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What GK MB500 EQ settings are closest to flat?

Discussion in 'Amps, Mics & Pickups [DB]' started by jmlee, Aug 19, 2012.

  1. jmlee

    jmlee Catgut? Not funny. Supporting Member

    Jun 16, 2005
    Halifax, Nova Scotia
    Hi all:

    I've been using my GK MB500 and an Avatar SB112 for upright gigs and enormously enjoying the lightness of the head.

    I was wondering if anyone knows with some certainty what setting of the 4 EQ knobs on the MB500 would take the amp closest to flat frequency response? I've been keeping the contour and boost off, and taking 12 noon to be flat based on the cut/boost description in the manual. However, on many amps, flat is not at noon.

    Anyone know if the flat points for those EQ circuits is at noon?
  2. PlungerModerno


    Apr 12, 2012
    I've heard it's like (with 0 - 10 being the values)

    bass - 4
    low mid - 6
    hi mid - 6
    treble - 4

    Approx. I think some say you need to cut the high mids slightly... I don't have one so I don't know.

    P.S... post in BG amps.

    Much more mb 500 users will likely see it! (I think)
  3. GrowlerBox


    Feb 10, 2010
    Nude Zealand
    Try a search amongst fdeck's posts on the MB200, which is likely to have a similar preamp-voicing and EQ section -- he measured the response and provided some clear instructions regarding flat settings.
  4. jmlee

    jmlee Catgut? Not funny. Supporting Member

    Jun 16, 2005
    Halifax, Nova Scotia
    Thanks! He quotes his analysis as:

    "I couldn't resist hooking my GK MB200 head up to an analyzer. The amp has the characteristic "scooped" voicing of GK heads, which I consider to be problematic for DB. On the other hand, I discovered that the MB200 can be dialed to within a dB of flat with the following settings:

    Contour = Off
    Treble = 10:00
    Hi Mid = 2:00
    Low Mid = 1:00
    Bass = 10:00

    This still gives all of the controls plenty of adjustment range in both directions."​

    That makes eminent sense and pretty much my experience as well. Thanks for the pointer, GrowlerBox!
  5. drurb

    drurb Oracle, Ancient Order of Rass Hattur; Mem. #1, EPC

    Apr 17, 2004
    It's reasonable to know where the "flat" setting is. I'll say what I've said many times before: I abhor the practice of "voicing" amplifiers. Now that you know where the flat setting is, you can pretty much ignore it. There's nothing particularly virtuous about setting your amp flat in a real room. Few pickups or cabs have flat responses and, even if they did, once you are contending with room/speaker interactions, all bets are off. If you're setting your amp flat at a gig, you are almost certainly not achieving the best sound that you can. Good tone-shaping controls are, IMO, essential. The more flexible, the better.
  6. jmlee

    jmlee Catgut? Not funny. Supporting Member

    Jun 16, 2005
    Halifax, Nova Scotia
    Oh, not really interested in running the amp flat. Your points are well taken. I wanted to A/B the GK's inboard preamp set flat (and it's 1 Mohm input impedance) versus my Raven Labs preamp set flat (and it's 10 Mohm input impedance). Without knowing the flat settings I can't evaluate the merits of using the Raven Labs preamp into the GK's power section as I have been. It sounds really sweet with my Full Circle but it's one more box to carry.
  7. Don Sibley

    Don Sibley

    Jun 27, 2005
    Fort Worth, TX
    Well stated. I usually reset all the controls to 12 when I get in a new room and start over. Once I know an amp it only takes a few moments to compensate for a room.
  8. BHBassman


    Jan 5, 2013
    Just used my GKMB 200 w/ a Markbass 210p & Fishman PPEQ.
    Dialed the hi & mid way down, little boost on bass, & used the FPPEQ for the EQ. Great sound!
    Just ordered the GKMB 500.
    Suggest trying a little contour boost, & backing off the highs & midsz

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