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Author Topic: speaker wire advice  (Read 3858 times)

Ivan Beaver

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Re: speaker wire advice
« Reply #10 on: January 28, 2016, 10:45:02 pm »

I thought about the 70 volt thing and have used it before, with matching amps at each end, may be a way to go. I had the idea of running each cab in series, 16 ohms instead of 4, but if one driver acts up you loose both drivers. I, like anyone, over-think things that really don't add up to anything in the end. It worked last year, it will work better this year, even if no one can tell. Thanks again for the advice, and Luke for all the math.  Thanks to all...  KC.
A 70V system is all in parallel.  So if 1 fails, only that one fails.

What you tap the speakers at determines the impedance and the load "draw" on the amp.

It is a simple impedance issue.

Generally you simply add up all the taps-then add 10% or so and that is the size of 70V amp you need (or larger if desired)

A 1 watt tap is 4900 ohms, 10 watts is 490 ohms and a 100 watt tap is 49 ohms.

So if you used 1 of each of the above taps, you have a load of 111watts.  Or a total load of 44 ohms.

Assuming everything is "perfect"-which it is not.  Hence the reason to add 10% for just in case.  Or 122 watts

An amp that can produce 600 watts@8 ohms will drive a 70V line to full power.

I would not suggest 70V for subs-at least real subs.  The transformers get to be a problem at low freq.

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A complex question is easily answered by a simple-easy to understand WRONG answer!

Ivan Beaver
Danley Sound Labs

PHYSICS- NOT FADS!

Kevin Conlon

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Re: speaker wire advice
« Reply #11 on: January 28, 2016, 11:35:39 pm »

A 70V system is all in parallel.  So if 1 fails, only that one fails.

What you tap the speakers at determines the impedance and the load "draw" on the amp.

It is a simple impedance issue.

Generally you simply add up all the taps-then add 10% or so and that is the size of 70V amp you need (or larger if desired)

A 1 watt tap is 4900 ohms, 10 watts is 490 ohms and a 100 watt tap is 49 ohms.

So if you used 1 of each of the above taps, you have a load of 111watts.  Or a total load of 44 ohms.

Assuming everything is "perfect"-which it is not.  Hence the reason to add 10% for just in case.  Or 122 watts

An amp that can produce 600 watts@8 ohms will drive a 70V line to full power.

I would not suggest 70V for subs-at least real subs.  The transformers get to be a problem at low freq.
Right, i only thought about it. The 70 volt stuff i have done was to power the speakers on the utility poles around a town square, worked great but sounded like a transistor am radio, but the ones paying were happy. Never tried it with subs, and now i won't with that info. With all my amps on 240 volts, all logic says put the needed amps and a spare close to the speakers. I have what i need to do that. Volt lines are great for a department store, do they have any real use in quality live sound? Delays maybe, but i like wireless for that. Thanks again..KC
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Ivan Beaver

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Re: speaker wire advice
« Reply #12 on: January 29, 2016, 07:13:43 am »

Right, i only thought about it. The 70 volt stuff i have done was to power the speakers on the utility poles around a town square, worked great but sounded like a transistor am radio,
Don't blame the 70V distro system for the sound quality.

Blame the speakers hooked up to it.

Yes the deeper lows can suffer in a 70V system, but larger transformers will help that-at the expense of size-cost and weight.
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A complex question is easily answered by a simple-easy to understand WRONG answer!

Ivan Beaver
Danley Sound Labs

PHYSICS- NOT FADS!
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