Taming JMP 50w

Discussion in 'Amps and Cabs' started by Residentia, Dec 23, 2009.

  1. Residentia

    Residentia Member

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    I think in some Marshalls two of four power tubes can be removed to halve the output. Can I do anything like that with my JMP which has a total of two power tubes?.
    I'm also considering a less efficient speaker, and a
    hotplate won't fit in the budget right now.......

    Thanks in advance-
    Mike
     
  2. hammersig

    hammersig Member

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    I'm pretty sure the two output tubes work in tandem, so if you remove one, you should lose all output. I would save for a good attenuator. It would be a good investment in the long run.
     
  3. (s)hellofaman

    (s)hellofaman Member

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    i'll usually replace the phase inverter (one closest to the power tubes) tube in a marshall with a 12at7. seems to sweeten the tone and tame it a bit. i've found rca 12at7's to be particularly good for this purpose.
     
  4. guitarded_1

    guitarded_1 Supporting Member

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    Are you talking about taming the volume? Removing tubes in a Marshall essentially does nothing to tame the volume.
     
  5. riff1006

    riff1006 Member

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    An attenuator or a PPIMV would do it. I've had both and been happy with both.
     
  6. rooster

    rooster Member

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    Turn the cabinet around and face it towards the wall?

    rooster.
     
  7. soulloud

    soulloud Member

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    That is what I used to do. I used a jcm 8oo half stack for years & I almost always turned the cab around pushed against ther wall & cranked it up. Really a great tone like that. God I miss that amp.
     
  8. Residentia

    Residentia Member

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    Removing two of four power tubes accomplishes what then?
    M
     
  9. sdd17

    sdd17 Member

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    get a port city 1x12 os when lower volume is needed
    smaller rooms etc
    not an amp mod thought but its a thought
     
  10. thelionsden

    thelionsden Member

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    I reduces the amps power in a 4 tube amp. U need both tubes in a push pull 50 watt amp
     
  11. thelionsden

    thelionsden Member

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    There are some really good attenuators out now. That is the best solution IMO. PPIMV sounds bad to me.
     
  12. sdd17

    sdd17 Member

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    Alex is great
     
  13. thelionsden

    thelionsden Member

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    Also, when removing 2 tubes from a 4 tube amp it changes the impedance, the amp does not quite match up right with the transformer and it alters the tone a bit. You have to set the impedance selector differently for the same cabinet. 8 ohm cab into 4 ohm tap (selected impedance)
     
  14. Residentia

    Residentia Member

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    guitared 1 is suggesting it doesn't affect the power, from what I understand (or don't)...
     
  15. QRSS

    QRSS brutalist

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    if your plate voltage is 450v or less, you could throw some jj6v6s in there. still pretty loud though.
     
  16. thelionsden

    thelionsden Member

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    I think what he implied is that it didn't change the volume much, not the power

    It takes ten times the amount of power in watts to double the volume. So a 50 watt amp is only twice as loud as a 5 watt amp.

    To double the volume of a 50 watt amp, you would need 500 watts. So a 100 watt amp is quite a bit less than twice as loud as a 50.

    Removing two tubes, even tho halving the power, doesn't really reduce the volume as much as you would think.
     
  17. Residentia

    Residentia Member

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