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ohms and crossovers

Discussion in 'Amps [BG]' started by basss, Feb 7, 2014.


  1. basss

    basss Supporting Member

    Aug 27, 2001
    NYC
    Can I swap out a 4ohm speaker for an 8 ohm speaker in a cabinet with a crossover - assuming all other specs are the same?

    In other words - are crossovers designed for a specific ohmage?
     
  2. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    Yes you can swap them.

    Depending on the speaker's frequency response, you might want to change the crossover frequency to optimize performance. There is usually enough of an overlap that it shouldn't be an issue in a musical instrument cab.
     
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  4. will33

    will33

    May 22, 2006
    austin,tx
    Can't do it unless the "crossover" is only a highpass filter that only protects the tweeter while the woofer still plays the full signal, many bass cabs are made like that.

    If you have an inductor coil in line with the woofer, it's a true crossover and you can't do it.

    Would need some pics of the internals to be of further assistance.
     
  5. will33

    will33

    May 22, 2006
    austin,tx
    Wouldn't doubling the woofer impedance either halve or double the corner frequency of the LPF (if there even is one)?
     
  6. B-string

    B-string Gold Supporting Member

    Most all MI (musical instrument) cabs run the woofer full range, not high passed by the crossover. Changing them does not affect the crossover. Changing the impedance (ohms) of a midrange or tweeter does cause problems as the crossover frequency changes.
     
  7. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    In many MI cabs, the crossover and woofer are in parallel like in the example below. Some cabs have an off position on a switch that disconnects or pads the crossover and tweeter or horn.

    In practice I find that an 8 or 4 ohm woofer is going to sound the same with the crossover in the circuit.


    [​IMG]
     
  8. will33

    will33

    May 22, 2006
    austin,tx
    I don't see anything blocking treble from the woofer, in which case the swap is fine.

    Yep, a lot of bass cabs are made like that, but not all. Even the budget Avatars have a LPF.

    Good question for the OP might be just what cab he has and how it's wired.
     
  9. basss

    basss Supporting Member

    Aug 27, 2001
    NYC
    Thanks for the replies. I guess the answer is "it depends"

    Anyone know what kind of crossover is standard issue in LDS cabs?
     
  10. Don doesn't really have standard issue Xovers. Best to ask him about your specific cab and he will have the answer.
     
  11. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    If you contact LDS, let us know what he says.
     
  12. basss

    basss Supporting Member

    Aug 27, 2001
    NYC
    will do
     



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