Jcm 900 Questions

Discussion in 'Marshall Amps' started by LRT#1, Jul 2, 2018.

  1. LRT#1

    LRT#1 Well-Known Member

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    On the jcm900 how do I get a more saturated higher gain sound

    Would switching the mode to low allow me to crank the amp causing tubes to run hotter with lower volume out put
     
  2. ampmadscientist

    ampmadscientist Well-Known Member

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    You turn up the gain to 7 or higher, and lower the master.
    The tubes won't run hotter, but it will have less loudness. And crank it up as high as you want.
    Low mode is triode which draws less current and the tube runs cooler.
     
  3. LRT#1

    LRT#1 Well-Known Member

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  4. LRT#1

    LRT#1 Well-Known Member

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    Thanks I'll give it a try

    What I have found with this amp is that it sounds best when its dimmed and the tubes are heated was looking for that sound without being dimmed out

    Also don't know anything about the effects ports does the vr1 pot only work with the effects
     
  5. LRT#1

    LRT#1 Well-Known Member

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    Something else I'm wondering about would I benifit from changing ohm settings on amp and what else would need to be done if I changed ohms would I need to rebias amp
     
  6. Söulcaster

    Söulcaster Well-Known Member VIP Member

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    Drop a patch lead in the FX loop and increase the loop level.

    Peace
     
  7. LRT#1

    LRT#1 Well-Known Member

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    By using a patch card looped port to port what will this do for me
     
  8. John BNY

    John BNY Well-Known Member Silver Supporting Member

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    It'll give you a much fuller sound. Once you plug in the patch cable, play around with the screw next to the FX loop and turn it to the place where you get the best tone. I think it shines at around the middle position.
     
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  9. LRT#1

    LRT#1 Well-Known Member

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    Thanks I'll give it a run
     
  10. 6StringMoFo

    6StringMoFo Well-Known Member

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    You ohm setting needs to match the cab or you risk blowing up your output transformer.
     
  11. LRT#1

    LRT#1 Well-Known Member

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    I'll have to look and see what can is thanks for keeping me from killing my gear
     
  12. iron broadsword

    iron broadsword Well-Known Member

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    If the dimed sound is best, the only way to get it is to use an attenuator, there's a bunch. Alternatively you could use a clean boost pedal out front to drive the preamp harder, but it will only be preamp tube distortion, not power tube distortion like when the amp is cranked. They're both great, but definitely different.
     
  13. LRT#1

    LRT#1 Well-Known Member

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    Do I need a stereo or mono patch lead I thought the ports were stereo

    Also really appreciate the advice if there is any more advice all would be great
     
  14. Wailing

    Wailing Active Member

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    D449859D-B250-4F00-8356-A9A7962AEBA9.jpeg This setting on my EQ in the loop works on my JCM900 MkIII
     
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  15. John BNY

    John BNY Well-Known Member Silver Supporting Member

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    Mono patch cable.
     
  16. LRT#1

    LRT#1 Well-Known Member

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  17. LRT#1

    LRT#1 Well-Known Member

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    Can't an attenuated work the head to causing early failure or is this just some Marshall model heads
     
  18. LRT#1

    LRT#1 Well-Known Member

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    To hard
     
  19. ampmadscientist

    ampmadscientist Well-Known Member

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    Not really.
    If the attenuator is a professional model ,and matched correctly to the speaker and amp impedance, it should operate as a normal speaker.
    Operator error is more likely to cause problems, as in: mismatched impedance or bad speaker cables.
     
  20. LRT#1

    LRT#1 Well-Known Member

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    So I tried the patch cable last night was happy with how it worked now I want to try an eq and see what that does for me thanks again for the advice from everyone
     
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