Stromberg AP-55 question

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Technical and speculative discussion of amps, cables and other topics.

Hi, I have a pair of the AP-55 mono amps that I have been restoring, and while I have gotten them to work well, I have a bit of a buzz (120 hz) in the output. The scope shows 25v p-p as a sawtooth. These have new PS caps in them at the same value (30 ufd) that comes from a pair of 5Y3 rects. I would have assumed that these amps would not have had this buzz in them from the factory, but, other than the output tranny hookup, I am a bit flummoxed on this particular problem, any suggestions? I note the output tranny connection has me scratching my head, it has three windings, one for the output tubes (primary) and 2 for the secondary, one winding side going to the neg feedback loop with the other end shown as ground, and the other winding going from 0V to 4, 8, 16 ohm up to 70 V. I assume that I would connect from ) to 16 ohms, correct, not from the ground to 16 ohms, is that correct? Also, should the ground connection be connected to the chassis ground or? thanks!

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Topic - Stromberg AP-55 question - gkargreen 10:22:46 03/09/10 (1)

RE: Stromberg AP-55 question - shermanr@prw.net 14:06:01 08/25/10 (0)

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