GK 800RB

Discussion in 'Amps and Cabs [BG]' started by Rain King, Oct 6, 2021.

  1. Rain King

    Rain King

    Aug 22, 2021
    Hello all!

    I picked up my beloved GK 800RB (not sure what year, open to help there) about 5 years ago and have been enjoying playing it through a SOVTEK 4x10 with Eminence speakers.

    Maybe it’s the extended lockdown I’ve been experiencing but I’m dead keen on hooking up another cab but the whole bi-amp/crossover thing has got me confused as hell. I’ve read through quite a few forums on TB but I just needed to ask for myself. If I was to hook up a 2x15 with my 4x10 for example, would this work & which connections would I use?

    Any help would be massively appreciated! Do not worry about treating me like a fool and send photos to illustrate your point if need be :)

  2. BLDavis

    BLDavis May the Tort be with you. Gold Supporting Member

    May 21, 2009
    Ellenboro, NC
    The 2x15 is gtg on the 300 watt low side, but be careful what you plug in on the hi side. If your 4x10 is 8ohm or higher you're ok, but a 4ohm cab will most likely cook the 100 watt amp on the hi side.
    FWIW, I always ran mine full range into either 2x15 or a 4x10. Either one was killer by itself and I never felt like I needed the bi-amp mode.
    Rich67, jjk2007, BrentSimons and 3 others like this.
  3. basscooker

    basscooker Commercial User

    Apr 11, 2010
    Northern KY
    Cab fan, hobbyist
    Bi amp into full range cabs really won't do much for you, IME.

    Think more PA type setup. Either 410 or 215 is only being used for its high mid and up in that set.. Better putting a guitar cab or mid box off the high side.
  4. Redbrangus

    Redbrangus Supporting Member

    Nov 19, 2018
    Under The X In Texas
    I agree with @basscooker: you can do it, but it's pretty much pointless to do it with another bass cab. If you do decide to do some experimenting, it is absolutely imperative that the cab connected to the HF output is 8-ohms or higher. (GK's concept was this output would be used for a HF horn.) If you have a small, passive 2-way PA cab, you might enjoy the effect of using that on the HF out -- set the amp's crossover frequency control down as low as it will go.
    Cal Foley and basscooker like this.
  5. basscooker

    basscooker Commercial User

    Apr 11, 2010
    Northern KY
    Cab fan, hobbyist
    Yes and notice two mentions of the 8 ohm output. I think this design is known for being very finicky about that. Like, really watch that.
  6. TomB

    TomB Supporting Member

    Aug 24, 2007
    Just to clarify, the 8 ohm concern applies to the high-end amp, if I recall correctly. You can daisy chain 2-8 ohm cabs from the main amp just fine (4 ohms). I did it for years - never needed or missed the crossover amp.
  7. B Dax

    B Dax

    Sep 8, 2018
    Yep, I occasionally jam with a guitar player who has a 4x10, a 15 cab and another 18 cab hooked to his 800rb.

    I don’t know why other than he really likes his lows.
    BrentSimons and Cal Foley like this.
  8. TomB

    TomB Supporting Member

    Aug 24, 2007
    I wonder how he stays at or above 4 ohms? The 800 RB main amp is not designed to go below that threshold. Does he run one off the tweeter amp maybe?
  9. B Dax

    B Dax

    Sep 8, 2018
    I’m not sure how he has them hooked, but yes, I assumed he has a cab on the high side and running two of them at 4 ohms on the main side.

    He’s had them hooked up that way for a year or two without any issues, although I think the 18” is just a muddy waste.
    Cal Foley and TomB like this.
  10. shadven

    shadven Twang-tastic Bass Player and Song Writer Supporting Member

    Dec 30, 2009
    Tampa, FL
    I rock, therefore I am.
    I believe that daisy chaining 2 x 8 ohm cabs would present 16 ohm to the head.
  11. TomB

    TomB Supporting Member

    Aug 24, 2007
    Um… just to be clear, I was talking about running 2-8 ohm cabs in parallel = 4 ohms. You would need to arrange a custom cable to run two cabs in series = 16 ohms.
    Last edited: Oct 6, 2021
    wave rider and Cal Foley like this.
  12. I respectfully disagree. I ran a 2x15 and a 2x10 (both bass cabs) with my 800RB and it was a joy to play. I ran both full range since it didn’t sound any better with the lows trimmed up top. The 2x10 added some extra punch that was nice.
  13. Kukulkan61

