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Loud siren sound in one speaker, tube preamp

108.92.196.7

Posted on June 24, 2020 at 17:10:52
jeanft
Audiophile

Posts: 4
Location: Texas
Joined: October 21, 2015
Used to happen once in a while, going from low notes to higher pitch.
Permanent now after playing a few minutes. Bad capacitor?

 

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That is called an oscillation, posted on June 24, 2020 at 17:51:13
Chip647
Audiophile

Posts: 2308
Location: The South
Joined: December 24, 2012
Make sure your tube pins are clean and your sockets are tight. If you are a "tube roller" you could have a poor connection between a tube pin and a socket due to many insertions. If that is not solving it, pop in a new tube. You could swap your tubes between channels to see if the noise moves. If it does, bad tube, if it does not, bad socket,

 

RE: That is called an oscillation, posted on June 24, 2020 at 18:22:50
jeanft
Audiophile

Posts: 4
Location: Texas
Joined: October 21, 2015
Thank you. It has 2 tubes. I replaced them a few days ago. 6829 and WE 396A. No change. Have been playing with many tubes during 20 years, never happened.

 

RE: Loud siren sound in one speaker, tube preamp, posted on June 25, 2020 at 11:18:57
Jonesy
Audiophile

Posts: 2204
Location: Winnipeg, Manitoba
Joined: September 1, 2005
Contributor
  Since:
March 1, 2018
What preamp do you have?

Pre-amp definitely the issue? You've switched left/right pre to amp interconnects to confirm the problem channel follows?

If not a tube issue, check tube sockets as Chip647 suggested. Also solder joints, output jacks, clean all contact switches, pots, and even the interconnects themselves for integrity of connection.

Basically taking a look at anything you can before starting to measure caps, resistors, etc for wear.

Cheers!

Jonesy


"I know just enough to get into trouble. But not enough to get out of it."




 

RE: Loud siren sound in one speaker, tube preamp, posted on June 25, 2020 at 14:45:39
jeanft
Audiophile

Posts: 4
Location: Texas
Joined: October 21, 2015
John Tucker built it. No issue with diff preamp in system.
Tech looking at it. Leaking cap he said. Doing more tracing

 

RE: Loud siren sound in one speaker, tube preamp, posted on June 25, 2020 at 14:57:32
Jonesy
Audiophile

Posts: 2204
Location: Winnipeg, Manitoba
Joined: September 1, 2005
Contributor
  Since:
March 1, 2018
Must be a sweet pre-amp! "Exemplar" came up in my search as a pre-amp using your tube combination. I was tempted to ask.

Great pedigree.

Am sure you're looking forward to it's return.

Cheers!

Jonesy


"I know just enough to get into trouble. But not enough to get out of it."




 

Bad socket then?, posted on June 26, 2020 at 08:12:35
Lew
Audiophile

Posts: 10316
Location: Bethesda, Maryland
Joined: December 11, 2000
Nt

 

RE: Bad socket then?, posted on June 26, 2020 at 13:46:58
jeanft
Audiophile

Posts: 4
Location: Texas
Joined: October 21, 2015
Bad Mundorf capacitor.

 

RE: Bad socket then?, posted on July 18, 2020 at 11:59:45
Stuben
Audiophile

Posts: 654
Location: Guber Ohio
Joined: December 30, 2005
Contributor
  Since:
May 22, 2009
Lots of ways to make an oscillator.

I would be interested in seeing a scheme of your voltage amplifier.

Stuben

 

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