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Update on my Coincident Dynamo 34SE

Hi everyone,

A while back many of you gave me guidance on some hum issues I had with my new Coincident Dynamo. I ended up sending it back to Coincident for service. They said the filter caps were the problem and replaced them. I got it back today, plugged it in, and….the hum started up right away. It is not only just as bad, now it's equally bad in both channels (it was worse in the right channel before). I have to imagine that the techs listened to the amp after changing the filter caps, so perhaps this level of noise is normal?

I'm somewhat new to single ended tube amps, and I know that there is some hum associated with them. However, I can hear the hum from 20 feet away. It makes headphone listening impossible. It's also not going to work for near field listening at my work desk. From about 8 feet away in my listening chair, the hum is audible during very quiet passages and between songs. I guess it's just not meant to be...

I guess this falls under the "live and learn" category.

Scott
smrex13
mapman's avatar
mapman
15,679 posts
 
" Yes, it buzzes with no sources plugged into it."

Same noise as with source plugged in (hum) or different (buz).

Buz with no input attached is not uncommon and could be normal.

Hum is not normal should not be considered part of the experience in any case, SET or otherwise.

If not the same noise, could still be a ground related issue when source attached. Are source and amp definitely on the same circuit currently? Both plugged into same outlet would mean yes. OTherwise, even if different outlets in same room, they still may not be.
mikirob
950 posts
 
Smrex13,
Concur with Brownsfan. Sorry the Emotiva didn't work for you. I'm sure you will get this resolved. Something weird is truly going on. Good luck and keep us posted. I'm positive Israel Blume will do his utmost to help. Best.
jesusa0
149 posts
 
Have you powered on the amp with no loudspeakers connected?
smrex13 OP
423 posts
 
As far as I have been able to determine, the buzz is exactly the same regardless of where I plug it in, what's plugged into it, and whether it's through headphones or speakers. When I start it up there's no buzz for the first few seconds, and then the buzz begins. It sounds like the coils in a toaster oven heating up, for lack of a better description, but it stays constant for as long as the amp is on. I have tried two sets of tubes in it as well.

Any more thoughts?

Thanks,
Scott
grannyring's avatar
grannyring
4,637 posts
 
Is the hum just out of the woofer? If so...it is most likely a grounding or ground loop issue. Put a cheater plug on the amp and see what happens. A buzzing tranny is most likely mechanical only and has no impact on noise coming out of the speaker.
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