Worked fine for a couple of years but now I have a scratch crackling sound

[canuckaudio]

First off, I have enjoyed this amp for a couple of years - thank you Bottlehead!
I've enjoyed it so much that I purchased a Speedball upgrade that I would like to install after I solve my current issue.

This is where I'm hoping this forum can help please 

Here's the summary:

• worked without issue for at least 2 years
• now have scratchy crackling sound in left channel
• this occurs shortly after amp is turned on (seconds) and does not go away
• scratchy sound is there with no input attached and volume pot turned down
• scratchy sound remains regardless of volume and with RCA inputs shorted
• voltage readings are normal except for A1, A6, B1, and B4, which are all at 72 Volts which seems low compared to the voltages in the build manual (note that all of my readings are slightly lower than the manual but these 4 were quite a bit lower

I would appreciate your thoughts on next steps. I was thinking:
1) resolder all joints
2) clean tube contacts
3) swap tubes (would need to purchase)
anything else?

Thanks,

Edmond

 

[attmci]

Because the crack has been working fine for a couple of years, so I would find some new tubes for the amp.

Tube rolling is fun!

Happy New Year!

 

[raymondp1138]

I had the same problem with my left channel too. In my case, the crackling sound developed a few days after building my kit. Using the chopstick test (https://bottlehead.com/smf/index.php?topic=6744.msg65838#msg65838) I found a poor solder joint on the left channel output cap. Re-soldered and the problem was fixed.


-Raymond

 

[canuckaudio]

I had the same problem with my left channel too. In my case, the crackling sound developed a few days after building my kit. Using the chopstick test (https://bottlehead.com/smf/index.php?topic=6744.msg65838#msg65838) I found a poor solder joint on the left channel output cap. Re-soldered and the problem was fixed.


-Raymond

Thanks for the reminder. I'll give this a troubleshooting step a try as well.

 

[canuckaudio]

Because the crack has been working fine for a couple of years, so I would find some new tubes for the amp.

Tube rolling is fun!

Happy New Year!

Thanks for the tip. Would I be replacing both the CRC-6080 and the 12AU7?

 

[canuckaudio]

Update: I've rolled both input and output tubes, and did the chopstick test.
Same problem still persists with scratchy sounds on the left channel with no input attached.

Any ideas what else I can try?

Thanks

 

[Doc B]

Have you cleaned the volume pot and the tube sockets?

 

[canuckaudio]

I have not. Thanks for the suggestion. I'll try that next and then report back