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Author Topic: Choosing 8ohm or Constant Voltage  (Read 2509 times)

Brett Keller

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Choosing 8ohm or Constant Voltage
« on: June 14, 2013, 07:02:33 pm »

My regular job is providing mobile sound for bands, but I've been given the opportunity to do a small install in a retail space. I know that many of you will want to yell at me for trying to do this when it's not what I normally do, but it's an extremely small job, and I'm not doing it to really make any money, but simply to dip my toe into these waters and give my friends shop a good deal.

The shop is very small, and they want the music volume to be pretty low, so I'm planning on installing just two JBL Control 65P/T's. I may also add a single QSC AD-S52 outside if they decide they want it and it's in the budget. With only three speakers, and the small size of the shop, I'm considering just running the speakers at 8ohms. The shop is about 25'x25', but has pretty high ceilings with metal I-beams. The ceiling is black, so I'll most likely conceal the cable by keeping it tight along the beams. There is a covered lofted area above the register where I can keep the amp and it will be relatively close to the ceiling. The computer where they will be playing the music is directly below this. I thinking about putting a passive volume attenuator on the wall for them next to the computer. If they opt for the outside speaker I'll probably put it on it's own channel on the amp, and put the two indoor speakers on the other side.

So my main question for the real pro's is, am I right in thinking it's simpler to do this job at 8ohms? Can I save them significant money on cabling with a 70v system? What do you think of my plan in general?

Thanks
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Hal Bissinger/COMSYSTEC

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Re: Choosing 8ohm or Constant Voltage
« Reply #1 on: June 14, 2013, 08:10:20 pm »

With only two speakers you would save a few dollars by not using 70 volt. Price it up both ways and see. You can use the same amp, there will be a small difference in wiring. Most difference will be in the cost of the speakers- with and without transformers. The only consideration should be whether they will ever add more speakers. If there is even a remote possibility go with 70v.
 
-Hal
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Ivan Beaver

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Re: Choosing 8ohm or Constant Voltage
« Reply #2 on: June 15, 2013, 08:38:15 am »

When you say "2" speakers-is this a mono or stereo system?  so is it 1 speaker per channel or 2?

Either way-I would want a different volume control for outside.

An L pad for each location would work just fine.

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Ivan Beaver
Danley Sound Labs

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Hal Bissinger/COMSYSTEC

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Re: Choosing 8ohm or Constant Voltage
« Reply #3 on: June 15, 2013, 01:13:08 pm »

When you say "2" speakers-is this a mono or stereo system?  so is it 1 speaker per channel or 2?

Either way-I would want a different volume control for outside.

An L pad for each location would work just fine.

Hopefully mono. Stereo makes no sense in a distributed ceiling speaker system. Also, if you are in love with those JBL pendent speakers it looks like they are only available in transformer versions so you might as well go with 70v. Makes it easy to add that outdoor speaker. Likely outside will want to be at a higher level than inside so the usual AT type 70v volume controls for each zone would be nice, locate them in a convienient location (like behind the counter) in the store so nobody plays with the amp settings.
 
-Hal
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duane massey

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Re: Choosing 8ohm or Constant Voltage
« Reply #4 on: June 16, 2013, 02:16:44 am »

From your description I'd go 70v mixer/amp. Put a 70v volume control at a convenient location for the shop speakers, and put a separate one for the outdoor speaker if you add it. Shouldn't need a big amp, look at TOA, Atlas, Speco, even Radio Shack.....
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Duane Massey
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Houston, Texas

Ivan Beaver

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Re: Choosing 8ohm or Constant Voltage
« Reply #5 on: June 16, 2013, 11:38:25 am »


Hopefully mono. Stereo makes no sense in a distributed ceiling speaker system.
Doing stereo for a 25'x25' area is no big deal.  Many living rooms are that size or larger.

Unless there is something we are not aware of- 2 speakers (aimed to provide stereo) should not be that big a deal.

I would not think of distributed in an area that small-again-unless there is something I am not aware of.
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Ivan Beaver
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Hal Bissinger/COMSYSTEC

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Re: Choosing 8ohm or Constant Voltage
« Reply #6 on: June 16, 2013, 02:44:25 pm »

Doing stereo for a 25'x25' area is no big deal.  Many living rooms are that size or larger.

Unless there is something we are not aware of- 2 speakers (aimed to provide stereo) should not be that big a deal.

I would not think of distributed in an area that small-again-unless there is something I am not aware of.


These are pendent speakers hung by cables from the ceiling trusses. So aiming is not really something they do. You are either under them or not.


-Hal
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Brad Weber

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Re: Choosing 8ohm or Constant Voltage
« Reply #7 on: June 17, 2013, 12:44:30 pm »

The computer where they will be playing the music is directly below this.
Totally different aspect but since it is an area that often gets overlooked in in DIY projects or where trying to minimize costs, hopefully that computer is somehow related to a business music service or they have otherwise adressed music licensing for the business use.
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Hal Bissinger/COMSYSTEC

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Re: Choosing 8ohm or Constant Voltage
« Reply #8 on: June 17, 2013, 04:52:33 pm »

Totally different aspect but since it is an area that often gets overlooked in in DIY projects or where trying to minimize costs, hopefully that computer is somehow related to a business music service or they have otherwise adressed music licensing for the business use.
+1
 
-Hal
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Re: Choosing 8ohm or Constant Voltage
« Reply #8 on: June 17, 2013, 04:52:33 pm »


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