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bohemian

Valve amp problem, suggestions?

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I have heard some pops and booms from one of my speakers and in petrified mode I turned everything off!

Could it be the mono power amp on the left channel?  I swapped the leads from the preamp and the pops started in the other speaker. Haha!, I thought, the problem is not specific to that power amp!

I use two sources, a cd player and a raspberry pi into a wyred4sound dac.  Changing source made no difference.  That seems to limit the problem to the preamp.  Two rectifier valves (no hum in either speaker) so I reckon they are ok, so I come to the six 12au7 valves. The outer 4 are original to the amp, purchased in December 2017, the middle two are mullards of uncertain vintage.  I began by swapping these two valves and the popping remained the same. I swapped the outer valves left and right and popping has stopped!  Not moved, but stopped.

Could this mean that a valve was loose a little and the reseating has solved the problem? 

I do have some spare valves which I could swap in, but I want to identify the problem first of all.

Has any kind soul any positive suggestions I could try, or should I just wait to see if the problem recurs?

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Sounds like a bit of corrosion on the pins which you have now cleared by reseating them. Unless it returns I wouldn't think any further about it.

Sent from my BLA-L09 using Tapatalk

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Dealer
21 hours ago, Jazid said:

Sounds like a bit of corrosion on the pins which you have now cleared by reseating them. Unless it returns I wouldn't think any further about it.

Sent from my BLA-L09 using Tapatalk
 

Agreed. And taking valves out and putting them back in every now again is quite a good thing to do as a matter of course to get rid of corrosion on the pins before it becomes an issue.

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