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Bi-amping and Cat5

Discussion in 'Cables & Switches' started by Kobus, Mar 16, 2005.

  1. Kobus

    Kobus
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    I have read every thread about Cat5 and also all the Tnt stuff. I find it surprising that there are no talk about bi-amping and the method for winding/braiding. How many cables per channel, is it double or not?. I see for bi-wiring they suggest 6 per channel split in two. I assume that you require more for bi-amping. How many would be sufficient for a high powered (120 w per channel amp & 200w speakers) set-up?.

    Please help, others will also benefit.

    Thanks
     
  2. johnnycab

    johnnycab
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    Kobus,

    You have not searched properly enough or read these posts thoroughly! I have also read quite a few of these CAT5 articles, and most of them tell you how to biwire. I created mine just a couple of days ago - and I will be making a few more with CAT6 next week.

    However, just to help you along - here is one such post that helped me quite a bit, and will give you the answers you seek - http://www.avforums.com/forums/showthread.php?t=141489
     
  3. Reiner

    Reiner
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    Why would you want to use CAT5 cable in the first place? AFAIK there is no difference in the cables compared to a standard LS cable that would make an audible difference (assuming same cross-section).
     
  4. Kobus

    Kobus
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    Thanks for the reply.

    There is still no talk about bi-amping. How many wires are recommended for low & high frequency.

    I would love to believe/trust that there are no real diff to the ear.

    What does LS mean?.
     
  5. cwick

    cwick
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    From a cabling point of view, there's no difference between bi-amping and bi-wiring. The terminations (at the amp end) would be different, but the cables & speakers end terminations would be the same either way.

    Take your pick on the configuration - I run a three-way braid, with two Cat5's carrying the bass, and one the highs. But it seems to me you can pretty much run whatever config works best for you.

    Cheers, Carl.
     
  6. andyAV

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    Kobus

    Having just moved offices and come into possession of 30+ 5-10m lengths of Cat5 I've just undergone the Cat5 finger wrecking transformation with Kef Q7 speakers driven from a Rotel 1098 amp (so 150w spk / 200w amp but not played "weekend" loud yet). Previously used cable talk 3.1 biwire for L/R and QED SA Biwire for remaining 3.

    I'm currently trying single cable/non-biwired configuration (after biwire failed to inspire). I then tried using two sets of these cables in biwire mode - you could do the same but send the second cable bundle (of 3 cables) to the second amp to move from to bi-wiring to bi-amping. I guess biamping is almost always going to need two sets of cable runs as the two amp terminal sets are usually too far apart for any break out from a single braided cable.

    When I've finally settled on a config I'll be sure to comment in the forums on whether it makes an improvement for my system & ears. First thoughts on non-biwired are that everything became a little bit clearer - noticable on plucked strings and background sounds but the wife suggested it wasn't as exciting/involving (perhaps cos we were down to low volumes by then, it being late). Certainly seems to work more noticably for centre speaker (Kef Q9c) so improvement from QED SA may be more significant or it may be frequencies present or less effort required to drive it compared to Q7's.

    Andy
     
  7. Kobus

    Kobus
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    Thanks Andy

    You are saying that 3 Cat5's per channel/speaker should be OK. This is a very low gauge/diameter for a high powered setup.
     
  8. CJROSS

    CJROSS
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    Kobus

    I take it your bi-amping to a Treble Feed (1st Power Amp) + Bass Feed (2nd Power amp), If it were me I would simply run these cables for that scenario :

    1st PA – 2 CAT cables (1 for +pos the 2nd for –neg feed on amp/speaker terminal)
    2nd PA – 4 CAT cables ( combined & split in half – read through CAT5 threads for how to colour code the internal conductors of each cable ie white striped conductors for black - neg & coloured striped conductors for red – pos) :

    Heres a couple pics of 2 CAT5s combined and split “colour code wise”. Simply do the same with 3 CAT5s (this is called “colour coding” or “CC mode” you pos & neg feeds in CAT5 circles). This type of CAT5 cabling varies slightly compared to the FFRC TNT mode. But its safer and very hard to confuse wiring when its colour coded IMHO.

    http://evildonut.34sp.com/diy/graphics/CJ_2_FFRC.jpg
    http://evildonut.34sp.com/diy/graphics/FFRC_concept.jpg

    FWIW : A treble feed does not need the same CSA of copper as a bass feed (they have very different electrical loads), so there is no point of using the same amount of cable for each scenario. In a bi-amp scenario I would keep the wires separate for ease of connection TBH.

    The amount of Cables you use in a CAT5 setup is down to personal preference and the kit your going to use, For example using the standard 3 CAT5 scenario from TNT, you can safely use that area of CSA of copper up to 6m. I use this length. Then you see other CAT5 recipes like the TTT which is double that amount ie 6 CAT cables. Depending on length of speaker cables required and power requirements I would try to gauge a happy medium TBH, thus to me 2 for your 120W treble feed & 4 for your 200W PA is a good palce to start, why not experiment as see what you like, its simply about increasing CSA till you find a length/CSA relationship that suits your kit, your ears, your layput. Another way to think of CAT5 cables in CSA terms is say Kimber Kable so 3 CAT5 is euquivalent to 4TC, double that and your up to 8TC. Etc etc. Its DIY dude, so no parameters are in place for cabling like it – ie what do I use in a 2 PA setup. Thus in your setup you could safely use 6 CAT5s as per the TTT recipe, but laid out differently IMHO, ie 2 for Treble – separate & 4 for Bass (Ive seen a few CAT5ers do this TBH.

