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Adding a pre/post DI switch to a LMII

Discussion in 'Amps and Cabs [BG]' started by zenrad, May 3, 2010.

  1. zenrad

    zenrad Supporting Member

    Feb 4, 2009
    Bergen County, NJ
    I had my LMII open the other day to move the jumper on the PCB that controls whether the DI out is pre or post EQ. I noticed that there's a small plate covering a hole on the back of the chassis that's held on by two screws. That hole seems like it would be a prefect location to place an SPST switch that would do the job of the jumper. Has anyone done this? It seems like it would work without problems, but I could be wrong.
  2. As a serious question - just how many times do you open up your amp to change the DI settings????

  3. rok51


    Sep 2, 2002
    Crawfordville, FL
    Funny, I had thought about the same possibility as the OP when I first got my LMII...and then I asked myself the above question...the answer was not often enough...

  4. zenrad

    zenrad Supporting Member

    Feb 4, 2009
    Bergen County, NJ
    So far twice. For the amp's first live gig I had switched it to pre EQ, in my home studio I like to go post EQ.

    They added the switch to the LMIII, and there's a hole in the back just waiting for it. Many heads have the option. Even if I don't use it often, for the small amount of effort and 15 minutes of my time it would take to pop a pushbutton switch in there it would be worth it.
  5. Then go ahead and do so. It's your amp do as you wish but be prepared for a voided warranty.

  6. Jim C

    Jim C Is that what you meant to play or is this jazz? Supporting Member

    Nov 29, 2008
    Bethesda, MD
    Make a new plate and don't cut any wires (uses spade connectors as I remember) and it will be our little secret
  7. philter25


    Mar 26, 2010
    Germantown, MD
    Im only suggesting this because I just posted the same thing in another thread...... why not keep your amp at post eq, and then if you have a gig and need it pre eq, why not plug into a simple rolls db25 before going into your amp? They cost 25 bucks or something like that.

    For warranty purposes, I could justify spending 25 bucks to keep it intact and that way you have post eq on your amp and then a portable pre-eq box that you can plug into when needed.
  8. JimmyM

    JimmyM Supporting Member

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    it's your amp and it probably would be a very easy mod, so why not?
  9. lefty007


    Jan 19, 2004
    Miami, FL
    I've been thinking about this, too.

    I have a Precision that I play with the EQ flat, but my Jazz requires a bit of EQ'ing, which often is not the sound the soundman prefers. I would love to be able to switch from PRE EQ to post with a switch. . .
  10. zenrad

    zenrad Supporting Member

    Feb 4, 2009
    Bergen County, NJ
    If I can get the little cover off of that extra hole I'll do it. Out of curiosity last night I removed the two little screws on the cover but it didn't come off - I'll have to open it up and take a closer look. If I have to drill a small hole, well, it wouldn't be the first time I drilled holes in an amp chassis for a switch. At this point it's just a matter of getting the little spade connector and deciding whether to use shielded wire or not. I'll take photos for the curious if I do it.

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