2. amps-preamps
  3. 131980-16764

Loud popping sounds after warm-up

I run a Unison Unico hybrid integrated amp which uses a pair of 12au7 tubes in the preamp side.  Over the weekend it started acting up.  After about 1 - 1.5 hrs of listening (with both tuner and cd), there started a very loud popping sound every 3-5 seconds.  As I was worried about damaging my speakers, I immediately turned things off, so not sure if the sound was from both channels or just one (my wife seemed to think it was only from one channel).  The popping occurs even after turning down the volume to '0'.  Initial thought was that one or both tubes were going bad, but the problem reoccurred after swapping out to another set of tubes.

Would appreciate any thoughts on what the problem might be, or how I could explore the problem further without damaging the speakers.
ihor
mattmiller's avatar
mattmiller
1,497 posts
 
It sounds like a grounding problem...so many times people look at the tubes right away ...I have found this NOT to be the case (I run 10 tubes in my front end). Try using a cheap power strip with a ground plug (3 prongs), then plug everything into the strip. It sounds like you have plugs going to different sockets and that can lead to problems with too many ground plugs going every which way. I take it your not using a turntable at all right?  Also, Maybe the amp needs to be looked at ??

Matt M
randy-11
1,913 posts
 
if it is 15 or 20 years old, you may have electrolytic caps that are going bad

----> serious business as they could blow your speakers AND the rest of the amp
oddiofyl's avatar
oddiofyl
3,797 posts
 
I had an amp that popped intermittently and it was the caps....fortunately i pulled it out before any damage.
Post removed 
gs5556
1,233 posts
 
If the popping is just as loud with the volume down and is in one channel, I would suspect a bad solder joint on or near an output transistor.
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