I need some help with one of my St-70s. I have one with what I think is a rather large DC offset on the input. I'm measuring -129mV. The other ST-70 has -49mV
These are rebuilt units with the stock circuit but new components and a cap board. I use one for the left channel and one for the right channel bi-amping the speakers.
I was quickly making some measurements using my voltmeter and a calibration CD. There is so much DC offset in one amp, above about 10K, the meter won't measure AC signal. Since I am using the amp with one input cable, I have the switch in mono mode and I have my meter connected to the unused input RCA connector.
I checked my preamp and there is minimal DC on the output and I even switched the left and right input signal cables-no change. I did not switch the 7199s yet, but that is next.
I'm not sure if this is an issue or not. I'm used to SS gear where you can null the output offset (if it is non-servo) and usually there is no offset on the input side.
Thoughts?