Which cables to leave long, speakers or XLR?

Discussion in 'Accessories, Cables, and Remotes' started by George Kouzev, May 1, 2003.

  1. George Kouzev

    George Kouzev Stunt Coordinator

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    Once I upgrade to my new system and move stuff around I will have to increase the speaker cable length from 14' to 30'. I have a pair of Mirages M5, using bi-wire Audioquest.

    Should I have a good quality 30' speaker cable, or try to move the future Bryston amp close to the speakers and have 25' good quality XLR interconnects between the pre amp and the amp?

    GK
     
  2. Philip Hamm

    Philip Hamm Lead Actor

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    NO QUESTION go with long XLRs. Others may be able to explain why. XLRs are isolated and grounded specifically for the purpose of handling long runs silently; speaker cables aren't.

    This may be a better question for the Tweaking forum. I hoe you don't mind I'm going to recommend that it get moved there.
     
  3. JamesDB

    JamesDB Stunt Coordinator

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    You should use the XLR cables for long runs, and the amp to speaker higher-current cables as short as possible. This is because the XLR balanced cables are designed as a two way signal that cancels external interferance which can be picked up by long cable runs. Cables running higher current will usually tend to amplify greatly these external signals giving you impurity in your sound (ie taxi cab CB radio, or simple fuzz).

    Another common misconception some people have is that one should turn the amp (can be in the subwoofer too) all the way up and correct the signal (turn it down) in the receiver or preamp. In reality it's the other way around. Try to send the strongest (reasonably strongest due to headroom) signal from your receiver/preamp to the amp, and only turn the amps up as much as you need with calibration. Again this is to maximize the signal to noise ratio. Noise floors become increasingly strong as elements are added to the chain.

    Although in many home stereo settings you might not notice huge improvements from doing the latter, all professional sound engineers (I run sound for large concerts, but recording industry is the same) benefit greatly from this.

    Hope this helps
     
  4. Chu Gai

    Chu Gai Lead Actor

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    and unless one get's silly, long XLR runs aren't that expensive.
     
  5. RobWil

    RobWil Supporting Actor

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  6. JamesDB

    JamesDB Stunt Coordinator

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    Hey Rob,

    I was thinking about your question since I admit there are some caveats to my statement due to the fact that this is home audio. For instance I have a Denon 3803 at home and if one raised the signal strength at the preamp stage past the 0, it subtracts it from the total gain available on the dial (although denon claims that it is not actually lost). Additionally in home audio there is nothing to show you if your signal is too hot and reaching the headroom of the circuits thereby clipping at preamp stage. So there may be some tradeoff to consider.

    However in your situation I still stand by my statement. Noise is added to your "pure" signal at many stages in your chain. For example your DVD player send the pure original signal to your preamp. If it's an analog signal the first noise is added on the line between the two. Your preamp then sends it down a wire to your main amp. Here again noise is added both in the preamp circuitry and the line. Then it is amplified to high current and goes to your speakers where noise is added in the amp circuitry and the high current line.
    If you can have the most relative amplification as early as possible down your chain you amplify at the best signal to noise ratio location. Therefore by the end you have amplified the least amount of noise into your signal.

    One caveat. Since each item in your chain will add noise, only amplify later in your chain if you are certain that the later item's tolerences are so much better than the previous items that it offsets its position. For instance if you have a crappy preamp with nasty circuits that create lots of noise and a really hot expensive amp that is super clean and transparent then by all means amplify more on the amp stage. But most of us have pretty balanced level of equipement on our chain.

    BTW, noise is added due to many things such as EM radiation ie. CB radio (which XLR is good at shielding out), lighting, ground loop, microwaves etc. so sometimes changing those nasty 60Hz florescents, or high power spot lights can really help. In pro audio its probably our major challenges.. balancing the lighing companies needs and sound needs.

    As far as XLR is concerned its mainly different than your typical RCA in that it is balanced (it carries the same signal in two directions resulting is negating noise that was picked up on the line or circuit). Usually XLR is also shielded using very tightly braided foil for additional quality. You need to have XLR connections (or TRS) to use balanced signals. Its available on some higher end home audio stuff like Lexicon, or you can pick up an RCA to XLR active convertor for it. Remember though that the convertor will itself add some noise so unless you have really long runs to your amp or live in an EM saturated environment it might not be worth it. Just keep your amp to speaker lines as short as possible and amplify early in your chain.
     
  7. RobWil

    RobWil Supporting Actor

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    Thanks, James...appreciate the input [​IMG]
    You know...looking at your quote again ...
    quote:
    ------------------------------------------------------------Another common misconception some people have is that one should turn the amp (can be in the subwoofer too) all the way up and correct the signal (turn it down) in the receiver or preamp.
    ------------------------------------------------------------
    ... I realized something. Not only do I have to turn the amp volume controls all the way up, but I also have to turn the volume control on the receiver up to the normal listening position, i.e. 9-10 o'clock. Unless I use the direct connect, CD to amp, I get no sound otherwise.

