Thumb BO Weird Passive/Active Problem

Discussion in 'Basses [BG]' started by KORBIN PURCHASE, Dec 18, 2021.



    Dec 18, 2021
    Hello all,

    I have had an odd issue with my 5 string Warwick Thumb BO for years now and I'm finally getting around to fixing it. In my troubleshooting I came across some more details that I can't make sense of.

    The bass works perfectly fine while in Passive (Volume pot pulled out)
    Tone knob works and the stacked EQ knobs do nothing because...passive.

    Until today I though the active just didn't work at all. But I cranked my volume input and output on my amp and there IS signal, just really quiet. The EQ stacks knobs do their job and the tone knob also works. Just way quiet.

    If I played pretty hard the signal would try to cut in and just make a terrible loud sound like I pulled the cable while the amp is still on.

    Here is the super weird thing. Or at least to me. I pulled the battery and tried the passive again...It still works but the output signal is really low compared to passive with the battery.

    That to me doesn't make sense. Passive should be completely bypassing anything that requires power right? So I can't decide if the issue is with the preamp...or with the push-pull volume pot.

    I like the feel and tone of the bass with the stock equipment so repair would be ideal over "upgrading" but that is an option if I need it.

  2. Grounding issue or bad connection in your electronics. If you wiggle the right wire you'll probably hear all the volume come back. Or if you touch the wire that came ungrounded.


    Dec 18, 2021
    Ok. I'll mess with it a bit. If I can't figure it out perhaps it is time to upgrade pickups and circuitry.