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Mesa 400+ A/B-ing

Discussion in 'Amps and Cabs [BG]' started by squish_man24, Sep 24, 2008.


  1. So, I'm about to get a Mesa 400+ in a trade for my SVT 2 Pro, and I was wondering... A lot of people ssaid they were able to get a really gritty kind of sound by using an A/B footswitch and plugging into channel one and two on the 400+. i was wondering how this was done, and what kind of EQ settings people have used to get that sound.

    If you have any sort of sound clips with this kind of thing done, that would help

    thanks for the help guys
     
  2. Tim1

    Tim1

    Sep 9, 2005
    New Zealand
    Just use a Y cord to send the signal into both inputs. You should also seriously consider PsychoBassGuy's driver tube mod - replace the 12AX7 driver preamp tube with a 12AU7.
     
  3. K-Funk

    K-Funk

    Sep 24, 2007
    Auburn Hills, MI
    True, but you should try both the 12AX7 and 12AU7 before you decide.... the 12AU7 cleans up the sound and generally "stabilizes" the quirks of the amp, the 12AX7 makes it gainy, gritty, etc.

    I don't play a lot of heavy stuff, so I use a 12AU7 in my Bass 400.
     
  4. Fealach

    Fealach Guest

    Apr 23, 2003
    Gone to a better place
    I wouldn't call the result of running A and B "gritty." Sounds good, though.
     
  5. Tim1

    Tim1

    Sep 9, 2005
    New Zealand
    K- Funk wasn't calling the results of running A and B gritty, he was referring to the 12AX7 driver tube as opposed to a 12AU7. FWIW I agree with K-Funk's point - try both tubes first, he describes the differences accurately.
     
  6. K-Funk

    K-Funk

    Sep 24, 2007
    Auburn Hills, MI
    You're really going to be happy with this amp; do a search through TB to learn more about any little anamolies you may/will encounter with it.
     
  7. xshawnxearthx

    xshawnxearthx

    Aug 23, 2004
    new jersey
    i couldn't get grit with an aby box. so i got rid of it.
     
  8. Banky

    Banky

    Apr 24, 2007
    Windy Kansas
    I got an ABY pedal by Radial called the Big Shot. It functioned better than a Y cord because it isolates the two signals. There's a very noticeable difference.
    As for the gritty sound; input two is higher gain than input one. It has a more aggressive sound. The 12AX7 in the driver stage makes it easier to push it to distortion but the 12AU7 makes it a LOT more usable for everything else. I was ready to sell the amp before I made the famous "Psychobass Mod".
    I just retubed with a set of Shuguang 6L6s from Lord Valve and I couldn't be happier. The new drivers for my Bag End should arrive tomorrow and I should be all set.:hyper:
     
  9. I guess soon I'll be ready to join that Mesa club!!!! Thanks for the help guys. Banky, any EQ settings that you used? Any sound clips?
     
  10. K-Funk

    K-Funk

    Sep 24, 2007
    Auburn Hills, MI
    One more bit of advice for the new Mesa 400+ guy: On the rotary EQ, "flat" is actually Mid-10, Bass-2, Treble-2, like a Fender amp. It's weird, but it's how it is. The mids are cut only, and the bass and treble are boost only. On the graphic, it's boost and cut.
     
  11. MHensleyJr

    MHensleyJr Supporting Member

    May 5, 2008
    Redlands, CA
    What's this ""Psychobass Mod" that i keep hearing so much about? :eyebrow:
     
  12. Banky

    Banky

    Apr 24, 2007
    Windy Kansas
    I run Mid-Bass-Treb 7-3-3. Bass and treble knobs pulled out.
     

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