The defining element of a Supro amplifier is its “Class-A” cathode-bias power section. This unique Supro circuit topology provides remarkable touch dynamics and power-tube saturation when driven. The unmistakable mid-range bite of the Supro output stage, combined with extremely low-noise performance, are the hallmarks of the legendary Supro sound.
6973 Cathode-Bias Class-A Power
6973 tubes were found in many of the mid-power Supro combos in the 1960s. This classic American jukebox tube possesses a characteristic warmth, and soft, blooming attack when played clean. When pushed into overdrive, the 6973 tube provides some of the most satisfying power-amp compression and distortion we’ve ever heard from any tube. Using the traditional cathode-bias configuration, a pair of 6973 tubes puts out roughly 15 Watts when used with a tube rectifier (as in the Saturn Reverb) and up to 25 Watts when used with a silicon rectifier (as in the Dual-Tone and Tremo-Verb models).
6L6 Cathode-Bias Class-A Power
6L6 Tubes are the Classic American high-power valve. Running a pair of these big bottles in a cathode-bias, Class-A configuration results in the very loud 35 watt power section of the original tube-rectified Supro Thunderbolt. A pair of 6L6s in one of our power amps can produce up to 50 watts when used with a silicon rectifier, as found in the Titan. With superior headroom, higher voltages and much larger transformers, the 6L6 power amp delivers far more punch and clean headroom than the 6973-based power amp.
6L6 35/45/60W Switchable Power
This unique power amp topology found in our flagship amplifiers provides musicians with the ability to switch between three different wattage levels. The 35-watt setting configures the amp in the traditional cathode-bias method, like a vintage, tube-rectified Thunderbolt. The 45-watt setting configures the output stage for grid-bias operation while still using the tube rectifier. The 60-watt setting switches out the tube rectifier for a silicon rectifier to achieve maximum output power and headroom, which is particularly useful for players who like to use pedals.