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Gallien Krueger MB-500 Question

Discussion in 'Amps and Cabs [BG]' started by Corevalay, Jul 17, 2017.


  1. Corevalay

    Corevalay Supporting Member

    Sep 10, 2009
    New Jersey
    I recently picked up an MB-500 amp and am a tad confused about the Boost and G.I.V.E. options. Is the boost only ON when the G.I.V.E. button is engaged? If the G.I.V.E. button is not engaged, does the Boost effect the amps sound at all?

    Any insight is greatly appreciated! Photo for reference... static1.squarespace.
     
  2. Pumpkin

    Pumpkin

    May 19, 2016
    Washington, DC
    1. Yes
    2. No

    I use a GK MB500 as my main gigging rig and don't mess with the boost much. It's tied to the 2nd master volume so you can keep your levels even with the boost. There is a foot switch you can get if you don't want to press the GIVE button in a live setting.
     
    Corevalay likes this.
  3. lz4005

    lz4005

    Oct 22, 2013
    You have the amp in your hand. Turn the knobs and see what happens.
     
  4. I tried turning the knobs on the pic included above. It seems everything is stuck in "GK Flat." :roflmao:
     
  5. Al Kraft

    Al Kraft Supporting Member

    May 2, 2016
    Northern Virginia
    Actually I think this is "GK flat" :):
    GK MB500 Maximally Flat Settings.
     
  6. kap'n kro

    kap'n kro Supporting Member

    May 7, 2003
    New Jersey
    Alright, in order - the boost is only used when the GIVE button is engaged - in which case it incorporates boost and uses the master just to the right of the button. When GIVE is not engaged, the master on the far right is used and boost is disabled.

    I gigged with an early MB2-500 for many years that eventually was replaced by GK with a later model that I believe is essentially just an MB-500 by a different name. My thoughts on the GIVE circuit are as follows:

    While I have always loved the boost feature on my RB units (you're basically forced to use at least some boost on those RBs), I never bonded well with that channel on my MB. Allegedly they're the same circuit and should be doing the same thing - adding a bit of harmonic complexity to the signal along with a bit of natural compression a-la tubes (Gate Induced Valve Effect), but in reality it just seemed to go to fuzz too quickly for me on that unit, and squashed dynamics a bit too much for my taste. YMMV
     
  7. Corevalay

    Corevalay Supporting Member

    Sep 10, 2009
    New Jersey
    Yea, you basically summed up what I was thinking. The reason I was a little thrown-off was because on my 800RB the boost was just always on, you just turned it up. Now I have to actively engage the boost and it seems to add more "stuff" then the 800RB boost. I also have my MB212 which there is simply just a boost knob, so I assumed the MB-500 standalone would be exactly the same.... apparently not!
     
  8. kap'n kro

    kap'n kro Supporting Member

    May 7, 2003
    New Jersey
    I've often wondered why they play so differently between the MBs and RBs - especially since when the MB2-500 came out, word on the street was that the preamp was based off the 700RB preamp (including, I assume, boost).

    My personal theory is that it has something to do with the gain structure on those MBs between gain, boost, and master. Maybe it was due to my crazy MB units, but it always seemed like the master went straight from "whisper" to "earbleed" if you even blew on the master knob in a clockwise direction. ;) Because of that, I think I often ran my gain lower than I otherwise would have which may have affected boost performance. Just my 2c, YMMV
     
    Corevalay likes this.
  9. Al Kraft

    Al Kraft Supporting Member

    May 2, 2016
    Northern Virginia
    The resultant voicing associated with pushing the MB heads has never been as nice as when you pushed an RB head, at least to my ear. I think this is one of the few areas that even those of us who like the MB heads would agree didn't translate as well in the design process from the classic RB sound. Overall, in busy mix, I think the MB sounds close enough (certainly when run clean) that very few folks could tell it from an RB head.

    I don't want to start a class AB vs class D war, but when designing the new MB circuitry there may have simply been some unique things (characteristics/artifacts) associated with the RB circuits and pre-amp/amp interaction that couldn't be duplicated in the MB operation. Mesa folks will recognize this concept from the discussions about the Walkabout and some very unique things happening in that amp that can't be scaled-up or even easily replicated again in either class AB or D.
     
    Last edited: Jul 17, 2017
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