How long is too long

Discussion in 'Hi-Fi and General Audio' started by granville, Jun 25, 2010.

  1. granville

    granville

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    Going for a re design of my manger based speakers, to reduce cables have decided to mount amp modules and active crossovers within the cabinets. My question is;
    How long is to long for a rca cable ? I would need a run of 6M for right hand speaker.
    Is this a non problem or should I make up some cables incorporating mystical geometries with rare elements and specialist dielectrics ?
    Please don't start another violent thread war.
     
    granville, Jun 25, 2010
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  2. granville

    danworth81 english through n through

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    U should be fine with 6m shielded pair as long as its not from a passive pre
     
    danworth81, Jun 25, 2010
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  3. granville

    Fnuckle Trade

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    Unlike balanced connections, single-ended (RCA) connections are eventually prone to signal losses. The good news is these losses are really unlikely to make their presence felt until you get beyond 10m (unless you are going without active gain stages in a passive preamplifier). The bad news is you won't be able to find an off-the-shelf audio cable longer than 5m and you certainly won't find them at uneven lengths.

    If you are going to make your own cables for long runs, it's slightly better to use coaxial rather than 'microphone' cable. The shielding helps.
     
    Fnuckle, Jun 25, 2010
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  4. granville

    bottleneck talks a load of rubbish

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    doesnt make a lot of sense to me, personally.

    Crossovers inside speakers are bad enough, an amplifier even worse.

    If you're going for a DIY speaker, can't see any reason at all to put the crossover or the amplifiers inside a vibrating box..
     
    bottleneck, Jun 25, 2010
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  5. granville

    RobHolt Moderator

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    The answer depends on what you are using to drive the cable and the load.

    I'd avoid long interconnects if driving from a passive attenuator or most active valve pre amps.

    Most active pre amps will be fine with long cables but it makes sense in all instances - active and passive - to keep capacitance to the absolute minimum.

    Personally I'd always go with short interconnects and long speaker cables.
    I'd say that ultimately the best way is a passive pre, short low cap cables and a very benign power amp load. This needs to be designed very much as a system with all aspects carefully considered.
    I'm convinced that the bad press some give to passives is due to improper load matching.
     
    RobHolt, Jun 25, 2010
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  6. granville

    felix part-time Horta

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    This is incorrect. Both suffer at the same rate w.r.t length.

    In fact there is no benefit to 'balanced' signals unless you are in an exceptionally 'noisy' environment and the 'balancing is done exceptionally well. That's because what makes 'balanced' desirable is not the idea of equal, 'balanced' +/- signal strength; nor an inherent symmetry to notional 0v. It's all in the way the fed item reacts to seeing the same impedances at the + and - inputs.

    Sadly that means the way hifi press supposes balanced lines to bring benefits and the way they actually work are often two entirely different things - even companies like Bryston with their 'balanced everything' approach have got this quite wrong at times too! HTH.
     
    felix, Jun 25, 2010
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