    RE: the xlr cables....I'm assuming for short runs regular audio interconnects are OK? Does xlr stand for extra long run or something?

    NOTE: George ....don't mean to hijack your thread, but it looks like your ? was answered. Let me know if this is inappropriate.
     
  8. John Royster

    John Royster Screenwriter

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    I guess I'll chime in with my experience on source/pre-amp/amp.

    Adjust the gain on your amp so that right before your pre-amp clips you'll be at maximum power (basically before the amp clips).

    This is hard to explain but you can do it by ear...there comes a point where your pre-amp will start to clip and distort. You'll hear it. That's bad.

    Turn the volume/gain on the pre-amp down a little to get max voltage from the pre-amp with no clipping and then bump up the amp gain right up to distortion/clipping.

    now both pre-amp and amp are at the highest signal to noise ratio you can get them. pre-amp sending highest voltage it can without distortion, amplifier is amplfying it.

    For the original question - XLR all the way.
     
  9. RobWil

    RobWil Supporting Actor

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    Hmmmm.....this is a little over my head. I either have to turn the amp up all the way and then turn the preamp up to normal, or turn the amp up partially and then turn the preamp way past normal.
    But back to the XLR......assuming I have an ext. amp for each channel , one 10 ft from the preamp and one 18ft...does the XLR cable length difference matter at all like speaker cable lengths? I'm guessing not.
    Also...any preference over something like Canare L-4E6S as opposed to Belden 1800F?? Something better?
     
  10. Wayne A. Pflughaupt

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  11. Chu Gai

    Chu Gai Lead Actor

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    of course it is entirely possible that the sum of all this distortion is still an order of magnitude or two below the threshold of audibility. 'course we don't worry about that when its tubes now [​IMG]
     
  12. Brett DiMichele

    Brett DiMichele Producer

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    LOL Chu,

    Youn just had to go there huh [​IMG]

    Balanced Lines are the superior way to cary any signal but
    in home audio you only find this in the upper echelon of
    components. With short runs (1 to 6 foot) there generaly
    is not any issue. And even if you were absorbing some EMI
    from nearby wiring you could choke the internconnect with a
    Ferrite Choke.

    As has been stated you can convert any non balanced Phono
    output to fully Balanced but you need an external conversion
    box which in it's self will add some more noise. But if you
    are running 30' of cable it may well be worth it.

    BTW this is what an XLR Connector looks like for future
    reference.


    Female
    [​IMG]

    Male
    [​IMG]
     
  13. Chu Gai

    Chu Gai Lead Actor

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    heck i'm not slamming you Brett, but I do think you've been around your equipment too much when that's your idea of a female! well some of these boxes that you talk about use little bitty isolation transformers to effect the 'change' so they're essentially passive. also rather remarkable for actually cleaning up a signal.
     
  14. Philip Hamm

    Philip Hamm Lead Actor

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  15. RobWil

    RobWil Supporting Actor

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  16. JamesDB

    JamesDB Stunt Coordinator

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  17. JamesDB

    JamesDB Stunt Coordinator

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    Hey John Royster

    I agree with your input on how to calibrate the equipment on everything except turning the amp up to right before clipping. This is usually what we do at concerts since we want to blow people's ears out, shake the walls and floors to fracture point and therefore push the equipment to the limits [​IMG]

    But for home use I'd say just turn the amp up until you hit reference levels on your SPL meter. So turn your preamp to reference 0, maximize the signal to headroom with some CD that was recorded very hot to find your clipping point, and then turn up your amp slowly to reach reference SPL 105db or whatever you like. Then when you watch your movies you'll know that your 0 is where it should be and have kept your noise floor to a minimum.

    Oh, I do like the Sonifex red box series of unbalanced to balanced convertors. A bit pricy but good stuff. I would use balanced for anything past 15 ft but it depends where I lived. For rural maybe one can go longer.

    I have a question for everyone.

    Do you guys really think that a normal shielded $20 RCA cable will really deliver crappier sound than a $150 monster cable? I just can't hear a major difference and I think my ears are not too bad.
     
  18. RobWil

    RobWil Supporting Actor

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    [​IMG]
     
  19. Chu Gai

    Chu Gai Lead Actor

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    list your questions Rob...I'll see if I can give a more reasonable, detailed, answer later this evening. hang in there and have a beer.
     
  20. ChrisHeflen

    ChrisHeflen Supporting Actor

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    I am in the same predicament. My equipment is far away from my speakers and tv. My runs are at least 30' and I like to bi-wire. I couldn't afford 100' of Audio Quest bi-wire cable or any other better than entry level cable. I am using Monst%$#$%er cable 4 conductor to bi-wire, but then a friend of mine said double up the wires and just use the jumpers on the speakers. This way I'd (my paraphrasing) have more current carrying capabilities. What do you guys think?
    I can't move my amp and while my pre-pro is my amp is not balanced.

    And sorry George if I'm budding in with my problems.
     

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