home system wiring

[colterphoto1]

I will be wiring my attic for a distributed whole-home sound system this week. Some of the lines will just be speaker wires, 14ga in vinyl sheath, for low volume background music to front porch, bedrooms, etc.

I want to link my two main systems, the big HT rig in the Hearth Room and my office system, which uses the iMac computer for CD jukebox, this system is also the control system for the whole-house system. The two receivers are probably 50 feet apart. I've written about this before but never received a complete answer.

What sort of wiring should I run between the receivers to line the line sources? This will be two pair, from the HT receiver OUT to the office/home system, and from the office/home system OUT to the HT receiver. Should I use RG6 or RG58 shielded with RCA plugs? If so, should I hook up the shield at both ends or only one? Do I need to use transformers to go Low Impedence?

THanks,

Michael

[DrWho]

I personally would run wire capable of running balanced lines (2 conductor and a shield) in the off chance that you might need the noise reduction benefits it could provide. You might even consider running a 3 or 5 conductor cable plus shield to give you additional expansion options in the future (or just make it so that you only have to run one wire instead of a few).

Btw, transformers are $30 each at radio shack

The cool thing about running a "balanced capable line" is that you can install an XLR wall plate which looks really professional and gives you the option to go both ways. Short XLR to RCA cables are real easy to find and gives you an unbalanced line (the cheapest route). But if the unbalanced doesn't work well, then you'll be all set to throw in some transformers and now you've got yourself a balanced line with minimal extra work.

[colterphoto1]

Thanks DrWho! Can I buy loose xformers to put inside the wall boxes myself? I'd hate to have to get the PA type plug-in jobs that are like $20 each. I'm talking 4 lines here x both ends so it would be 8 xformers!

And if I go shopping for wire or xformers, what am I looking for? SOunds like your recommendation is for basic balanced w/ shield Mic wire, right?

Michael

[DrWho]

I have no clue about how to go about finding loose xformers, but it should totally be possible. Heck, you could probably twist your own if you really wanted to

As far as wire goes, I was suggesting basic shielded mic wire or whatever you wanna call it. If you go to a local electronics supply store, they will cut you a spool of cable however long you need it. They should also have options for the same basic mic wire, but with more conductors running in it (kinda like a small snake). I personally always purchase the 3 conductor wire because it gives me the option of running one balanced line (where I can choose whether or not to ground the shield), or two unbalanced lines. A 100ft spool of this stuff only costs an additional $5 or so which is a really good deal.

Theoretically, unbalanced lines are good for lengths up to 100 feet so you'll probably be fine keeping things that way. The longest sucessful unbalanced run I've used was 300 feet, running the line level signal through a speaker cable.

[Marvel]

And transformers from RS will have what kind of freq. response? If you want transformers that will work, get some Jensens (or Lundahls).

http://www.jensen-transformers.com/

But the price varies from $35 to over $100 each. You can buy little boxes to do the same thing, with active electronics, for less. With the right cable, you can run long distances unbalanced.

[colterphoto1]

so then if I get wire that's two pair shielded (4 wires) and run unbalanced, I should be able to do two stero pairs (two going each direction) for my 50' run?

WOuld there be less chance of interference if I make it two wires of one pair?

Then since it's unbalanced, do I just hook up the shield to the RCA at ONE end of the line or BOTH?

Thanks guys

Michael

[JJkizak]

One of America's greatest orators (JJK) once said, if you are wiring your attic make sure that if you need 10 wires, add 100 more because of what you will add in the future or you will be sitting in the chair saying to yourself, "why didn't I add 500 more wires when I was up there".

JJK

[DrWho]

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On 5/16/2005 11:50:36 AM colterphoto1 wrote:

so then if I get wire that's two pair shielded (4 wires) and run unbalanced, I should be able to do two stero pairs (two going each direction) for my 50' run?

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yes

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WOuld there be less chance of interference if I make it two wires of one pair?

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I don't think it'd make a difference, but it's easier to pull one wire than two.

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Then since it's unbalanced, do I just hook up the shield to the RCA at ONE end of the line or BOTH?

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Start off with both ends and then if you have noise, you can always see if removing the shield on the recieving end helps. If it doesn't, then it's time to go balanced (but you should already be prepared for this so it's just a matter of rewiring your terminals, not of rerunning cables).

[Marvel]

If you are running unbalanced, you have to have the shield connected on both ends.

[Spkrdctr]

I would be suprised if you have any problems. The shield in the cable will most likely do the job perfectly. Good Luck!

[colterphoto1]

Thanks guys. Here's a nice article I'd saved a while back on the topic, just wanted to poll the pros first!

http://www.wildtracks.cihost.com/homewire/wg_feats.html

Michael