Restaurant (multichannel) Speaker System Questions


2016-03-04 4:58 pm
Hey everyone,

I have a friend who owns a medium sized Bistro and is currently remodeling and wants to install a new speaker system. I want to help him out and save him money but don't know a huge amount about big systems like this. I'll just list the necessities of the project and then say what I have in mind and if you guys could correct it/give additional advice that would be fantastic.

- must be able to play music from an iPad
- will have 8-12 ceiling mounted speakers
- should be able to control volume of each speaker individually in case one table of customers thinks it is too loud and another thinks it isn't loud enough
- the simpler the better

So it really isn't that complicated of a project, and the part I'm unsure about is mainly the amplifier bit. I found stereo 8" ceiling speakers to use and found a 6 channel speaker selector with volume control but the most channels I found with volume control in one unit is 6. Could I just use 2 of these boxes for more than 6 speakers?

So that's what I was thinking for the controller/speakers. Now for the iPad hook-up I'm thinking a nice looking stand (since the iPad will be visible behind the bar) and just a standard AUX hook-up. Please correct me if that wouldn't be sufficient.

Which leaves me with the question of what to plug the AUX into/what amplifier to get. I don't think it needs to be a receiver since it will only ever have one source input (iPad) and one or two outputs (volume controller). So this is the part where I don't know where to start. I know it has to do with the impedance of the speakers but I don't know if the volume selector affects it or not.

Thanks for you time and help!!
I have been in professional audio for decades, and also spent time in the coin industry - meaning jukebox installations, many in restaurants. SO I have opinions. Others may think differently.

First, it is a restaurant. No one goes to a restaurant to sit there and listen critically to the muzak. I don't care if it is a carefully selected "mix tape", it still is background to the diners. Turning it down if too loud is great, but rarely will you get a customer asking to turn it up. Not unless they are college kids.

Restaurant sound is often "zoned", meaning groups of speakers separately controlled. Mostly that amounts to the bar side getting louder sound than the tables side, and the speaker near the waitress station is way lower than all, so the barkeep and servers can hear orders.

But I have never seen individual controls for each speaker. That is too finicky for me. There are available individual table boxes with speakers, if you want individual controls. But a control for each speaker means at least separate wires to each speaker.

Multispeaker systems like ceilings usually use constant voltage systems, often called 70v systems for the most common. There are many commercially available "PA amplifiers that include 70v outputs. Plain old 8" ceiling speakers are generally fine for this use. 10" if you want to get fancy. No woofers and tweeters necessary. Again, this isn't a concert, it is dinner. The beauty of CV or 70v systems is you no longer have to figure out some convoluted series/parallel system of speaker wiring to get a reasonable impedance load on the amp. All the speakers are tapped off a parallel pair of wires from the 70v output of the amp. Each speaker has a small matching transformer right on it. Those matching transformers typically have up to 10 taps for power levels. We use those for balance. In my previous example, I could wire all my speakers together on one amplifier, and tap the speakers over the bar at 2w each, the tables at 1w, and the waitress station at a half watt or a quarter watt. Believe me that is plenty. Walk into an IHOP or a Bob Evans and listen. Not ear shattering, is it?

Balanced like that, if I turn the amp up and down, all speakers get louder or softer, but they maintain that relative loudness with each other - the bar speaker stay louder than the table speaks.

We add up all the speaker taps wattage. five 2w and five 1w adds up to 15 watts. I'll throw in the waitress one for free. SO a 20 watt amplifier will handle it. If you want a 40 watt amp, fine, just don't turn it up loud. Mono or stereo? I always do my ceilings mono, otherwise the folks under some speakers hear the left channel and other folks hear the right. Only a few seats between them hear stereo at all. And no one cares. No one ever looks up from his arugula salad and cries "Wait, the french horns are supposed to be on the LEFT." If I use a stereo amp, I click the mono button anyway.

In jukebox situations, I leave the box itself stereo, but run all connected ceilings in mono.

You can use a regular amplifier and mount a 70v transformer on the output to get the 70v needed for the speaker distribution. or just buy an amp already set up for it.

If your ipod has a usable line out, then the regular aux in on an amp ought to work. WHy does this need to be visible behind the bar? Customers won't get their hands on it will they? I find it is rarely good for customers to SEE the controls on an amp. That is begging for them to chime in on how it is only on 2, so CRANK IT. Or it is on 4 so turn it down. Music should be like seasoning a steak. You want it to make the experience better, but you don't want salt-flavored steak. Music should not be their focus, just an enhancement. "Oh my god, is that the new Maria Carey?" should not be the reaction.

Google constant voltage speakers or 70v speakers for more info. and 70v amplifiers through google should provide info and sources.
Just one little nugget of wisdom: Don't use a good stereo amplifier in a 70V audio distribution system. Those typical low-cost matching transformers easily go into core saturation at low frequencies if the volume is turned up, resulting in blown fuses or worse. Use an actual designed-for-the-job PA amplifier or add low frequency band limiting if you want reliability.