We plan to start gutting our living room soon, and I’ve got a wiring question.
We want to go with a 42″ plasma and surround sound system. The screen will hang on the wall with no wires visible, with the cabinet for the electronics underneath. The system has to be moveable to three different walls in the same room.
I plan to have ducts running vertically between the studs on the walls for the AC and control cables to the screen. These will be covered by pictures when not in use.
I’ll run phone cable behind the SR to take care of the satellite reciver. I’ll use coax for the reciever connections.
I need to know what kind of cable to use for the surround sound. This will be in conduit behind the SR running to different areas.
The celing is vaulted so I don’t have access to the attic.
Thanks in advance.
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Tom,
I would use 14ga romex and pigtail stranded to it for the connection to the plug terminals. 2 conductor should suffice, but your equipment will dictate whether you need a ground anywhere.
Romex will negate the need for conduit, and IMO, will outlast any standard "speaker wire." It will handle 1500 watts of audio power easily, and will have less crossover than the zip cord type as the individual wires are farther apart.
You may want to spray paint the roll green before running it, so as to give any future remodelers pause to think when they see it.
SamT
Romex (and zip cord) isn't twisted. Standard jacketed speaker wire is twisted (ie, the two wires are twisted around each other), reducing "crosstalk" and hum pickup. Use jacketed speaker wire.
Crosstalk with romex would in theory be worse than with zip cord, because the wires are farther apart.
Crosstalk with romex would in theory be worse than with zip cord, because the wires are farther apart.
Crosstalk varies inversely with distance between conductors.
SamT
> Crosstalk varies inversely with distance between conductors.
The closer together the wires are IN A SINGLE CIRCUIT, the less radiation/pickup of fields there will be. When you put the wires of two circuits near each other you get crosstalk. To minimize crosstalk, keep the wires of an individual circuit close together, twist them, and keep separate circuits as far apart as feasible.
Run conduit for everything. That way, when the new hyper-optical cable system comes out you can switch to it without ripping out the walls.
Just remember that 120v AC must be run in a conduit separate from the signal wires.
For speakers you probably want #16 speaker wire, except possibly for an unpowered subwoofer which should probably have #14. Don't waste your money on any of the Monster junk.
I was told by my AV guy that audio wire must be stranded rather than solid. I carries the signal better. Maybe he told me this because it was easier to pull. The guys at the store said the same thing. Maybe theyt are in cahoots!
The crossover issue is solved when wire - stranded or not - is twisted. When bundled, each pair must be twisted at a dif. schedule as in CAT 5.
F.
There is more cr*p in this field than any place else in the world including the sewer plant.
"I was told by my AV guy that audio wire must be stranded rather than solid. I carries the signal better. Maybe he told me this because it was easier to pull. The guys at the store said the same thing. Maybe theyt are in cahoots!"
There is a grain of truth it that statement. Just like it is true that ####2x6 is stronger than a 2x4 and a 2x8 is stronger than both. But that does not mean that there is any advantage to building an 8x10 storage shed with 2x8 walls.
There is something called "skin effect" where the higher frequency signals will only be carried on the outter surface of the conductor. Thus stranded wire gives more seurface area and is a better conductor. But for the frequencies that we are talking about the effect is neglitable.
"The crossover issue is solved when wire - stranded or not - is twisted. When bundled, each pair must be twisted at a dif. schedule as in CAT 5."
Crossover is a device to separate the different audio band signals to the appropriate speakers (sub-woofer, tweeter, mid-range).
I think that you are talking about crosstalk. That is where one signal in one cable/wire/system is affected by that in another cable/wire/system.
And yes there is crosstalk, but it depends on the power level of the interfering signal vs the powerlevel of the affected system. And twisted pair is one of the ways of dealing with cross talk.
But if cross talk was the problem that they talk about for speakers then you would have would like lights that turn on when other circuits are turned on because Romex is never twisted.
It just ain't a problem for speaker wiring.
Ouch!
Take a breath.
As to my referance to CAT 5 wiring: We use CAT 5 whenever we need tel wire. Not only because it has ethernet capabilities but because the twisting prevents crosstalk as in when someone is trying to send a fax on line 2 while someone else is talking on line 1. This is not only SOP in installations but also for the temp phone lines at job sites. That fax and modem whir drive me nuts!
