THD Electronics UNI15R-BLU UniValve, Rack-Mounted, Blue-Anodized 120V

THD Electronics UNI15R-BLU UniValve, Rack-Mounted, Blue-Anodized 120V Review

THD Electronics UNI15R-BLU UniValve, Rack-Mounted, Blue-Anodized 120V Feature

• 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
• "It's one of the world's best sounding, best looking and best made amps." - Guitarist Magazine
• The face is green-anodized brushed aluminum. All other parts are black powder-coated steel.
• Provides ample ventilation for the preamp and power tubes.
• Hand-built in Seattle, WA.

The THD UniValve Rackmounted Guitar Amplifier Head 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 quite small and light, yet easily capable of driving a 4 x 12" cabinet. It has a built-in hot plate power attenuator that allows for full output distortion at almost any volume. And it doesn't cost as much as you might think.What is a 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 set of tubes and the other set, each for one half of the wave. The set not in use is turned off by a positive swing of the grid voltage. Single-ended output stages always operate in Class A. Most push-pull amplifiers, including the venerated Vox AC-30 operate in Class AB when overdriven, even if they are in Class A while clean. The upshot is that Class A operation has its own unique tone characteristics that set it apart from other tube amp classes. Class A amps sound great at low volumes, and even better as you turn them up. Thus, with the relatively low wattage of the UniValve you can turn up the amplifier to take full advantage of its stunning output distortion tone without deafening anyone. Why the self-biasing feature? The UniValve's circuitry senses the current needs of the output tube and provides the correct bias volt-age to the cathode of the output tube regardless of tube type or wear. This means that, without any trip to an amp technician, you can simply replace the output tube with one that has different sound characteristics. (Of course, you can also change the preamp tubes at will for even more tonal varia