    HTHs and good luck.
     
  9. CJROSS

    CJROSS
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    PS 3 CAT5 per channel, is not a low guage for a hi-power setup, bellwire, 79 strand etc etc now thats low CSA copper. As another suggestion you may wish to consider the Van Damme Black Series of speaker cables for example in your setup :

    2 x 2.5mm2 For 120W
    2 x 4.0mm2 For 200W

    http://www.vdctrading.com/products.asp?SubSectionID=1&ProductID=14

    Best type of decent CSA of copper sold direct as speaker cabling, of course CAT5 is cheaper but this is quite cheap in the greater scheme of things IMHO. VDC also sell CAT5 FYI.
     
  10. Reiner

    Reiner
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    Loudspeaker.
     
  11. Kobus

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    Thanks Reiner & CJ, I recked my brains with LS. - loudspeaker - damn.

    I would just be wary with splitting the colours if the wires must get pulled through conduits or are at any risk of damage as those + & - are very close to each other.
     
  12. CJROSS

    CJROSS
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    Never happened to anyone I know using CAT5 speaker cables, certainly not me in the 5+years Ive used them, You would need to do cables so serious damge to achieve this TBH, FWIW the TNT FFRC recipe has the exact same colour code method for the single treble feed CAT5 cable with the 2 CAT5s for bass being separate. But if your happy keeping the cables seperate totally - there is no problem - as long as you market each end clearly - this can be done very cheaply with balck & red electrical insulation tape BTW.

    ATB.
     
  13. johnnycab

    johnnycab
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    erm...I made a slight error, whilst completing my cables. I had wired just 'one' of the strands from LF set into a HF groupset on one of the cables, and was getting an error message on the amp. The cable worked fine until a full LF signal passed through it.

    To cut a long story short...the Yamaha amp was clever enough to work out there was a short, and peformed a shutdown. I assume any new amp, must have this fail-safe in place.

    HTH
     
  14. CJROSS

    CJROSS
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    Johnny, simply put that was user error not a fault of running close proximity opposing polarity cables - you made the mistake not the CAT5 – you of course have to be careful (which you were not) and the best way to be careful IMHO is to colour code the conductors, in each CAT5 cable once you bunch each set of colours & whites together you need 4 of each to create a “4 no. pair”, then combine those with the corresponding pairs from other CAT5 cables, when your all hooked up there is no cross polarity in any cables. Its all down to the colours indicating which polarity terminal to use.

    Not being harsh dude, just pointing out that you need to be careful when setting up CAT5 cables, it is in fact very simple, but for first timers it can be confusing. Most amp have a trip circuit to protect against shorts as you mention.
     
  15. johnnycab

    johnnycab
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    You are not being harsh, it is the truth - It was user error. I should have checked everything with a multimeter - before rushing to plug those cables in!

    I just thought it would be good to document it. So, if anyone who is reading this topic - would understand that simple mistakes can cost big. I got off lightly - as my older amp would not have been this forgiving. However, it is immensely rewarding once everything is working OK.

    Cheers
     
  16. gerbilly

    gerbilly
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    I changed from 3 strands of CAT5 on my budget system to the 6 and it made a noticeable improvement to my system.
     
  17. Kobus

    Kobus
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    Gerbilly, on what type of system and over what lenth did this make a difference.
     
  18. gerbilly

    gerbilly
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    budget stuff for me I am afraid I cant afford 600-700 quid for a cd player or 400-500 for speakers and another 600-700 for an amp the wife would kill me.
    Marrantz cd player and amp which cost about 450 quid and speakers around the 120 mark.

    The cable i have used is a 2 1/2 metre one utilising 6 lengths of cat5.

    There are many more people using this though on real high end equipment like Knightshade and CRoss and they are the biggest fans of CAT5.
     
  19. CJROSS

    CJROSS
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    Dont know if mine classifies as high end dude, I certainly did not pay high end prices for my kit. :smashin:

    FWIW just to show that you can use a variety of "everyday" cables on hifi kit, here is a shot of my study systems just now and the back of the amp. The cable is bog standard 2 core mains flex, used over a length of 750mm. This works perfecty fine and to deafening levels, as does 3-6 CAT5 cables 6m in length.

    http://i3.photobucket.com/albums/y57/CJRHifi/TAF-30ESBinds.jpg

    The problem IMHO with cabling in audiophiles systems, is that we have been force fed the notion by dealer/press so long that once you move above budget kit, you should use more expensive cabling, quite daft IMHO but it a true facet of how new people into AV/Hifi automatically think from what they hear / read in the mag.

    Power to DIY brothers.
     

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