GK 800RB

Discussion in 'Amps and Cabs [BG]' started by BrightHead, Jul 22, 2013.

  1. BrightHead


    Jul 22, 2013
    Hi guys, newbie here.

    I have a GK 800RB head and a Yorkville Y210B 2x10 8 ohms cab. I'm running a cable from the low 300watts 4 ohms into the cab. Now, my understanding is that I shouldn't have the Bi-Amp button pushed since I'm not using two cabs. However, with the Bi-Amp button NOT pushed, I can hear a loud annoying hiss along with the sound of the bass (the bass sounds great, but with lots of hiss). If I push the button and turn it into Bi-Amp, there's no hiss anymore, but the bass doesn't sound the same anymore... It sounds muffled.

    I know I'm not supposed to use the Bi-amp option but that's the only way to get rid of the hiss. But why the bass sound gets muffled?

    Am I doing something wrong here or is just the amp that needs repair?

  2. When you switch to "Biamp" it cuts the upper frequencies (where the hiss is and note definition) from the 300 watt amp. Sounds like you have some noisy opamps in your 800RB.
  3. His BOLD print is specifying to us that he does NOT have the hi-out plugged into a cabinet. When he engages the Bi-Amp button all the high end is being removed from his signal. This is why the hiss goes away in his situation. Not sure what type of damage can be caused by operating the amp like that but I would avoid it. I believe the amp should be checked out because there is probably something going on causing that hiss and it's most likely easily fixable. The 800 RB ( unless you bought it new ) is probably fairly old and needs a little TLC.

    What Fretlessmainly is saying about the bi-amp set up IS NOT true of the 800 RB which uses a completely different Bi-Amp config from the modern GK amps. The 800RB has TWO power amps - 1 is 300watts/4ohms the other is 100watts/8 ohms. The design is not set up to feed the signal to a tweeter like the new design.
  4. Razman


    Feb 10, 2005
    Orange Park, FL
    Does the 100 watt section hiss? More importantly, what are your settings? Mine hissed a bit depending upon how I had it set.

  5. This is 100% correct. The 800RB's Biamp was designed for mid range (with high frequency if desired) cabs.
  6. FretlessMainly


    Nov 17, 2010
    I deleted my post. I erroneously thought that the 800 was the same as the 700, 1001, and 2001 RBIIs.
  7. BrightHead


    Jul 22, 2013
    Yes Razman. It hissed either plugged in the 100 watt or 300 watt section. However I think I found what is causing the problem: While trying your suggestion, I plugged my bass directly into the GK 800RB and the hiss went away... Then I realized what's causing the hiss are a couple of pedals the bass signal goes through before getting into the amp head. I never thought unplugging them because they are just A/B or A/B/Y pedals. Now I have to find out why are the A/B pedals causing the hiss.

    The thing is my band has a setlist where sometimes I play bass, sometimes the singer and I play bass together (yes, there's a 2 basses song on our setlist) and sometimes I play bass + an iPhone synth connected to the bass like on this video (but not as rough cheap as shown here)

    That said, there are a couple of A/B and A/B/Y pedals connected together to allow to quickly switch between settings as we play.

    Is there anything out there that can attenuate or filter the hiss coming from a chain of pedals?

    Thanks again. I'm happy the issue is not with the GK (it's from February 86').
  8. Razman


    Feb 10, 2005
    Orange Park, FL
    Good catch - basic troubleshooting should always be done first (remove all pedals, effects, etc.)

    Fixing the hiss by finding the problem with your pedals would be the preferred solution as opposed to fixing it with more equipment. The less you put in your signal chain, the better off you'd be.

    Perhaps you can detail your setup so other configurations may be suggested?

    Glad the amp is OK though...

  9. lowphatbass

    lowphatbass **** Supporting Member

    Feb 25, 2005
    west coast
    Could it be a cable issue?
  10. BrightHead


    Jul 22, 2013
    Well it may be a bit hard to describe current setup, but let me try:

    We have a LS-2 pedal running on "A+B mix" mode. There's input A, then on top of that a ODB-3 pedal that affects input A and then input B. Then there's a set of AB pedals that route the three basses (mine, my bandmate's and my iPhone) to inputs A and B as needed (e.g. in one song I play the bass with OD, so it sends the signal of my bass to input A; on the song I play the iPhone as a synth (see the video I posted before), it sends my bass to input A and the iPhone goes on input B, with ODB-3 bypassed; etc). I can post a visual map latter if you want.

    Basically, we have 2 basses and an iPhone used as a synthesizer. Sometimes I play bass, sometimes I play bass and the iPhone synth in the same song, sometimes I play bass at the same time my bandmate plays bass as well, sometimes I play overdrive, sometimes my bandmate does. And to be able to achieve that with one amp and one overdrive pedal, we chain a series of A/B and A/B/Y pedals to the GK 800BR. Maybe there's a better way of achieving what we need? The pedals are just to help us not having to plug and unplug basses as we go from one song to other.

    So far it works. The issue is the hiss caused by them.

    Thanks for your help.
  11. BrightHead


    Jul 22, 2013
    It could be. I'll check. However the cables are new. We bought those short cables to connect all the 5 pedals in chain.

    Maybe I'll try connecting one by one and see the results.

  12. Razman


    Feb 10, 2005
    Orange Park, FL
    IMHO it sounds like you're trying to do too much with the limited equipment you have. While it may be possible to connect your gear in this manner, the quality you are expecting might not be possible given the complexity of your configuration.

    Are you familiar with the time vs. quality vs. cost triangle? Pick two, but you can't have all three (i.e. high quality in a short timeframe for very little $$ - not reality). I tried something along this same vein with the split coming from my MXR Bass DI+ over to an EHX POG and then into a guitar cab with similar dismal results.

    Best solution is K.I.S.S.; run the other bass through another rig, part ways with the LS pedal and run your iPhone through the FX send/return of the GK or something. The level of complication you described is asking for problems, especially in a live setting.

    If resources do not permit this, then you may need to sacrifice some quality (the hiss) to accomplish your goals (keeping your current setup as-is).