Tube amp crackle/static sound????
Dec 2, 2008 at 1:41 AM Thread Starter Post #1 of 13

sclamb

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I noticed tonight that I had an intermittent crackling/static sound coming from the right earpiece in my GS1000s and K701s using my WA6SE amp. I heard it on starting up the amp and also during some low level passages of music, but as I say it was intermittent. Not knowing what it was, I swapped the 6EW7 tubes around to see if it moved from the right to the left earpiece but with the move the sound seems to have disappeared.

Does this sound like a tube issue or is it something more serious. I have not heard it before tonight.

Thanks.

Simon
 
Dec 2, 2008 at 1:49 AM Post #2 of 13

sacd lover

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Quote:

Originally Posted by sclamb /img/forum/go_quote.gif
I noticed tonight that I had an intermittent crackling/static sound coming from the right earpiece in my GS1000s and K701s using my WA6SE amp. I heard it on starting up the amp and also during some low level passages of music, but as I say it was intermittent. Not knowing what it was, I swapped the 6EW7 tubes around to see if it moved from the right to the left earpiece but with the move the sound seems to have disappeared.

Does this sound like a tube issue or is it something more serious. I have not heard it before tonight.

Thanks.

Simon



Rectifier tubes are often noisy until they warm up. By the time you swapped tubes the amp was probably up to speed. Let the amp play for half an hour or so and then mute the music and listen for noise. All should be quiet by then. If not, you could have a noisy tube. If there is noise and you replace the tubes and the noise persists then you should start looking at the amp or a ground loop etc... Sometimes the noise is from a sound card if you are using a computer as your source.
 
Dec 2, 2008 at 1:54 AM Post #3 of 13

atbglenn

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Sounds like oxidized tube pins to me. Try cleaning them with a pencil eraser, then 91% isopropyl alcohol to clean off any residue.
 
Dec 2, 2008 at 10:18 AM Post #4 of 13

sclamb

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Quote:

Originally Posted by sacd lover /img/forum/go_quote.gif
Rectifier tubes are often noisy until they warm up. By the time you swapped tubes the amp was probably up to speed. Let the amp play for half an hour or so and then mute the music and listen for noise. All should be quiet by then. If not, you could have a noisy tube. If there is noise and you replace the tubes and the noise persists then you should start looking at the amp or a ground loop etc... Sometimes the noise is from a sound card if you are using a computer as your source.


Thanks. I didn't think it was the rectifier tube as I did not touch the 274B, I just swapped over the 6EW7 output tubes. I thought it odd as I had not heard this sound before today.
 
Dec 2, 2008 at 10:20 AM Post #5 of 13

sclamb

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Quote:

Originally Posted by atbglenn /img/forum/go_quote.gif
Sounds like oxidized tube pins to me. Try cleaning them with a pencil eraser, then 91% isopropyl alcohol to clean off any residue.


The pins on one of the 6EW7s look as though they are going blue - is that what you mean? I guess by swapping them I may have created a better contact. I shall find some alcohol. Is what you mentioned what is sometimes termed rubbing alcohol? What type of shop in the UK would I be able to buy it?

Thanks.

Simon
 
Dec 2, 2008 at 10:30 AM Post #6 of 13

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Pop into B&Q, you should be able to get ipa in there.
Methonol or ethanol (Meths) will also work fine, just be wary of slight residue issues and the price! IPA is much cheaper, but its not a magical solution!
 
Dec 2, 2008 at 10:33 AM Post #7 of 13

sclamb

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Thanks BigTony! What does IPA stand for? Is this better than the methanol or ethanol? What are the residue issues and how should I overcome them?

Thanks.

Simon
 
Dec 2, 2008 at 10:34 AM Post #8 of 13

sclamb

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OK, IPA I presume is Iso Propyl Alcohol!
 
Dec 2, 2008 at 10:36 AM Post #9 of 13

sclamb

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Dec 2, 2008 at 10:48 AM Post #11 of 13

sclamb

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Thanks. I have a Maplins down the road from me so that is great!!
 
Dec 3, 2008 at 2:18 AM Post #12 of 13

TFox

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Quote:

Originally Posted by BigTony /img/forum/go_quote.gif
Pop into B&Q, you should be able to get ipa in there.
Methonol or ethanol (Meths) will also work fine, just be wary of slight residue issues and the price! IPA is much cheaper, but its not a magical solution!



While methanol would probably work as well as iso, it's somewhat hazardous. I would avoid it unless for some reason you have no other option.
 
Dec 3, 2008 at 5:16 PM Post #13 of 13

sclamb

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Well, I cleaned the pins on the 6EW7 tubes with a pencil eraser and then cleaned them off with IPA, but the intermittent popping/crackling sound is still there, and still more evident in the right channel. The pins on one tube are very blued and I could not get the blue colour off.

I have now switched to a pair of 6DE7 tubes and will listen tonight to see if they have resolved the issue, albeit they don't sound as open as the 6EW7 tubes.
 

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