    Kukulkan61 Inactive

    Feb 8, 2011
    Northern Arizona
    Just run it the basic way, both outputs to two separate 8 ohm. cabs, biamping is overrated with not much difference IMO...
    Marc DLarosa likes this.
  14. Rain King

    Rain King

    Aug 22, 2021
    Thank you all for your helpful replies so far! It certainly seems like the bi-amp is very divisive… jury’s out on that one. I didn’t mention in my original post but yes I am very aware of the need for 8 ohm cabs, but thank you for the strong reminder!
    So, current 410 is 200 watts 8ohms - if I added a 215 8 ohms and ran both of them from the low outputs, they would each receive 150 watts at 4 ohms and we would be all good, correct?
    Would I need to worry that the 215 is getting worked harder than the 410?
  15. Rip Van Dan

    Rip Van Dan DNA Endorsing Artist Supporting Member

    Feb 2, 2009
    Duvall, WA
    The Bi-amp capability was the hall mark of the GK800RB back in the 80's when if first came out. We didn't have a whole lot of full range bass cabs back then so high-mids and highs were not very good. With that GK amp you could send the bass frequencies to the woofer cab (300-watts) and the high-mids or just the highs to a tweeter horn or cab. Wasn't unusual to stack a full width tweeter horn on top of a 115 or 215 cab back then. If I recall correctly you could then select the frequency point where it split the sound. It sent 100-watts into the tweeter horn or speaker, which was plenty as you know if you've played with any loud guitarist using their 100-watt amps.

    Bi-amping is rarely done now because virtually all bass cabs have a tweeter horn or speaker built-in to their cab and they can handle all the frequencies. If you ran two full-frequency 410 cabs with your GK800RB and ran them bi-amped using one cab for the low frequencies (tweeter would do nothing) and sent the high frequencies to the other full frequency cab, you'd be wasting the woofers in the full frequency cab. The only thing that would be working in that high-frequency cab would be the tweeter and none of the 410 woofers would work in that cab. So it's pretty much a waste for modern full-frequency bass cabs. It still is commonly used in FOH systems where you may have a subwoofer that only produces up 120Hz and lower or 200Hz and lower. But for running your own bass cab with it, I wouldn't. I think you can use all 400-watts directly into a cab instead of running it in bi-amp mode.

    There are other more powerful and lighter amps than that GK400RB, but it's an absolute workhorse and definitely gives you that GK sound but you do NOT want to hook up that "high" output to a 215 cab. As long as you don't go below the minimum ohms rating on that amp, you can hook up a 215 by daisy-chaining it and I think...not sure...there's a switch to let you run 400-watts out as a full frequency signal. If you do that each of your two 8Ω cabs will get 200-watts.
    Rich67 and Cal Foley like this.
  16. J-Bass RMR

    J-Bass RMR Supporting Member

    Sorry. Too long ago / can't remember. :smug:

    gk rig small.jpg
  17. sonic 7

    sonic 7 Supporting Member

    Aug 10, 2011
    Queens, N.Y.C.
    There was a rehearsal studio that I played at many years ago. They had a GK 800rb into a SWR 4x10/ 1x18 stack. I played there at least once a week for a few years. I tried that setup both bi-amped and full range and it sounded much better just running it in full range, to me anyway.
    Cal Foley likes this.
  18. Rain King

    Rain King

    Aug 22, 2021
    so that was running each cab from the outputs as shown in the picture? Thanks for the info

    Attached Files:

  19. sonic 7

    sonic 7 Supporting Member

    Aug 10, 2011
    Queens, N.Y.C.
    If I remember correctly, there’s a button on the front to switch from full range or Bi-amp , in full range mode you use the “low “ speaker outputs. It wouldn’t matter if you run a separate cable to each cab or run a single cable to one cab and daisy chain it to the second cab , as long as the impedance isn’t below 4ohm. But it has been at least 25 years since I used that setup, so hopefully some one that’s used one more recently can correct me if I’m wrong.
    Cal Foley likes this.
  20. PotsdamBass8

    PotsdamBass8 Supporting Member

    Jan 23, 2005
    Long Island, NY
    Same experience for me, I had an 800RB that I used with two Aguilar GS112 cabs. I tried it biamped one time just to see what happened and it didn’t sound as good as running both into the main amp full range. I never had a 3rd 112, but that is the cool thing with that amp, you can run 3 8ohm cabs. I miss that amp sometimes, it just sounded so good all the time.
    Cal Foley likes this.
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