Re: Puzzling audio circuitry
Getting back to the original shunt-regulated circuit, my understanding is that this was originally developed as an economical way to drive TV transmitter video modulator stages. These presented a very difficult load, generally of quite low and varying (frequency-dependent) impedance. When the load conditions were such that the drive output voltage might be pulled down, the shunt valve provided the additional current required to maintain the voltage to the modulator.
That being the case, why would it be used in a simple audio circuit? A single-ended 6L6, presumably always operating in class A, would not seem to be a particularly difficult proposition for the driver stage.
Cheers,
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