Genz-Benz NeoX 400T issue...

Discussion in 'Amps and Cabs [BG]' started by TheMightyWoot1, May 2, 2012.


  1. I have been using this amp for a little over a year now, it's super punchy, and usually makes even a cheap bass sound phat...

    But lately it has been giving me this buzzy hissy sound, like distortion from too hot of a signal. I have the crossover all the way down, and cut treble freqs to help alleviate the issue, but it is still there, and of course losing those trebs makes tapping sound less full.
    Think its time to replace the preamp tube? It sounds cleaner on the FET channel, but I loves me that tube channel.

    FWIW I use tube compression (EHX Black Finger) as the first effect in my signal chain, to a MXR Blow Torch, to a Qtron, then chorus, tuner into the amp.

    All responses appreciated! :) :bassist:
     
  2. Bump. Need a few opinions, if anyone can help...
     
  3. Well I guess I'm on my own with this one...
     
  4. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
    Geez, it's only been a couple of hours ;)

    First of all, let's see if it's really the amp or possibly something else in the signal path first. Once we determine the source of the noise, THEN we can work on a solution.

    1. Have you tried the combo with the bass directly into the amp (physically bypassing the effects) and see how that works?

    2. Is your bass active? Have you changed the battery? Some on-board preamps will get very noisy as the battery begins to fail.

    3. With nothing plugged into the alp's input, set all your amp's eq controls at noon, and the gain/volume/tone shaping controls at 0.

    4. Set to FET channel

    5. Increase the master volume to noon... is it still quiet?

    6. Increase the fet gain to noon... is it still quiet?

    7. switch to the tube channel

    8. Increase the tube volume to noon... is it still quiet?

    9. Increase the tube gain to noon... is it still quiet?

    10. engage the mix switch... is it still quiet?

    There will be a little more hiss with the tube channel than the fet channel and a little bit more with the channels mixed.

    Once we know this information, we can work from this.
     
  5. Great advice! I will try this out asap and post my results! :)
     
  6. Ok. This is kind of strange....

    Both of my main basses are active, and I am diligent about changing batteries. Scratch that one off the list.

    I did exactly what you said, but as I was doing it, I noticed that there is a slight hum/hiss that is constant. It became more noticable when I switched to tube, as you had said, and even louder with mix engaged.

    So I plug my bass in straight to the amp, sounds fine!
    At this point I'm like "Great, my pedal board is the issue... ":rollno:

    Well, it was my compressor that was out of whack.
    I should know better than to blame my amp. Doh!

    Thanks for your help :bassist:
     
  7. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
    No problem, glad it was a simple problem.

    Incidently, probably 70% of the problems we field in tech support end up being something other than the amp. It's just the way it is.
     
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