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GK 700RB - dead or alive

Discussion in 'Amps and Cabs [BG]' started by MAGUS®, Nov 12, 2005.


  1. MAGUS®

    MAGUS®

    Dec 23, 2004
    UK
    Slightly weird story.
    Bought a Mark 1 700 RB, connected up to both my 8 ohm EBS 1 x 12 Neo's. Power light on ok, not using the optional 50 watt amp section. Speaker cables are ¼" Jack one end ( from the head ) to Speakon on the EBS cabs.
    I couldnt get a sound out of the thing.

    Swopped cables for regular old guitar cables, ¼" Jacks both ends, and still nothin. Swopped the IEC power cable for the head to the mains socket, still nothing.

    Even tried a different wall mains socket - nothing - zip - nada

    Took head round to friends, connected up to his cabs using different cables, and another IEC head mains cable - same again.

    In desperation, thinking the head was fubrarred, i bought a brand new GK700 - and whaddaya know ? Exactly the same symptoms. Power light on ok.
    Tried different guitars, swopped all cables over again, and tried different mains sockets. Nada / zilch x 2

    Its like there's a conspiracy or sum ting..?

    Is it me people, or are they really out to get me :help:
     
  2. oldrocker

    oldrocker

    Feb 13, 2005
    Long Island, NY
    I once plugged my bass into the bass boost switch instead of the input jack of my GK 400 RB.

    No sound at all, I thought it was toast.


    :oops:

    Also, check the mute, is the tuner out working?
     
  3. MAGUS®

    MAGUS®

    Dec 23, 2004
    UK
    Hi there OR - yup i checked the mute switches on both heads, and i was definately using the proper input socket...

    Even flicked the gound lift in and out, even though the ground wasnt a problem. Its just a mystery, moreso when its happened to both heads
    The new one can go back for a refund, but not the other one. Its too old
     
  4. MAGUS®

    MAGUS®

    Dec 23, 2004
    UK
    Anyone else got a clue ?

    I love a mystery, but only at the cinema
     
  5. oldrocker

    oldrocker

    Feb 13, 2005
    Long Island, NY
    I just noticed you are in the UK.

    Could it be the input volatage, US 110V/60Hz vs whatever it is you guys use over there?
     
  6. tadawson

    tadawson

    Aug 24, 2005
    Lewisville, TX
    Well, lets see. Nothing plugged into the effects loop, right? OK, then . . .
    bass into "Input", mute switch off . . . pre-volume not at zero. Main volume(s) (on right side) above zero . . . . cab plugged into "output" jack . . . that should do it. Do you hear any faint background hiss or any other noise from the cabinet once the amp powers up? (On my 1001RB-II, I get a real faint hiss . . . no matter what the level controls or mutes . . . )

    If no noise/hiss at all, then I would think that the cable/cab/output hookup is wrong. Since you have tried two heads, I am not inclined to think bad amp section, but two duds is not impossible. If you have a hiss (or other noise), then the problem is upstream of the power amp - preamp/input jack/intrument cable/or the instrument itself.

    If you have the volume really low, and touch the tip of the instrument cable with your finger, so you hear a hum? If so, the problem is in your bass . . .

    Oh, and on the new one, I am assuming a 700RB-? If so, what color is the power light once it comes on? On the 1001, it is red if in protect, and blue when ready to go . . . .

    - Tim
     
  7. oldrocker

    oldrocker

    Feb 13, 2005
    Long Island, NY
    Now that I think of it, it can't be the power as the power LED turns on.

    I would now agree with Tim and suspect the bass to amp or amp to cab connection. Try using something other than the supplied GK speakon cable. I think this cable may only work with GK cabs. Use a standard speakon or better yet try using the 1/4 inch connection to your cab.
     
  8. MAGUS®

    MAGUS®

    Dec 23, 2004
    UK
    Thanks for your input Tim
     
  9. MAGUS®

    MAGUS®

    Dec 23, 2004
    UK
    OR, i wasnt using GK speakon cable. I first tried non GK speakons that had ¼" jacks on one end. I then swopped them for regular ¼" jack cable. In fact i went back to my small practice amp again with these regular cables and they work fine.

    By the way Rocker - UK voltage is 240v mains. The new head ( Mark 2) is a proper UK spec GK700RB
     
  10. peter G

    peter G

    Sep 28, 2004
    ohio's northcoast
    do you have the woofer vol turned up last knob on right side under bi-amp output
     
  11. MAGUS®

    MAGUS®

    Dec 23, 2004
    UK
    No i didnt - isnt that part of the extra 50 watt amp section, which i'm not using ?
     
  12. Nedmundo

    Nedmundo Supporting Member

    Jan 7, 2005
    Philadelphia
    No, the "woofer" volume acts as the master volume when you're not using the G-K bi-amp system. I think that's the problem, but also you mentioned you used instrument cables to connect head to cab. You need to use speaker cables. I doubt it, but maybe instrument cables trigger G-K's protection circuitry.

    Also, the speakon-quarter inch cables you tried might not have had the proper connections to use the G-K in full range mode. If the speakon has 1+ and 1- pins, it should work though.
     
  13. MAGUS®

    MAGUS®

    Dec 23, 2004
    UK
    Thanks you people - sorted !
     
  14. MAGUS®

    MAGUS®

    Dec 23, 2004
    UK
    Although i should add, it only works with one cab. Theres just silence when 2 are connected
     
  15. peter G

    peter G

    Sep 28, 2004
    ohio's northcoast
    how are they connected? when I run 2 cabs,I use 1 1/4"-1/4"
    cable from head to 1st cab, second cab speakon cable from head to 2nd cab.
     
  16. MAGUS®

    MAGUS®

    Dec 23, 2004
    UK
    Thats a bit strange Pete - why not either both ¼ Jacks out or both Speakon out ?

    Is that my problem ? Jeeeeeeeeez this is the most complicated amp i've had the pleasure of using
     
  17. Mattski

    Mattski

    Jan 6, 2003
    Cleveland, OH
    Try everything with 1/4 inch jacks. I have rewired the speakons on my Avatar cabs for my GKs, but they didn't work before that.

    Good luck! I love my GKs.
     
  18. peter G

    peter G

    Sep 28, 2004
    ohio's northcoast
    when I bought my head I was only doing 1 type of gig.All I used was the aggie 1-12" with the head set on top so I just got the shortest 1/4-1/4 cable GS had 3'. when I bought my 15" M123 had a closeout sale on speakon cable so I bought a 10'. most times I use 1 cab or the other and use what ever cable is connected to it,but when I need to rock-it I connect both cabs with the cables I have.
     
  19. tadawson

    tadawson

    Aug 24, 2005
    Lewisville, TX
    For what it is worth, GK speakon cables are dead stock, generic, biamp capable cables which are totally interchangeable with any other standard cable. A two wire "music store" cable is identical, except it does not have the second pair for the tweeter . . . .

    - Tim
     
  20. tadawson

    tadawson

    Aug 24, 2005
    Lewisville, TX
    Hey! They beat me to it - that was the second volume control I was referring to in my initial post, but forgot the specific label! The one on the left is the preamp in level, and as others have said, the two on the right control the two sides of the amp in biamp - woofer for low (or full range, if tweeterless cab) and tweeter for the 50W high end amp.

    Glad to hear that all is well!

    - Tim