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We are trying to build a PA system on our speed venue, and I'm looking for a little advice. It would be used for an announcer and occasionally music.

Since our time and budget is very tight, I'd really like to avoid running extra wire/conduit if at all possible. Does anyone have experience running a PA through timing cable? We have a 50 conductor, 24 gauge cable running top to bottom and only use ten conductors for timing. My original plan was to run line level audio signal through the timing wire and use powered speakers. We have lots of 120v power available on the hill from our snowmaking system. However, I spoke with our local audio vendor and he told me that powered speakers wouldn't work in the cold temperatures/extreme weather and that we'd need to use a 70v distributed system powered by an amp at the bottom.

My question is, has anyone ran a 70v system through a timing cable successfully? I'm nervous about getting false starts/finishes or having a bad hum on the com line. Or, has anyone run line level signals with powered speakers successfully in the cold?

Thanks a lot for the help,
Zach
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There really is not enough information such as length of the timing cable to make an accurate determination of what is needed. James is 100% correct about running 70V speaker line over one of the cable pairs in your timing cable. However, there are two possible options that could be tried. One would be to send a "line level" signal (600 ohms)over one of the timing cable pairs up to a "line level" input to an amplifier up in your start area. From that amplifier you can feed each speaker with 70V from that start amplifier. If the signal is low, up at the start amplifier, then a 600 ohm amplifier may be needed. This would be your lowest cost option.

The other option would involve setting up a network between the finish and the start area using a set of DSL type adapters and using one of the cable pairs in your timing cable. You can then use a set of VoIP adapters to get the paging signal from the finish area up to an amplifier in your start area over that network set up. One other plus of this set up would be the fact that you would have a network connection up in your start area for other uses too. The downside of this set up is that it is not cheap to do and you also need an understanding of networking and VoIP equipment.

Steve
Even before the wrong pulses, you might be in serious trouble with the law.
What you want to do is really far beyond any safety rules. Highly dangerous.
Do not mix a nontrivial voltage in a cable used with very low voltage equipment
such as timers and headsets.

Have a cable contractor suggest you the best way to do it.
Stocks are full of good not-so-expensive cables.

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