I know fax and modem tel lines are becoming old school with e-mail and broadband so prevelant we forget how we used to do things but...
My referance was as an example and should not be interpreted as the only case. Yes, you are correct in that it would have been better if I addressed 120v and low voltage lines crossing but I did not think that twisted or not wire would be the issue. It is my understanding that either the wires need to be in proper conduit, or X distance apart if parallel, or need to cross at 90 degrees.
As for the speaker wire and stranded or solid, my info source was an AV guy. Most AV guys I know are pretty much extremists - everything must be this; we only use X; this is the best and anything else shouldn't be concidered. No reference is made to degree. That's why I disclosed the source.
Still, I always enjoy your feed back and always appriciate any insight you bring here.
F
PS: My anger management seems to be paying off!
I may not have made my self clear.
Twist pair is one proper way to reduce cross talk problems. And you have potential problems where you have realatively low signal levels and close distances. That well describes what goes on within a cable with multiple pairs of telephone lines (ie 4 pair cat 5).
However that does not describe speaker wiring at all.
Measurable and audible are two different things. Yes, you can measure that the performance of stranded is better. No, you can't hear it. I like 14 GA romex in case somebody wants to use a larger old speaker, like a Bose 901. You can hear the difference if you try to use very small wire, like telephone wire. Data is different since you're dealing with much higher frequency signals. Up to a gigahertz instead of just 20 kHz. There, the details matter. Monster cable is very pretty. At a couple bucks a foot, I'd want it out in plain sight with the price tag on it so people can admire it.
A bigger problem is that many of the surround-sound packages come with wire and their own special speaker connectors right on the back of the speaker. Bose for example. You have to splice those connectors onto whatever wire you use. Bose also runs an RJ45 digital cable from the control box to the powered subwoofer/power amp. That needs to be in an audible location, not inside a cabinet, and needs its own power cord. So, even though you plan for a pretty generic system, its very easy to have it all fouled up for you.
Best to pick the brand and model of the components first. If not, you can easily find out that their wiring scheme is not compatible with yours. For Bose, the sub-hooter is a central point for your wiring. For others, they just have 5 or 6 speaker cables like you might expect. Also the HDTV switching is not as well developed as it should be. Often need to use several remotes to switch modes on the TV and players/receivers to get a picture. Some TVs have a bunch of inputs. Some only one of each kind. Bose uses an RF remote. Most everybody else uses IR. Took me weeks to teach one customer how to switch it all because one remote could not be programmed to do it all. Got fairly tired of calls at 9 or 10 PM. "I want to watch a DVD. What buttons do I push?"
The "skin effect" with stranded wire is negligible at audio frequencies. But stranded wire is a lot easier to work with in larger sizes, and there's no real advantage to using solid wire.
If two speaker wires are routed through the same conduit for some distance, there is a significant chance of audible crosstalk if twisted cable is not used. Plus there's a chance of hum pickup if untwisted cable gets near an AC line.
Keep in mind that the ear can hear sounds through several orders of magnitude, so a very minor amount of crosstalk can degrade things.
All audio pickup cable in a recording studio or any that feed to a pre-amp mixer must have twisted, shielded pairs as they are feeding an amplifier. Any distortion from crosstalk or any other source will be amplified. The signal to noise ratio in these low strength sources must be kept as optimal as possible.
Crosstalk is the electromagnetic coupling between 2 conductors. It is reduced by keeping the conductors unparallel or seperated. At hi power, after amplification, it has little effect on the percieved signal as the signal to noise ratio is very high. That is, the crosstalk (noise) is very low in power compared to the music (signal.)
Here are two links that attempt to throw some water on the speaker wire flames.
http://sound.westhost.com/cables-p2.htm#spkr-leads
http://sound.westhost.com/impedanc.htm
SamT
I'm well aware of the merits of twisted pair in a studio, as I have a masters degree in EE and served as a TV studio technician in my younger years. I'm also well aware of the significance of impedance when it comes to all this.
Certainly, the "Monster" class of cables are a waste of money. There is a very slight advantage to having gold-plated connectors in that you're slightly less apt to develop a bad connection over time, but there's no need to have the huge #4 cables, "directional" wire, etc.
