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What could be wrong with my OBP3?

Discussion in 'Pickups & Electronics [BG]' started by gimmeagig, Feb 10, 2014.

  1. I have a strange problem with my OBP 3.
    I recently had my repairman install it in my KSD bass. My repairman has installed other preamps for me and even though he is not an electronics specialist he get's the job done. But this may be a bit over his head so I'm asking you guys for advice.
    When I compare the KSD to my other J Basses the tone control calibration seems to be way off. The preamp has a three band boost and cut setup with the mid frequency at 800hz.
    In order to get the OBP to sound natural in the bass I have to boost the Treble all the way, the mids 3/4 and the bass control seems to be like on my other instruments.I can only boost it a little before it overpowers everything..
    When I switch the preamp off, the bass sounds a little darker than my other basses but the difference is not drastic.
    All my basses are Jazz basses , all of them have preamps in them (Barts, Sadowskis,OBP1). I have two basses with the identical pickups in them, Fender SCNs So I can really tell that there is something not right with this OBP3 setup.
    Again, the treble at full is about the same as the treble boosted just a tiny bit on the other basses. This preamp is the only one I have with a mid EQ so I can't compare that directly but it seems that at 3/4 boost the mids are about neutral.
    This is really odd, I opened the bass up even though I don't know much about electronics either but I don't see any loose wires.
    Can you guys help me troubleshoot this for me?
  2. You'll probably thinking this is crazy but i would check to see what type of pot the treble pot is. It could just be one pot with the wrong rating. When i had my obp installed i had to replace 3 pots on my bass because of this.
  3. That's probably not it, the treble and bass pots are marked the same T04 B 50k 0351, the mid has a different shaft but it is also a center click B 50k.
  4. Ender_rpm


    Apr 18, 2004
    St. Louis MO
    To my ear, the KSDs have always had a high/mid emphasis in their preamp, maybe what you are hearing now is the "natural" sound of the pickups?
  5. Again , the preamp in the bass is the Aguilar OPB 3 and the pickups are Fender Samarium Cobalt Noiseless.
    There is nothing stock about this KSD everything has been changed.
    I just got it back from my repair man and everything is wired correctly. I also called Aguilar where I got some general pointers about trouble shooting. I suppose there could be an internal defect in the preamp itself, I don't know
    But even if I can't find what the problem is I'm still OK because with the treble boosted all the way and the mids at 3/4 I get the sound I want. It's just that the preamp treble boost should be 18db but there is no way that what I'm getting is 18 db. So I know there is something wrong, but I can live with it.