2. tech-talk
  3. 1013875690

Need help solving hum problem

This one really has me stumped....

The system:
Sony SCD-777ES
analog out into Placette Active Line Stage
digital out into Dodson DAC into Placette
Turntable also into Placette
Placette into CJ11A
ALL front end components plugged into Shunyata Hydra PLC

I get constant, low-volume hum when the Placette is switched to either the Dodson OR the Sony analog out, but not when switched to vinyl or any unused input.

The problem is cured when the Dodson is plugged into another outlet (same circuit). Why would the Dodson contaminate the system at all, and (this is the kicker) for two of the sources (itself and the Sony analog out) but not for the phono?

Any ideas? thanks. --dan
drubin
drubin OP
3,285 posts
 
Thank you. I had tried a cheater on both the DAC and the preamp, with no success. I will try it on the amp, but as I said, the hum goes away if the amp and DAC share the same wall outlet. Based on the results of my various troubleshooting attempts, I don't think that the location or proximity of components and cables is the issue in this case, but I do appreciate that those can be factors in system noise.
sean
6,231 posts
 
I have tried EVERYTHING known to man to minimize the hum that i'm experiencing. I'm wondering if it doesn't have to do with how these designers are are using the upsampling devices and trying to keep circuitry to a minimum ???

I recently did a "tweak" that did help this out a bit while making other noticeable improvements though. Since this applies to and can benefit ALL systems, i don't want to "pigeon hole" it to this thread. Look for a new thread on the subject in the next 24 hours. Sean
>
drubin OP
3,285 posts
 
(a bit chagrined...) I thought that I had tried lifting the ground on the Dodson. But I happened to try it again, and it seems to have fixed the problem.

Nevertheless, I will attempt to work through the process Sean describes in his excellent other post.
drubin OP
3,285 posts
 
Appears I spoke too soon. It's baaaack.....
fbi
92 posts
 
I have found the easiest way to eliminate the hum is to isolate where it is comming from and then teach it the words. This works for any whistles you might come across.

I think it's time for me to go to bed.
More to discover