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Blend control problem -- No sound in center position?

Discussion in 'Pickups & Electronics [BG]' started by Lockout, Feb 5, 2005.


  1. Lockout

    Lockout

    Dec 24, 2002
    Illinois
    I bought a set of Bartolini 59J pickups for my Lull a few days ago, but it appears that I'm having some trouble installing them.

    The Lull was originally set up in a Vol/Vol configuration, but I decided to replace the bridge volume pot with a blend control and use the neck volume as a master volume.

    I have everything wired up according to the diagram here. The pickups appear to be working fine when solo'd. However, as I move the blend control from either extreme (Neck solo or Bridge solo) the volume drops significantly until I get no output in the center position.

    Does anyone have any ideas what the problem could be?
     
  2. Bardolph

    Bardolph

    Jul 28, 2002
    Grand Rapids, MI
    This certainly isn't my area of expertise, but it sounds like the pickups might be out of phase with eachother. Something to do with switching the hot and ground wires around. I could be totally wrong. :confused:
     
  3. Metal Mitch

    Metal Mitch

    Jul 14, 2003
    NJ
    If they were just out of phase, you'd still get signal.

    Did you use the same value blend pot as the original volume pots?

    My best guess is you mixed up the hots from the pickups with the hots out to the vol control.

    That diagram is correct, but usually you see the outer posts wired together in a X shape instead of seeing the wires spliced together. One leg of the X is your grounds, the other joins your hots out from the blend. Make sure you have the hots from each pickup wired to the center posts, and join the output hots from the outer ungrounded posts.

    I usually wire up the X first, using a black and a white wire to remind me where I am. Then ground the top right corner, and send the top left to vol. Then attach the pickup hots last. And if you want to change the direction of the blend, just reverse the pickup hots on the 2 center posts.
     
  4. Lockout

    Lockout

    Dec 24, 2002
    Illinois
    Yeah, they're both 250k.

    Based on your description, my wiring seems correct. I'll try to make a little illustration to be sure, though.

    1 2 3 - Blend
    4 5 6
     | |
     | |

    1 2 3 - Volume
     | |
     | |

    If I was looking at the pots with the shaft down like this and lugs facing towards me, this is how I have everything wired:

    • I have 1 & 6 on the blend pot wired together, with another wire that goes from 1 on the blend to 1 on the volume.
    • I have 3 & 4 on the blend wired together with another wire attached to 4 that goes to ground.
    • I have my neck pickup hot wire connected to 2 on the blend.
    • I have my bridge pickup hot wire connected to 5 on the blend.
    • The 2 on the volume pot goes to an active/passive switch before heading to the preamp, and 3 is grounded.
    • And of course the pickup ground wires are grounded.

    Does this seem right?

    Why does StewMac show a different wiring for the blend control? http://www.stewmac.com/freeinfo/i-4137.html
     
  5. Metal Mitch

    Metal Mitch

    Jul 14, 2003
    NJ
    Very good question... notice they have the L/R lugs reversed from the other diagram.

    So instead of looking at diagrams, I just opened up one of my blend-equipped basses (which is working) to check the wiring. It's like the stewmac diagram. 3+4 go to vol 1 and 1+6 go to ground.

    PITA to change it, I know. Hope you have one of those desoldering wicks... I get the NTE at a local electronics store. It's a lifesaver.

    Good luck, let me know how it turns out.
     
  6. Lockout

    Lockout

    Dec 24, 2002
    Illinois
    Aha, I got it.

    I was looking at it last night, and I decided to see what would happen if I swapped the wire going to ground with the wire going to the volume pot, and it fixed the problem of having no sound in the center position, but the fully clockwise and counterclockwise positions were opposite of what I'm used to (it was giving me the solo bridge pickup when fully clockwise) so I just swapped the hots from the two pickups around, and it worked.

    Thanks for your help. :)