I need advice please. This is for my restaurant with a seating capacity for 50 persons.

My amp is a CROWN 180MA with a minimum guaranteed power of 80W into 4 ohms or 70V/100V output.

My speakers are 9 units of JBL CONTROL 26CT each with a capacity of 150 Watts continuous program power or 75 Watts continuous pink noise. The speakers each have 60W, 30W, 15W, and 7.5W transformer taps at 70V/100V.

My plan is to connect all the 9 speakers in phase to have a line distributed system with the transformer taps set at 7.5W for the all the 9 speakers.

So the computation will be 7.5W x 9 = 67.5 total watts, which will be suitable for the 80 watts power rating of the amp.

Am I correct ?
What type and gauge of speaker wire shall I use ?

Thanks so much.
Nilo

You need to base your power taps on the required SPL in the specific areas, not a generalization.

What does "connect all the 9 speakers in phase" mean- parallel? That's fine, but the terminology used should match the standard wording.

16 ga is all you need- what is the distance from the amp to the farthest speaker?

[Link: prosoundweb.com]

[Link: en.wikipedia.org]

[Link: crownaudio.com]

Nilo Santos,

Read through the references given by highfigh. While one or the other approach may not be familiar to you, it is the same physics, just different math as you figure out how many speakers you can attach to an amplifier. The 70V math is much easier when configuring large systems. This is why the Pro's use it for commercial projects.

A huge advantage of 70V is that you can easily accommodate rooms of different sizes by changing a room's transformer tap. For example, you can use a low power tap for a small restroom, and a higher power tap in the larger dining room. Just make sure that the sum of the taps is within the amplifier's rating.

And make sure to leave about 20% of the power as headroom- an 80W amp should have speakers set to a bit over 60W, total. You should be fine with 7.5W per speaker.

The manual I found for this doesn't show the back of this model, but I think there's one channel of power amplification.


"In phase" means the + of the power amp goes to every + of the speakers and the - goes to every - of the speakers. This is how speakers are always connected. I think you think this means something special, but it's so ordinary that nobody ever mentions it. It's so ordinary that highfigh wonders what you mean by it.

Yes.

Two conductor solid or stranded, 20 gauge or larger. I'd use 18 gauge, probably.


You're welcome, Nilo. Sounds like you're embarking on something that's new for you. Enjoy, and come back and ask questions if you have any.

An important detail is that the audio will all be monaural, which means one channel... while music sources are usually two channels. There's a bit of art to combining the two channels into one without having problems. Look up the essay "Why not Wye?" and read it through. It will be good for you to understand what it's about.

Best of luck, and enjoy.

Ernie

Comments on the other comments:
Highfigh is right.
Buzz is right. However, since you're planning to use the lowest tap on each speaker, you cannot adjust the volume in the way he mentions. You're already at your lowest volume per speaker while being set up to match the power amp's output. That info is for further systems.

I agree with highfigh's general idea about SPL, but that's WAY too advanced for you right now, and not necessary with what you're doing. See, you want all the speakers at the same volume; your speaker load does not exceed the amps' output; and you can't specify the SPL in that room unless you could use a different amp... you're going to get what the 180MA puts out.

Come on back with questions.

Two other things that I didn't see mentioned:

1. You mention that the amplifier has 70 volt and 100 volt taps. In the USA the 100 volt output would be considered Class 1 and would need to be in conduit. The 70 volt (70.7v) would be Class 2 and would not need conduit unless your local jurisdiction requires it.

2. Assuming you'll be using the 70 volt output, the next issue is the location of the cable. If it's out in the open, fine. But if it's run above a drop ceiling, and if that space above is used as a plenum, then you will need to purchase plenum rated cable.

delete, please

The user manual is available on the Harmon site- it's the third link from the top if you google search 'Crown 180MA'.

The manual for the 180, 280 and 1160 series, which shows two channel inputs for each source-

file:///C:/Users/USER/Downloads/180MA-280MA-1160MA-Operation-Manual-137783_original.pdf

This link shows the back of the 180MA- good to see it has clipping indicators for master and each input, as well as bass and treble controls for each.

[Link: parts-express.com]

Yes, my plan is for a 70V / 100V line set-up. So then "connecting all the speakers in phase" means that the “0 volt” or the “Com” of the amp will be connected to the “0 Volt” or “Com” of each speaker transformer.

The distance from the amp to the farthest speaker is about 100 feet. - (indoor/drop ceiling, no plenum)

Any type of speaker cable preferred? - (shielded, solid, stranded, etc.)

I have the option to go with 70V or 100V. Which would be better? - (sound quality, etc.)

Thanks everyone. Your great advice is so very much appreciated.

Nilo

70V or 100V (25V is also an options with some systems) makes no difference on sound quality. The different voltages allow for different configurations of a system. Which by the way; at 100V the tap settings on those speakers is 15w not 7.5w anymore. So you can NOT run 9 of those speakers at 100V setup, without eventually burning that amp up. You have to use the 70V configuration, so the minimum tap is 7.5 watt.

