Circuit Description
Gain Stage/Phase Splitter: The 6SN7 tube is chosen for its superb sonic characteristics. The first triode is a gain stage which is directly coupled to the second triode, utilized as a concertina phase splitter. The phase splitter is capacitively coupled to the next stage with matched Jensen copper foil caps.
Differential Driver: The 6BL7 is nearly identical to the 6SN7, with the exception of having higher plate dissipation. Matched Jensen copper foil caps provide coupling to the output stage.
304TL Output Stage: The 304TL is a low mu power triode, produced from the 1940s to the 1960s. It has exceptionally linear characteristics and an enormous plate current capability, making it ideal for audio power amplifiers.
- Maximum plate dissipation 300 watts
- Bias and plate current adjustable from the front of the amplifier utilizing Simpson analog meters
- Output transformer custom-designed and wound by Jack Elliano of Electra-Print Audio for ultra wide frequency response
High Voltage Supply: The high voltage supply utilizes custom wound transformers from the Peter Dahl Company in Texas. Smooth DC is obtained by high performance choke filtering, using a swinging choke and a second smoothing choke. The amp contains no electrolytic capacitors - all high voltage capacitors are DMK self-healing oil filled units from High Energy Corp. Recification is carried out by 3B28 xenon rectifiers (866 mercury vapors can be substituted, if desired.) The high voltage supply is physically isolated from the signal carrying circuit, and high voltage is indicated on the front of the amplifier via a Simpson meter.
High Voltage Supply Number Two: The high voltage supply for the 6SN7 and 6BL7 is rectified by a 5V4 tube and capacitive input filter. The capacitors are Solen FastCaps.
Wiring: All wiring is point-to-point. There are no circuit boards in the 304TL, and all critical resistors and capacitors are matched.