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Discussion Starter · #1 ·
I have read in other posts here, that it is possible to run the Chroma and Luma signals,

which make up S-Video, on separate RG6 cables for about 75 feet with MINIMAL quality loss,

and without the introduction of any repeaters or other hardware. I guess the same

would apply for composite video, with the only difference being that only one RG6 cable

is required.


For example:


SVideo Source (ie. PC Video Card) ------->2 pair RG6 Coax (75 ft) ----> A/V Receiver.



So, what about running line level, stereo audio over the same distance? Should I use a pair

of RG6 cables as well?


Thanks.

Hobbieman
 

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You CAN use RG-6

The problem is there will be an Impediance Mismatch.

I would try GOOD Shielded audio cabels first.


BTW.

If the audio signals are unbalanced(RCA)then you may run into unwanted hum and buzz.
 

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Discussion Starter · #3 ·
Where can I find audio cable? The local hardware stores don't seem to

carry anything else other than coax and speaker cable. It is not speaker

cable, or is it?


Also, how do I know if the signal is unbalanced? The stereo audio signals

that I want to transport are coming from my PC's soundcard.


Thanks.

HobbieMan
 

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HobbieMan,


I would go ahead and try regular RG-6 with F to RCA adapters. It costs almost nothing to try it and you might be suprised how well it works. I am using it for a 35' run with very good results. Good luck.


Jay
 

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Most PC cards use an RCA type connector and the signal is referenced to ground. That is an unbalanced signal. A balanced audio signal normally uses an XLR or TRS connector and requires a differential input to handle it properly. Essentially you have 2 signal lines and a ground shield. The balanced line is much more immune to noise and hum pickup because the 2 signal lines are inside the shield as a twisted pair and that offers a high amount of common mode rejection. That means that any signal induced onto one line is also induced on the other line pretty much equally and when they appear at the differential input amplifier the common mode signal does not get amplified since both inputs are rising and falling together. The amplifier is amplifying the diffential portion of the signal (one rising and one falling at the same time). So, how does this apply? Long runs are best handled with balanced lines because of the noise and hum immunity. Broadcast studios and live theaters have microphones that use XLR type connectors and balanced lines. The preamps and amplifiers are also connected with balanced lines and XLR connectors. They are sometimes referred to as Professional series connectors because they are used by most theatrical groups and musical bands. Your 75 foot run is pretty long but in a home situation you may be ok with coax.

The typical output impedance of a line level audio circuit is in the neighborhood of 75-200 ohms. Conversely the input impedance of a line level amplifier is often 5K to 25K ohms. The low output impedance can easily drive the high input impedance and your 75 ohm coax shouldn't be a big problem. However, PC cards often have small drivers and the larger problem may be that the drivers on your pc card cannot drive the 75 foot long line because of its capacitive loading. In the end, you are going to have to give it a try and see what it sounds like. The 75 foot long cable is not the best situation. (hope I didn't ramble too long)


..Doyle
 

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Discussion Starter · #6 ·
Wow! Thanks for the replies, especially this last one.

Lots of good info! I will give the setup a try and post

my findings here.


HobbieMan
 

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Quote:
Originally posted by HobbieMan
Wow! Thanks for the replies, especially this last one.

Lots of good info! I will give the setup a try and post

my findings here.
Using 3 RG-6 cables, I'm sending left/right audio and composite video from my home theater system's second zone (located on the first floor) to my PC (located on the 2nd floor) without any problems at all. The picture and sound quality are fine. The cables run from each room to a central wiring location in the basement where the appropriate cables are patched together. Cables from the 2nd floor go to the 3rd floor attic, down the outside of the house (with the other service lines) and into the basement to the central wiring location. The total cable lengths between my home theater system and my computer exceed 100 feet (probably more like 150 feet).
 
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