SRPP 45 and 2A3
In general I prefer the simplicity and purity of a plate loaded voltage amplifier [R-C couple], however i found SRPP [shunt regulated push pull] sonically satisfying using low-gm, hi-mu tube like the 6SL7/5691. if you find the Simple 45/2A3 a bit slow or lacking in definition, then this may be your solution.
I do not have the technical background to fully explain how SRPP works however through pure logic, the top half of the triode acts like a constant current load to the plate of the bottom triode and the drive signal is basically a combination of the low impedance nature of the top half's cathode and voltage amplification ability of the lower half, Giving this input/driver circuit greater potential drive signal to the grid of the output power tube.
SRPP 45
Power Supply
SRPP 2A3
Power Supply
Under the hood of an SRPP 45 amp with Tamura F475 OPTs.
This is a simple and straightforward design and the only thing I need to point out is the voltage divider network in the power supply that lifts the cathode potential of the 6SL7/5691 around 70-90 volts above ground. Thus, the +/- 90V heater [filament] heater to cathode rating is not exceeded as per the RCA manual's recommendation.
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Updated: 04/17/07
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