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#58595 11/14/05 02:11 PM
Joined: Nov 2005
Posts: 3
W
Junior Member
Maybe some info in this link will be of help... http://www.epanorama.net/documents/groundloop/

#58596 11/14/05 08:37 PM
Joined: Nov 2005
Posts: 187
HCE727 Offline OP
Member
Holy,moly this is turning into a circus. Nothing is easy is it? The track heads are 120v, 50w, r-20's.


Hank
#58597 11/14/05 10:26 PM
Joined: May 2003
Posts: 2,876
E
e57 Offline
Member
Well you wanted answers, and suggestions.... You got 'em! [Linked Image]


Mark Heller
"Well - I oughta....." -Jackie Gleason
#58598 11/14/05 10:36 PM
Joined: Nov 2005
Posts: 187
HCE727 Offline OP
Member
I got answers all right, but I'm stiil not sure what to do. I'm not complaining, I think this is a good thing. It never hurts to get other electricians imput, especially if they have already done something that you are looking for answers for.


Hank
#58599 11/14/05 10:42 PM
Joined: Nov 2005
Posts: 187
HCE727 Offline OP
Member
I just reviewed some of the posts, one said something about multi-wire circuits, well I think thats how I wired it. The outlets are on a couple of 20-amp, 3-wire circuits and the lighting is on a couple of 15-amp, two wire circuits.


Hank
#58600 11/16/05 12:47 PM
Joined: Nov 2005
Posts: 187
HCE727 Offline OP
Member
Good news! The homeowner is calling in a "studio engineer" later this week. The GC and I will walk thru it with him. I will ask as many questions as I can and take as many notes. I will keep you posted.


Hank
#58601 11/16/05 09:54 PM
Joined: May 2003
Posts: 2,876
E
e57 Offline
Member
"Feedback-Hum... Hmmm... Sound studio....
3-wire circuits, and/or 2-wire circuits of seperate phases will do this too, if equipent is connected/re-connected on the audio side."


If that is the case, it may be as simple as moving some equipment around to be feed from the same phase. Otherwise, if amperage is low enough, make your 3-wire into 2-wire on the same circuit. That difference in voltage can manifest itself in various different ways when the equipment is fed from different voltages. Assume each piece has its own power supply, and drops voltage to whatever, and then reconnected to create another smaller voltage. Regulated or not... That differance in those two or more smaller voltages, could be what your hum is.


Mark Heller
"Well - I oughta....." -Jackie Gleason
#58602 11/16/05 10:31 PM
Joined: Jun 2005
Posts: 821
S
Member
I can tell everyone here for sure that I definitely learned something from this thread about humming noises and the relationship it has to grouding. The most valueable lesson is to use Hospital grade MC whenever working a circuit for sound equipment. The neutral wire in a multiwire branch circuit works that much harder because of frequency difference in the equipment and that's being served (harmonics).

This site is really the best. Thank you all.

Oh, and good luck to the guy who has to fix the problem.

[This message has been edited by ShockMe77 (edited 11-16-2005).]

#58603 11/16/05 10:36 PM
Joined: Nov 2005
Posts: 187
HCE727 Offline OP
Member
Me either, I will take advice about the hospital grade MC cable and I will wait to see what this engineer has to say.


Hank
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