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GK MB200 "flat" settings

Discussion in 'Amps, Mics & Pickups [DB]' started by fdeck, May 10, 2011.


  1. fdeck

    fdeck Supporting Member Commercial User

    Mar 20, 2004
    Madison WI
    HPF Technology LLC
    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.

    Has anybody else noticed the "fit and finish" of this amp? The parts of the enclosure are nice thick sheet aluminum, with a nubbly surface that will hide scratches. They fit together tightly. All of the screws go into threaded steel inserts -- a classy touch.
     
    BritFunk and Hallic like this.
  2. Greg Clinkingbeard

    Greg Clinkingbeard

    Apr 4, 2005
    Kansas City area
    KC Strings
    It's helpful to know what 'flat' is so now I know my ears weren't lying. This is about how I eq the amp, cut the bass and maybe bump the Hi mids.
    So how do you like sound of the amp?
     
  3. fdeck

    fdeck Supporting Member Commercial User

    Mar 20, 2004
    Madison WI
    HPF Technology LLC
    I'm quite happy with it. Of course I now own two micro heads that both sound great, and in fact, probably both sound the same when the MB200 is dialed flat. I got the MB200 because the price was right, and I was curious about it.

    For now I will probably continue to use the Micro300 because the surplus power and second channel are handy. I've used it to support guitar, piano, and even vocals, when something went wrong with their gear. In the main band that I play with right now, the guitarist doesn't have a car, so I'm going to offer to let him plug into my amp.

    This summer I will throw together a very small PA from all of my surplus speaker parts, and then I will have a use for both amps at once.
     
  4. rake

    rake

    May 4, 2004
    Michigan
    Very cool.
    Have you any tips on how to do this with my amps?
    I would love to find the actual flat settings, especially when using the Acme Low-B2.
     
  5. fdeck

    fdeck Supporting Member Commercial User

    Mar 20, 2004
    Madison WI
    HPF Technology LLC
    If I had to guess, the 1001-RB has a similar curve and similar "flat" settings.

    I finally figured out a good way of doing all of this on a PC with free software. I've been slowed down a bit by installing a new OS on my PC, but will soon publish some brief instructions on how to do this.

    The real-time analyzer program at my website doesn't work. I will be removing it from my site soon. Out of its ashes, a new phoenix will rise.

    A free program called "Visual Analyzer" is the cat's pajamas.
     
  6. TimmyP

    TimmyP

    Nov 4, 2003
    Indianapolis, IN
    Trouble is, as soon as you connect the head to a typical cabinet, the result is nowhere near flat (ever play a CD through a bass cab? Awful).
     
  7. fdeck

    fdeck Supporting Member Commercial User

    Mar 20, 2004
    Madison WI
    HPF Technology LLC
    That's true. The overall response of the system depends on both the amp and the speaker. In my case, I've modeled and measured the response of my speaker.

    But even if you don't have that information, you can still make some educated guesses, because most bass speakers follow a couple of basic box designs with similar response curves in the low end, and similar problems with overexcursion. My goal in sharing the "flat" settings wasn't to make every system sound good, but to provide what I think is a preferable starting point from a functional standpoint.
     
  8. Buzz Grim

    Buzz Grim

    Dec 2, 2003
    Ohio
    Francis,
    Did you ever post any more info on how to do this?
    Are you still liking "Visual Anayzer"? Do you think it would work with the sound card in my old Dell Inspiron 8600 ?
    thanks,
    Buzz
     
  9. fdeck

    fdeck Supporting Member Commercial User

    Mar 20, 2004
    Madison WI
    HPF Technology LLC
    Visual Analyzer has a pretty good chance of working with your computer.

    I'll front-burner my project to describe using Visual Analyzer for frequency response testing. It turns out that I have an audio test file that gives a lot more readable real-time display than typical white noise.
     
  10. Nice. Good to know, as DB amplification always gives me 'the eyebrows'.

    Cheers
     
  11. Buzz Grim

    Buzz Grim

    Dec 2, 2003
    Ohio
    Francis ,
    That would be great. I have an old GK 400RB and an SWR Bass 350 that I would really like to see the graphs for. The SWR has a pretty extreme baked in voice and I'd like to see how flat it could get with tone control and aural enhancer knob changes. These supposedly don't have a built in HPF being tailored, I think, for low B players.I've seen the SWR Aural Enhancer mod thread on the electric bass side of TB and am considering doing it. I'd also like to see how much control is available on the bass tone pot on the SWR. Do you think your HPF would work into the instrument input to limit the extended low end?
     
  12. C.NILE

    C.NILE

    Nov 7, 2007
    just a little addon. when i got my gk 700rb11 i was really happy except with the sound. the tonal variation was not what i expected. i also had the response plotted by gearguru friend of mine and the panel control positions do not indicate the true flat position, as indicated in previous posts. this is fairly simple to change if you want and are able to with resistor values. also, the presence control effect is determined by the input level control and is effectively a variable hf cut anywhere below max gain. i have disabled this control as it confuses the hell out of me. google the circuit schematic and consult a tech.
    happy modding.
     
  13. Mike Law

    Mike Law

    Sep 16, 2014
    CT
    This is cool have you done this with any other amps?
     
  14. fdeck

    fdeck Supporting Member Commercial User

    Mar 20, 2004
    Madison WI
    HPF Technology LLC
    Only those that i've owned: GK mb150e combo cannot be dialed flat, according to my best efforts. GK backline 600 is similar to the mb200. EA micro 300 is flat from the git go.
     
  15. ReiPsaeg

    ReiPsaeg

    Dec 1, 2012
    Rochester, NY
    How close can it be dialed to flat?
     

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