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RG-59U coax cable for audio interconnects? (1 Viewer)

Kevin C Brown

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Been thinking about this for a while. Even good audio interconnects aren't recommended for a digital coax connection. But how about the opposite? Using 75 ohm, RG-59U coax cable (essentially video cable) as interconnects for audio? Analog connections between SACD/DVD-A player to pre/pro, and from pre/pro to amps?
 

Bob McElfresh

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May 22, 1999
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Here is the issue:

The higher-speed signals can reflect in the cable if the signals see sudden changes in the impedence. For this reason, Video, RF, Coaxial-Digital cables should all be made with 75 ohm coax.

Audio signals/low frequency dont have these issues so you can use any of the popular styles of coax: 50/75/110/300. While the bulk of audio cables use 50 ohm coax, 75/RG6/RG59 coax works fine as well.

Using 2 sets of component video cables would work fine for a SACD system. Personally, I'd hit the custom web sites and get them to sell you a 2 sets made with flexable mini-coax and use this.
 

Kevin C Brown

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Using 2 sets of component video cables would work fine for a SACD system
Exactly what I'm thinking of.

Awesome site Chu!

Here's a question. Marketing blurbs from AR: "Improved sound accuracy from twisted pair conductors." But, ... "High quality video signal delivered by solid oxygen free copper center conductors." Same add for a set of 3 cables: 2 audio, 1 video, and I'm trying to figure out if the video cable is constructed differently than the audio cables. It does look like the video cable is made differently (i.e., 2 audio plus 1 video is cheaper than a set of 3 component cables).

I also think I'm understanding that Mylar foil is good for RF interference, and that copper braid is good for EMI.

But standard RG59U is just the negative wire (in foil form) wrapped around an insulator with the positive wire in the center?

Just trying to gauge the difference between for example:

1) "Std" shielded audio interconnect (think Radio Shack, not the cheap stuff though; gold ended, strain relief, etc)
2) RG59U
3) Slightly more specialty audio/video interconnects

Probably should have title the thread differently, in that I'm really looking to maximize the quality of cable for the money I spend.
 

Chu Gai

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Jun 29, 2001
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Well if you thought that site was somewhat informative, then perhaps these will provide some further food for thought and act as some sort of a guide for you.
As you're reading this, at least I hope you will, consider the equipment you have and the various specifications such as those for your DVD player, etc.

How wire fails
High Definition Cabling and Return Loss

Regarding foil and braid, often you see both on cables. Braids are effective down to around 1000 Hz while foils start exceeding the capabilities of braids once you get over about 10 mHz. The reason why the braid starts becoming less effective is simple. EMI or RFI, as a radiation source is subject to the equation:

c= frequency * wavelength

c is the speed of light...186,000 miles/sec.

Since c is a constant (Einstein!), as the frequency of the RFI increases, the wavelength decreases such that the product of the two is always c. Eventually the wavelength gets to the point where it's small enough to penetrate through the pores or openings of the braid. Simple!

If you're soldering, then you'd want the outer braid to be copper. If you're crimping, either copper or aluminum is fine. Makes sense right?

For virtually everybody, whether you go twisted pair or coax on interconnects it's a crap shoot. If you've got noise that is somehow being introduced into your system by magnetic induction then the nod goes to twisted pair with star quad types going one better.

Strictly on theoretical considerations, not those of audibility, the way to go for interconnects is to find those of the smallest capacitance. If you want reasons, I'll be happy to provide them or just search over here in tweaks. Not saying you'll hear the difference...well you know :)

To elaborate a bit on Bob's post, reflections or impedance mismatches generally become a problem when the length of the cable or conductor is about 1/4 of the wavelength of the signal. For short cables, it's not a big thing at all. However it's easy and cheap enough to get 75 ohm stuff and even those 'true 75 ohm' Canare connectors. While they're not truly 75 ohms, they happen to be a well made connector and not priced too badly so why not use them?

Now read those ads carefully and critically analyze what it is that they're saying.
High quality video signal delivered by solid oxygen free copper center conductors.
No claims whatsoever in this little blurb. All they're saying is that if you've got a high quality video signal the way it's getting from point A to point B is by using a solid center conductor. It's very difficult today for wire to not be oxygen free.
 

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