2. tech-talk
  3. 1184995641

hum, please, please help

I have a hum issue that I am starting to troubleshoot but need some help on what I can eliminate as the problem. If I plug all components in normally to the dedicated 20 amp lines I get a hum. If I use cheater plugs I still get a hum but it is quieter and somewhat tolerable but audible. If I crank up the preamp the hum gets a little louder. I know that dimmers can cause this problem. I have no dimmers in my dedicated music room but in the next room I have a dimmer switch for recessed lighting. So I decided to turn it on and turn up and down the brightness of the lights and this definately affected the hum. If I turned it way up it got a little louder and got more quiet as I lowered it and when I turned it off the hum stayed like it was before. So my question is if this dimmer is affecting the hum or contributing to the hum is this a ground loop issue or a grounding issue or an electrical issue? My equipment consists of Escalante Fremonts clayton audio m-300 monoblocks, hovland hp-200 preamp and amr cd77 for cd player. I also tried running a ground wire from my preamp to one of my amps and this did nothing. Any help would be very aprreciated.
billyg1
mwp7373
29 posts
 
You might try the following (if you haven't already - you did mention cheater plugs). Create a makeshift star ground configuration by using cheaters on all your components except the preamp.

Sounds like a probable ground loop problem to me, and a star ground often helps. One other thing you might try is listening to your system while turning off the other circuit breakers in your panel box one at a time. If you can isolate a circuit that is causing the problem, you can try replacing or moving the appliances drawing off that particular leg.

If all that fails, you can try an AC isolation transformer. The good ones are expensive, but even without a ground loop problem they definitely enhance the sound of SS gear. I'm really impressed with my Furman transformer. I believe music direct also sells a star grounding separate-chassis unit via their website as well that might be worth a try.

Hope this helps.

Good luck and good listenting.

Mark
jax2
3,031 posts
 
As an addendum to the excellent advice Mark gave you; an alternative would be to have an electrician install a dedicated circuit(s) with an isolated/dedicated ground. This would certainly be a minor expense compared to the cost of your system. I didn't know what star grounding was, but found a good post on that subject as it applies to an amplifier. It also gives some insight into the hum problem with audio gear and household circuitry. Thanks for that, Mark.

Marco
jmcgrogan2's avatar
jmcgrogan2
6,346 posts
 
This might be too simple, but how about replacing the dimmer switch with a regular switch? Dimmer switches are notorious for noise. Otherwise I agree with Mark and Marco that an isolation transformer should resolve the problem, but cost a lot more.

John
More to discover