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Old 21st January 2012, 04:30 PM   #1
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Default Wiring Auditorium Speakers

Hello Everyone,

First of all, this looks like a great forum and I'm excited to be a part of it. In many respects I'm a newbie so I appreciate your patience explaining stupid things to me :P

I'm involved in a school auditorium and we're completely reworking the sound system. I'm in need of a way to get the amplifiers to the speakers. We have several amps in the booth (back of auditorium) and all of the speakers are wired to a small panel at the front of the auditorium.

Currently we run a long snake from the booth to the front and plug the speakers into TRS (1/4" balanced) jacks in the snake. The cables connecting the speakers to these jacks are unbalanced, so I'm guessing the entire cable becomes unbalanced. These cables then run up to the booth and are connected to the amps with bare wire (though I would prefer using banana plugs in the future for ease of use). This system works, although it has its moments of being a little buggy.

I'm not entirely sure how bad or inefficient this setup is, but in any event I'm trying to eliminate the need to run this snake. There is a bunch of unused XLR cable that runs from the stage to the booth, through the walls (guessing it's 3-conductor, though I haven't checked). I want to know if I can use this cable to connect the speakers to the amps in the booth, because I'm really hoping to avoid (and might be completely unable to) run hundreds of feet of speaker cable.

So here are my questions:
1) Is the current system terrible, dangerous or just bad for some other reason?

2) Can I use the cable that's already running from the booth to the stage to connect the speakers to the amps?

Thanks very much
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Old 21st January 2012, 04:38 PM   #2
Pano is online now Pano  United States
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Hi BenTech, welcome to the forum.

I had to read your post a couple of time to be sure, but are you saying that you run the output of the amps thru the snake to the speakers?
And that you want to do the same via the in wall cables?

Maybe I didn't understand, but it sounds like you are running speaker level signals over line level wires. Not a great idea. Obviously it works, but you really need something like 12 gauge wire for long speaker runs.

Otherwise put the amps at the stage if you can, and run balanced line level to them.
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Old 21st January 2012, 04:56 PM   #3
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Quote:
Originally Posted by Pano View Post
Hi BenTech, welcome to the forum.

I had to read your post a couple of time to be sure, but are you saying that you run the output of the amps thru the snake to the speakers?
And that you want to do the same via the in wall cables?

Maybe I didn't understand, but it sounds like you are running speaker level signals over line level wires. Not a great idea. Obviously it works, but you really need something like 12 gauge wire for long speaker runs.

Otherwise put the amps at the stage if you can, and run balanced line level to them.
Thanks for the welcome!

Yes, the output of the amps currently runs thru the snake to the speakers. I want to eliminate the snake by any means possible.

So you're suggesting I put the amps on the stage and output directly to the speaker wire. Then run a line out from the equalizers in the booth to the amps on stage, correct? This seems doable, though it is convenient having the amps in the booth.

Would you mind elaborating a little on what's wrong with the current system? I realize it's not how it's supposed to work, but I'd like to know just for my personal knowledge.

Last edited by BenTech; 21st January 2012 at 04:59 PM.
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Old 21st January 2012, 08:16 PM   #4
Xoc1 is offline Xoc1  United Kingdom
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Hi Ben
The snake would usually be designed to take line level signals only. The correct way to do this is to have the amplifiers close to the speakers, and feed them with a balanced signal from the booth.
The cables embedded in the walls would be the ideal way to feed the signal. If tampering with the amps is a posibility, maybe a cabinet for the amps on the stage would be a good idea. I usually try to keep the amplifier vol controls at 100% - That way no one can turn them up!
By using such a long run of thin cable you will have losses due to the resistances of the wire. You risk causing instability in your amplifiers , and there is also the risk of the cable overheating if there is a short.
Regards Xoc1
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