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MF MD HG01 Electric Guitar Month 06-19-18

THD UniValve 15W Class A Amplifier Head

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Product 481282
Product Price $0.00
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The THD UniValve 15W Class A Amplifier Head delivers tones from smooth and clear to warm and full to aggressive overdrive. The single-ended Class A c...Click To Read More About This Product

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Tube-swap your way to a whole new tonal territory.

The THD UniValve 15W Class A Amplifier Head delivers tones from smooth and clear to warm and full to aggressive overdrive. The single-ended Class A circuit design uses the highest-quality parts and hand-built construction for clean and faultless operation.

The single output tube can be switched at will with nearly any octal-based power tube for different tones without re-biasing the amp, and the 2 preamp tubes can be switched for any combination of 12AX7, 12AT7, 12AU7, 12AY7, or 12AZ7 tubes.

The UniValve is easily capable of driving a 4x12" cabinet, yet is also small and light. Its built-in Hot Plate Power Attenuator lets you experience the indescribable freedom of wailing away with full output distortion at volume levels that are quiet enough to let your neighbors sleep.

There are 2 inputs”one for high gain and one for low gain. With 12AX7 preamp tubes, the low gain input gives a wide range of sounds from Nashville clean and crisp to Memphis down and dirty. With the controls pegged and a relatively high-output humbucker, the low-gain input delivers a tantalizing Texas blues overdrive. Plug into the high-gain input for a whole new world”from early British Invasion tones to modern high-gain metal attack”but with none of the mush and confusion normally associated with high-gain tones.

The controls include the traditional Volume, Treble, and Bass along with an Attitude control knob that determines how the driver stage responds to signal and how it drives the power tube. There are also controls for the Hot Plate, including a hard-bypass switch. The noise reduction circuit in the Hot Plate features a light bulb fixture on the front panel that glows when you play. There is an On-Off switch for the light bulb.

On the back panel the UniValve has a transformer-isolated line out with an adjustable level control and a switch to choose line-level or instrument-level signal. The speaker outs on the UniValve can drive any speaker load from 2 ohms all the way up to 16 ohms. When there is no speaker plugged into the speaker jack, the amp uses its own built-in dummy load so no damage will occur, and it's also awesome for direct recording.

  • 15W Class A amplifier
  • Single-ended Class A circuit
  • Handbuilt
  • Accepts almost any power tubes in any combination
  • Ships with 2 - 12AX7s (preamp) and a single EL34 (power amp)
  • 2 preamp tubes can be any combination of 12AX7, 12AT7, 12AU7, 12AY7, or 12AZ7 tubes
  • 2 inputs: one for high gain and one for low gain
  • Volume, Treble, Bass, and Attitude knobs
  • Built-in Hot Plate output attenuator
  • Volume, Treble, and Bass controls
  • Attitude control knob
  • Hard-bypass switch for Hot Plate
  • Light bulb noise-reduction circuit
  • On-Off switch for light bulb circuit
  • Transformer-isolated line out with adjustable level control
  • Choose Line-Level or Instrument-Level signal
  • 2 ohms to 16 ohms speaker load
  • Built-in dummy load

An amplifier born to produce every sound you've ever wanted—and some you haven't thought of yet—with the highest tonal quality. Order now.

  • 15-1/2"W x 8-3/4"H x 10-3/4"D
  • 27 lb.

Review Snapshot

by PowerReviews

(based on 8 reviews)

Ratings Distribution

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Reviewed by 8 customers

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(1 of 1 customers found this review helpful)


THD Univalve

By Tacoma John

from Tacoma, WA

If you have read the reviews here, you already have a lot of info. There are just two things I want to add. 1)This amp is heavy on the mids. I crank it all the way up for searing lead, then stomp in a graphic with the mids cut and the overall pedal gain cut about 12dB for a clean funk rhythm, just like channel switching. 2)Even when overdriven this amp has the least hiss of any amp on the market without gating, and gating is always audible and annoying. I've been building tube amps for over 30 years, but when I heard this one (NO hiss) I knew my building days were over. If you have questions for me, join the unofficial Univalve Forum.



