2. amps-preamps
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Random pop sounds in my system are scaring me

Hi, I need some help and expertise on this potentially expensive situation! The last few times I've powered up my 18wpc SET amp it has been plagued by some startling "pop" sounds at random intervals. The amp switch is in the mute position, with no source selected and yet at random intervals I hear an alarming pop sound coming from the speakers. The volume of the popping isn't SUPER loud, but it does startle me and has me worried. The weird thing is, sometimes it happens, sometimes it does not. I'll have to do some more testing, but I haven't noticed this happenig when a source is actually playing through the speakers. When I bias the tubes immediately after hearing a pop, I don't see any weird numbers or behavior on the bias meter. The amp is only about 3 months old and it took so long to get, I'd hate to lose it! I know it could probably be a million different things, but does anyone have an idea of what might be happening here? Help!
Thanks!
mbleming
rodman99999
3,557 posts
 
Try tapping the driver and output tubes with a pencil. Sometimes a bad internal connection will cause the noises you are describing. If that doesn't narrow it down for you and the noise only occures in one channel: Swap all the tubes and see if it follows. At three months old: Isn't the unit still under warranty?
mbleming OP
33 posts
 
Yes, the unit is definitely still under warranty, but I'd need to ship it back to Japan! I'd like to avoid that if at all possible for cost reasons, as well as wear and tear from shipping. Thanks, for the suggestion, I'll give it a shot.
rodman99999
3,557 posts
 
Hopefully- It will simply be a defective tube. Let us know your results.
beerad
40 posts
 
I had the same problem a couple of monthes ago. I swapped my tubes left to right, the sound followed. Replaced the bad tube (kt88), no more popping. I hope this is your problem; cheap and easy fix. good luck
jaiello
50 posts
 
I vote for a bad tube. As has already been suggested swap the tubes from left channel to right and see if the popping sound follows the tubes. I had this once with some 300B tubes that went bad after a very short time so that's the reason I lean toward suspecting the tubes.
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