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Have go at making a good speaker cable

Discussion in 'd.i.y.' started by CJ14, Jun 18, 2021.

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  1. CJ14

    CJ14 Retired

    To get you started here is the TQ UB spec.


    Cable Specification

    Resistance/Metre/Pair 18mΩ
    Inductance/Metre/Pair (common mode) 25nH
    Capacitance/Metre Between Pairs 2nF
    Capacitance/Metre Between Conducting Pairs 4pF
    Maximum Continues Current 11Amps
    Breakdown Voltage/Metre Between Pairs >2500VAC
    Breakdown Voltage/Metre Between Conducting Pairs >5000VAC
    Maximum Working Temperature 150°C
    Recommended Frequency Range (DC) 10Hz – 250KHz
    Recommended Maximum Power Amp Load @ 8Ω 450WRMS
    Recommended Maximum Power Amp Load @ 4Ω 950WRMS
    Lose in Cable @ 11Amps/Metre 2.7Wmax
    Cable Width max 13mm
    Cable Thickness max 1.7mm

    Conductors are Litz Inductively matched to length each pair.
    At 60 Hz, the skin depth of a copper wire is about 8 mm. At 60 kHz, the skin depth of copper is about 0.254 mm. At 6 MHz, the skin depth is about 25.4 µm. Round conductors larger than a few skin depths don't conduct much current near their axis, so that material isn't used effectively. This causes a lose in detail and due to differences in Power/Frequency can cause phase changes producing error in depth of sound. Ordinary twisted conductor do not act like Litz as they conduct on there un-insulated surface to produce a solid conduct, only allowing the possibility to conduct more current as size increases, thus giving a larger diameter and solving the problem with brute force not science or thought. And large diameter wire increases the cost of raw materials and the wastes of money.
    Please also note as the diameter increases and the gap stay relatively small the capacitance also is increasing reducing the bandwidth and having the opposite response to your need, not counting the fact of the wasted power to charge and discharge this capacitor as the amplifier swing its output voltage following the audio, this often cause another undesirable effect the amplifier become unstable and burnout in the worst case scenario.
     
  2. Craig B

    Craig B Re:trophile

    So, lamp cord will do fine then?
     
    Rockmeister, Paul Burke and CJ14 like this.
  3. mega lord

    mega lord Centre tapped

    Colin, I thought you had been reading this place long enough now to have learned that cables make no difference :)
     
  4. martin clark

    martin clark pinko bodger

    Milliken solved this for even very high power cables a very, very longtime ago - and it is not even a Litz insulated-strand configuration: just that the wind ensures each strand equally passes through the conductor centroid, and in opposite sense, by layer, for really-stupidly heavy cables for LV AC power. Still in use over century later - as is the resulting company iirc : )
     
    Dan K, S-Man and CJ14 like this.
  5. CJ14

    CJ14 Retired

    Now come on wet string is better honest.
     
  6. 337alant

    337alant Negatively Biased

    I really like my 6mm Van Damme blue studio grade (8m runs), going thicker from 2.5 and 4mm was a significant improvement for me.
    I also regularly listen to my friends system with TQ blue and I rewired the inside of his speakers with it as well and it is excellent.
    Alan
     
    torstoi likes this.
  7. geoturbo

    geoturbo pfm Member

    Longing to have a try at LS80 if it will ever make it south to this other side of the pond, I was thinking to have a go in trying to challenge my Duelund speaker cable with some diy efforts, still a lot to go though.

    Above mentioned inductance seems remarkably low.
    Is there actually a twisted pair of positive Litz conductors (with very thin single wires) and same goes for negative in the TQ ultra black? Or could some single bigger awg size up-occ wire be used if it makes/makes better sense for the negative side?
     
  8. martin clark

    martin clark pinko bodger


    Notice also, capacitance is correspondingly-high: it's the essential compromise, and you have to pick your poison, no exceptions.
     
    geoturbo, tuga, booja30 and 1 other person like this.
  9. torstoi

    torstoi pfm Member

    ...so in theory the H construct of a cable a la Linn and Naim putting a well defined gap between + and -
    wires is not a bad idea ?
    Compared to a round looking package ?

    What cable do you use, Martin..?

    (edit: I had a really expensive LS cable here just for testing..it was completely round
    and had a diameter of probably nearly 10mm including isolation.
    And it sounded much different to mine..first impression was as if everything was packed in cotton..a bit overdamped...and perhaps a tiny bit compressed too.
    Could give an impression of better control, but may have been a false impression due to just being less loose or relaxed flowing compared to mine.
    Left a mixed impression and gave it back..
    What I heard may hence have been a high capacitance simply..)

