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Really Hot Receiver

Sun Sep 18, 2016 6:56 pm

Hey guys, I've inherited a white noise system for a call center building just purchased. The receiver/amp is driving probably somewhere between 50-75 speakers in the building. You know, those old school ones you always see in the ceiling of any grocery store or what not.

Anyway, the receiver is getting DAMN hot. Definitely hot enough that if I touched it for more than a few seconds I'd come away with a burn. Not quite hot enough to burn paper though apparently (I tested it for about 20 seconds). Is this a sign it's on it's last legs, under powered for the job, or that I just need to be sure to direct a fan at it? It IS in my server room, so the room itself is gonna be kept fairly chilly.
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Re: Really Hot Receiver

Sun Sep 18, 2016 7:03 pm

Are they normal ceiling speakers or more of the commercial 70V type?
How are they wired? What ohm-rating are the speakers? My first guess is that they are presenting too low of an impedance. I would wire them try to stay at or above 8 ohm. Most receivers really don't like 2 or 4 ohm loads.
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Re: Really Hot Receiver

Sun Sep 18, 2016 7:15 pm

Adding a fan wouldn't be a bad idea, either.
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Re: Really Hot Receiver

Sun Sep 18, 2016 10:09 pm

You got a model number (or pictures) for this setup?  There's no way that an ordinary home receiver (as we typically think of it) would be successfully driving "50 to 75" ceiling speakers without a really convoluted wiring scheme.  Especially not when driving a continuous white noise signal, since that typically saturates the entire frequency band and draws a fairly high continuous load, which most home receivers cannot handle for very long.

As someone else noted, a 70V system would be most typical for an older PA -- and if you can't get info from the base unit, you can find out pretty quick by pulling one of the ceiling PA speakers, and seeing if there's a small transformer mounted with it.

As long as the unit has good ventilation, it can run moderately hot and still be in design parameters, although a bit of extra ventilation can help.  In any case, the threshold of human pain is somewhere between 130-140F, while the threshold of lighting paper on fire is around 450F and would probably be throwing enough infrared heat to feel radiantly hot at a foot or more, so... :wink:
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Re: Really Hot Receiver

Sun Sep 18, 2016 10:21 pm

You should borrow an IR thermometer from someone for science

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