Hooking up 14 speakers in a retail store, Help??

I'm hoping someone can help me out here. I have been tasked to install a 14 speaker system in a retail environment. Ideally we would like to control the sound in different zones but not the end of the world if we can't. I have 6 speakers in a higher ceiling, 6 in a lower, and 2 in separate room. This is not really my thing, but I'm a smart guy. Smart enough to know when I need to ask someone at least. I do best with simple wiring drawings, treat me like a child! Use crayon if you like, snap a pic with your phone and post it! If we need to add volume controllers I'm okay with that, just include it in the drawing ;>). Here is the equipment I have to work with:

Amp
http://www.inter-m.net/en/products-list/amplifiers/commercial-audio/mixing-amplifiers/pa-4000a/

4 Ohm Speakers
https://azdenproshop.com/product/acs-6-5-speaker-each-ceiling-mount/

Thanks in advance!!!

 

Pretty easy stuff, but I don't' have the time at the moment to respond. If nobody has responded by tonight I'll try to come up with some time to help.

 

I was just going to recommend PCing you Doug knowing this is one area of your expertise.

 

Looks like you've got plenty of speaker outputs on the amp. I'd do
a) each group of six wired together, as three pairs in parallel (two 4 ohm speakers in parallel = nominally 2 ohms) then those pairs wired in series (three "2 ohms" in series - nominally six ohms, easy load)
b) the two speakers in the other room in series on another output channel. All on the 8 ohm taps.

 

Why wouldn't you just hire a contractor that knows how to do this?

 

Your amp is designed to drive a 70v line, which is the best way to handle so many speakers. However, the speakers you're working with are not equipped with 70v transformers. You could get some of those here: http://www.parts-express.com/70v-10w-line-matching-transformer--300-040 Here's a good guide to 70v systems: http://www.crownaudio.com/media/pdf/amps/138905-1_10-05_constant_voltage.pdf

 

Here is a link to a JPEG of the layout of the speakers with the connections on the amp as well. All of the speaker connections are numbered. If someone could help me connect the dots. A simple 2-3, 4-5, 1-COM, 6-SP1 type of explanation works. Thanks.

http://www.cuttingedgedecor.com/#!speakers/c1009

 

I don't see anything at that web address.

 

Try refreshing the page. Something weird happens when I click on it too, but when I refreshed it came right up. Or you could try this link to the image itself:

http://static.wixstatic.com/media/b...pg_srz_p_811_612_75_22_0.50_1.20_0.00_jpg_srz

 

Anybody?

 

Agreed. I did this stuff for a living, too.

The easiest is to add 70 volt transformers to the speakers, as mentioned upthread, and wire the speakers in series. That way you could use the speaker switches on the front panel of the amp to turn off the high, low or secondary room speakers. I'd also recommend a volume control for each area so you could adjust that area's volume. Otherwise you'll get blasted out of one area while it's too quiet in another. You'd need to use a 70v volume control but those are easy enough to find.

The disadvantage of 70v is sound quality. It's fine for background music but not great for quality listening. You don't say what your application is but if this was for a restaurant or an office, 70v would be fine. I did a ton of large excursion boats for a local yacht manufacturer and they were all 70v systems.

If you want better sound, then you have to come up with a series-parallel design to keep the load a nice, safe 4 or 8 ohms at the amp. You'd lose the speaker switches but by again using volume controls, you could shut of an area with them. I also wired up maybe a dozen bars and record stores back in the old days and they were all 4 ohm systems.

What's your application, jdkaeser? You say it's for a retail store. Is sound quality critical or is it background music that you want?

 

I agree with most of this but in a 70v array the speakers are wired in parallel, not series. The transformers essentially raise the impedance of the speakers to well over 100 ohms, so you can hook many of them up in parallel.

 

Yes, parallel, as Doug said. I was just thinking of the wire running from speaker to speaker, all of them daisy chained together, which made me think series, but at the speaker itself, the hookup is in parallel.

My error.

 

GGERGM, I think I want to go the series/parallel route instead of the 70V route. Shutting off zones is not a necessity, the ceilings are at a close enough height that I think they can all be at the same volume, mostly backgound music. Looking at the image I posted, do you think you could hook me up with a labeled wiring diagram?

 

Yes, I can come up with a design that will work. I figured out one would be about a 3 ohm load at the amp, which should be close enough for rock 'n' roll. I'd also recommend you use impedance matching volume controls which we can use to up that a bit closer to 4 ohms, keeping a nice load at the amp.

