pickup mix, 2vol>1mix+1vol shecter bass

[Chadwick]

My friend got me to change his schecter bass from two volume knobs, one per pick up to one mix knob and one volume knob. I'm having trouble getting an even balanced mix without volume changes at the enter tap of the mix pot. The volume pot works fine. Its obviously a problem of resistance across the range of the voltage dividers and I'm not seeing a way to get the center tap to be full volume on both pickups.

I saw this one at seymour and it has a volume drop in the middle of the pickup knob, but maybe not for passive setups. I don’t know. http://www.seymourduncan.com/support...ass_blend.html

This has an active tone circuit with the following schemes probably loading an op amp.

So here are my three situations and problems. Thanks for looking and let me know if it is possible to balance this thing out without any more active electronics. Thanks!
High res:
http://www.achadwick.com/user/store/basspupmixer.pdf
image for post:

[Sweetfinger]

If the pickups are in parallel, you will get an apparent drop in volume with both pickups on. Its just that usually you don't notice. Put the blend knob on a strat between two of the pickups. As you get to the center detent, which would be like positions two or four on a 5 way, you'll notice a drop in volume. Without going to active buffers, I think the easy answer is with your third diagram. play with the mixer resistor values until it sounds right. What're you up to these days? I own Precision Guitar in Phoenix, now.

[Chadwick]

sup

hey, Ya I think instead of connecting the wiper to one side of the pot I'm going to put 100k plus or minus and it should bring the volume up on either end balancing it out with the volume in the middle of the mix pot.

I'm just doing the cover thing in www.capitaldown.com and doing a lot of CAD and Prototyping for Krank amps. Drop a line.. achadwick.com

[David Schwab]

Where did you get your blend pot? I ask this because I was wiring a bass last weekend, and the owner supplyed all the parts. He bought a beld pot from Stew-Mac. I was curious how they had it set up, because they say it's a "unique audio-taper" pot.. so I'm thinking to do an audio taper blend properly you need one side with the taper reversed. So to find out I took a reading with the pot at the center detent, and read from the wiper to either outer lug.

What I discovered is both halves of the pot have the audio taper going the same way! So you get something like 160K from the left lug to the middle, and only 30K from the middle to the right lug.

This obviously can't blend two pickups evenly. I used it anyway, but told my customer that if he didn't like the way it worked we could find another blend pot.

It actually seemed to work OK, but not as well as the one that EMG sells.