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Finding Speaker's Impedance

Discussion in 'Amps and Cabs [BG]' started by M0ses, Oct 2, 2009.

  1. M0ses


    Sep 11, 2009
    Los Angeles
    Ok, so I've got two speakers. All I know about them is that they were made by Leslie and they are 12" wide. There is a parts number on the back - 33 5120 4 - but this number does not appear in any database I can find.

    So, how can I find out how many ohms these things are? They're pretty nice speakers, I want to wire them up in a home-built cab, but obviously I can't just wire them up and expect them or the amp to not be destroyed if I don't even know the impedance. Is it going to take some kind of expensive test equipment to find out?
  2. johnk_10

    johnk_10 vintage bass nut Supporting Member Commercial User

    Feb 16, 2008
    Thousand Oaks, CA
    John K Custom Basses
    a volt ohm meter will tell you. set it on DC resistance and tell us what you get.
  3. Those speakers were probably designated for Leslie organ cabinets. I doubt they'll work well for bass especially in a cabinet not optimized for them. The best you can hope for is a crapshoot.

  4. ric426

    ric426 In my defense, I was left unsupervised. Supporting Member

    Mar 27, 2002
    Southeast Michigan
    Like johnk said, just measure the resistance. It will be slightly lower than the impedance. A 4 ohm speaker will typically read somewhere between 3 - 4 ohms, an 8 ohm speaker will be in the 6 -7 ohm range, etc.
  5. hbarcat

    hbarcat Supporting Member

    Aug 24, 2006
    Rochelle, Illinois
    Use a multimeter and measure the resistance of each speaker. The number you get will be a little bit lower than the actual rated impedance of the speaker. Example: an 8 ohm speaker will typically read around 6 ohms and a 4 ohm speaker will typically read about 3 ohms.

    Edit: ric beat me to it. :D

    And I agree with Paul, that these are likely not suitable for bass and could very easily be destroyed by playing bass through them.

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