# A Few Questions

Discussion in 'Archived Threads 2001-2004' started by Greg_L_C, Mar 10, 2002.

1. ### Greg_L_C Stunt Coordinator

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Hi All,

First I would like to think those who operate this forum. I have been lurking aroud here for about 9 months almost daily and have found no other source of quality info on the net.

I going to run some new wiring to my rear speakers and because of the routes I have to take to make this job as easy as posible one wire will be about 20ft longer than the other. Will that make any difference, or should i make them the same length and hide the excess.

Also any tips on pulling wire through walls. I have a vaulted ceiling that I have to cross too and I don't feel comfortable crawling on top of it.

Thanks

2. ### David_Stein Second Unit

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if i remember my physics correctly (and i may not) the speed at which the signal moves through the wires is so fast that it makes small differences in wire negligible. however, whether or not 20 ft is considered a small difference is beyond me. i would guess it is.

ill go see if i can find out the speed of the current in speaker wire for you...

doing a rough calculation using the speed of sound (~600 mph), an extra 20 feet would mean a .02 second delay (so thats if your one speaker were 20 feet further away from the other), but as i said im pretty sure the signal moves a _lot_ faster as an electrical current

3. ### David_Stein Second Unit

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some lab
if you look at part 3 of the lab the guy uses speaker cable and calculates the speed of transmission as:
2.03 * 10^8 m/s, or 68% of the speed of light
so converted to ft/s, thats 6.18744e+7 ft/s
and for 20 ft extra wire, the time delay would be:
3.23e-7 s
i doubt anyone can tell that difference...

4. ### Bob McElfresh Producer

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Hi Greg. Welcome to HTF!
My first bit of advice is to run 3 sets of 12 ga speaker wires to the rear. This allows you to add that rear-center speaker for Dolby EX. The wire is dirt-cheap compared to your time/labor to install it.
Make sure to label the 3 wires at several locations so you can tell which is which. Use a perminent marker to do A/B/C or I, II III as a label will scrape off/jam the wires when you are pulling it.
As the guys have already said - dont worry about making the wires the same length. While this IS important for say video signals (the 3-wire Component Video cables), its not an issue for audio. (And you DONT want loops/coils of speaker wire sitting there).
Radio Shack has a little handbook on installing HT systems with some diagrams of pulling cables through walls. Worth a look.

5. ### Greg_L_C Stunt Coordinator

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Thanks Guys for the quick answers, Im off to Home Depot for supplies, They have a 250ft roll of 14 or 12 gauge wire I think ill buy, about fourty bucks, I also saw some wall plates for speaker connections is that worth the trouble?

Thanks

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