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Delayed distortion

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Posted on January 30, 2023 at 20:47:17
My Transcendent Sound T8-LN is giving me a bit of trouble. It sounds great for a few hours but eventually after about 4+ hours listening, it will start to sound "warbly", as if the music was playing through a leslie speaker. It is not extreme, but it definitely is there after a few hours of play.

I suppose it is a tube but they all appear normal and I do not have a tube tester.

What else could it be but a tube since it plays fine for a few hours before the "warbly" sound output?

 

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RE: Delayed distortion, posted on January 31, 2023 at 11:05:02
rhinohifi714
Audiophile

Posts: 174
Location: oklahoma
Joined: June 13, 2009
you should start by testing the front end tubes, if you don't own a tester
ask your friends who may own one,
is that a stereo or mono?
I owned the mono version with the 6c33c output, seems like the only problem that came up was with the 12au7 tube.
But Warbly is a hard to imagine condition to diagnose.

 

RE: Delayed distortion, posted on January 31, 2023 at 11:09:05
thanks. stereo version. I bought it from Transcendent factory wired, although I replaced a few capacitors and all the EL509 plate caps a couple years ago.

I should just go ahead and replace all the front end tubes. can't hurt and they aren't expensive.

 

RE: Delayed distortion, posted on February 1, 2023 at 07:38:00
Chip647
Audiophile

Posts: 2633
Location: The South
Joined: December 24, 2012
it could be the coupling caps are starting to get a bit (voltage) leaky when they get hot. It is usually always caps when you get variability.

 

RE: Delayed distortion, posted on February 1, 2023 at 08:05:25
I guess it's time to open it up and have a look inside. I ordered a set of front end tubes also and they are on the way.

A few years ago after a move I had a power tube get a little loose in the socket and it went nova on me. Lit up the whole room.

That's when I replaced all the anode caps and a few 600v capacitors on the boards. Could be more capacitors are due for replacement. The manufacturer previously has told me he no longer uses some of the installed capacitors due to reliability issues.

And the amp is 20 years old so there is that. Another 20 years is about the max lifetime I can expect for both myself and the amp anyway :)

 

I think this is a power supply problem., posted on February 1, 2023 at 09:00:38
Ralph
Manufacturer

Posts: 4769
Location: Minnesota
Joined: April 24, 2002
Specifically, a failing filter capacitor.

If you cycle the amp off after the warble starts and turn it back on 30 seconds later is the problem still there? It might come back after only a minute, but if cycling it off and on like that temporarily cures it that is a clue that a filter capacitor is failing.

 

RE: I think this is a power supply problem., posted on February 1, 2023 at 11:37:16
I'll experiment and let you know. thanks for the suggestion!

 

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