• THD BiValve 30 watt Combo Amp
  • THD UniValve 1x12 Combo Amp feet
  • THD Vintage 12" driver
  • THD UniValve 1x12 Combo Amp
  • THD BiValve 30 watt Combo Amp

THD BiValve 1×12″ 30 Watt Combo Amp NEW

Price Au$ 2870.00

To Purchase – please use ‘CONTACT’ FORM and we will quote on shipping

NOTE: THD Amps only ship within Australia – we will quote on shipping

The THD 1×12″ BiValve 30 Watt Combo Guitar Amp 240V AC – NEW – in THD original packaging.

The BiValve delivers tones from smooth and clear to very aggressive overdrive, and is truly at home in THD’s 1×12″ Combo Cab. The cabinet has been custom-tuned for and fitted with a single THD “Vintage 12” speaker, which has a sweet clear treble and a full, tight bass response.

Cabinet construction is finger-joint/dado Baltic Birch ply throughout.

The BiValve-30 exceeds in versatility and harmonic richness, delivering tones from smooth and clear to very aggressive overdrive. At 30 watts Class A it is an amp well suited for stage use, is transportable with casters, also lead, tubes and manual included.



SKU: THD AC BV Categories: ,

The THD 1×12″ Combo Amp Cab utilizes a tuned port, bass reflex design, employing proprietary techniques to eliminate the standing-waves that haunt typical ported cabinets. The cabinet has been custom-tuned for, and fitted with, a single THD “Vintage 12” speaker, which has a sweet, clear treble and a full, tight bass response.

Like all THD speakers, the “Vintage 12″ is hand-treated and custom-aged to remove the harshness normally associated with new speakers. Tone and technology aside, perhaps the most exciting aspect of this new product is its flexibility. The 1×12” cabinet’s design allows it to be easily retrofitted with any of THD’s current line of amplifiers, including the UniValve, BiValve-30 and the Flexi-50. The Cab is made fully from void-free Baltic Birch ply, finger-joint/dado construction.

The THD BiValve-30 is a Single-Ended Class A amplifier head with two output tubes that can be switched at will among many octal-based power tubes for different tones without re-biasing the amp. Unlike any other amplifier on the market, the BiValve-30 gives each power tube its own cathode-bias circuit and its own transformer winding.
This permits the BiValve-30 to run two completely different tube types, creating a new dimension in tube amp sounds. Useable tubes include 6L6, EL34, 6550, KT90, KT88, KT77 and KT66.

With the amp in “LoV” setting you can use the 6V6 power tube for reduced output power. BiValve-30 Yellow Jacket™ Converters are available, allowing the BiValve-30 to use the popular EL84 power tube, also in “LoV” setting.

Likewise, the two preamp tubes can be any combination of 12AX7, 12AT7, 12AU7, 12AY7 or 12AZ7.

The BiValve-30 exceeds in versatility and harmonic richness, delivering tones from smooth and clear to very aggressive overdrive. At 30 watts Class A it is an amp well suited for stage use, yet is quite small and transportable. It has a built-in Hot Plate™ Power Attenuator that allows for full output distortion at any volume.

CEO Andy Marshall minces no words. “It’s one of the best sounding cabinets I’ve ever heard,” he said “It’s every bit as full and tight as our 2×12″ cabinet, but smaller and it records beautifully.”

Switchcraft plugs and Belden wire ensure the combo cabinet will sound great and hold up to even the most rigorous gigging schedule. Another feature unique to the 1×12″ is its included wheels which simply slide into the inset caster plates. Combined with its small size 52 x 58 x 32 cm approx. (20.5″x22.9″x12.5″) the 1×12″ combo is one of the most easily-transported cabinets ever produced by THD.

“… the BiValve 30 – running a 6550 and an EL34 – produced a level of tonal complexity and sonic dimension that was simply off the scale. The BiValve 30 could easily be the richest, most detailed amp in its class…”
Guitar Player Magazine May 2002

What is Class A?
Class A is a term given to an amp that runs its tubes at full current all the time, unlike most tube amps that alternate between running one tube/tube set and then the other tube/tube set…

Being single-ended, the BiValve has more harmonic content to its overdrive and distortion, full and rich in both even and odd harmonics, unlike the push-pull configuration that most amplifiers use, that cancels out even harmonics, leaving only half of the sonic spectrum.
The wide choice availability of power tubes enhances the player’s tonal choices, while only needing the one amplifier to accomplish this…
The BiValve also has a GREAT-sounding transformer-isolated line out on the back panel complete with an adjustable level control and a switch to choose Line, or Instrument-Level signal.


All tubes – 2x EL34; 3x 12AX7

Click-in Casters w/ base-mounted holders, and heavy-duty rubber feet

Australian Power Cable

User Manual





Weight 37 kg
Dimensions 70 × 44 × 66 cm