Newsgroups: rec.audio.tech
Subject: Re: Speaker Hum coming from CD player.
References:    
Don Pearce  writes:

> On 16 Dec 2002 22:48:38 +0200, Tomi Holger Engdahl
>  wrote:
> 
> >This sound like classic case for ground loop problem. 
> >You are right on this. 
> >
> >But you are not right in the disconnecting the ground wire. 
> >It might solve the problem on sound, but is a positential safety
> >hazard. Cutting the ground on mains power cord is not the right 
> >way to solve this kind of problem! 
> >
> >You can find other proven alternatives listed at
> >http://www.epanorama.net/documents/groundloop/index.html
> 
> This is a strange site. It is full of ways to mitigate the hum problem
> if you insist on leaving multiple grounds connected. 

The aim is to get a hum free and safe system.
Multiple grounds needs to be left connected in 
very many audio and video applications for safety reasons.

It would be easy if you always could have just a single 
ground connection in your system. But this is not often 
a case in real life applications. Those applications I 
have worked have been home theater systems, live audio and
video systems, web broadcasting systems, on-location 
TV broadcasting, videowall/projection systems on concerts, 
etc. etc. 

The text is wirren based on real life experice on problems. 
And this knowledge is recognized in many forums. 
You can check newsgroups how many people has recomended 
checking it. Same document is also published by
in GB Audio web site at 
http://www.gbaudio.co.uk/data/ground.htm

> What is not provided is a way to eliminate the hum. 
> As the total elimination of
> ground-loop-induced hum is so simple, I really don't understand what
> this site is trying to achieve.

What is your simple approach which will solve all your proiblems 
and will meet the electrical safety regulations ?

-- 
Tomi Engdahl (http://www.iki.fi/then/)
Take a look at my electronics web links and documents at 
http://www.epanorama.net/