Bogner XTC 101b + feedback. Help please.

Discussion in 'Amps and Cabs' started by lesterchopper, Jan 3, 2008.


  1. lesterchopper

    lesterchopper Member

    Messages:
    496
    Joined:
    Jun 6, 2006
    Location:
    Austin
    I posted this as well on the Bogner Amp forum but wanted to get coverage here as well as many have experience with this amp.

    I received my 101b a couple of weeks ago. The tones are monstrous. Lots to tweak for sure. Only problem I'm having is what seems like an abnormal amount of feedback. A short description of the setup is as follows:

    ~13x13 rectangular room with sound board
    Guitars used: LPR8(BB1,2), 335(CL57), Nocster(SC)
    guitar cable = 8'
    Both channels (red and blue) affected, gain at noon (straight up), volume at ~11:30, power=full

    Another data point is my friend has an old Mesa dual rec/412 in same room. With LPR8, his doesn't feed back nearly as much.

    I realize being in relatively close proximity to the amp lends itself to some feedback. Also that the 335 and nocaster may be a little more succeptable. Just seems like way too much. I can't sustain on a power chord for more than a second or two before feeding back.

    Thanks for any thoughts/suggestions.

    David
     
  2. Braciola

    Braciola Silver Supporting Member

    Messages:
    4,703
    Joined:
    Jan 14, 2003
    Location:
    Oviedo Florida
    It very well might be a microphonic preamp tube.
    With the amp on and no guitar plugged in, turn up the amps volumes, then gently tap on each preamp tube (I like to use a Chinese chop stick).
    If one of them is microphonic, it will start to ring when you tap it.
     
  3. lesterchopper

    lesterchopper Member

    Messages:
    496
    Joined:
    Jun 6, 2006
    Location:
    Austin
    Interesting thought. I'll give it a try. Thanks.
     
  4. SvenHock

    SvenHock Silver Supporting Member

    Messages:
    1,055
    Joined:
    Mar 10, 2003
    Location:
    MD
    Sounds like a preamp tube as mentioned.
     
  5. billm408

    billm408 Member

    Messages:
    3,017
    Joined:
    Mar 16, 2007
    Location:
    San Jose, CA
    Maybe it's just me, but full power, volume at 11:30?? What windows are you trying to blow out? With a full band, I run mine around 8:30-9:00 and it's cranking!
     
  6. justonwo

    justonwo Supporting Member

    Messages:
    3,097
    Joined:
    Mar 2, 2005
    Location:
    SF Bay Area
    Yep, could be a pre-amp tube.
     
  7. Lution

    Lution Member

    Messages:
    7,745
    Joined:
    Oct 6, 2005
    Location:
    Colorado
    thats a small room to have it cranked like that...

    could be proximity. try turning down the volume of your guitar when it happens to see if the feedback goes away.

    Also, like the others have said, check your preamp tubes.
     
  8. Echoes

    Echoes Senior Member

    Messages:
    6,226
    Joined:
    Jul 11, 2007
    microphonic tube(s) or microphonic pick-ups in guitar...biggest 2 culprits
     
  9. lesterchopper

    lesterchopper Member

    Messages:
    496
    Joined:
    Jun 6, 2006
    Location:
    Austin
    Thanks to everyone for the input. Regarding microphonic pre amp tubes, since the amp is new, is it possible the tubes were harmed during shipping?
     
  10. Braciola

    Braciola Silver Supporting Member

    Messages:
    4,703
    Joined:
    Jan 14, 2003
    Location:
    Oviedo Florida
    Not necessarily.
    New production preamp tubes could go microphonic at anytime without provocation.
     
  11. Erik

    Erik Member

    Messages:
    1,683
    Joined:
    Oct 14, 2003
    Location:
    Late, great, state of NY
    ...or it could be caused by massive volume + small room + unpotted pickups.
     
  12. Lution

    Lution Member

    Messages:
    7,745
    Joined:
    Oct 6, 2005
    Location:
    Colorado
    yep. just asking for feedback and no hearing!
     
  13. rob2001

    rob2001 Member

    Messages:
    16,948
    Joined:
    Jun 16, 2006
    Location:
    Wisconsin
    I saw this quoted in someones sig somewhere

    Turn the gain down and step away from the amp!
     

Share This Page