Supro was a budget brand name for amplifiers produced by Valco in Chicago, IL during the golden age of tubes. The same model of amplifier could be sold as a Gretsch, National, or Airline brand (through the Montgomery-Ward catalog). Valco manufactured amps are now highly sought after and have increased in price accordingly. Jimmy Page reportedly used a Supro amp while recording Led Zeppelin's debut album and other guitarists have also employed the small combos in the studio for searing electric blues. In April of 2002, these amps were featured in the ToneQuest Report.

The original Supro 16T circuit design is similar to other single-ended Class A amplifiers from the period, but subtle differences are present. The T filter following the first stage rolls off bass content where the tonestack of a Fender Champ or Princeton normally resides. The Supro's single Tone control is placed after the second pre-amp stage. Thus, more high-end signal is present to drive the second stage. Also, there is no use of negative feedback to reduce distortion. This circuit produces a wide range of sounds that do not sound much like the Fenders, Voxes, and other famous names. This circuit has it's own character and identity.

The Supreaux differs from our previous FET-based designs based on tube amps, since we had the benefit of owning the actual amp to compare with the stompbox version. The Supreaux captures much of the amp's tone. The brilliant treble response is replicated, along with the Tone control range. A sweet overdrive even kicks in at nearly the same point in the Volume pot's rotation! If you are looking for an articulate blues or classic rock sound, this is a good place to start. Many sounds, from Albert King-type tones to a Led Zeppelin sonic blitzkrieg to sparkling clean can be produced with the Supreaux. Be sure to work your guitar's volume knob and your pick attack when playing with this circuit.

Listen to it!

Here are pin voltages from the official runoffgroove.com build to provide a baseline (supply voltage from a 9.1v battery):

Pablo De Luca (aka Gringo) contributed a PCB layout for the Supreaux (PDF, 168k)

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