Crackle in the left channel

tagomago · 1492

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Offline tagomago

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on: March 24, 2018, 10:53:14 PM
I built my crack yesterday. To my surprise there is now always a crackling sound in the left channel.
It's just always there, sometimes more, sometimes less. It does not get affected by the volume pot or the inputs.
I used a wooden stick to find a bad solder joint but did not find any. I resoldered all the joints. But it's still here.
I left it on now for about 15 hours but it's still the same.
Could it be that a tube is bad?
The music does play nicely on both channels, but the crackle is just always underneath.

What else can I do?


Offline Paul Birkeland

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Reply #1 on: March 25, 2018, 06:34:30 AM
How were your voltage checks?

This does sound a lot like a flaky solder joint.

As always, you can post photos of your build and we might be able to spot the issue.

-PB

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline tagomago

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Reply #2 on: March 26, 2018, 06:49:08 AM
Thank you for your answer

Here are my voltages:
terminal:
1 - 83VDC
2 - 166VDC
3 - 0VDC
4 - 166 VDC
5 - 86 VDC
6 - 0VDC
7 - 105 VDC
8 - 0 VDC
9 - 107 VDC
10 - 0VDC

I redid all the solder joints again now, not luck. I'm very certain that I don't have a bad solder joint. I'm an electronic engineer myself, I solder quite a lot at work.
I used sand paper on the tube pins also for better contact.
Could this be in the sockets? Should I use some contact spray?
What if it's really a tube, how could I prove this?
I don't think it's in the power supply part, that would affect both channels right?
Could this be resolved when I install the Speedball?


Offline Paul Birkeland

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Reply #3 on: March 26, 2018, 08:36:49 AM
Can you leave your amp on overnight to see if perhaps it's just a tube cathode forming issue that may pass with some run in time.


Installing the Speedball is not going to fix this issue and should wait until this is resolved.

-PB

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline tagomago

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Reply #4 on: March 28, 2018, 07:53:03 PM
I did leave it on for a long time, it got better but after turn it off again it was there really bad.
Yesterday I bought new tubes and the funny thing is the noise was still there.

But I guess I found the reason now. It's one of the 22k 0.5W resistors. If I swap the resistors from one channel to the other it also changes the channel of the noise. This is repeatable. I will get some new resistors today and check again. This is really strange  ;D


Offline tagomago

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Reply #5 on: March 29, 2018, 01:05:38 AM
Yup, it worked!! It was the 22k resistor.


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