From: rmontgom@orlith.bates.edu (Robert Montgomery)
Subject: Re: Speaker Connections
Organization: Bates College, Lewiston, Maine
Date: Sun, 13 Dec 1992 00:17:20 GMT

In article <1gakesINN51s@ossi.ossi.com> news@ossi.com (OSSI Newsstand) writes:
>gw214790@LANCE.ColoState.Edu (Galen Watts) writes:
>
>>In article <1992Dec9.173634.9231@news.cs.brandeis.edu> kenyon@binah.cc.brandeis.edu writes:
>>>Dave, why not use the third pin as a ground?  Then we wouldn't have as much line noise?  I don't know for sure if that would be a good practice, but it seems like it would work.  ( this is, of course, only app. if you go with the XLR )
>
>>What are you going to ground?  In the UK, I think you have to ground the frame
>>of the loudspeaker, but this is for safety, not noise reduction.
>>We had XLR's in our PA for a while, and we noticed they got warm during shows,
>>which says that some of the energy that should have been sound went into heat.
>>XLR's are nice because they lock, but they were never intended for speaker
>>levels.  Do yourself a favor and install either twist-lock connectors (ok, but
>>not ideal) or get Neutrik SPEAKON connectors.  When you plug them in, you give 
>>them a twist to connect.  This cleans the contacts every time you use them.
>>Another plus is they lock.  Unless you really mean to, they won't come undone.
>>Also, no one can get their finger on a contact because the contacts are set
>>inside so you can't get to them.  This helps if you have some bored performer
>>set on electrocution, they won't do it with your speaker lines.
>
>>Speakons come with four or eight contacts, in case you bi or tri-amp your systemYou only need one cable instead of two or three.
>
>>If your getting line noise in your system, check your grounds and if your audio
>>cables are in the same conduit as your lighting wiring.  I've had more problems
>>with dimmer noise than any other noises, and it's usually caused by the cables
>>being too close together.
>
 I posted a bit earlier asking about the "safety" issue. It didn't seem 
quite possible to me that anyone could get into much trouble with speaker
levels. I asked around after I posted (ok, a bit backwards) and it seems
that there is a method, usually used on huge amps, where the speaker level is
given a boost to about 70 volts. (This keeps the amperage down so the wire 
you run through doesn't have to be the size of Kansas.) 
 The question was also asked, what will happen if you power supply undergoes 
a catastrophic failure (that is the power supply in the amp). Personally,
I don't see how a ground will help you in any manner (your speaker coil 
should turn into pot roast, and that will kill your continuity) but then 
again, I'm not an electrical engineer. Just a bub.

>>Happy Trails,
>>Galen Watts
>
>
>
>I have never gotten hum over a speaker run.  You get speaker hum
>usually before the final stage of amplification.
>
But the XLR's will do wonders for your high-end. All that capacitance will
make it barely noticeable. ;-) Well, ok. Maybe not, but they won't help matters.
In the theatre where I work we use XLR inputs to the speakers, and they seem
to do just fine. However, we never get above 500 watts, and all but the final
stages is either quarter-inch or two-pin twist. All wire is 18A.W.G.

>XLR plugs are not intended for that much power, besides keeping
>your line vs: mic levels is bad enough, you dont need a third
>system using the same plug.
>
>Your XLR dealer is trying to get rich off of you.  They make some
>real nice recessed boxes with bannana plugs mounted inside out of
>the way of accidents.  You can either plug into 5 way bannanas or
>you can screw down loose wire or a lug.
>
>Reply to ME, not my server at:
>
>texx@ossi.com
>
>-texx
>(AKA: Tejas, Audio Supervisor, Outlook Video)
>


Later,
   Rob

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| rmontgom@orlith.bates.edu  ROB MONTGOMERY  rmontgom@abacus.bates.edu |
|         IF AT FIRST YOU DON'T SUCCEED, TRY A BIGGER HAMMER.          |
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