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Speaker wire too thin 50ft-18AWG-4Ohm, restaurant installation
andy o
post Oct 1 2011, 00:13
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Hi guys, I'm retrofitting a restaurant with audio equipment. The simplest way to go about it (without having to run cables in the walls) that I've found is to use these wires: http://www.taperwire.com/speakerwire.htm

They're very expensive (not audiophile expensive though), but they serve a purpose. My problem is that the only store I could find only had them in 18 AWG. I'm gonna get a consumer AVR with Airplay (probably Pioneer), and I'm gonna connect 4 speakers to it (probably 8 ohm, I'm thinking Klipsch). I'm gonna be running them in mono, and connecting each pair in parallel for 4 Ohm, that's the easiest way to not run a lot of wire, since the owner wants the least possible cable runs, plus, the thing is expensive itself!

So, is frequency response the only drawback to this setup? I imagine dropping to 4 Ohm shouldn't be a problem for the amp, especially since it's not going to be pumping out very loudly since it's just background. I'm also thinking it can be somewhat compensated by EQ, if it needs any at all?
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DVDdoug
post Oct 1 2011, 01:09
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I think you'll be fine. With a little searching I found an "ohms per foot" chart on this page. With the 100-foot "round trip" you're looking at 0.75 Ohms. And, this applies only to the farthest speakers.

Of course we don't know how the resistance of the speaker varies over the frequency band, but the series resistance of the wire will probably have less effect than room acoustics... And, in my experience (and to my ears) most speakers sound better in larger rooms.

Don't worry! You're going to have a better-than-average background music system! As you may know, the average restaurant or grocery store has 8-inch full range (1 way) ceiling-speakers like this, and they're run through a transformer crying.gif that probably does awful things to the already-poor frequency response!

This post has been edited by DVDdoug: Oct 1 2011, 01:26
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Glenn Gundlach
post Oct 1 2011, 01:53
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DVDDoug: I don't think you read the table correctly. It says 76.8 ft/Ohm or 1.3 Ohms/100 ft so its a little worse than you thought. OTOH it's a restaurant so they're not likely pushing the system so a little extra resistance in the wiring will only reduce the damping. Might even give it that nice tube sound.

G

This post has been edited by db1989: Oct 1 2011, 15:40
Reason for edit: replacing unneeded full-quote w/ name
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andy o
post Oct 1 2011, 10:07
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Thanks guys. Any recommendations for speakers? Klipsch doesn't seem to sell smallish speakers. I'm eyeing at the JBL Pro Control series, the smallest ones like these:

http://www.jblpro.com/catalog/general/Prod...d=415&MId=2

http://www.jblpro.com/catalog/general/Prod...d=181&MId=2

Although, something a lighter, and if possible if it comes in white, would be better. I would like a tweeter as well.
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andy o
post Oct 1 2011, 10:18
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I think one of those could be the one:
http://www.parts-express.com/pe/showdetl.c...source=googleps

1.8 kg (lighter), and it has a larger midrange woofer than the Control 23. It's 4 Ohm though, I think I'll have to do a series connection instead of parallel, and waste a few feet more of wire.

EDIT: Also, I just took a look at the manuals of a couple of Pioneers, and they don't offer a mono mixer setting. Anyone knows an AVR which does, and which also offers either Airplay or Bluetooth audio?

This post has been edited by andy o: Oct 1 2011, 10:56
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dc2bluelight
post Oct 1 2011, 11:36
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Your biggest problem here isn't the wire, it's the fact that you're trying to cover a restaurant with background music and only four speakers. Nearly every speaker has a full-range coverage angle of 30 degrees, give or take, with severe high-end loss above 3KHz outside of that angle. That means people close to a speaker and on-axis will get as much as 20dB more volume and a much hotter high end than those off axis and far away. Clearly, you're concerned with quality of sound, given the questions you're asking, but the fundamental issue is, if you want it to be background music throughout and cover evenly, you need lots of speakers. That generally drives projects like this to lower cost speakers, and 70 volt wiring systems (gets you the ability to add dozens of speakers and control the total load and power distribution, AND use thin cheap wire to do it), but with proper EQ (and I'm talking highly detailed "surgical" EQ now, not a 1/3 octave graphic) a $20 8" speaker can be quite respectable in everything but the response extremes, which you don't want for background music anyway. So many restaurants are done wrong, and the resulting hot-spots are really nasty to sit in and try to have a conversation, and the un- covered areas might as well have no music at all.

