| THD UniValve Tube guitar head with built-in power attenuation. List: $949
by Brett Ratner
January 30, 2001
Hopefully we’ve learned something since the days when Eric Clapton and Cream trainwrecked 100 watt Marshalls in the studio and performed live with walls of cranked Marshall stacks on stage. The story goes, by the way, that Cream’s stage volume was so loud, one time Clapton and Ginger Baker stopped playing and Jack Bruce obliviously kept on jamming (he couldn’t hear the drums and guitar over his wall of bass amps so he had no idea they stopped).
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Contrary to popular belief, you can get dimed Marshall sound at reasonable decibel levels. And aside from allowing band members to hear each other, you can save your ears and also give the project studio engineer or front of house engineer the flexibility to give the whole band a better mix.
Few companies understand this better than Seattle-based THD Electronics. For years, they have offered their “Hot Plate” power attenuators and “Yellow Jackets” class-A tube adaptors. These products enable players to enjoy true power amp distortion at club, bedroom or project studio volume. It only makes sense, therefore, that THD offer a dedicated club/studio-sized amp .
THD’s approach differs dramatically from most of today’s amp manufacturers. Most modern designs utilize circuitry to distort the preamp tubes, using the clean power amp only to provide volume. Anyone who has ever turned up an old Marshall Plexi, Fender Bassman or Vox AC30 to “10” likely believes power tube distortion sounds fatter, fuller and meaner than preamp distortion. So what THD did is design a 15 watt amplifier incorporating their “Hot Plate” power attenuator.
This allows the player to crank the amp up to “10” (like Clapton used to do) then use the attenuator to control the overall volume. “It’s like a master volume that doesn’t steal your tone,” THD spokesperson Ed DeGenaro said.
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Rear panel
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Due to its smooth, class-A power delivery, you can crank the amp and use your guitar’s volume control and picking attack to adjust the level of distortion.
With a normal Strat, setting the guitar volume at “5” yields a spanky clean. Roll it up to “6” or “7” and you have a hint of edge or a nice crunch (depending on your pick attack). Roll up to “10” and you have an expressive, singing lead tone that still retains enough clarity to play complex chords.
“You can play big time chord inversions and it works,” DeGenaro said, demonstrating a few.
To our ears, the amp sounds superior played with a Strat, at full power, using the low gain input, with all the knobs set to “5.” The amp is so expressive and musical you can cover a lot of sonic territory just by adjusting your picking attack. Add an Ibanez Tube Screamer pedal and you have a liquid yet punchy lead sound. Need less volume? Roll back the attenuator.
A nifty pulsing light, meanwhile, actually doubles as a noise reduction circuit while it keeps time with your licks.
Another friendly feature is the ability to change the power tube, without rebiasing the amp and even while the amp is on standby (THD is thinking of selling the amp with a free oven mitt). The extensive list of preamp and power amp tubes the UniValve will accept are printed on the chassis. “It changes character drastically when you change the tubes,” DeGenaro said.
While 15 watts is plenty for a club gig (if not, fire your drummer), the UniValve comes with a line out featuring volume control plus a switch to toggle between “line level” and “instrument level.” This would allow you, if you wanted extra volume or coverage, to run the UniValve right into a stereo rack system or straight into the front of a vintage Fender amp. “It’s like a Bradshaw system for poor people,” DeGenaro said.
At present, the UniValve only is available as a head. A combo amp, however, should be on the way. For more information, visit www.thdelectronics.com. | 
