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impedence

Discussion in 'Home Cinema Speakers' started by mattruston, Jan 25, 2003.

  1. mattruston

    mattruston
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    what the hell does impedence / impedience (spl??) mean? i have no idea, i suppose it goes hand in hand with wattage for something but i have no idea :confused:
     
  2. HotblackDesiato

    HotblackDesiato
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    As far as speakers go...it gives you an idea of how demanding a speaker is for an amp to drive. Speakers around 8ohms being less demanding, drawing less current from the amp, than those around 4ohms.

    spence
     
  3. lynx

    lynx
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    Impedance is the passive opposition against the flow of current.

    A further more detailed explanation can come from someone else as i have little inclination to write an essay on the subject. :D
     
  4. BK Electronics

    BK Electronics
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    Resistance is the passive opposition to current flow when E and I are in phase. Impedance is the not so passive resistance when coils and capacitors are involved and E and I are not in phase.

    A speaker coil has a resistive element Re that can be measured with an ohm meter. but as a speaker has an inductive, capacitive and a mechanical resistance its impedance changes with frequency. This impedance is averaged over a wide spectrum or just calculated at 1kHz.

    The resonant frequency of a speaker in free air can be in the hundreds of ohm.

    Sorry to make this all clear as mud
     
  5. lynx

    lynx
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    Which is another reason i left it for someone else. :devil: :D
     
  6. BK Electronics

    BK Electronics
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    Its always a bit difficult to explain when you wind wire around a former you make an Inductor, ( Voltage leads current) then this inductor has inherent capaitance due to the wire wound close to each other (voltage lags current) and of course this wire has a finite resistance. Then theres capacitance between the coil and pole peices of a speaker and the mechanical impedanceof the weight of all the cone materials, suspension and spider and the resistance of air Etc. Etc.

    The best thing to do is to ignore all this and pay heed to the Re as this is what your amp will really see most of the time.

    Most speakers rated at 8 ohms are rarely 8 ohms more like 6.

    Boy I wish I hadent started now I think linx had the right idea, this is a can of worms.
     

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