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Re: Mac 275 question

Everyone has made some good points here. I recently picked up a 275, 10B, etc that spent their whole life in a console. This MC275 was not touched by human hands for at least 40 years, all original, no rust, dents or scratches. I removed the ouput tubes and have had it on a variac for a week incresing the voltage 10 volts a day. I connected a voltmeter up and started probing the output tube sockets. On one channel the neg. bias voltage was -33v and the other channel was -89 and -59, while feeding the amp 70 V AC. My point is no matter how much we may want these amps to remain original the chances of the original caps working after fourty years in nill.
When a one of these old Mac amps has all of the power supply and signal caps replaced they operate and sound like new or beter. been there done that.
Ron-C


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  • Re: Mac 275 question - Ron-C 08/30/0209:24:16 08/30/02 (1)


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