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Thumping sound in right channel of Amp

I own a Cayin A88T for almost a year. I would say it sees moderate use. Recently I am noticing a rather loud thump in the right channel after the initial 30 second warmup. This can happen a couple of times during the first 10 minutes of having turned on the unit. After this time the unit sounds fine. I haven't altered anything on the unit which I bought new. From what I have been reading tube rolling is common practice with the Cayin but this is something totally new to me. I must thank Danlib for the detailed instructions he e-mailed me on biasing the unit.
Should i be concerned about the initial thumping, Will tube rolling solve the problem?
flyfisher

Showing 1 response by herman

herman
2,277 posts
 
The fact that it just started doing it after a year AND it only does it in one channel clearly indicates that something is wrong.

Are you sure it is the amp thumping and not something before it? Swap the left/right inputs and see if it moves.

Sometimes this is caused by a tube arcing. Darken the room, watch closely, and see if a tube flashes during warmup.

If not, swap tubes from left to right. If the thump moves you have a defective tube. If it doesn't move you have a defective amp.
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