    Interesting topic ! :)
     
  10. martin clark

    martin clark pinko bodger

    Ah, well, to be clear - I have an end-run about such things; the speaker cable is inside the amplifier's feedback loop. ( The amps I use take feedback from the speaker terminals, 'kelvin sensing' i.e four-wire style, out to c.160kHz. )

    For everything else/more regular I play with / enjoy / fix - I only need 2m a side and I dontneed loud, so Van Damme 2.5sq.mm works fine for me :)

    ETA: regardless of approach - I still think the effect of such things is way,way down in the weeds, utterly negligible - esp. when compared with so much simple/obvious /easy/free choices - like sympathetic speaker set-up in room, for a start.
     
    Robert, S_J, Mike P and 4 others like this.
  11. CJ14

    CJ14 Retired

    We use remote feedback on our big amps, but even so we and many more can here a big improvement, so it must be personal choice or your system does not need it, or we are all deaf as posts.
     
  12. russel

    russel ./_dazed_and_confused

  13. torstoi

    torstoi pfm Member

    I've had another nice listening session today at my mate's place & during that, we also touched the topic of
    loudspeaker cables.
    I told him what Martin had stated above, that capacitance raises with increased diameter.
    And he replied that's not the only point.

    He told me that a simple PVC isolation (the clear double barrel designs mostly) have a capacitance of 4,
    whereas a better polypropylene or teflon isolation has capacitance of around 1,8.

    So, whether you hear that or not is another topic,
    but obviously if you'd like to have low capacitance but still prefer to have a bit of diameter, say 2,5 or a bit above that, you can have substancial diameter with relatively low capacitance
    by choosing a better dielectricum.

    I won't discuss if you hear that or if it's better for now, as I don't know.
    All I heard last time was the cable definitely sounded different to mine.
    As I have only 2 meters of length soon by placing my pwr amp between the speakers,
    I'll give it another attempt..I think I'll try a 4² as it was mentioned above with positive perception and a good dielectricum..and see what happens.

    Any suggestions for a good 4² ?

    Thanks & kind regards..
     
  14. sq225917

    sq225917 Bit of this, bit of that

    I must be doing something wrong, with dac, pre and power amps all well beyond -105db for thd + noise and managing, -118db, -102db and -111db for imd, full power for dac and power amps I can't hear any difference with cables. Maybe it's not resolving enough?
     
    wow&flutter, booja30 and torstoi like this.
  15. torstoi

    torstoi pfm Member

    I don't think you're doing anything wrong & I also think it's not due resolution..
    I have a theory that perhaps many cables sound very much alike,
    and some sound different for whatever reason.

    For example I cannot make out any much difference between my Van Den Hul the clearwater and Naim cable
    other than the clearwater is much more flexible.

    I just checked from curiosity and the cable I had been borrowed by then was a Straight Wire
    Rhapsody S...also googled it and found it is obscenely expensive.
    But anyways...that one sounded substancially different to the Clearwater...for whatever reason..
    I couldn't come to a proper decision if it was better or worse & given I needed 2 runs of about 3-4 meters by then
    I decided I don't wanna find out bc the price forbid about even thinking of that.

    But now I need shorter runs, I'll try the same again.
     
  16. CJ14

    CJ14 Retired

    russel likes this.
  17. davidsrsb

    davidsrsb pfm Member

    I don't see how remote feed back can avoid all manner of RF immunity problems unless it is configured as a low frequencies only feature
     
  18. CJ14

    CJ14 Retired

    Now this bring me back to FET,s in power amps, everybody all damped the gate of the FET,s with big value resistors so the beasties would not go into parasitic oscillation, all wrong, the drive should work at a higher frequency than the Parrot Sick Oscillations (for Andy Williams) so I used and use transistors with a BW of 140MHz plus and rated at 12W+ now no problems, so my amps have very fast rise and fall time and slowing the feedback down would cause problems with phase , and it would sound like crap IMHO.
    Now the Damping factor is huge over 2000 this also helps, so RFI at present does not seem a problem and I use our cable it has EMC and a small amount of RFI rejection due to the CML.
    I limit the BW to below 1MHz with a small filer network on the input but the feed back BW is wide or should I say rise and fall times are very fast.
    I hope this helps without me giving far to much away to spies' ?? Best Col.
     
    Johnjo and mega lord like this.
  19. torstoi

    torstoi pfm Member

    Hi Colin..is your suggestion UB about the Ultra Blue or Ultra Black ?
     
  20. CJ14

    CJ14 Retired

    Not a suggestion but it was the early Ultra Not Blue
     

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