Remember, full bandwidth coverage from a speaker acts like a 30 degree cone. Picture what you'd get with a 30 degree spot light. You're trying to light the room with spot lights, so how many do you need for even light? Also, recall that if you every time you double the distance from a speaker, you drop level by 6dB. And a 10dB change is perceived as doubling or halfing of volume. A -20dB can sound like it's turned off when mixed in with restaurant noise.

It would have to be a very small restaurant (15'x15'), or one with a very high ceiling with the speakers mounted way up for 4 speakers to be even close to adequate. The closer people sit to speakers, the more you need for even coverage. Not mounting them on the ceiling, but on the walls makes everything much worse.

To learn more, take a look at this free speaker layout software by Toa. It's flawed, and geared to their speakers (not recommended, BTW), but it'll give you a pretty good idea of what's going on:
http://www.toaelectronics.com/speaker_software.asp

One last thought, if you're thinking Airplay, that implies iTunes, and that means several other problems, one of them legality. You don't have a license to play iTunes music for a retail or commercial space. Yes, they do check, and the fines are quite high. Also, to be effective as background music, the music needs processing, and lots of it, to keep volume under control, and keep that background music in the background. iTunes "soundcheck" is not up to the task, it's not really processing anyway. You need real hard-core compression. However, there are music services that stream background music to you, rights cleared, processed, and ready for your sound system. It's not only a better and legal way, it's cheaper in the long run.

Sorry, more than you wanted I'm sure, just a reality check.
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andy o
post Oct 1 2011, 12:21
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Thanks. I'm aware of the inverse square law and more speakers needed to compensate for it. That said, this restaurant is not big, it's a smallish, independent noodle restaurant. Unfortunately, since I'm retrofitting, it doesn't allow a much more complicated setup, and the owner doesn't want wires showing or making holes in the wall/ceiling, hence my choice to spend more money on that tape-like wire. His other restaurant is bigger and as far as I could tell they only did 2 speakers, though the ceiling is quite high, and he seems OK with it.

Regarding Airplay, it's not tied to iTunes music. Though I don't know what they will be playing, you can put anything on an iOS device, of course, and also on iTunes as a player. The owner said the employees connect their iPods to the system at the other restaurant though, and he wanted the same for this restaurant. It really is not my concern, but I'll let him know anyway.
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Speedskater
post Oct 1 2011, 14:32
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As above many restaurants and other commercial building use 70 Volt (or 25 or 100 Volt) Constant-Voltage Audio Distribution Systems.
This is a paper on how it works:

http://www.rane.com/note136.html

A catalog of equipment, starting at page # 235.

http://www.parts-express.com/catalog/flipB...2011/index.html


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Kevin
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dc2bluelight
post Oct 1 2011, 17:06
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QUOTE (andy o @ Oct 1 2011, 06:21) *
Regarding Airplay, it's not tied to iTunes music. Though I don't know what they will be playing, you can put anything on an iOS device, of course, and also on iTunes as a player. The owner said the employees connect their iPods to the system at the other restaurant though, and he wanted the same for this restaurant. It really is not my concern, but I'll let him know anyway.


My point is, if it's on an IOS device, it's NOT automatically licensed for business use. It's not specifically the method of delivery, though. BMI and ASCAP licensing is tied to usage. When you buy music on CD or download, you're buying a license for personal use only. You can buy a licensing plan that covers you for using music you've bought for personal use via retail channels for business applications but it's expensive and you need to report what the music is in log form, or accept a blanket plan. Hardly anyone does that in retail, but every radio station pays to play the music it has on-air.

