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changing ohmage on 2x10 cabinet

Discussion in 'Amps and Cabs [BG]' started by monkeybass68, Oct 11, 2013.


  1. I've got a 2x10" cab that's wired to 4 ohms. It has 2 - 8 ohm speakers. Can someone tell me how to I wire it to 16 ohms (so I can run it parallel with another 4 ohm cabinet & make rig run at 8 ohms)?
     
  2. Connecting a 16 ohm cab to a 4 ohm cab will NOT give you an 8 ohm load (it will be under 4 ohms).
     
  3. LowEZ

    LowEZ Supporting Member

    Mar 29, 2011
    Central NJ
    [​IMG]

    BUT... running a 16ohm cab with a 4 ohm cab will NOT give you an 8 ohm load!
     
  4. JTE

    JTE Supporting Member

    Mar 12, 2008
    Central Illinois, USA
    A 16 ohm load in parallel with a 4 ohm load is 3.2 ohms. Formula for parallel impedance is (R1xR2)/(R1+R2). That's (16x4)/(16+4) = 64/20 = 3.2.

    And, "ohmage" is NOT a word. You want to know how to change the impedance.

    John
     
  5. That is a series connection.

    You could easily use the diagram to make a "series speaker cable", and use both of your 4 ohm cabs together.

    Just solder 1/4 jacks where the speakers are in the diagram.
     
  6. BassmanPaul

    BassmanPaul Gold Supporting Member

    Aug 25, 2007
    Toronto Ontario Canada
    if you have two 4Ω cabinets they need to be run in SERIES to produce an 8Ω load. This will require a special cable. If both of the cabinets contain a crossover you might run into some difficulties if they interact poorly.

    No matter what Wicki says there is no such word as "Ohmage" the word is Impedance.
     
  7. LowEZ

    LowEZ Supporting Member

    Mar 29, 2011
    Central NJ
    That is correct. He wanted two 8 ohm speakers to give him 16 ohms.
     
  8. Ouch !

    I really need to read better myself :D

    I'll edit my other post.
     
  9. P Town

    P Town

    Dec 7, 2011
    If you look a the diagram posted by LowEZ, but change each speaker to a speaker cabinet, the impedance of each cab will add to become the total load. If each cab is four Ohms, you will have them wired in series, and you will have an eight Ohm load. If both cabs have speak-on connectors it is very easy to wire the speaker cable this way. Make sure to confirm that the speakers are all moving in the same direction in unison, by applying a nine volt battery to the input cable, and observing that the cones all move in, or out. If they don't, reverse the connections at one cabinet.
     
  10. JTE

    JTE Supporting Member

    Mar 12, 2008
    Central Illinois, USA
    But you can't simply connect two cabinets together and get a series load. Every speaker cabinet I've had experience with (since ca. 1975) have the jacks wired in parallel. Physical appearance means nothing, it's all about how it's wired. You will need a special series speaker cable.

    John
     
  11. flatfender

    flatfender Ad eundum quo nemo ante iit Supporting Member

  12. P Town

    P Town

    Dec 7, 2011
    I was not trying to say you could just plug a standard speaker cable from one to the other. It requires a series wired speaker cable. That is what the drawing shows. It is showing two speakers, but if you substitute a speaker cabinet for each speaker shown in the drawing you have a pair of speaker cabinets wired in series. Think about the connections at each speaker as the input jack to the speaker cabinet. Notice that the polarity is positive to negative. Wire the cable up with a temporary connection, and do the battery test to ensure all the speakers move in, or out in unison, and then solder it.
     
  13. Thanks for all the info guys. I'd just like to clarify one thing though. If I do indeed re-wire this 2x10 to be 16 ohms, would it still be safe to run it parallel with a 4 ohm cab (i.e. run amp to jack of 4 ohm cab and other jack of 4 ohm cab to the 16 ohm cab)?
    Many times over the years I've run 8 ohm cabs that way and never had impedence problems with my amps. Only time I've had problems was running a 4 ohm cab & 8 ohm cab together (which I did over 20 years ago & I blame on being young & ignorant).
     
  14. SunnBass

    SunnBass All these blankets saved my life. Supporting Member

    Aug 31, 2010
    Columbia, Mo
    Simply put: DO NOT RUN CABS OF MIXED IMPEDANCE.
    Forget this idea of a 4 ohm cab and a 16 ohm cab at the same time.
    It is the same "mistake" as when you ran that 4 ohm and 8 ohm cabinet 20 years ago.
     
  15. ggunn

    ggunn

    Aug 30, 2006
    Austin, TX
    A 4 ohm cab and a 16 ohm cab in parallel will give you about a 3.2 ohm total load and most of the sound will come out of the 4 ohm cab. If both cabs are 4 ohm two speaker cabs, I recommend wiring them both internally in series to make them each 16 ohms, and then running them in parallel for an 8 ohm total load. Your amp will thank you.
     
  16. You can run the two cabinets in series to get an eight ohm load.

    To do that, I think it is better to make a little box with the connectors wired in series. That way you can use standard speaker cables for all connections. Otherwise you have to be sure to label your custom cables and be certain that you don't use them in unintended ways.

    The wiring diagram posted previously shows how to do it. Instead of the speaker terminals you would wire to jacks in exactly the same way.
     

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