And you will want volume controls, even if you don't want to shut off an area. There is nothing more disturbing in a retail environment than music that is too loud. Considering the different size spaces you are trying to fill, fine tuning the volumes for the three spaces is almost a requirement. Three volume controls mounted back by the amp, adjustable by staff but not by the public, will solve the problem and only add $150-200 to your parts charge. Heck, your wire costs will be a lot more than that. You'll have to use plenum speaker wire to meet code and you'll want some thick stuff. I don't know what 14 gauge plenum speaker wire costs nowadays but it can't be cheap. Normal in-wall CL2 or CL3 rated speaker wire is fine for home use but won't meet code in a commercial setting. I know because I once ran into a tough electrical inspector who made me rip out all of my speaker wire on a job and start over again.

Let me modify your diagram to show you a series/parallel set-up. We'll rely on Doug to check my work.

 

As you know, that's the beauty of using the 70v system. You can add a new speaker anywhere by just tapping into the line with little concern for what you may do the rest of the system. But hook a 8 ohm parallel speaker to the system and you're dead.

I once did some work for a guy who had 70v paging systems at car dealerships. They'd often get a service call that the system was down, and it was almost always somebody hooking up a low impedance speaker to the line.

There was an easy fix for this. Hook up line voltage to the distribution line, after removing it from the amp. The transformers will protect the speakers, but the ones without transformers will make their presence known quickly before popping open. In any event, the line will be cleared and you can now hook it back up to the amp. I was fairly shocked the first time I saw this done but it was the easiest way to find the fault.

 

Glad to. Much easier than doing the work, or design, myself. We can all learn from the experience.

And you can do it with less than 14 gauge, but surely there is no harm in using that heavy cabling. If you can raise the impedance of the overall load the size of the wire can get smaller, not that it has to. The heavier cable can offer more flexibility down the load if you want to make any design changes.

 

Let me see if I can get it closer to 8 rather than 4 ohms. The 3 ohm design was a back of the envelope calculation. In fact, I was drawing out something since my last note and realized I wanted to go higher in impedance, anyway. jdkaeser, it will probably be tomorrow until I can get this done.

And Doug, I seriously doubt you will learn anything from me.

 

I've hooked up line voltage to a speaker driver in order to blow it on purpose but never as a trouble shooting tool. I would need to rent a bigger set of cajones before trying this trick.

 

Back in the 70s, Cerwin Vega hooked line voltage up to one of their big woofers to prove that it could take it.

It could, but the AES convention crowd couldn't. That's over 1000 watts no matter how you cut it.

 

You never know. I learn from all kinds of folks and usually I learn new things every day.

 

I should probably sleep on this drawing for a night before posting it but I'm foolish enough to think I got it right the first time. Start with the speakers and follow the signal path back through the volume controls to the amplifier to read the legends. They will make sense that way.

I showed the speakers hooked up to the 8 ohm tap on the amplifier, which is what I'd try first. I'd also experiment with the array on the 4 ohm tap. You might find a difference in sound quality, volume, and/or heat put out by the amp. Obviously you want the way where it sounds best and the amp runs cool to the touch if at all possible.

If you want a full sized version of this diagram, it is here.

To figure out the impedance loads, I used this calculator.

Here's a link for an impedance matching volume control through Amazon. Audio Source generally makes cheaper but OK stuff. I also see Russound volume controls on Amazon. They could be beefier. They are rated to handle more power and have used Russound favorably in the past. Doug, please weigh in here with your opinion of what the OP should go with. Three of the Audio Source controls would be under $100.

Doug, what gauge wire would you recommend the OP use?

 

Well, the contractor just dropped a bomb on me this morning. The ceiling is riddled with stuff that cannot be moved which is affecting our ceiling can light placement as well as these speakers since they are about the same depth as the lights and we have to maintain our ceiling height. So it looks like I'm returning these speakers. I probably end up going with 70V at that point since it seems like that will be easier in the long run.

GGERGM, you are the man! Thanks for going the extra mile. Seriously, I appreciate the effort you put into this. I may hit you up for some advice on the 70V system. For right now, I'm in limbo.

 

You're welcome. This is one of the things I did for a living. It was fun to revisit it.

I'm sorry to hear the ceiling is such a challenge. Don't give up yet. I assume the problem is HVAC. It usually is. I have had luck working around ducts with ingenuity. It's not easy but that's the advantage to a dropped ceiling. Once you're done, nobody can see your sins behind it.

If you want info on a 70v system, let me know. Those are a piece of cake.