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Onboard preamp vol pot

Discussion in 'Pickups & Electronics [BG]' started by fig, Apr 14, 2019 at 5:19 PM.


  1. I have a Bartolini AGB918-2 Adjustable Gain Buffer/Preamp (single channel) on order to boost my low output passive pickups and compensate for cable losses (I use long cables).

    Documentation recommends a 25k pot (I'd have to order one) for volume. I have on-hand a 50k pot that fits the bass. Research in these forums suggest it really doesn't matter, but never described any differences between one or the other.

    I figure there will be minimal tonal difference which I don't care about, but I could be wrong about that. Also figure volume rate of change will be quicker with the 50k pot which is fine with me.

    Any other differences I might expect by using the 50k pot instead of the recommended 25k?

    I contacted Bartolini regarding this just before I posted here. Just wanted to get some field experience from folks who regularly change onboard preamps of any type. I'll post Bartolini's response when I hear back.
     
    Last edited: Apr 14, 2019 at 5:28 PM
  2. Increasing the pot value raises the noise floor of the signal. This may result in more prominent hiss when treble is boosted or just more white noise in general when sitting idle.
     
    fig likes this.
  3. Thank you, carvinbassplyr, that's the type of info I was looking for.
     
  4. HA! After I posted the above, I checked my email and heard back from Bartolini.

    carvinbassplyr, you called it.

    From Bartolini:
    "50K is fine. No worries. Technically the 25K will be "quieter" but the difference will be imperceptible."

    And today I learned a little something. Time to celebrate with some breakfast.
     
    carvinbassplyr likes this.
  5. For anyone interested, I tested (temp setup with test leads) the Bart AGB918-2 today. Works as advertised. Boosted the output of my bass and didn't add coloring. The 50k vol pot was quiet, had to remind myself to listen for noise. Used a 9v battery (18v optional).

    With the trimpot on the AGB918-2, I as able to set my amp's overdrive (o/d) to start kicking in at 80% gain setting. Previously, even with the pickups wired in series for stronger output, the bass would barely start triggering the o/d at 100% gain.

    Seemed to add more life, or clarity, to the sound. Maybe the cable losses (used my 30ft.) being compensated.

    Just gotta officially wire it later. Better than I expected for under $50.

    And today I got a little happier. Time to celebrate with some ice cream.
     
    ctmullins likes this.

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