A studio ace's decades of session experience informed this combo's galaxy of tones—and all without a traditional tone stack.
What would you expect from an amp named JOAT—an acronym for “Jack of All Tone?” I’d imagine some bloated monstrosity overloaded with cascading channels, switchable tube configurations, and an appalling number of knobs and switches. You know, something that promises the sounds of everything from a Fender Champ to a Bogner Uberschall, while never sounding as cool as either.
Thank heavens, this 1x12 combo version of Sharp’s JOAT 20RT head-and-cab model is nothing of the sort. The “T” stands for tone, singular—as in, “this amp is all tone.” Sounds like total marketing B.S., right? But amazingly, this 20-watt, dual EL84 amp delivers on the promise of its name.
The JOAT 20 Combo is masterfully made from great materials. But what sets it apart from other ultra-premium amps is its radical approach to tone control. Almost all guitar amps (and, for that matter, most distortion pedals) rely on passive tone stacks. That is, they trim frequencies by shunting parts of your signal to ground. Being passive, conventional tone controls can only shape sound by subtraction, never by addition. You build up massive energy with the tubes, and then sculpt it down with the tone controls, sort of like carving a statue from a block of marble.
Sharp omits conventional tone controls, employing instead an ingenious array of biasing, phasing, and feedback tricks to conjure a broad palette of tones without energy-sucking shunting. Yes, you can cut bass, but you don’t use a conventional high-pass filter. Instead, the bass cut knob alters how components are coupled downstream. The treble cut knob doesn’t dump treble frequencies to ground. Instead, it activates a feedback circuit across the output tube plates, trimming top end via varying amounts of phase cancellation.
In lieu of midrange controls, there’s a 5-position attitude switch. It alters the biasing of the initial tube (a 6AU6 pentode, instead of the more common 12AX7 dual triode). The settings vary in midrange contour, compression, and attack.
But what does Sharp’s circuit sorcery actually sound like?
The differences in tone and feel relative to conventional amps aren’t subtle. I’ve never encountered a more present and touch-responsive amp. It produces a remarkably loud 20 watts. Notes have rock-solid fundamentals. The touch sensitivity is off the charts—notes seem to blast from the custom-spec Vin-Tone speaker (a fab-sounding model in the Celestion Alnico Blue vein).
Every design choice contributes to the amp’s harmonic richness, clarity, and impact. Pentode tubes overdrive less readily than 12AX7s. The EL84s deliver their famed, electrifying treble presence. The alnico speaker performs its expected magic, rounding off nasty highs without sacrificing lively sparkle. And yes—the absence of a conventional tone stack makes everything bolder and brighter.
Actually, such extreme dynamic response won’t be an ideal fit for all players. I had to play for an hour or so before feeling comfy with the combo’s hair-trigger response, and getting it to bark in the right ways. Likewise, you may need experimentation time before you can deploy the alternate tone controls in repeatable/predictable ways. (I wound up simply flicking through the attitude settings till something sounded appropriate for a particular guitar and/or part, and then applying treble and bass cuts as needed.) Don’t be surprised if you dial in and use relatively deep treble cuts. This thing emits intense top-end energy.
The amp highlighted the best qualities of every guitar I connected. Lipstick tubes pickups maintained their airy high end. Baritone guitars retained as much bass mass as if they’d been recorded direct. Strats shone exquisitely. Pauls were perfectly Pauline. JOAT 20 doesn’t impose its own sonic agenda. It just delivers more of whatever you plug in.
JOAT 20 is slower to distort than most 20-watt combos. But with so much harmonic intensity, you might find yourself playing a bit cleaner than usual. When you push things, the overdriven tones are gorgeous—focused and rich, with extraordinary harmonic coherence, string separation, and note attack. And while I recorded the demo clips without stompboxes to highlight the amp’s innate character, JOAT sounds smashing with any good overdrive or fuzz.
The amp offers more tone-shaping tricks: Its dual inputs are optimized for single-coils and humbuckers, but both pickup types sounded superb through both inputs—one is just a bit hotter. A switch lowers the power from 20 watts to 10, and you’ll probably use it—this thing is loud. The 3-way “bite” switch is Sharp’s take on a traditional bright switch. It’s not a conventional filter, either. It manipulates the 6AU6’s grid, exploiting varying degrees of the tube’s natural brightness. There’s also a fine-sounding bias-based tremolo circuit with a click-off position (again, for minimal circuit loading). A rugged metal footswitch is included.
The JOAT 20 is phenomenally well made. The chassis is heavy-duty powder-coated aluminum. Magnetic Components made the hefty transformers. The pots, jacks, and fittings are strictly top shelf. The vinyl covering is immaculate. The isolation mount for the initial tube performs superbly. I’ve always dug the core color of pentode tubes, but man, can they be noisy! (I’ve got a sizeable collection of expensive EF86 pentodes that were too fussy to use in a Marshall 18-watt kit I once built.) Here, though, the tubes are dead quiet. There’s just one downside to that stout construction: The amp weighs a hernia-poppin’ 48 pounds.
Between its near-$3K price tag and hypersensitive feel, Todd Sharp’s JOAT 20 Combo won’t suit all budgets or playing styles. Still, I gave it an unusually high value rating for an amp in this price range because of the staggering amount of R&D its design surely demanded. But guitarists whose playing relies on fine nuances of touch are unlikely to find an amp with greater sonic detail and explosive touch response.
Watch the Review Demo: