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Using coax for audio

Discussion in 'Home Theater Projects' started by Roger D, Oct 7, 2006.

  1. Roger D

    Roger D Active Member

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    I just received my $3 "Premium RCA cables" from Monoprice and noticed that they don't sound as good as my old skimpy cheapo RCAs. Anyway, this is what it says on the cable. Can anyone tell me if these are ideal for 2 channel audio? Maybe there's too much resistance?

    RG-59/U 75 OHM COAXIAL CABLE

    I chose to go cheap since I had to buy 3 pairs for my near future 970HD. I was looking for cheap, but better than dollar store quality.
     
  2. SethH

    SethH Well-Known Member

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    RG59 should be perfectly fine for audio. If you really are hearing a difference I would assume the cable is damaged. If you want to be sure, pick up some cheap RG6 cables.
     
  3. Bob McElfresh

    Bob McElfresh Well-Known Member

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    Most of the time, audio coax is 50 ohms and you bought video cables at 75 ohms - so it's about 50% more impedence.

    The sad part is that impedence affects the higher frequencies more than lower frequencies so your new cables might be rolling off the higher frequencies a bit more than you are used to. (It's a bit like adjusting the tone control).

    Now as long as the L/R wires are identical, the 75 ohm coax should be fine. (I wont claim I could tell the difference with my system between a 50 ohm and 75 ohm interconnect). But people are much more sensitive to changes in their music so you may just be noticing the slight reduction.

    My advice: stick with the new wires for 1 week to see if you get used to them. (No - you are not 'burning-in' the cables. You are adjusting your ears.). Then - hook back up your old cables and listen. You may notice that your old cables produce a more shrill/higher-pitched sound that you never noticed before.

    I've had this experience with a different subwoofer. At first - it sounded 'different' and I did not think it was better. I listened for a week, then re-attached my old sub and was suprised at how harsh/rough the sound was, but it was a bit louder which fooled me into thinking the new sub was not as good.

    Hope this helps.
     
  4. Chu Gai

    Chu Gai Well-Known Member

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    Hold on there now! The 50/75 ohm thing is simply the characteristic impedance and that's only an issue at high frequencies and for where impedance means something. The center conductor in these coax cables can vary (18 gauge or 23 gauge for example) in size but so what? With audio connections, especially in the length's the OP bought, pretty much none of the typical electrical parameters: inductance, capacitance, or resistance, have any particular relevance with regards to audibly affecting the frequency response. In audio connections, one is typically going from a low impedance output to a high impedance input such as 300 ohms into 47kOhms. To roll off the high frequencies would take an extraordinarily large amount of overall capacitance and that's just not the case here. After all, you're not using audio interconnects from Alpha Goertz!

    As to why they sound different, maybe you were expecting something and just got a bit disappointed. Verifiable audible differences are exceedingly rare. If the cables make a good connection, aren't overly tight, and you're not experiencing any interference then you have no problems. Spending more on interconnects generally gets you a nicer looking interconnect. Spending a lot more gets you a load of BS to go along with the nicer interconnect.
     
  5. Roger D

    Roger D Active Member

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    Well I do have to say that the difference I thought I heard was in the vocals. Just not as clear. Overall (highs and lows), I found the sound was just a little muddy if that makes sense.
     
  6. BruceD

    BruceD Well-Known Member

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    I agree with Chu, and this was explained only a few threads earlier:

    other thread

    The reason A/V cables (75 Ohm cable) have the industry-wide label of A/V (Audio/Video) is because it works perfectly for all three of the following scenarios:
    1) 50 Ohm analog audio with RCA connectors
    2) 75 Ohm digital audio with RCA connectors
    3) 75 Ohm analog video with RCA connectors
     
  7. Chu Gai

    Chu Gai Well-Known Member

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    Hell, you could even wire up analog connections with twisted pairs if that was your thing.
     

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