I've been trying to find out for years what the NS Design Polar (TM) pickup system does. For something so simple, it's not easy to find. It turns out it's been discussed many times, just not under NS Design's name for it.
Here's the ending configuration of my Ergo 7-string electric cello. I'll be recording a show with it July 3 so I can share with you folks finally.
* Replace the built-in jack with a stereo jack. Very inexpensive part, screws right into the existing jack plate.
* Wire the two built-in pickups, under the feet of the bridge, _out of phase_. In other words, twist together red from one and black from the other, then twist together the other remaining pair of wires.
* Get a set of K&K Big Twin pickups. Clip off the output jack they provide, but leave plenty of wire. Super glue each pickup as close as possible to one foot of the bridge; one right above the left foot, one right above the right foot. Twist together the shield wires and the hot wires (they were white on mine).
Now, wire
* one red/black pair of wires, from the internal pickups, to the jack's "tip" terminal.
* one white pair of wires, from the K&K pickups, to the jack's "ring" terminal.
* One pair of uninsulated shield wires, from the K&K pickups, AND the other red/black pair of wires, to the jack's "sleeve" terminal.
Of course, you have to trim the wires first so they'll fit into the jack cavity.
Now you have two separate outputs.
* The "tip" set works better with arco, because wiring the under-bridge-foot pickups out of phase senses mostly the rocking back and forth of the bridge. Much more resonant tone.
* The "ring" set works better pizz. If you wire the second set of pickups as close as possible to the feet, on the edges of the bridge, the sound isn't much different from the original set of internal pickups.
I preamp this with a K&K Dual Channel Pro preamp; I have separate gain and tone controls for each channel, and a user-controllable volume on the outside of the preamp. Only requires a single 9V battery. I stick it right to my instrument above the output jack, not with velcro, but with the similar-looking adhesive strips that have a bunch of tiny plastic pegs on them. It holds it more securely than velcro.
You can use either set of pickups alone, or mix between them with the two volume controls, _or_, if you use both 1/4" outputs, you can get two separate signals out, one for each pickup. I use the last option to plug into the guitar and aux inputs of a Line6 Pod X3 Live; as I switch patches, it selects which pickup to use by controlling which input it uses.
You could use other preamping schemes, of course.
This doesn't just make me "kind of happy" with the sound of my Ergo, it makes me overjoyed with it. It's a matter of taste whether any individual enjoys this pickup configuration; if you never use the bow, and enjoy the sound as it comes from Ergo, don't bother. But I think people that use the bow would really enjoy this.
So I retract any earlier indications that I was less than happy with the sound. Pizz work always sounded great, now that the bow sounds just as good I am amazed.