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Mesa Nomad 55 Reduce the gain

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  • #1

    Mesa Nomad 55 Reduce the gain

    hi

    I have a mesa boogie nomad 55. The owner wants to me to repair it and reduce the gain. he say's its too much. Wants to do some shows with playing blues
    Ive fixed the reverb and sorted out the main issue with new TAD 6L6's. biased at about 22ma per tube. I don't know what channel he uses

    http://schems.com/manu/mesaboogie/boogie_nomad55.pdf

    I do amp repairs for friends only. I do ok on the repair side but mod's are not my thing. I'm aware of changing 1st and 2nd stage tubes for 12at7 or 12au7
    Would increasing values on some of the anode resistors do the job

    Is there anything else you would do

    many thanks in advance

    bassman
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  • #2
    Increasing anode loads typically raises gain. I've used 12AY7's in early gain stages with good results. Not so much with 12AT7's. That's what I'd try first. Avoid circuit mods. They only compromise the amp and reduce it's value. Not to mention that most Mesa products are more difficult than average to work on. One could just turn the gain down. I can't imagine your friend has the gain as low as it will go. It should be possible to get an undistorted tone from almost any amp if dialed in correctly. Is it possible he doesn't know how to use the amp very well?
    "Take two placebos, works twice as well." Enzo

    "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

    "If you're not interested in opinions and the experience of others, why even start a thread?
    You can't just expect consent." Helmholtz

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    • #3
      Before attending distortion levels in channels 2 and 3 is most striking the different behavior with low gain settings. One sounds very thin and the other very opaque and without agility. Completely opposed. Neither has a good transition in gain from 10 to 1.
      To play blues I would consider the pushed mode as priority.

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      • #4
        I wouldnt use an AT7 or AU7,they tend to be very "flat" sounding in the V1 position.In my own MKIIC+,and a few other Mesa MK amps I use a 5751 in the v1 position and in the Lead drive position.If a 5751 doesnt lower it enough try a 12AY7.An AT7 in the PI position takes a bit of the "hair" off,and is the only useful place in any guitar amp.

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        • #5
          Many thanks guys. i will order some 12AY7's and 5751. I agreed with you chuck about the boards in mesa being hard to work on / Remove

          bassman

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          • #6
            I have found the current production 5751's to sound like weak chinese AX7's,old stocks are much better/worth the extra $$$.

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