Trimodal audio power, Part II
The same components that dominate amplifier noise performance also determine the output d.c. offset; if R9 is reduced to minimise the source resistance seen by Tr3, then the value of R8 is scaled to preserve the same closed-loop gain, and this reduces the voltage drops caused by input transistor base currents.
My previous amplifier designs assumed that a ± 50 mV output d.c. offset is acceptable. This allowed d.c. trimming, offset servos, etc. to be greatfully dispensed with. However, it is not in my nature to leave well enough alone, and it could be argued that ± 50 mV is on the high side for a top-flight amplifier. For this reason, I have reduced this range as much as possible without resorting to a servo; the required ...
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