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Why is my cabinet farting?

Discussion in 'Amps and Cabs [BG]' started by jburr, Mar 17, 2009.

  1. jburr


    Mar 17, 2009
    Ok, so got a new GK backline 600 (300 watts @ 4 ohms) hooked up to a new Fender Bassman 15" cabinet which is 8ohms and 250 watt, 500 watt peak. I figured that even at 8 ohms the 150 watts from the GK head would be enough to power the cabinet but I think I was wrong. I get horrible farting, fluffing, sounding distortion even at low volume.

    My bass is an Ibanez soundgear with active electronics and I changed the battery thinking that was it, but it sounds find on my smaller 100watt ampeg combo.

    Is this a case of underpowering the cabinet? Do I have a defective amp or cabinet?
  2. ihixulu

    ihixulu Supporting Member

    Mar 31, 2000
    South Shore MA
    Do you have the bass cranked on the head? On the bass itself?

    and the obligatory:

    What did you feed the cab for dinner?
  3. JPhoenix19


    Mar 5, 2009
    Tampa, FL
    what are you EQ settings set at? when you get this noise, does the 'clip' light come on?

    try pushing the -15db pad button in and adjust your volume.
  4. David1234


    Jun 1, 2004
    Sydney, Australia
    Endorsing Artist: SWR Amplifiers
    Sometimes a bass puts out enough voltage to overdrive the input of an amp. If this is the case you'll get the same farting no matter what the amp's volume knobs are set too.

    It's worth finding the source of the clipping / farting. It might not be the cab. Maybe you can run a line out of the effects loop into your ampeg and see if the clip is still there, then try the opposite using the ampeg as the preamp and the GK as the 'slave' power amp. Etc.
  5. fdeck

    fdeck Supporting Member Commercial User

    Mar 20, 2004
    Madison WI
    HPF Technology LLC
    Follow the link in my sig to my review of the BL600 head. Its default voicing is pretty bass heavy. I explain how you can dial it flat for a possibly more favorable starting point when exploring a new setup.

    Make sure you aren't clipping the input section.
  6. JonnyAngle

    JonnyAngle Dropping Acid Pedal Etching .com Supporting Member Commercial User

    Nov 24, 2008
    Maple Grove, MN
    are your pickups too high?
  7. jburr


    Mar 17, 2009
    Thanks for the quick response, here is some more info:

    1) Makes the distorted sound even with the Bass knob turned down on the amp, have tried many different EQ settings
    2) Tried pressing the -10Db button, same thing
    3) Have lowered volume on pickups as well as turning each completely down in turn
    4) The clip light is not coming on unless I really crank it
    5) Sound goes away when I play real high on the D or G strings
  8. Ric5

    Ric5 Supporting Member Commercial User

    Jan 29, 2008
    I Grow Organic Carrots
    don't let it eat beans dude ...
  9. stflbn


    May 10, 2007
    Are you running both cabinets or just one?

    Will the head run both cabinets?
  10. Rick Auricchio

    Rick Auricchio Registered Bass Offender

    1. Try playing at a low volume. Does the sound improve?

    2. Try another amp driving the cabinet. See what hapens.
  11. Did you try a different speaker cable and/or cabinet?...Or different head with same cab?....You may be asking too much out of the rig..
  12. JimmyM

    JimmyM Supporting Member

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    I don't know...the more I hear about it, the more I think it's a physical problem with something loose on your cab. Check all screws, connections, etc., and possibly even check the speakers themselves and make sure wires aren't touching the cones or rattling around loose inside if tightening screws doesn't work.

    Also, try it in a different room or outside as well. Sometimes room rattles can sound like they're coming from your cab. Took me 3 days to figure that one out when I re-assembled my B-15. They're prone to rattles, so I thought for sure I missed something in the cab when I discovered it was a loose latch on my toolbox :eek:
  13. panaran


    Dec 1, 2008
    did you buy the cab used? Is the cab possibly blown?
  14. Wes Whitmore

    Wes Whitmore

    Mar 10, 2003
    Columbus, OH
    Do you have access to second bass, amp, or cab? That would help you troubleshoot.

    Here is the manual:
    http://www.gallien-krueger.com/manuals/Backline Series OM.pdf.pdf

    Watch the settings on the overdrive channel of that amp. Bypass the overdrive for now. Set all EQ flat on the amp. Set it flat on the bass guitar. Turn boost off. If you light up the input led, then your bass is too hot and you need to engage that -10dB pad and turn up the master volume on the amp to compensate. My gk1001 doesn't sound good either when I'm clipping the input.

    Make sure you are using a speaker 1/4" and not an instrument 1/4"...
  15. ga_edwards


    Sep 8, 2000
    UK, Essex
    Try a different/passive bass through it. I had a similar problem with the Ashdown compressor pedal. Turns out they were only built with passive basses in mind and highoutput/active basses overloaded the circuitry.

    They did offer a free mod service, but still didn't help much.

    So yeh, try another bass, yours may be too hot. What happens if you turn down your basses volume control BTW, does that help?
  16. tomzilla23


    Aug 11, 2008
    Oakdale, PA
    +1 this happened to my gk blx410 cab and i opened it up and found a crack in the cone of one of my speakers
  17. MNAirHead

    MNAirHead Supporting Member

    If the speakers are old.. they do come unglued at the perimeters.. this will distort..

    I'd start with testing one cabinet at a time.. then checking the physical setup.. (handles, screws etc).

    Check your amp settings (meaning read the manual cover to cover) .. there are some amps designed VERY speifically to do VERY specific things.

    It is kind of ideal to impedence match your cabinets...
  18. Gries Amps

    Gries Amps Commercial User

    May 14, 2008
    Mattapoisett, MA
    Owner, Gries Amplification
    When you say "fluffing" do you mean it sounds like air? I had a problem with a new 15 spkr. that turned out to be the rubber gasket that contacts the baffle board. It was 4 separate pieces of rubber and there was a gap about 3/32" between two of them, just enough to let air "wheeze" through on low notes. I removed the spkr., cut some foam to fit very tight, & reinstalled it.
  19. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    Try the amp with another cab and/or try the cab with another amp to find where the problem lies, then you can zero in on the source.
  20. jburr


    Mar 17, 2009
    Thanks for the great suggestions. After trying most of these with no results, it looks like I will be taking the head to the music store and trying with another cab tomorrow. The cab and amp are brand new but were shipped so maybe there was some damage. I will be sure to post the final outcome.

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