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Pre-Owned THD Univalve Amplifier

SKU 0405
The THD UniValve is a Single-Ended Class A amplifier head with a single output tube that can be switched at will among many octal-based power tubes including 6L6, EL34, 6550, KT90, KT88, KT77 and KT66, for different tones without re-biasing the amp. Likewise, the two preamp tubes can be any combination of 12AX7, 12AT7, 12AU7, 12AY7 or 12AZ7. The UniValve delivers tones from smooth and clear to very aggressive overdrive. It is easily capable of driving a 4 x 12" cabinet, yet quite small and light. It has a built-in Hot Plate® Power Attenuator that allows for full output distortion at almost any volume. Its carrying bag is included.  

The UniValve has two inputs: one for high gain and one for low gain ranges. The low gain input with 12AX7 preamp tubes in the amp gives a wide range of clean sounds from "Country" clean and crisp to Jazz-direction warmth. With the controls pegged and a relatively high-output humbucker, the low-gain input can deliver a very convincing "Texas Blues" type of overdrive. Plug into the high-gain input and you are in a whole different world from early "British Invasion" tones to contemporary Heavy Metal sounds.

The controls are the traditional Volume, Treble and Bass controls along with what we call an "Attitude" control. The Attitude control is not a Presence control, as the amplifier has no negative feedback from the output transformer back into the driver stage. The Attitude control determines how the driver stage responds to signal and how it drives the power tube. There is also a built-in THD Hot Plate power attenuator that lets you have full output distortion at any volume level. The Hot Plate has its own hard-bypass switch on the front panel, which completely removes it from the circuit for Full-Power playing into a speaker.

The UniValve features a lightbulb on the front panel that not only glows when the amplifier is played, but it also provides very effective noise-reduction. For occasions when you do not want this feature, there is an On-Off switch for the light bulb circuit right on the front panel.

The UniValve has a GREAT-sounding transformer-isolated line out on the back panel complete with an adjustable level control and a switch to choose Line-Level or Instrument-Level signal.