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THD Bi-Valve 30 30W Class A Tube Amp Head

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The BiValve-30 amplifier head from THD is the big brother to THD's popular UniValve model, but with one major difference: dual output tubes. Both the output tubes and preamp tubes give you free reign ... Click To Read More About This Product

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The BiValve-30 amplifier head from THD is the big brother to THD's popular UniValve model, but with one major difference: dual output tubes. Both the output tubes and preamp tubes give you free reign on endless combinations to experiment with. The BiValve-30 delivers tones from smooth and clear to very aggressive overdrive, like the UniValve, but with more power and a much more compliant output transformer which means richer, thicker lows. It's easily capable of driving a 4x12" cabinet, yet light and easy to handle unlike many other amp heads. It's built-in Hot Plate power attenuator allows for full output distortion at almost any volume, and the unique combination of THD's touch-sensitive input circuit and the wonderfully active and reactive tone control make for a front-end that really responds to subtle and not-so-subtle changes in the signal.


  • THD BiValve-30 30W Class A Amplifier Head
  • 30W Class A amplifier
  • Single channel
  • Hand built
  • Accepts almost any preamp and power tubes in any combination
  • Ships with 3 - 12AX7s (preamp) and 2 EL34s (power amp)
  • More and Less inputs
  • Volume, Treble, Bass, and Attitude knobs
  • Built-in Hot Plate output attenuator
  • Customer Reviews

Review Snapshot

by PowerReviews
THDBi-Valve 30 30W Class A Tube Amp Head

(based on 1 review)

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Reviewed by 1 customer

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(11 of 11 customers found this review helpful)


A Guitar Player's Dream ... if you can play and are patient!

By Sonny Ceciana

from los angeles, ca

Comments about THD Bi-Valve 30 30W Class A Tube Amp Head:

I have owned this amp for five or six years. It is a hand built master piece. The ability to mix and match tubes with worrying about biasing is a dream come true. However with this power comes responsibility. Unlike a class ab amp its tonal clarity is close to perfect. Which means it is completely unforgiving. There is no hiding behind distortion. I am certainly not the best guitar player in the world but I can do it and so can you. Few guitar players understand how truly unique and powerful this tank of an amp is. So all the Vox, Marshall, Mesa conformists may hate on you. That is until they do a little reading and research. I have gotten so many different sounds out of this amp. I am addicted to tubes and I have fried a few RCAs from the 1950's because the tone was mind blowing. Ton's of fun if you are into your own sound but not for the conformist. Changing the preamp and power tubes produce so many different tones it is like no other amp I have encountered. Make sure you have the right cabinet for this amp though. Avatar makes some awesome cabinets. THD also makes their own series now. I would recommend some nice speakers but no half stacks. The 30 watts don't seem to drive it right for my taste. (The BiValve 60 would do just fine.) I like a punchier sound from a single 12", 2 x 12" or even a 4 x 10" (but I have yet to try that one out!) In short, if you want to forge your own tone and do it with purity and perfection the THD BiValves are unmatched. Unlike other amps where you buy their tonal voicing with a THD you are free to create your own! AWESOME FUN! PS Be prepared to become a tube junkie! Controlling tone with foot pedals or fancy DSPs can't compete with changing tubes.

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