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Amp/Speaker Impedance

Discussion in 'Amps and Cabs [BG]' started by wolvertone, Feb 6, 2006.

  1. wolvertone


    Feb 6, 2006
    Hey, long lurker, first post!

    I have a head that has a 4 ohm minimum requirement. I have it connected to a 4-10 cabinet which is also 4 ohms. What do I do if I want to connect another cabinet, say a 1-15?

    Is there such a creature as an adapter that has a resistor in line which will increase the 4-10 cab to 8 ohms? Does anyone have any experience with this? How does it affect the overall sound, if at all? I can make it myself, but was wondering what type of resistor I would need, or if it can be done. My amp puts out 350 watts at 4 ohms.

    thanks y'all

  2. theshadow2001


    Jun 17, 2004
    I dont thinik you could change the impedance of the box itself properly. I think your pretty much stuck with the speaker that you have. I dont think you could add another. You could get another 4 ohm cab and wire it in series with your 4x10 which would give you 8 ohms however this would probably defeat the purpose of having an extra speaker due to the reduced wattage.

    The impedance of a cabinet is more than just the resistance of the voice coil, it also as inductance as well and capacitance if it has some kind of passive crossover. So simply adding a resistor won't change the impedance correctly. It would work if the signal into the cabinet was DC but its not its an AC signal.

    I suppose its possible to replace the drivers so that you could get it to 8ohms but I think the easiest option would be sell your existing cabinet adn buy two 8ohm speakers
  3. K Dubbs

    K Dubbs Just graduated from OSU, Go Bucks!

    Mar 16, 2002
    Toledo, Ohio
    Have you read the FAQ yet? Lots on ohms in there.
  4. greenboy


    Dec 18, 2000
    remote mountain cabin Montana
    greenboy designs: fEARful, bassic, dually, crazy88 etc
    [insert barrage of Accuswitch jokes here]
  5. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    It can't be done, your only alternative is to rewire your cab to 16 ohms, then you could use another cab of at least 8 ohms along with it.
    Find out how to rewire your cab here: