Introducing the new 12Vac SRPP PCB and part kits. The key advantage of the 12Vac SRPP is that it can be operated from a lowly wallwart power supply, yet develop a fairly high-voltage B+ for the triodes. Where the typical tube-based line-stage amplifier requires a B+ of 200V to 400V, the 12Vac SRPP can get by with only a B+ voltage of 120Vdc. A wallart's low-voltage AC from is all that is required to power the Aikido 12Vac.
12Vac SRPP HPA holds two hybrid SRPP headphone amplifiers. The output stage is actually a small power amplifier in its own right (a Zen single-ended amplifier). It consists of one MOSFET that is loaded by a constant-current source, which is made up of an LM317P voltage regulator configured as a constant-current source. A two-resistor negative feedback loop sets a gain of 1 (unity) for the inverting output power amplifier. Each channel sees a 200mA idle current flow, which is enough to deliver 3Vpk of output voltage into 16-ohm headphones and twice that into 32-ohm drivers. Of course, can easily drive 300-ohm headphones.