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Genz Benz Shuttle unearthly noise

Discussion in 'Amps and Cabs [BG]' started by ckrelove, Oct 3, 2016.


  1. ckrelove

    ckrelove

    Oct 3, 2016
    Just joined Talkbass and am doing initial post. I have looked at the site a couple of times in past and it seems there are quite a few members with a depth and breadth of expertise. I am hoping some folks here with greater knowledge than mine can add some info or insight about a problem I have with a bass amp.

    I have a GenzBenz Shuttle 6.0 that I bought used a few months back and have just had an occurrence that is unprecedented in my experience: when I turn up the Mid pot past 3 o'clock (and this is the only pot that has the effect), a sound that is exactly like a microphone feedback howl occurs and the blue limiter light goes on/flashes. This is a continuous noise and stops as soon as pot turned clockwise past 3 oclock. It occurs in all cases - either something plugged into input jack or not.
    IIt may have always done this, but i haven't noticed it before, as I had never turned up that pot that high before, that I recall.
    Some things I had recently done to amp:
    1. I had replaced the 12AX7 tube with a new one about a month ago (sovtek)
    2. I had used Deoxit spray in all pots to clean scratchiness two days before.(I discovered this phenomenon when I started turning dials to show someone how much of the scratchiness had been eliminated the next day)

    The amp works as normal when Mid pot is set less than 3 o'clock. As stated earlier, no other pots are affected the same way.

    Any ideas that others here have that may help in diagnosis would be welcome, especially those with GB knowledge.
     
  2. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    Hi - yeah I can help you with this.

    It is likely that the mid sweep pot got damaged, possibly by spraying it with too much DeOxit (assuming it was the real DeOxit) and causing the bushing lube to leach out onto the wiper fingers and mix with some abrasive dust. This causes an imbalance in the mid eq bridge circuit, unbalancing the circuit and causing it to oscillate. The only way to fix this is to replace the pot, not a DIY endeavor.

    You can PM me and I can get you some options for repair.
     
  3. BassmanPaul

    BassmanPaul Gold Supporting Member

    Aug 25, 2007
    Toronto Ontario Canada
    Welcome to TalkBass.

    We are lucky to have in our ranks both the designer and the owner of Genz Benz. Andy will be along shortly to assist you

    Edit: See what I mean? :D
     
  4. ckrelove

    ckrelove

    Oct 3, 2016
    I am grateful and honored to have agedhorse offer solutions. My problem is - as a tyro - that I have no idea how to PM anyone on this site.
     
  5. Welcome to TalkBass.
    Click on his picture or name, a window comes up click on Start A Conversation, make a title and write you message. Then hit the Start a conversation button at the bottom of the message.
     
  6. ckrelove

    ckrelove

    Oct 3, 2016
    Agedhorse:

    I am using "reply" to respond to your post: I am hopeful is equivalent to a PM.

    I would be grateful for any assistance you cam give. I should add that I am in Canada (Toronto), so solutions may be different than for USA.

    Look forward to your reply. (and I'd appreciate your letting me know if this indeed a PM that I have sent)

    Ckrelove
     
  7. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    Not quite a PM. Canada is different with regards to shipping but the factory service program I offer still applies. Follow S-Bigbottom's instructions. This way I can keep track of who is who and what unit.