By phg

from california

This is the most versatile amp i have ever played. Any sound can be produced with it with the simplicity of switching a tube. There is no re-biasing or modification required. truely a work of genius

(0 of 1 customers found this review helpful)


Love the Univalve

By gruveb

from Arizona

See all my reviews

The THD Univalve is incredible. A lot of people knock the features but fail to recognize that this amp is class A, meaning, it cannot have an effects loop and so on.Anyhow, the amps features are incredible. Line out is a nice feature, hot plate is a must. Swapping tubes in and out to achieve different sounds is pretty fun. Great amp, very reliable, and incredible for recording. Plus, at 15 watts, it's definitely loud enough to play along with a band, no problems.


A work of art

By Dave-1PoZe

from Rochester Hills, MI

See all my reviews

The first thing you notice about this amp is the quality and craftsmanship. It doesn't get much better. I think it's gorgeous too. It's ability to use almost any tube, power or preamp, means you can customize your sound. Very cool. The ultimate recording amp. The sound is just wonderful, from clean to overdriven. It won't do a Dimebag Darrell sound, metal-heads should look elsewhere. Just very complex, harmonically rich tones. It's very sensitive to pick attack and your guitar's volume setting. You feel like you're actually 'playing' this amp. It's dead quiet too. The built in Hotplate attenuator works perfectly. You can have huge, saturated power tube distortion at bedroom levels. Master volume, gain? Forget it! I do miss having a mid control though, the Univalve has Treble, Bass and Attitude. The Attitude knob works like a presence control although technically it's not. All the tone controls are beautifully voiced. This amp compares to boutique amps costing 2 and 3 times as much, it's really a bargain at just under. Highly recommended.


Just blown away..

By THDisgreat

from Ontario

I played this head in a music store through the ported THD 2x12 cab.For 15 watts this thing is a monster. I love the hot plate control and the distortion is to die for. Play it lightly and you can get some sweet clean tones, dig in harder and unleash the overdrive! I was very impressed with this head. Yes a mid control would be nice, but thats nothing an EQ pedal can't take care of. This unit would be perfect for the studio, rehearsal, bedroom practice, performing live...


great amp!

By tech 21 owner

from nyc

See all my reviews

This is a great amp! For recording there may be no better. It stacks VERY well and has some really cool unique features. I would say it is more than capable to be a live amp. Seems very solidly built. . . I'm very sold on mine!!


A truly superb tube amp...

By Satur9

from Torrance, CA

See all my reviews

Because I do most of my writing/practicing/tone-searching in my bedroom, this is probably the best amp a guy like me could hope for. It has a friendly low-wattage (with attenuator) which allows me to achieve big sounds at small volumes, and the ability to switch between tubes without rebiasing allows for a wide variety of different tones as I call them. My favorite power-amp tube so far is a KT88 (which are about the most expensive type out there--the fact that I only need one instead of a matched quartet takes a huge load off my wallet). Right now I'm using it for great classic rock tones (The Who to Led Zep style on the Rock Channel, crank a boost pedal in front of the Roll Channel and you can get that great Bluesbreakers crunch at low volumes) and some 90's rock (Using a Big Muff Pi in front of the KT88's makes an excellent Smashing Pumpkins Siamese Dream tone).


Who needs an amp modeler?

By AWH821

from South Easton, MA

See all my reviews

This amp is awesome for home or studio recording. The ability to try different tubes for new tones coupled with the built in plate attenuator makes a very versitile tone machine. My guitar sounds great plugged straight into the amp, then the amp direct to the board for recording thanks to the line out and the built in dummy load. It sounds great when used with the THD 2x12 cab. Use with your favourite analog pedals and you will not be disapointed.

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