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July 08, 2020, 04:59:51 PM

Author Topic: Faint 60-Cycle Hum  (Read 179 times)

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Offline Paul Birkeland

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Re: Faint 60-Cycle Hum
« Reply #15 on: June 29, 2020, 09:39:34 AM »
Yes.  When the coarse and fine are all the way up, it's noisiest.  I will do as you've suggested.
But if fine is all the way up and coarse is all the way down, it's still quiet?
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline jtori

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Re: Faint 60-Cycle Hum
« Reply #16 on: June 29, 2020, 10:09:56 AM »
But if fine is all the way up and coarse is all the way down, it's still quiet?

Not present, or very, very faint.

Offline jtori

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Re: Faint 60-Cycle Hum
« Reply #17 on: June 29, 2020, 12:57:50 PM »
Followed Paul's and Deke's guidance and desoldered at all the points on TwoQuiet where black leads land.  These connections are now clean.  With no signal, hum is nearly inaudible until -9dB on the coarse attenuator, where it becomes audible.  At 0dB, it is as before.  So, not sure where to go from here.  I defer the the sage wisdom of the most august members of this forum.  :)

Offline Paul Birkeland

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Re: Faint 60-Cycle Hum
« Reply #18 on: June 29, 2020, 01:06:31 PM »
Is this still with shorted inputs?
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline jtori

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Re: Faint 60-Cycle Hum
« Reply #19 on: June 29, 2020, 01:59:07 PM »
Is this still with shorted inputs?

No.  Dead quiet with inputs shorted.

Offline Paul Birkeland

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Re: Faint 60-Cycle Hum
« Reply #20 on: June 29, 2020, 02:28:40 PM »
No.  Dead quiet with inputs shorted.
Then your amp is working properly.
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man