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RE: HELP: DC at the input of an old MA1's.

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First of all, that much DC is likely NOT coming from your AC line. You mention some problem with a DAC; please elaborate. Also, what preamp are you using, if any? Tube preamps can contain such DC voltages, but solid state ones are not likely to be the culprit. Likewise, if you are running your DAC straight into the MA1, then assuming that your DAC is all solid-state, it is not likely to be the source of so much DC voltage. I really suspect that you have a problem internal to the amplifier itself. (What happens if you disconnect the amplifier inputs?) What confounds me is that you seem to say that the same condition exists in both of your MA1 monoblocks; please confirm. By the way, is the DC voltage doing anything audible on your system? After it goes away, does your system perform normally? And was there a previous time when you could not measure any DC offset at the input during turn-on/warm-up? It's remotely possible that you have a transient cathode to anode short in your CCS tube, which might put a lot of voltage on the grid of the input tube, but I cannot buy that such a problem is occurring in both monoblocks simultaneously. Could also possibly be that your B+/B- supplies are coming up ahead of your filament supplies so that the cold tubes are momentarily allowing some voltage overshoot during warm-up. This would be "normal" for the way the amp was built. By the way, Ralph can probably tell you right off the top of his head what's going on. I am just taking some shots for the fun of it.

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