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Marshall JCM800 strange behaviour

Discussion in 'Amps and Cabs [BG]' started by oZZma, Jul 25, 2019.


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  1. oZZma

    oZZma

    Sep 13, 2018
    Italy
    My Marshall JCM800 Kerry King signature has a led on the boost switch that is red when no signal is coming in and green when you have signal
    Lately it started behaving weirdly (since I have started using a Peavey T-40...)
    - if I stop the strings, it becomes red as if the bass was unplugged
    - while not playing, the led flashes occasionally between green and red as if I had intermittent signal
    - when connected through the ABY switcher, and I DISENGAGE the Marshall amp, if I use the tuner BEFORE the ABy switcher the amp led turns green (this is the weirdest and makes no sense at all and may even be a separate ABY switcher problem :eyebrow:)
    My main concern is that the amp may be damaged by these things, what could possibly be? Should I worry about that?
     
  2. basscooker

    basscooker Commercial User

    Apr 11, 2010
    cincy ky
    Owner, ChopShopAmps
    oZZma likes this.
  3. oZZma

    oZZma

    Sep 13, 2018
    Italy
    thanks a lot!! :)
     
  4. basscooker

    basscooker Commercial User

    Apr 11, 2010
    cincy ky
    Owner, ChopShopAmps
    Looks like the guys over there got you some suggestions to figure this out.

    So you're trying your hand with bi-amping...
    What cabs are you using? I definitely agree with Dogs of Doom about getting a crossover in there. Right now you aren't really bi-amping as much as splitting and running dual mono. Cleaning the bass out of the guitar side will tighten up the sound. I would let the bass side run full range if you only use the KK for grit.
     
    oZZma likes this.
  5. oZZma

    oZZma

    Sep 13, 2018
    Italy
    I'm using two Ampeg PF (410 and 115) on the bass signal and a Fender Supersonic 2x12 for guitar
    Yeah I read about the crossover, but actually I like how the KK roars on the lows (and it has some HUGE lows for a guitar head!)... So I'm not sure I'm willing to change that, both me and my drummer are liking a lot the sound right now (I'm a little bit less satisfied with the "bass" side but that's another story... I'm planning to try different head and cabs)
     
  6. oZZma

    oZZma

    Sep 13, 2018
    Italy
    Anyways I hope to perform some troubleshooting (based on suggestions from the Marshall forum guys) tonight and tomorrow. I think the problem is the bass.
     
    basscooker likes this.
  7. Primary

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    Here are some related products that TB members are talking about. Clicking on a product will take you to TB’s partner, Primary, where you can find links to TB discussions about these products.

     
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