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    Polk cobra cables

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    tubenutr

    Posts : 61
    Join date : 2015-01-25
    Age : 59
    Location : Northern Ontario

    Polk cobra cables

    Post by tubenutr on Sun Dec 13, 2015 11:37 pm

    Has anyone ever tried these cables with a VTA 70?

    corndog71

    Posts : 444
    Join date : 2013-03-19
    Location : It can get windy here

    Re: Polk cobra cables

    Post by corndog71 on Mon Dec 14, 2015 4:32 pm

    Never heard of those. I'm a fan of Kimber 4TC or 4VS if you want to save a few bucks.

    deepee99

    Posts : 1260
    Join date : 2012-05-23
    Location : Wallace, Idaho

    Re: Polk cobra cables

    Post by deepee99 on Tue Dec 15, 2015 1:07 pm

    I have had nothing but good luck with Blue Jeans cables. They are the only folks who use Belden wire, which is the best copper on the planet and their terminations are very good, cold-welded.

    tubenutr

    Posts : 61
    Join date : 2015-01-25
    Age : 59
    Location : Northern Ontario

    Polk cobra cables

    Post by tubenutr on Tue Dec 15, 2015 4:44 pm

    I've had a pair sitting around for about 25 yrs and was just wondering if they will cause any problems
    with a VTA 70

    deepee99

    Posts : 1260
    Join date : 2012-05-23
    Location : Wallace, Idaho

    Re: Polk cobra cables

    Post by deepee99 on Tue Dec 15, 2015 5:55 pm

    Never heard of copper rotting, but I guess there's a first time for everything.

    GP49

    Posts : 718
    Join date : 2009-04-30
    Location : East of the sun and west of the moon

    Re: Polk cobra cables

    Post by GP49 on Tue Dec 15, 2015 7:07 pm

    I wouldn't touch them.   Polk had an idea that they could reduce the cable inductance by making the cable out of a multitude of individual insulated strands...half of them comprising one conductor, the other half, the other.  They succeeded in reducing inductance but greatly increased capacitance, like hooking up a big capacitor across the output of the amplifier.  This drives some amplifiers nuts.  Some amplifiers oscillate under a capacitive load (stock Dynacos do not).  Some transistor amplifiers would BLOW UP!  Polk finally tried to compensate by adding a resistor/inductor network, which would defeat the whole purpose of the design to reduce inductance in the first place.

    Even if a high capacitance load doesn't cause the amplifier to oscillate, it can roll off the high frequencies at the output, affecting the feedback loop's operation and altering the amplifier's sound.

    If the enamel insulation cracked or was otherwise compromised, there was the chance of a dead short across the amplifier output terminal to ground.  Not good under any circumstance.

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