Regular stranded speaker wire is all you need, with the appropriate UL listing. Meaning use plenum rated for plenum spaces, riser rated for between floors, etc.
Do NOT use solid wire. Why would you do that? It would work but you are causing yourself and anyone else that has to work on it grief.
You could use shielded wire if you want to but there really is no need. 99.9% of the time, shielding isn't going to do anything for you on speaker wiring. That last .1% is because there is always some weird installation waiting out there - neon tubes laying parallel to speaker wire or something.

Something not mentioned anywhere is this thread so far - 70V volume controls!
This is a restaurant. Inevitably you are going to need to have the ability to adjust volume in different areas of the restaurant. Even shut volume off completely in a section. Installing some 70V volume controls is a simple & cheap way to accomplish this on a simple system like this.
Just need a volume control for each area. So if there are 5 speakers up front in the main area and 4 speakers in a back area, you might only need to get 2 volume controls. If you have 4 divided areas, then 4 volume controls.
Wiring will become a little more complicated if you are not familiar. You need to either home run from each volume control location, or wire your loop thru each volume control location. A separate loop wires out from each volume control location to the speakers.
I like home running as much as possible. It uses more wire and more time to install but is easier to troubleshoot and make changes in the future.

For the moment, ignore the man behind the curtain and just assume some wizard is running things.

You know what wiring changes you have to make to convert a 70 volt system to a 100 volt system? NONE. Sorry, but I feel that at this point in your education it's not worth trying to explain. A reason that there's a single output point labeled "70/100 Volt" is that the wiring is the same but the concept varies slightly from one to the other. Just be sure you're ALWAYS looking at the 70 volt numbers when you're wiring a 70 volt system. Ignore the 100 volt numbers.


I see zero grief caused by using solid wire. What about solid wire would cause anyone grief?

Simple, yes, cheap, not necessarily. A properly done 70 volt system can be a daisy chain of wires out from the amp. If you then decide you want to lower the volume of a certain set of speakers, you have to modify the original wiring, which might require adding one or more home runs from a distance from the amp. It all depends on where you want to add the controls. It is BY FAR best to think through whether you'll need to trim the volume of any speaker(s) and run separate home runs for each such group of speakers.

This is totally correct.

Absolutely true.

Never state that you're wiring speakers in phase because you're ALWAYS wiring speakers in phase (unless you make a wiring error). There is zero reason to wire any speakers out of phase with the others, so you're just bringing up subjects worthy of no discussion at all. Saying you're wiring speakers in phase is like pointing out that you're going to hold your breath when you swim under water: of course you are, everybody does, and you'll get in trouble if you don't. The only difference is that wiring speakers out of phase won't be fatal, while breathing under water will be.

Hilo Santos,

With respect to “phase”, by convention, when we connect the (+) terminal of a battery to the (+) terminal of a speaker, the speaker cone will jump away from (out of) the basket.

Sonically, you can think of this as a positive pressure wave. This implies that when two nearby speakers are wired differently, the negative wave of one speaker tends to cancel the positive wave of the other speaker. This is why we want all of the speakers to be in phase. It’s a complex interaction because the wave must travel some distance before encountering and interacting with the other wave, giving up some energy along the way. Because of this you will not experience complete cancellation. As a practical matter, bass is more easily cancelled than the treble. If you hook up an additional speaker and the bass diminishes, check the phase of all speakers.

Experiment with this by deliberately wiring a speaker out of phase. In addition to bass reduction, there are other effects. Listen carefully. With some practice, you will be able to recognize out of phase situations.

Have you ever tried to wire an 'audio' system with solid wire before? A system that every connector in it, was designed to be used with stranded wire. Yes it works and can be done. But I guarantee at least one curse word before all the connections are finished.

We aren't talking about a generic 'audio' system, so your opening question doesn't apply.

One big advantage of using 70V is that since the voltage is higher than it would be if feeding an 8 ohm speaker, the current is lower. That means that voltage drop along the wire will be less than with larger gauge wire. That means that you can use smaller gauge wire with 70V than with 8 ohm systems. That ends up with these two results:

If you're wiring a cheap speaker that has a 70 volt transformer and flying leads on it, it is simple to wire it up using solid wire and wire nuts.

If you're wiring more expensive speakers, they're likely to have binding posts or other connectors that work well with solid wire.

I see no objection to using stranded wire except for the amateur occasionally letting a strand of wire get loose and short the line... above the ceiling. We did a furniture store a couple years ago where we used 20 ga solid wire feeding FIFTY SPEAKERS... imagine how difficult troubleshooting would be if a strand was loose in a place with fifty speakers! Solid wires have only one strand, thus a loose strand is not a possibility.

A loose strand might not be a possibility with solid wire, but if that wire is bent too often, it can/will break. With solid wire, you get one chance.