[QUOTE="Additionally, there was a low distortion mod that Phase Linear first used on the 300 series II amplifiers (see R118 and C108 on the 300 II schematic) that they eventually used on some later 700 series II fully comp amp PL-36 pc boards. This involves removing the 120pF cap (C106/C206) that is in series with the 12K ohm resistor (R128/R129) next to Q106/Q206 and installing a 56pF cap in parallel with the 12K ohm resistor. This will greatly reduce the classic crossover notch and THD levels (particularly at lower volume levels) that you see with many Phase Linear amps (at 1kHz, 1 watt, 8 ohms). In which case the bias should be adjusted to approximately 385mV (which also works better when the 10 ohm resistors are nearer the nominal value of 10 ohms). .[/QUOTE]
Updated Thanks Ed
Updated Thanks Ed
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