Mixing different ohms. Is it possible?

Discussion in 'Cabinets & Speakers' started by Wolvieberzerker, Oct 25, 2020.

  1. Wolvieberzerker

    Wolvieberzerker Well-Known Member

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    Gentlemen. I have a question.
    I have a Marshall 1960b cab with g12t75s. I also have to Mesa v30s lying around. But they only run 8 ohm where the 75s run at 16. Was thinking about putting the v30s in the Marshall cab in an X pattern. Due to the difference in ohms is that possible? Like if I run the heads in 4ohm mode. Or would I have to re wire everything? Or it might not be worth the hassle. Just want to try it for shits and grins. It’s what we do after all
     
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  2. StingRay85

    StingRay85 Well-Known Member

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    Maybe if you put the V30s in series, and then parallel them with the 75s. This will give you an impedance of 16/3 ohm
     
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  3. Frodebro

    Frodebro Well-Known Member

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    Beyond the impedance issues, you will also have fairly significant volume discrepancies between the 8 ohm speakers and the 16 ohm speakers. Could you make it work with creative wiring? Yes, but chances are that you won't like the results due to the volume mismatch because the louder speakers will dominate.

    For best results when mixing speakers, keep the impedance and SPL ratings matched.
     
  4. StingRay85

    StingRay85 Well-Known Member

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    Sure, its not optimal but it can be done
     
  5. _Steve

    _Steve Active Member

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    It'll be fine the the way you described. For a tube amp the speaker SPL is what matters for volume, not the impedance - so long the output impedance and speakers are matched. I'm going to create and post an experiment/demo to bust the lower-impedance-is-louder myth. It's a misunderstanding between solid state vs tube amps that gets perpetuated over and over.
     
  6. StingRay85

    StingRay85 Well-Known Member

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    It all depends how you wire them up of course. This way they will of course be more silent
     
  7. SkyMonkey

    SkyMonkey Well-Known Member

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    If my memory serves correctly a 3dB difference equates to a doubling of volume.
    G12T-75 sensitivity is 97dB.
    V30 sensitivity is 100dB.
    That is a 3dB difference.

    The V30s may sound like you are powering them with an amp that is twice the rating of the G12T-75s.
     
  8. StingRay85

    StingRay85 Well-Known Member

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    In that case they'll match when you put the V30s in series, as total impedance will be 16 ohms so the both get half of the power compared to the 75s.
     
  9. GIBSON67

    GIBSON67 Well-Known Member

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    It's best to match your amp's impedance setting to your cabs impedance, especially with older Marshalls.

    What amp are you talking about? Mixing a cab that way would yield about a 12 ohm load.
     
  10. Marshall Boogie

    Marshall Boogie Well-Known Member

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    buy 16 ohm v30's and save yourself the damaged Marshall(especially if it is dagnall) transformer, they are notoriously weak....trust me....they blow....mine went on the 6 volt heater leg(fried out and blew sparks in the amp head, luckily the only thing fried was the transformer, bought classic tone upgrades....and they rock....i hope they are still in business when this covid thing clears).
     
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