The designer/builder of our custom amps told me that fixed bias provides more "snot" than cathode bias. He meant power by snot. I know you’ve stated in this thread that there is no power difference between these two biasing configurations. Can you please discuss the bias configuration elements related to power magnitude?
@xenolith
Fixed bias does have that reputation (and FWIW, we use it in our amps as well).
The power output is the same for a given bias point, but for cathode bias you need a higher power supply voltage since a voltage is dropped across the cathode resistor and that might have to be 30 or 40 Volts in a lot of cases.
The cathode resistor has the additional issue, if its unbypassed, of creating degenerative feedback. This makes it harder to drive. The feedback means it will be lower distortion, but that might not mean much if the driver circuit makes more in order to drive it.
So there are a lot of variables and each has to be managed properly to pull it off. I would expect it to be pretty difficult to do a side by side audition if that were the only variable, on account of all the secondary variables involved.
