another Ohms ?

Discussion in 'Amps and Cabs [BG]' started by KingOfAmps, Dec 11, 2003.

  1. I did a search for previous posts about my concern and found several relevant threads. Posters have asked about the readings (ohms) they get when testing a speaker or cabinet. They are usually concerned after discovering (or are told that they will discover) that the measurement they get is less than the printed or stamped impedence. For example, their cab will say 8ohms but will measure "6.4ohms" or something less than "8".

    I have an 8 ohm cab also. It contains four 32 ohm speakers wired in parallel. It measures 10 ohms at the input jack. None of the earlier threads (that I found) mentioned getting a higher actual reading.

    Is something screwy???
  2. Perhaps one of the speakers is fried. That's be 32 divided by 3, or about 10 ohms. Disconnect each speaker and test individual resistances.

    Alternately, put a 9 volt battery across your speaker cable, see if all 4 speaker cones move in or out as you make contact with the battery.
  3. BillyB_from_LZ

    BillyB_from_LZ Supporting Member

    Sep 7, 2000
    What kind of meter were you using to measure the resistance? If it's a cheap VOM with an analog meter, are you sure that you zero'd out the meter before you took a resistance reading? And that the batteries are still good?

    How did you connect to the cabinet to measure the resistance?

    I guess my first question should have been...were you measuring the resistance because you were just curious, or are you having a problem that you're trying to troubleshoot?
  4. (Thanks Bill, be sure to read my next few posts in this thread for the rest/end of the story.) Each tested at about 30 ohms.
    Yes. All four move. And they move the same distance.
  5. It's a Micronta analog 50,000 ohms/volt multitester with "range doubler". I read the whole 4 page booklet before I got started. I very carefully read the section on measuring resistance and it did mention how to zero the meter. But somewhere along the way I forgot about that part. That and the battery thing.

    I set the switch on RX1 and was not able to zero the meter. According to the booklet that meant the AA battery was low. It also utilizes a 9 volt. I replaced both batteries, zeroed the meter and:
    ...I put the red lead on the #1 pin (it's a Switchcraft C4M 4-pin XLR type) and the black lead on the #4.

    Now I got almost 7 1/2 ohms!
    Mostly double-checking. I just bought the cab used. I am restoring it to original. I have no 8 ohm head to hook to it yet either.

    Thanks to all!
  6. Petebass


    Dec 22, 2002
    QLD Australia
    BillyB strikes again!
  7. no4mk1


    Feb 21, 2003
    Seattle, WA
    Threads like this are why I love this place!