Can I use cat 5 wire for a second zone?

Discussion in 'Home Theater Projects' started by Bruce N, Oct 2, 2003.

  1. Bruce N

    Bruce N Second Unit

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    I want to use the 2nd zone on my AVM20 pre/pro to send music to a receiver in my garage. Is cat 5 wire okay or is there something else I should use? It just for garage music so it doesn't need to be a super duty hi-fi type deal.

    Thanks,
    Bruce
     
  2. Chu Gai

    Chu Gai Lead Actor

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    If you're thinking along the lines of a twisted pair and simply soldering on some RCA's, sure. It's strictly a question of whether your preamp can drive a signal that distance. I'd sure try it.
     
  3. Bruce N

    Bruce N Second Unit

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    Yep, that's exactly what I'm thinking. I'll give it a shot.

    Bruce
     
  4. Bob McElfresh

    Bob McElfresh Producer

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    While you can try it - I doubt you will like the results.

    You are trying to pump line-level signals through un-shielded wires for 40-80 feet. Think about it: you have a 40-80 foot antenna that you are adding 1-2 volts of signal at one end and hope to get a clean signal out the other.

    (The twisted-pairs in Cat5 cables allow you to send DIGITAL signals over long distances. It really wont help for analog signals.)

    Dual runs of CATV coax would be a better choice for this.
     
  5. Bruce N

    Bruce N Second Unit

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    Hmmm... Never thought of it that way. I see what you mean. Any specific type of coax? Something that's not really stiff would be nice. Cheaper would be better also.

    Bruce
     
  6. Chu Gai

    Chu Gai Lead Actor

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    Well my first choice would be coax but....
    Consider that many companies, such as CatCables and others use a variant of twisted wires without it being coax. Also many interconnects for car stereo applications are also twisted or braided. Cars are fairly nasty environments when it comes to airborn noise and these products are used quite successfully.
     
  7. Bob McElfresh

    Bob McElfresh Producer

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    The twisted-wire cables are usually for speaker-level signals. And speaker-level signals are usually strong enough to swamp any noise effects.

    Cars ARE a tough environment. But the cable-run length between CD/Amp/Headend are usually short (under 2 feet). And the electronics are built with the noise environment in mind so the better equipment has strong filters for anything outside the audio-frequency range.

    What Coax: I'm afraid the best/cheapest stuff is generic RG6 or RG59 CATV coax. It IS stiff and ugly, but you cannot beat it for the price and long-life.

    My advice: Go to Radio Shack and buy 2 coils of pre-terminated CATV coax and 4 of those "F-to-RCA-Male" adaptor plugs. (Try and get one coil of white, the other black so you can tell L/R). Save the receipt.

    Chu made a good point about wondering if your pre-processor can drive a signal that far. Get home and run the wires THROUGH the house to the garage receiver. (This is just a proof-of-concept). Fire it up and listen for a while to hear if the results are acceptiable. If not, return the un-damaged coax to Radio Shack. If it sounds fine, now take the time to run the wires through the wall. (I like the plastic electrical-outlet box's and wall-plates for a clean looking install.)

    Good luck and let us know the results.

    PS: We have a fourm dedicated to "Home Theater Builder" magazine. They may have thoughts on this.
     
  8. Wayne A. Pflughaupt

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    I ran shielded line-level signals from the tape outputs to a remote stand-along system in my garage – at least 80 ft, maybe more. Worked fine.

    Re twisting, the constant turning-over of the signal (i.e., the positive and negative trading places) is very effective way to reduce or prevent interference, and it works as well in line-level signals as it does in speaker level. Indeed, in addition to excellent shielding, you will find twisted pairs used in all high-end pro audio signal cabling from companies like Belden, Canare and Mogami.

    Thus I wouldn’t reject the notion of using Cat 5 outright – after all, AudioControl sells whole-house distribution equipment that uses Cat 5 for sending both audio and video – but I do have some concerns.

    For instance, Cat 5 uses extremely thin wire – what, 24-26 gauge? With long distances I would be concerned about the resistance factor, as Bob noted.

    Along the same lines is the termination issue. Since RCA’s are going to be soldered on, you will have to make sure all flux is fully cleaned and removed. Flux residue becomes corrosive over time, and the ultra-thin wire in Cat 5 will eventually break through at the solder joint. This would be much less of an issue with larger-gauge coaxial wire, especially RG-6.

    In addition, I generally have more confidence in shielding for protection against interference, especially in long runs.

    Bottom line, while Cat 5 may be viable, I’d still go with coaxial. As Bob noted, it is probably the cheapest route.

    Alternately, you could use installation-grade shielded mic cable. It might not be as cheap as coaxial, and usually you have to buy it in bulk. However, if you live near a pro audio company they will probably sell you by-the-foot the amount of cable you need.

    Regards,
    Wayne A. Pflughaupt
     
  9. Rick_Brown

    Rick_Brown Second Unit

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    I always use RG6 - much better performer over long runs compared to RG59.
     
  10. Wayne A. Pflughaupt

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  11. Chu Gai

    Chu Gai Lead Actor

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    actually, it's not so much a question of the gauge of the wire as it is the capacitance for very very long runs when it comes to audio interconnects. it's the overall capacitance that 'some' preamps have issues with. not really a problem for a few meters...but 100 or so I'd just find me the cheapest lowest capacitance cable and roll the dice.
     
  12. Rick_Brown

    Rick_Brown Second Unit

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