In my opinion, distortion needs to be made inaudible but does not need to approach unmeasureable. Those limits seem to be around -80dB and -120dB respectively.
As I previously wrote, higher levels of distortion cannot be "pleasant" because instruments no longer remain distinct.
The purpose of the emitter resistors is to stabilize current. 0.22 ohms is the smallest practical value. Amplifiers with parallel output transistors can use a larger resistor on each transistor. The voltage drop remains ~20mV. The parallel resistance is small compared to a speaker.
Ed
As I previously wrote, higher levels of distortion cannot be "pleasant" because instruments no longer remain distinct.
The purpose of the emitter resistors is to stabilize current. 0.22 ohms is the smallest practical value. Amplifiers with parallel output transistors can use a larger resistor on each transistor. The voltage drop remains ~20mV. The parallel resistance is small compared to a speaker.
Ed
See US4334197 and US3883813 for possible solutions of this problem. The US4334197 evolved into commercial amplifier model.
Thanks!
I prefer EF3 with the pre-driver and driver transistors run in class A. Those contribute negligible distortion. The other studies showing higher distortion are running the driver transistors in class AB.
Ed
I prefer EF3 with the pre-driver and driver transistors run in class A. Those contribute negligible distortion. The other studies showing higher distortion are running the driver transistors in class AB.
Ed