Marshall JTM30 combo

Discussion in 'Amps and Cabs' started by Alistair6, Jun 25, 2008.

  1. Alistair6

    Alistair6 Member

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    So i had seen these a couple times in the past but never gave it much thought. I bought an orange 1x12 cab a while back with the intentions of getting a head for it but its just sat around. The other day I threw it up for trade on a local buy/sell for kicks and worked out a deal for a jtm30 2x10 combo. Thus far i cant say enough good things about it.. great clean, good drive.. the 10s really make it feel tight. ive only given it a go with a tele but cant wait to hear a lester with it..
    just wanted to share my praises
     
  2. bosstone

    bosstone Member

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    I have some history with these amps. They were biased way too hot from the factory and will burn out the output tubes much faster than they should. That also effects the longevity of the small, under built output transformer. Take it to your favorite tech and make sure it gets biased properly. If it starts to sound like the speakers are going bad or has intermittent problems, Chuck the output transformer and get the suggested Mercury Magnetics replacement for it. I went up to the transformer for the JTM 45 and got fantastic results. I picked up 10 more watts and got much better sound. If you are luck you won't need an OT but a fresh pair of Tung-Sol 5880s and proper re biasing will make that thing sing. Mine had amazing cleans and authentic Marshall crunch.
     
  3. Alistair6

    Alistair6 Member

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    ive read that.. also about the overheating issues. im assuming the tubes must be changed in this one as it sounds great and no signs of any issues yet. The previous owner did say the tubes were pretty fresh.. ill keep the OT upgrade in mind though
     
  4. bosstone

    bosstone Member

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    Setting the correct bias takes care of the overhearing.
     
  5. Troubleman

    Troubleman Silver Supporting Member

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    Take my word for it - replace the crappy OT right away. Just do it. If it hasn't fried on you, I promise you it will. Replace that, get a set of decent tubes, set the bias properly, and you'll be rewarded with a great little combo

    jb
     

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