However, if you were to run two zip-cord speaker wires through the same conduit for 25 feet or so, you definitely will get measurable crosstalk. You would also run the risk of hum pickup from nearby AC circuits. Whether the crosstalk/hum will be audible or not is certainly subject to question (and will depend on a number of factors), but plain old jacketed, twisted-pair speaker wire is sufficiently cheap I see no reason to risk using zip cord (especially since the twisted-pair is easier to terminate and has clearer "color coding" of the two conductors).
Agreed.
Samt
For this application, zip-cord speaker wire is sufficient. Audio is low voltage, high amp stuff, so a thicker cable is better, especially for subwoofers. Any runs over 20 ft would benefit from 14 gauge as opposed to 16ga. A low impedance conduit between the output transistors and the speaker coil allows the amplifier to control the speaker cone movement to a greater degree.
And please, no romex, ever. Makes me ill just thinking about it. ;-)
Wire does become an issue in higher end audio systems. 99% of the people who buy premium cables have no idea of why they are even buying them, mostly because their gear can't resolve the signal sufficiently to see a difference in the first place. I've sat through enough A/B comparisons to know there are indeed differences. Friend of mine had a pair of solid copper 2P2T switches (probably 1000A capacity) just for this purpose. Most gear, especially solid state, simply can't resolve differences between wire. Only when you get into some of the better designed tube gear does it really become apparent. FWIW, I ran about 30 ft of audio concepts 10 ga between my NY audio labs TL-4 transmission lines and modified class-A dual-mono Dynaco ST-70, which was fed by an Eisonsen-Clarke PAS-3. And that is only because I didn't buy the Futtermans when I had the chance. :( :( :(
http://www.unibase.com/~ahucula/futterman/
Of course, since the kid was born, the tube gear has been packed away. Something about the 500V sitting on the power supply transistor cases. ;-)
Pseudoaudiophiles talk about equipment only. They mostly look at it and rarely turn it on. True audiophiles see equipment only as a means to get to the music. They are more concerned whether Rickie Lee Jones's first album sounds better on European or Japanese vinyl. CD? Hack, ptui. ;-) Well, maybe for the car.
The main problem with zip cord would be if you're running two speaker cables through the same conduit (or otherwise in close proximity for some distance). In that case there is a chance of significant crosstalk. Normally not a problem, but if, say, one speaker is a close-by one that is carrying a whisper while the other speaker is one in the far corner of the room carrying cannons or a kettle drum, the crosstalk could very well be noticeable. (And, as you know, even if it isn't noticeable, it can still detract from the "experience".)
If you're spending the money for a fancy home theater setup, you might as well drop a few more pennies for jacketed, twisted-pair speaker cable. For a more mundane setup, though, zip cord is fine, and it's a little easier to conceal running under the couch, etc.
And please, no romex, ever. Makes me ill just thinking about it. ;-)
Why not? I honestly don't see the difference between romex and zip cord except resistance and power carrying capacities, plus less inductive and capacitive coupling. Well maybe the romex is better armored too.
Have you ever put romex on your A/B switch? I have, except I didn't just use my ears and ego, I also used signal generators, waveform analyzers and other test equipment. I compared equal lengths of zip, twisted pair military comm cable, silver plated, teflon coated, twisted pair 14ga, rg58 coax, rg59 coax, romex, and loose floppy stranded 14ga.
Coax handles the highs better; romex, twisted pair, and loose the lows. Coax and the loose are better at rejecting outside signals. Loose is also the worst at rejecting outside signal, depends on how it lays and where the signal originates from. Romex can handle the most power across the widest bandwidth. This indicates that K&T would be better than romex. hehehe
My conclusions were that, unless you are engineering a dedicated audio listening space, about the only concern is will the wires carry the load.
Unless of course, you're an audiophile. For an audiophile, spending more than $15,000/foot for speaker cable is absolutely required (|;>)
Samt
You gotta define your TV first. Note where it's inputs are and how you'll handle any excess cabling. Then you position those ducts/conduits within tolerances thereby allowed.
I just got thru hanging a couple of flat panels in my new poker room. I got lucky because of curved walls and 45degree alcoves.