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My passive tone control works w/active pu's

Discussion in 'Pickups & Electronics [BG]' started by bongostealth, Jan 18, 2013.

  1. bongostealth

    bongostealth Supporting Member

    Jun 3, 2011
    Atlanta, GA
    I recently purchased a U-Retro Deluxe with passive tone control. BestBassGear.com told me that the passive tone control would not really work at all with active pickups and even John East himself told me that his passive tone control was designed for passive pickups. I have active Seymour Duncan Basslines soapbars.

    Well, I was disappointed but hooked the preamp up anyways. To my surprise, the passive tone control works beautifully in both active and passive mode! In this instance, it didn't matter that my pickups are active.

    So there you have it. In case you are wondering, John East's passive tone controls CAN work with active pickups and not just passive pickups. (at least Seymour Duncan Basslines pickups)

  2. A tone control is just a variable resistance in series with a capacitance, running parallel to the signal path. Changing the pot value will affect the usable range of control for any given impedance, and changing the capacitance will change the frequency cutoff point, but you're still basically doing the same thing with any signal.

    Active pickup users tend to prefer higher capacitances and lower pot values, to compensate for the lower output impedance of their signals, however.
  3. bongostealth

    bongostealth Supporting Member

    Jun 3, 2011
    Atlanta, GA
    So the lower the pot value the more signal that can come through the pot? Is this why active EMG pickups use 50k pots and active Seymour Duncans use 100k pots?
  4. steve_rolfeca

    steve_rolfeca Supporting Member

    No, it's just a matter of impedance matching.

    On a passive bass, you need a high-value pot to avoid loading the pickups down. An active system has enough drive that it's less affected by loading, but just like a passive instrument, there's an optimum value that gives you a nice smooth feel to the taper, and matches the output impedance of the circuit.

    No reason the passive tone control wouldn't work, but you'll probably notice that the taper feels different in active mode.