faced with getting rid of everything except ONE AMP, this would be the one i'd keep. I have friends who are marshall guys, but we agree that a band has to have diversity otherwise you just blend...they have not respected my choices in amps (mesa-legend-fender, etc), however EVERYONE LOVES MY UNIVALVE like I do.