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Old 08-09-2017, 11:34 AM
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maxhifi maxhifi is offline
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The amp is actually pretty neat for being from the 1940s, check out how the output transformer and interstage transformer are connected to get some negative feedback around the 6L6s.

The speaker's field is also pretty unique, it's partly in series with the screen and oscillator current, and partly in parallel with the low voltage part of B+.

If I remove the parallel part, the rating of the filter capacitors is exceeded during turn on. No problem with the original speaker but that could fry some tweeters for sure if it isn't dealt with.

I also have to figure out what they were doing in terms of hum cancellation... The amp is dead quiet, and with small capacitors and a fairly small filter choke that's sure no accident.

Another issue is the RF oscillator for the exciter lamp tends to pollute all the audio circuits with RF.

What I really need to do is figure out how to get a clean line out, out of it, to send to my main sound system.
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Last edited by maxhifi; 08-09-2017 at 01:32 PM.
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