Music that is pre-licensed for retail application is always delivered another way, and the music is not readily accessable for copying to a consumer device. There is a sort of security method between retail-licensed music and the outside world. Not perfect, but it's an attempt to keep it away from personal use.

One more thing to let your restaurant owner know, there has been decades of research on the use of music in retail. Background music providers, at least the good ones, don't just play favorites from employees iPods, the sequence music that promotes purchasing, or ordering food. It may not seem a big deal, and I know it's out of your world in this case, but just be aware that it is possible for the right music to increase sales, sometimes as much as 20%, over personally chosen music.
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dc2bluelight
post Oct 1 2011, 17:09
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On the 70V idea, it makes multiple speakers much easier, but in some areas building code requires 70V lines to be in conduit, thus the availability of 25V systems, which work similarly but don't require conduit.

This post has been edited by dc2bluelight: Oct 1 2011, 17:21
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andy o
post Oct 1 2011, 21:48
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Thanks. 70V is out of the question then, but I might go for a 25V solution if I can convince the owner to get at least another pair. I'm assuming it can be used with those wires without problem, right?

This post has been edited by andy o: Oct 1 2011, 21:49
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Speedskater
post Oct 2 2011, 00:04
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In the US most low voltage wiring in commercial buildings is covered by NEC Article725.
But I have never seen any rules discussion about tape on the wall speaker wires.


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Kevin
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MichaelW
post Oct 2 2011, 05:29
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FWIW, they only rate the 18 swg for 12 volts for lighting http://www.taperwire.com/speakerwire.htm . If it were your own house it would be one thing, but restaurant, public liability etc etc. Not that I'm any kind of expert.
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dc2bluelight
post Oct 2 2011, 08:23
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QUOTE (andy o @ Oct 1 2011, 15:48) *
Thanks. 70V is out of the question then, but I might go for a 25V solution if I can convince the owner to get at least another pair. I'm assuming it can be used with those wires without problem, right?


Yes, the wire is fine, but there's more to it than the wire. Read up on those links above, there will be transformers involved, one for each speaker, and a biggie at the amp. Of course, there are power amps designed for the purpose too.
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dc2bluelight
post Oct 2 2011, 08:31
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QUOTE (MichaelW @ Oct 1 2011, 23:29) *
FWIW, they only rate the 18 swg for 12 volts for lighting http://www.taperwire.com/speakerwire.htm . If it were your own house it would be one thing, but restaurant, public liability etc etc. Not that I'm any kind of expert.


Read carefully. That's not a maximum voltage rating, that's a suggested application, "12V Lighting". A 100 watt amp run to the max into an 8 ohm speaker will place around 28 volts on that wire, which is just fine. It's rated at 10 amps of current, that would be like an 800 watt amp producing 80 volts into an 8 ohm speaker. The wire's still fine with that, so long as it's audio and those are peak of 80 volts.

When a wire carries a voltage rating, that's an insulation breakdown rating, usually in the many hundreds of volts. Somewhere above that voltage, the insulation stops insulating and lets the juice through. The actual conductor never carries a voltage rating, but will have a current rating because a lot of current will heat the stuff up and eventually melt or burn something. Thinner wire gets hotter with less current because it has more resistance.

This post has been edited by dc2bluelight: Oct 2 2011, 08:35
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andy o
post Oct 10 2011, 13:45
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I've decided for the original plan only slightly different. Unfortunately sewelldirect is not very reliable. They've messed up one (unrelated) order, and this one they've messed up twice, so I'm only waiting for the wires now, and I can't rely on them to have them in stock regardless of what the website says. Pressure is mounting with the owner. I think I'm gonna just install the speakers and audio equipment, and later in the week run the cabling on the walls. What do you think?
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