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Author Topic: 70 volt or 8 ohm amplifier hookup advise needed!  (Read 18626 times)

John Roberts {JR}

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Re: 70 volt or 8 ohm amplifier hookup advise needed!
« Reply #10 on: May 08, 2005, 12:29:34 pm »

doho wrote on Sun, 08 May 2005 11:10

Thanks everyone for your advice. I should have mentioned that the 70 volt speaker system is composed of two 35 watt tower speakers and two 10 watt side speakers in the main sanctuary and three remote speakers. The longest remote wire run is 125 feet using 18 gauge speaker wire. The sanctuary is 40' X 70' all wood with massive wood arches and wood pews, creating terrible acoustics and feed back. There is carpet on the floor. There are 8 active microphones feed into the mixer.

When I hooked up the Alesis 500 watt with bridged output, the system volume control was almost maxed out to get an acceptable volume level. Yet with a Radio Shack 20 watt 70 volt amp, the volume was about 1/3 from max. I hooked up the mixer and amp in my shop with an 8 ohm speaker load and the Matica amp had plenty of adjustment left. Anyway, I ordered a Bogen HTA-125 amplifier to replace the Matica 500. Hopefully this is a good choice.

Thanks again for your comments.
Don


I will assume you don't have flexibility with how the speaker step down transformers are tapped. Your basic problem is that the 35W tap is based on 70V nominal. If you could push up the tap you would get more volume from the lower than 70V line.

The next cheapest solution is to purchase an outboard 70V step-up transformer. I know PV sold these for years (automatch?) and they were pretty inexpensive.

Of course a true 70V amp should work just fine.

Good luck.

JR


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doho

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Re: 70 volt or 8 ohm amplifier hookup advise needed!
« Reply #11 on: May 08, 2005, 04:57:06 pm »

The taps on the 35 watt speakers are set at 15 watts and the side speakers are set at 5 watts. Rather than try to make a mismatched system work, I thought it best to match the 70 volt speaker system with a 70 volt amp. Then, if any other problems develop, at least I know the main components are matched.
Don
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Re: 70 volt or 8 ohm amplifier hookup advise needed!
« Reply #11 on: May 08, 2005, 04:57:06 pm »


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