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Thoughts on GK HMS and DI "Post" Functionality

Discussion in 'Amps and Cabs [BG]' started by Kro, Feb 19, 2016.

  1. Kro

    Kro Supporting Member

    May 7, 2003
    New Jersey
    So, I’ve been having some fun lately experimenting with the HMS system with my 700RB and double Neo 112-iis (that I’ve started liking too much to offload), though in looking at the 700RBs schematic, I came across something that I found as being odd with the way the system works.

    My understanding of the general HMS functionality is as follows:
    Woofer high-cut: removes 5khz and above from woofer
    Tweeter high-cut: removes 10khz and above from tweeter
    DI pre/post: per schematic when set to post, sends woofer signal AFTER woofer high-cut

    So that means that if I utilize the HMS as intended, the DI (and hence FOH) gets nothing 5khz and above. Am I wrong in thinking that those frequencies would be desirable to have going into the mains?

    It seems odd to me, because my logic is as follows:

    1. GK distortion comes primarily from an overdriven power section (I don’t discount the boost’s function, but on RB amps my understanding is that it’s used to drive the power section harder as opposed to functioning as a distortion effect)

    2. GK developed the HMS system to keep the GK distortion out of the GK instrument cab horns where it can sound unpleasant

    3. If the above are true, why does the post button cut 5khz and above from the DI, if it isn’t at risk of receiving power section distortion?

    Maybe I’m wrong – and I’m really curious about others’ thoughts, but I kind of wish that I could send the full post signal to the DI (because I want the voicing), even when utilizing the HMS system to cut 5khz from my instrument cab woofers.

    It isn’t lost on me that the true method to get “post” sound to FOH would be to mic the cabs (thus getting that power-section distortion as well), though unfortunately in this day in age in the scene I’m a part of, that is considered asking too much of sound guys, and is likely to result in raised eyebrows and dismissal at best, and an engaged “suck” button at worst.

    Just curious as to others' thoughts.
  2. Kro

    Kro Supporting Member

    May 7, 2003
    New Jersey
    Maybe I'm the only one, though just in case I'll provide a tl;dr version:

    Do any other GK HMS users think it's odd, or are bothered at all by the fact that the HMS can't properly be used without it also cutting 5khz and up through the DI when running "post"?

    Post edit: Well, there wasn't too much interest in the community telling me were my fault was, so I won't add another full post and bump this back to the top. However, I think I realized where the error in my thinking was:

    I'm not sure why, though at the time of my original posting, I was under the assumption that the woofer high cut was what engaged the bi-amping feature, though I'm now relatively certain this is incorrect.

    After a bit more thought, my understanding is that simply utilizing the 4 conductor speakon hooked up to an appropriate cab engaged in bi-amp mode engages the 50w amp to the tweeter. Therefore, if I want to get that extra 5khz and up to the mains, all I have to do is not cut them from the woofer via the woofer high-cut button.

    The tweeter will still be clean, the full signal will still go FOH, and the only downside will be the potential for beaming from the cab woofer (that I've yet to experience from the Neo 112s when running full range).

    Of course, I'd still prefer to have a cab miked and have it mixed with a pre DI signal to the board, though I think I now know what I need to do to get the bases covered when that's not an option.
    Last edited: Feb 24, 2016

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