Univalve Guitar Amp a Powerful Tool for Studio, Gigging Musicians

The THD Univalve isn't the sort of guitar amplifier that will get 12-year-old neophytes drooling at their nearest big-box music store. But experienced musicians will find plenty to love for studio and live gigs.

The vacuum tube-powered Univalve can create a wealth of tones - pristine clean, classic rock crunch and 80s rock grind. That's because of a clever design that allows guitarists to experiment by plugging different types of tubes into it: It accepts a wide variety of preamp tubes, and can handle many octal output tubes. It even accepts some nine-pin output tubes with an adaptor. Most amplifiers require a trip to a technician to change output tubes, but not the Univalve. It comes stock with a pair of 12AX7 preamp tubes and an EL34 or 6L6 output tube. Tube amp enthusiasts with a smorgasbord of tubes will keep themselves busy for a long time exploring the possibilities.

Simple Controls Still Offer Flexibility

The Univalve's front panel is simple: four knobs for volume, high frequencies, low frequencies and "Attitude"; an input each for low gain and high gain; a power switch; a standby switch; a voltage selector; and controls to engage and set its on-board attenuator.

The attenuator is based on THD's HotPlate, and theoretically allows users to get blazing hard rock distortion at low volumes. I've used the attenuator occasionally, but I'm never enamored with the sound of the amp when it's heavily attenuated.

But when I have the Univalve cranked up, I'm in guitar tone heaven. With a 5751 and 7025 tube for the preamp and a 6V6 output tube, the Univalve roars with an early 80s-style distortion reminiscent of Iron Maiden, Van Halen, Judas Priest and The Scorpions. To get that sort of tone, plug into the High Gain input, crank the volume and the Attitude controls and set the high and low tone controls to taste.

Though the Univalve has only one channel, a clever player can clean the amp up from this heavily distorted setting by rolling off the guitar's volume. Since changing the tone radically requires changing the tubes, the Univalve can't completely change its character in mid-song. For live music, that means your stuck with however you set your amp up that night. Studio musicians can take their time, though. The amp can also get wonderful clean and semi-clean blues tones.

Solid Build Holds up to Gigging Rockers

The Univalve also offers great reliability and build quality. Its metal construction and ventilated roll cage not only look distinct, but protect it from bruises and bumps that would scar most Tolex-covered amplifier heads. Inside, extra-thick particle circuit boards ensure consistency and cost-effective assembly. Should something go wrong, though, THD's service is first-rate. My own Univalve was an early model, some which were affected by a faulty batch of transformers. Mine was among the affected; I sent it to THD, and they immediately replaced the transformer for no cost. Since that time nearly four years earlier, my Univalve has performed without flaw.

Live, the Univalve offers gig-worthy reliability and awesome rock tones at a relatively low volume. Tube amps sound their best when driven hard - and it's nearly impossible to crank a 50 or 100-watt amp that loud in most smaller venues. That's where the Univalve excels, especially with lower-power tubes like the 6V6 or 6K6. A guitarist (and audience) will be able to hear the amp, even un-mic'd, at most venues. Sound engineers who mic that guitar amps will than Univalve users for not overwhelming everything by turning up too loud.

One Word of Warning

If your technique is sloppy, the Univalve will make you sound awful. Flaws in your fretting technique, poorly set intonation, haphazard tunings - the Univalve will broadcast them for all to hear. It produces articulate sounds, even when heavily distorted. The amp will force you to improve if you're not there yet. It's humbling at first, but then it becomes a point of pride that you've mastered a demanding amplifier.

At the End of the Gig

It's easy to find a Univalve for less than $1,000. Plug it into a $350 Avatar cabinet, and you have an affordable, portable, reliable, high-quality rig. It might not be as easy to use as a channel-switching monster, and it won't cover flaws in your playing. But it'll give you a sound all your own at a decent price.