1. Please take 30 seconds to register your free account to remove most ads, post topics, make friends, earn reward points at our store, and more!  

Do Bartolini buffers invert polarity?

Discussion in 'Pickups & Electronics [BG]' started by edwinhurwitz, Jan 16, 2008.


  1. edwinhurwitz

    edwinhurwitz Supporting Member

    May 13, 2003
    Boulder, CO
    Endorsing Artist: DR Strings, SMS
    I have an ACG preamp and I wanted to blend the filter output with the straight pickup. So, I found a Bartolini quad buffer and ran the pickups directly into it. I then took the outputs of both buffers (after a volume pot for each one) and the ACG and brought them all the output jack. So far, the ACG is working great, but the outputs from the Bart is very very low and inverted in polarity from the ACG. Any ideas? Am I doing something wrong? I figured the Bart pres would isolate the pickup direct outs from the ACG out, but apparently it's not quite happening like that.

    TIA
    Edwin
     
  2. edwinhurwitz

    edwinhurwitz Supporting Member

    May 13, 2003
    Boulder, CO
    Endorsing Artist: DR Strings, SMS
    OK, I routed the summed outputs of the Bart pres into another channel of the Bart and the polarity reversed again, giving me the correct polarity so that there isn't a dead spot when interacting with the output of the ACG. However, the gain is still really, really, really low. I am using Dark Star pickups which aren't the wimpiest pickups in the world.

    Edwin
     
  3. DavidRavenMoon

    DavidRavenMoon Inactive

    Oct 20, 2004
    The problem might be the output impedance of the Bart preamp and the input impedance of the filter. Doing it that way needs a summing amp.

    But do it this way instead. Use the Bart buffer as a splitter. If the Bart has two channels, run the pickup into both channel inputs. Take one channel and feed it to the filter, and take one straight. Put something like a 2.2K resistor on the outputs of each and then to the volume pots.
     
  4. edwinhurwitz

    edwinhurwitz Supporting Member

    May 13, 2003
    Boulder, CO
    Endorsing Artist: DR Strings, SMS

    Thanks! I think that's a great idea. The ACG has buffered inputs, but I bet it wouldn't be bothered by pre buffering the pickups. However, then I run into the phase problem since I only have 4 channels in the buffer. I wonder if somehow the Bart isn't getting power properly. I need to test that.


    Edwin
     
  5. DavidRavenMoon

    DavidRavenMoon Inactive

    Oct 20, 2004
    You can also try buffering each pickup, and then split that signal, one half to the filter, and the other half straight. The filters might also be inverting the signal.
     
  6. Primary

    Primary TB Assistant

    Here are some related products that TB members are talking about. Clicking on a product will take you to TB’s partner, Primary, where you can find links to TB discussions about these products.

     
    May 18, 2021

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.