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impedance vs nominal impedance

Discussion in 'Amps and Cabs [BG]' started by Special_Ed, Feb 13, 2005.


  1. Special_Ed

    Special_Ed

    Oct 3, 2004
    What is the diffrence between "impedance" and "nominal impedance?" Is nominal impedance the lowest ohm's a cab can handle and regular "impedance" the highest ohms a cab can handle?
     
  2. No, that's not quite it. Let's look at a 2x4 at your lumber yard. The "nominal" size is 2x4 (duh!!) but if you measure it it'll actually be 1-3/4 by 3-1/2 or something like that. Nevertheless, we go to the lumberyard and tell them we want a 2x4.

    The speaker's nominal impedance could be 8 ohms, so you use it in an application calling for 8 ohms. The actual DC resistance will be less, maybe 6.5 ohms more or less. The actual impedance relates to the speakers reaction to an aC signal and is a function of the speaker's resistance, inductance, and capacitance and therefore is frequency-dependant. It actually may vary considerably. But we call it 8 ohms.
     
  3. Cabs don't handle impedance, they handle wattage.
     
  4. notanaggie

    notanaggie Guest

    Sep 30, 2003
    And, for added annoyance, the manufacturers that cheat.......

    One very well-known manufacturer used to call their 4 or 5 ohm IMPEDANCE speakers "8" ohms.

    They did this because that got them a couple or three dB more sensitivity on their specs......if the tester used equivalent voltage instead of actual power input for the "1Watt @ 1 Meter" measurement.

    This wasn't so bad, unless you wanted to parallel speakers. You could end up with a 2 ohm load on your 4 ohm capable amp....... :mad: