Influence of DC offset on bias

I'm guessing your referring to the DC voltage bias measurement used by a lot of amps. The DC voltage is most likely the difference (drop) across a resistor tied to the tubes plate. This is an easy way to measure the plate current milliamps load on the tube. Different amps use different value resistors, so the voltage difference may not read the same from one design of an amp, to another. If they all used a *one* ohm resistor for example, a 50 milliamp (mA) load, would read 50 millivolts (mV). Or if they used a 10 ohm resistor on the tube, 50 milliamps plate load would read .5 volts. So if they use a different value resistor that wouldn't translate into the same (mA) reading.

The hard part is your question. I think it was said at one time (years back), that you could have a 5% difference between the left and right channel bias, and not notice the difference. Don't hold me to this 5%, but I don't seem to notice a 5% difference myself. Someone may come along with a different value.

If your amp has adjustable pots for the bias, you should be able to get them fairly close. On a stereo amp, changing one side (channel) will cause the other side (channel) to vary some. Also, if it has several adjustable pots, changing one, may cause any other to vary. Adjust the bias cold at first. You have to keep going back and forth, let the amp run 10 minutes, check again. Check after a half an hour, adjust if needed, than in a hour, check and adjust if necessary.

My above post would be for tube amps in general. I just noticed a past thread of yours referring to SS amps.

I'm referring strictly to SS. Amp has both offset and bias pots. I understand anything up to 50mv offset on each channel is acceptable, 0 being ideal. However, the best I can get is 16mv on the left, 26mv on the right. Bias set at 150ma on each channel. My question is, does the stilted offset skew the bias adjustment? I could just change up the left channel offset to match the right, but not all SS amps have offset pots. I have others with dc servo control and still others with discreet components for the offset but they are never identical on both channels either. So I guess what I want to know is should there be a bias compensation on either channel to accommodate the difference in offset?