Dimmer causes a Hum in sound system


  #1  
Old 04-13-04, 03:37 PM
caleyg's Avatar
Member
Thread Starter
Join Date: Nov 2003
Posts: 306
Upvotes: 0
Received 0 Upvotes on 0 Posts
Dimmer causes a Hum in sound system

Our church has a light dimming board that causes a hum in the sound system (this is obvious because the hum varies with the dimming of the lights and disappears if the lights are shut off completely).

I assume this is a grounding issue. Is there a relativiely easy way to solve this without having to get completely separate service for one or the other? They are already on separate circuits.
 
  #2  
Old 04-13-04, 05:24 PM
J
Member
Join Date: Sep 2000
Location: United States
Posts: 17,733
Upvotes: 0
Received 1 Upvote on 1 Post
A dimmer causes an abruptly shifting magnetic field which can generate weak radio signals that can cause interference. Two possible solutions are to get the sound system farther away from the dimmers, or to buy better quality dimmers. It's not a grounding issue.
 
  #3  
Old 04-14-04, 07:45 AM
caleyg's Avatar
Member
Thread Starter
Join Date: Nov 2003
Posts: 306
Upvotes: 0
Received 0 Upvotes on 0 Posts
Thanks for your reply.

The dimmer is actually a pretty high dollar light board like the kind they use in live theater. So I don't know that higher quality there is an option.

Farther away from the sound system is tough too, because we've got it all in one control booth.

In my hazy memory I remember a similar problem in a previous church. We were blessed there to have an electrician from a local TV station in the church.

He came and installed a small capacitor on the dimmer switches and it solved the problem. Anyone got the info on that?
 
  #4  
Old 04-14-04, 08:28 AM
HandyRon's Avatar
Member
Join Date: Dec 2001
Location: New York
Posts: 1,287
Upvotes: 0
Received 0 Upvotes on 0 Posts
Don't arbitrarily install capacitors or inductors on a particular manufacturers product. It may be costly.
Contact the manufacturer of the light control panel for specific instructions from them.
 
  #5  
Old 04-14-04, 08:34 AM
caleyg's Avatar
Member
Thread Starter
Join Date: Nov 2003
Posts: 306
Upvotes: 0
Received 0 Upvotes on 0 Posts
Thanks Ron, That's a Good Word.
 
  #6  
Old 04-14-04, 11:38 AM
brian64
Visiting Guest
Posts: n/a
i do this for a living ,,,concert lighting that is... the problem is, do you have your control cable going through the sound snake??
if so run a new line ,control cable.. the sound snake is not sheiled thats why you hear it.. does it get lowder when you bring up more lights?? also check the DMX box to make sure the connection are tight
 

Last edited by brian64; 04-15-04 at 05:55 AM.
  #7  
Old 04-14-04, 01:15 PM
caleyg's Avatar
Member
Thread Starter
Join Date: Nov 2003
Posts: 306
Upvotes: 0
Received 0 Upvotes on 0 Posts
Thanks, I'll check those things but my quick inspection shows them running in separate runs (although in proximity)

But, the best I can figure the hum gets worse the lower we dim the lights (until they go completely off--then the hum disappears). I don't know about if we were to separate out the individual fixtures, we don't normally use it that way.

Also I forgot to mention it also sends a line that runs through the video projection (horizontal line which starts at the bottom and scrolls up)--which also gets worse when we dim the lights and disappears when we cut them altogether.

I know those cables aren't run through the light cabling (and not really that near it).
 
  #8  
Old 04-15-04, 12:05 AM
D
Member
Join Date: Mar 2004
Posts: 120
Upvotes: 0
Received 0 Upvotes on 0 Posts
I would call the manufacturere of the lighting equipment, they must have technical support. Even if the system is very old, there is usually a way to get help and a resolution.

Dimmers are generally not supposed to be installed within 6 feet of any sensative equipment.

How long has the system been in? How long have you had this problem? If the system has been installed for 5 years now and the noise has just surfaced in the last week, you might (a slight might) have a bulb issue, since the lighting panel you have would have caused a noise from the very beginning (usually)
 
  #9  
Old 04-15-04, 05:53 AM
brian64
Visiting Guest
Posts: n/a
caleyg


check your pm's you have mail
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: