Psst... Ready to join TalkBass and start posting, make new friends, sell your gear, and more?  Register your free account in 30 seconds.

Problems with GK/Mesa rig

Discussion in 'Amps and Cabs [BG]' started by Corvette Kid, Feb 7, 2003.


  1. To anyone who can give me the low-down on my problem. I'm currently running a GK 800rb and a DBX 160a through a Mesa 800watt 2x15 rr and a 400 watt 2x10 rr. Last night during practice the amp shut down on me. I had the 300 watt side about 75% up and the 100 watt side set to about 60% while the master was set to about 75%. The amp eventually came back but would continue to shut down so I called it quits. Do you guys think I'm asking too much from this 800rb and if I am, how many watts do you think I need to push these cabinets?
     
  2. Josh, the 210 is an 8ohm unit while the 215 can be used as a 4 ohm or double 8 ohm system.
     
  3. Josh, I'm not running it in the bi-amped mode. I'm running it full with the 2x15 cab into the speakers low jack and the 2x10 into the speaker high jack.
     
  4. Cantstandsya

    Cantstandsya

    Jul 27, 2001
    Fontana, CA
    Does the amp have adequate ventilation?Are any of the fan vents blocked?Your setup seems fine.As long as your not puting anything lower than 8 ohms into the 100 watt amp and 4 ohms inthe 300 watt amp it should work fine.I've seen plenty of guys run 8-10's with the 300 watt amps onthe 800RB and it has no problem.Where are the input gain and boost controls set?
     
  5. ChenNuts44

    ChenNuts44

    Nov 18, 2001
    Davenport, IA
    You're pushing the amp pretty hard. Also, I don't believe there are any fan vents, as I was under the impression that the old school 400 and 800RBs were convection cooled.

    Back to the point. Like I said, you're pushing the amp really hard. The amp may be going into shutdown due to heat or failure. You may also not be getting enough juice from the power outlet. It could be a number of things, but my first guess is that it's a heat related problem (since it works fine, shuts down, then comes back again, but shuts down soon after and so on and so on).
     
  6. Cantstandsya

    Cantstandsya

    Jul 27, 2001
    Fontana, CA
    Could it be a biasing problem?
     
  7. Too much for that amp. I sold mine for that reason. It will shut down when challenged. I also found the sound get "thin" as you pushed it.
    I agree with the biamping problem, I could never get it right with that amp.
    If you love the sound, get yourself a poweramp use it as a pre-amp.
     
  8. Thanks for the comments you guys. Chen is correct about the convection cooling and Psycho Funk, I agree with you about the 800rb getting thin when you push it. The more you crank the volume, the less warm it becomes. The amp shut down during the end of the first song we were rehearsing. The song is a pop rock tune with a hardcore low end slap groove. Could the amp heat up this quickly into a set?
     
  9. Cantstandsya

    Cantstandsya

    Jul 27, 2001
    Fontana, CA
    If it's heating up that fast I think it might be a biasing problem.Also what is the impedance on that 2-10 cab?That is the same cab setup(Mesa 2-15,2-10) Flea used to run with the 800RB.It should be able to go for more than one song.I think you should have it looked at by a tech.Also make sure your not boosting too many lows on the amp or your bass and watch the input volume.Sorry about the misinformation on the fan.I've only owned a 1001RB and a 2001RB and they both had fans........
     
  10. thelastofus

    thelastofus Guest

    Jul 3, 2002
    Bakersfield, Ca
    correct me if i'm wrong but i think you said that one of the cabs was 8ohms and one was 4ohms, well that combined equals 2.6 ohms and i dont' think the gk goes under 4ohms safely. so that with the fact you're using a lot of power and no fan probably is too much for the amp. if you like the sound of your head just pick up a power amp and run in through that to give you more headroom.
     
  11. Cantstandsya

    Cantstandsya

    Jul 27, 2001
    Fontana, CA
    The 800RB has two power amps.One is 300 watts and the other is 100 watts.It can run 4ohms minimum in the 300 watt amp and 8 ohms minimum in the 100 watt amp at the same time.As long as he has the cabs connected to the right power amps he should be fine.
     
  12. Petebass

    Petebass

    Dec 22, 2002
    QLD Australia
    Trip please comfirm this.... I was led to believe that the GK Bi amp mode required you to use a GK cab and buy a specially designed lead from GK......
     
  13. Cantstandsya

    Cantstandsya

    Jul 27, 2001
    Fontana, CA
    Not on the 800RB.You can use pretty much any cab for the 100 watt amp as long as it is 8 ohms or above.The crossover is also variable on the 800RB compared to my 2001RB where the crossover is preset to send everything above 5khz to the 50 watt horn amp.The 800RB can also be run with both amps full-range where the 700RB,1001RB and 2001RB 50 watt horn amps are always crossed over and are really only meant to power the horn in a GK cab.
     
  14. tripwamsley

    tripwamsley

    Jan 31, 2002
    Sulphur La,
    Hello there! Trip here. The GK 800 is "old school" bi-amping. It will work with any cab. Umm...it sounds to me like the amp heated up too much. I would strongly suggest that you get some kind of Wal-Mart clip on fan to blow on the heatsink of the 800, I used to do this to my old SWR SM-400S because it would to the same thing. When I got the fan, everything was fine.
    To understand the bi-amping of the 700,1001 and 2001 what it is, IS, this: With the RBH and SBX cabs you use a FOUR CONDUCTOR speakon cable and you get an amp that pushes ONLY the tweeter and another that pushes the 10s or 15s as the case may be. I have been using this system with no fatalities in either the tweets or the woofs. It's actually quite wonderful. I hit really hard and I used to blow tweets and drivers from other makers cabs on a regular basis.
    The impetus for the unique bi-amp mode of the 1001 and the like is, that, when an amp clips through a passive crossover it distorts the tweets along with everything else. In extreme cases it results in blown fuses, tweets, drivers and sometimes fried crossovers. Separating the two solves most of this (for me at least). It is actually more phase coherent as well. That's all. It's really simple. Players that don't use the GK 1001 variety bi-amp thingy wind up having to use massive amounts of power for their rigs. Hey, but that's OK you know? To each is own. I hope that I have helped. One more note though, make sure that the MESA 210 is 8 ohms. If you run less than 8 on the 100W side, nothing good will come of it. Again, I hope I have helped.
     
  15. tripwamsley

    tripwamsley

    Jan 31, 2002
    Sulphur La,
    Oh sorry, I'm about to fall asleep. The MESA is 8. It does sound like a heat issue.