Resistance question

Discussion in 'General Electronics Chat' started by rfrenkel, Dec 17, 2009.

  1. rfrenkel

    Thread Starter New Member

    Dec 17, 2009
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    A audio loudspeaker brochure says: "High loop resistances that exceed 0.07Ω
    (for each wire run) will cause the filter
    network to be mis-terminated, resulting in
    considerable degradation of sound quality."

    Does a speaker cable with a resistance of 0.12 ohms cause a little problem or a big one in sound degradation.
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
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    That is a high end audiophile question. You would have to have to believe that the speaker contributed nothing to the system in order for 52 milliohms to utterly upset it.

    What is a qualitative definition of "considerable degradation"?
     
  3. KL7AJ

    AAC Fanatic!

    Nov 4, 2008
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    Yep, the Audiophool quacks strike again. If I didn't have a conscience I could make a FORTUNE on this stuff!

    eric
     
  4. KL7AJ

    AAC Fanatic!

    Nov 4, 2008
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    By the way, the Audiophools make the perpetual motion groupies seem sane and rational by comparison!

    Eric
     
  5. smanches

    New Member

    Mar 27, 2009
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    It's not completely wacked. It's basically saying if the resistance of the wire is too high, it'll throw off the crossover frequencies, which is true. It would be changing the crossovers from an LC to an RLC network. Although I doubt the .05 ohm difference will make enough of a difference to make it worthwhile.

    If it was MUCH higher, then you would probably notice the difference.
     
  6. KL7AJ

    AAC Fanatic!

    Nov 4, 2008
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    Try MUCH MUCH MUCH MUCH MUCH MUCH higher. Like I said, if any of this stuff was beleivable, I would have retired by now, sipping mint juleps in the Bahamas. Well...I guess I don't have to believe it....just the suckers I'd sell it to. Along with all my oxygen free copper. Eeeeesh! :rolleyes:
     
  7. beenthere

    Retired Moderator

    Apr 20, 2004
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    That ignores the speaker loading. Speakers are hardly non-reactive or a constant impedance.

    The filter network referred to has to be the low pass network averaging out the peaks from a class D or higher amp. What effect might a honking crossover network in a speaker cabinet have?
     
  8. rfrenkel

    Thread Starter New Member

    Dec 17, 2009
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    When I posted the original question I did not mention that the speaker manufacturer is not in the business of selling audio cables, so their warning appears to have some credence.
     
  9. Mike33

    AAC Fanatic!

    Feb 4, 2005
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    Try it out with a nice low R cable, then A/B it with something really honking...do a qualitative test for yourself! The ears are the judge...
     
  10. Audioguru

    New Member

    Dec 20, 2007
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    896
    Old speakers designed for vacuum tube amplifiers having an output impedance of 8 ohms had built-in damping for their low frequency resonance. When connected to a modern amplifier that has an output impedance of much less than 0.04 ohms then their bass response is poor because the very low output impedance of a modern amplifier also damps the low frequency resonance.

    Modern speakers are designed to have their bass resonance damped by the extremely low output impedance of a modern amplifier. Series cable resistance ruins the damping then the speaker makes a boomy undamped sound.
    The same applies to crossover networks.
     
  11. kdillinger

    Active Member

    Jul 26, 2009
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    Excuse me, but you should not mock the audio gurus. They know what they are doing. For example, take a look at this Ethernet cable. Clearly, for $500 it is a prime piece of engineering for the delicate ears of audiophiles.
     
  12. boriz

    New Member

    Jul 16, 2009
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