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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.
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