Bottlehead Forum
Bottlehead Kits => Legacy Kit Products => Paramount => Topic started by: Bottle Rocket on February 17, 2016, 03:31:43 PM
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The right channel has a crackly/fuzzy sound for about the first 10-15 seconds when I turn on the amp. After that the channel suddenly clears and sounds fine. (However the right channel still has a little more hum than the left). Just wondering what might be causing this?
- I have swapped the tubes between the amps and this hasn't changed anything.
- I've also turned the amp on then off (disengaging the soft start). I soon after turn it back on and the fuzzy sound for the first 10 seconds is still there.
Thanks for any insights.
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That's about the time it takes for the driver/regulator tube heater to warm up. Could be a marginal solder joint in the Zener string, for instance. That string is inactivated when the regulator triode starts functioning.
Another theory is a marginal connection that stabilizes with the expansion from heating. I feel that's less likely because most items take more than 30 seconds to achieve operating temperature.
How long has the amp been functioning before this occurred?
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It was functioning for about 1 month (maybe a little less) before this started occurring.
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There isn't really any correlation to flaky joints and when they may or may not appear. I have worked on ST-70's that had flaky solder joints that didn't produce any problems until decades after initial construction.
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Paul, I resoldered the zener string and things have cleared up. Looks like your first hunch was correct.
Thanks for the help,
Michael