Can I get all 4 mono impedances in a 4x10 cab?

Discussion in 'Amps and Cabs' started by DiPa, Apr 19, 2015.

  1. DiPa

    DiPa Silver Supporting Member

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    Hey All
    My next project is to build a 4x10 cab to be used with various amps, fenders and a few others.
    The impedances I need are 2 ohm, 4 ohm, 8 ohm and 16 ohm all mono.
    I figure this way, I should be able to connect any of my amps to it as I would have the matching impedance available on the cab.
    But I am hearing that this is not an easy one to achieve.
    Has this not been done prior?
    How can it be accomplished?
     
  2. guitarjazz

    guitarjazz Member

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  3. amphog

    amphog Silver Supporting Member

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    If you want all 4 speakers, you get 2&8 with 8 ohm speakers, and 4&16 with 16 ohm speakers. Sorry, but thats Ohm's law.
     
  4. RobertUi

    RobertUi Thumper Silver Supporting Member

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    Yeah, this is kinda like trying to find unicorn's blood. If you're expecting to use all four speakers at once, then the answer's going to be a pretty flat no. You can definitely wire it up with a couple switches to use 2 at a time, or all four at once in series/parallel to get different combinations, but not exactly what you've described here.
     
  5. walterw

    walterw Gold Supporting Member

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    yep, can't get there from here.

    maybe one of those weber Z-matcher things is your answer,
     
  6. Bruce Clement

    Bruce Clement Gold Supporting Member

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    You could use four 8-ohm speakers thusly:

    2 ohms: all four in parallel
    4 ohms: two in parallel, two not connected
    8 ohms: all four in series-parallel or parallel-series
    16 ohms: two in series, two not connected.

    So, yes, you can achieve all of those impedance ratings, but two of them utilize only two of the speakers. Perhaps you could make use of a stereo cab.

    There are lots of reasons that all four speakers must be the same impedance.

    I'll leave figuring out the wiring to you. It could probably be done with a couple of switches and/or switching jacks.
     
  7. DiPa

    DiPa Silver Supporting Member

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    Yeah, thank you.
    The stereo feature should help some.
    I had put this problem out to a cab builder as well.
    He is looking at it as well.
    Having two switching plates with jacks will get me the max useage of the various impedance configurations. I think I can get the mono and stereo to cover all the impedances I need.
    It's not impossible as you have indicated.
    Let's see what the cab builder comes up with, and I will surely pass this on to him.
     
  8. DiPa

    DiPa Silver Supporting Member

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    I should have have added the stereo feature in addition to the mono feature in my initial problem. I think I can get something whereby the cab would be capable to be driven by any of my amps matched ( 2, 4, 8 and 16 ohms).
     
  9. DiPa

    DiPa Silver Supporting Member

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    So no one has requested something like this before?
    Or no builder has offered this?
    For folks that have a few Amps and with different impedances, I thought having one cab to cover all Amps by matching the impedances is a must have.
    Kinda gets old having different cabs for different Amps.
     
  10. walterw

    walterw Gold Supporting Member

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    the stereo thing means using two amps at once, or having half the speakers in the cab off. the first is a PIA and the second is less than awesome (the "dead" speakers can throw off the response of the "live" ones from the way they affect the air pressure in the cab).
     
  11. Tone_Terrific

    Tone_Terrific Member

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    Ohm's Law is not an opinion or option it MUST be obeyed.
    Now, bear in mind that speaker impedance actually varies with the program material and is a moving target, and most amps can tolerate some mismatch without damage.
     
  12. DiPa

    DiPa Silver Supporting Member

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    I don't see violating Ohms law.
    This problem is a search for a super switch configuring speakers to get you a series, or parallel or series-parallel, or parallel-series and whatever combination.
    Maintaining 2, 4, 8, or 16 ohms is exactly the search.
    Ideally preferable to be mono, but stereo will have to be included as limitations exist.
    Perhaps it's cant be done, but I just wanted to find out.
    Thanks.
     
  13. GCDEF

    GCDEF Supporting Member

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    Or you could just get a Weber Z-Matcher and not worry about it.
     
  14. DiPa

    DiPa Silver Supporting Member

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    Okay good point.
    Let me ask this, have never tried it, have thougt about it, for amps that have 2 speaker jacks, can one connect from each speaker jack to the two stereo jacks on the cab, and what would this result?
    Meaning each stereo input jack on the cab would connect to the amps two speaker jacks.
    Thanks.
     
  15. DiPa

    DiPa Silver Supporting Member

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    I don't know what it is, but I will look into it. Thanks.
     
  16. guitarjazz

    guitarjazz Member

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    With a modeler.
     
  17. DiPa

    DiPa Silver Supporting Member

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    I supposed that would be where it can be programmed.
    I am a tube amp guy and trying to make this work, but may not get everything I want.
     
  18. guitarjazz

    guitarjazz Member

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    What speakers were you planning to use?
     
  19. Tone_Terrific

    Tone_Terrific Member

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    The calculation using Ohm's law for any conceivable wiring configuration will show that cannot be done.

    The Z-Matcher is basically an additional (matching) transformer used to match impedances.
    There will be some loss and possibly some tonal change; I have never used one.
     
  20. DiPa

    DiPa Silver Supporting Member

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    I have not chosen a speaker, there are a few ALNICO ones I would like to consider.
    It looks like you get 2 mono impedances and 1 stereo is the standard speakers cab switch plate.
    I need a 2 ohm mono impedance as a must and will figure which other I get out of this configuration. Would be nice to get 4 ohms as well.
     

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