Dedicated Out Mod and Multiple Cab Question

Discussion in 'Marshall Amps' started by hagcel, Jul 1, 2020.

  1. hagcel

    hagcel Member

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    7F59CC4A-A5EF-4A43-A125-B32FB87922C0.jpeg Hello,

    I have a JMP 2203 that was modded to dedicated speaker outs.

    I have a 16 Ohm 1960BX and a 8 Ohm Mesa V30 cab.

    Would it be safe to run them together plugging the BX into the 8 ohm tap and the Mesa into the 4 Ohm tap?

    Or do I need to rewire the Mesa cab for 16 ohm then use a parallel splitter box to run them both from the 8 ohm tap?
     
  2. RLW59

    RLW59 Well-Known Member

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    Santiago Alvarez, designer of the JVM, says you can run a 16 ohm cab (plugged into an 8 ohm output) plus an 8 ohm cab (plugged into a 4 ohm output) on any amp that has 4/8/16 separate output jacks. Should be fine with your amp.
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    8 ohm Mesa cab can't be rewired to 16 ohms. You'd either have to replace the speakers, or disconnect half the speakers.
     
    hagcel and Jethro Rocker like this.
  3. mickeydg5

    mickeydg5 Well-Known Member

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    I said it too, actually I think before he mentioned it. :squint: No respect. :noplease:
     
  4. South Park

    South Park Well-Known Member

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    The speakers are power limiters for the power tubes . When you mismatch speakers you get to much power or not enough power may not sound the same .
     
  5. Jethro Rocker

    Jethro Rocker Well-Known Member Premium Member

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    This is not a mismatch. A 16 ohm cab from an 8 ohm tap is half a load. So is 8 from a 4 ohm tap. Both halves make a full load. Absolutely no mismatch.
     
  6. South Park

    South Park Well-Known Member

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    You are right if the two taps are linked together . Something to look into
     
  7. mickeydg5

    mickeydg5 Well-Known Member

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  8. Jethro Rocker

    Jethro Rocker Well-Known Member Premium Member

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    Any amp with individual outputs and no switch. As per Santiago as per @RLW59 s post.

    I quote.

    Yeah, even Santiago said this in the JVM forum!!
    Here's the link to the thread:
    JVM Forum • View topic - Can I run a 16 or 4 Ohm cab + an 8 Ohm cab?

    "There won't be a mismatch if you plug the 8ohm cabinet into the 1x4ohm output and the 16ohm cabinet into the 1x8ohm output. Everything will be perfectly matched and the power splitted equally into both cabinets.

    Santiago"
     
  9. hagcel

    hagcel Member

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    3F58AE90-170E-4178-89D0-79E4352FA7D6.jpeg Thanks a lot. Just tried it at low volumes. Can’t wait to crank it tomorrow to see what it sounds like.

    This is what this monstrosity looks like. Looks a little goofy with how big the Mesa cab is. The Mesa was $200 so I couldn’t pass it up. I have my eye on a 1960AX locally but he wants $750 so I’m holding off for now
     

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