Output impedance of Bartolini electronics

Discussion in 'Amps and Cabs [BG]' started by nonsqtr, Jun 20, 2004.

  1. nonsqtr

    nonsqtr The emperor has no clothes!

    Aug 29, 2003
    Burbank CA USA
    Hi all, does anyone know the output impedance of the Bartolini electronics (the 5-knob version with the switchable midrange)? I can't seem to find this info anywhere. I need to design a passive filter that goes between the bass and the amp (ie an outboard device, like a stompbox). The amp has a 1 meg input impedance (yeah, imagine that), and I need to know the output impedance of the preamp to design the filter correctly. I'm guessing it's very low, like 50 or 100 ohms?

    p.s. mods, this is an amp electronics question, not about the pickups. but feel free to move the thread if you must :)
  2. It would be preferable to have an opamp buffer in your outboard filter, or even better an active filter. Just so you don't have to account for the output impedance of the bass. If you ever hook up another bass, your filter could be WAY off.

    But I think 50 ohms is a good value. Then again, you could always try to measure it. Place a small transformer (for its 60 cycle hum) as close as possible to the pickup and measure the open output, then see how much it drops when loaded with a 100 ohms or 1 k ohms resistor. Then you can calculate the output impedance.
  3. nonsqtr

    nonsqtr The emperor has no clothes!

    Aug 29, 2003
    Burbank CA USA
    Excellent suggestion, thanks. Yeah, I could break out the scope and try to figure it out. I was hoping someone would just know "off the cuff". But I forgot that Bartolini pots their stuff with epoxy, so that might be a little difficult. :)
  4. David Wilson

    David Wilson Administrator Staff Member Administrator Supporting Member

    Oct 14, 2002
    Lower Westchester, NY
    The master volume pot on a 3 band bart preamp is 25k, if that helps