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Ohms and The Wizzy

Discussion in 'Amps and Cabs [BG]' started by ::::BASSIST::::, Apr 11, 2006.


  1. ::::BASSIST::::

    ::::BASSIST:::: Progress Not Perfection.

    Sep 2, 2004
    Vancouver, BC Canada
    I was concerned about running two wizzys as I read somewhere that the wizzy is rated at something like 3.87ohms and thus would drive an amp below two ohms. I emailed Carvin about this issue and their BXR series amps. Here is the reply:

    "Speaker impedance is based on the average impedance of the useable
    frequency range of the speaker (or cabinet of speakers).
    3.87 ohms is very normal or actually being high for a 4 ohm speaker.
    Also if you use an ohmmeter on a speaker you will find most speakers
    read .5 to 1.5 ohms less than the average impedance.

    The B500 will not have an issue with two of these cabinets.

    Kris @ Carvin"

    This makes me feel alot better. I was told that running two wizzys at high volumes will shutdown an Iamp 800 (it happened to this player). I thought it was because of the low ohmage and was a little concerned about finding an amp that could push below two ohms...

    But not anymore!:D
     
  2. tombowlus

    tombowlus If it sounds good, it is good Gold Supporting Member

    Apr 3, 2003
    Fremont, Ohio
    Editor-in-Chief, Bass Gear Magazine
    Keep in mind that ohm ratings are not exact, and that sounds like a fairly accurate read. I have some 8 ohm cabs that measure like 6.7 ohm. I do not think that this is a problem.

    As far as two Wizzy's shutting down an iAMP 800, that just floors me. I have run my two Wizzy's very loud with both my iAMP 800 and 500 (and we are talking for 4+ hours with the 800) with no problems whatsoever.

    Tom.
     
  3. Bass Boy

    Bass Boy Supporting Member

    I've been told by a few people (some of them dealers) that two whizzys can shut down an iAMP from time to time. (I think the protection can be adjusted by EA to avoid this however) I've also had my 2 cxl 112s shut down my Markbass once. I was using my octave pedal (Billie Jean bassline) and the tune was extended (singer does the MJ dance schtick). The impedance must've been low due to the extended range of the bass notes. I turned it off, then back on and haven't had problems since. Correct me if I'm wrong but doesn't impedance vary with frequency not volume?
     
  4. Fretless5verfan

    Fretless5verfan

    Jan 17, 2002
    NorCal
    IIRC you are either correct, or we are both wrong:ninja: :p
     
  5. Just a heads up - Reading a speakers resistance using a multimeter does NOT tell you it's impedance. Resistance and impedance are quite different things, and multimeters ONLY read resistance.
     
  6. metron

    metron Supporting Member

    Sep 12, 2003
    Denver
    Mathmetically isnt impedance the inverse of resistance?
     
  7. No, you're thinking of conductance.

    I don't want to get too technical on you guys, but here's a quick explanation.

    Resistance is defined for steady state voltages, ie; DC (direct current.) It's pure resistance. Irrespective of frequency (0hz to infinity hz) resistance is always the same.

    Impedance is defined for dynamic voltages, ie; AC (alternating current.) Resistance contributes to impedance, but impedance also takes into acount reactance, which is caused by the reaction of inductance and capacitance to an AC signal. So, impedance is dependent on frequency.

    A more accurate specification of cabinet impedance would be a graph of impedance vs. frequency. Generally they just average it out, round it off and say it's 4/8 ohms!
     

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