This is all I have ever needed.  Passive.  45-105 Ernie Balls.  LaBella Flats sound awesome as well.
Ampeg.  
 
Done.  
 

 
 

I seem to have the "bastard child" of the bass realm. No detailed wiring info exists and Ibanez' query page has an internal scripting error, although I just found another that seems to work (will see). The fact a company doesn't even op-test its own query form is just ludicrous (but they might be happy they are getting no emails ).
 
In the meantime, I shot an after-hours email to DiMarzio apologizing for asking them and got a reply in 30 minutes!! They said they didn't have specific info on that model either, but shot me a generic wiring diagram from Ibanez for 94-96 which looks like it might be it (but no details of the circuit card itself).
 
A company that goes "above and beyond" to this extent is an absolute keeper - DiMarzio, Focusrite, Carvin have all been this way for me. Semi-rant, but Ibanez is slip-sliding into the "well of shame."
 
Back to topic, the Ibanez' diagram labels those knobs as volume (top), balancer (front), middle EQ (bottom), and treble EQ (back) although there is definitely cross-over effects at play - that "middle" knob puts a hefty 6dB on the bass signal. There is a detent on the middle/treble knobs which seems to allude to "unity" with a boost/cut on either side. I guess the frequency shift on the balancer makes sense with the pickups being so far apart, but still seems there is something else going on in that circuit board.
 
Not jacked this into a DAW yet, but I probably should have just started there anyway.

This is a catalog page from 1992, which looks like the only year it was made:
 

 
Some questions:
 
Are all the controls mounted on a single board or just the EQ?
 
What exactly are you trying to achieve?
 
How does the bass sound unplugged? If it sounds "challenged" unplugged, I wouldn't recommend spending much money upgrading it. With new (good) active electronics it will likely cost a couple hundred bucks for PU's (which can be active or passive) and a preamp. With new passive PU's and passive tone controls it could be a hundred dollars or so, though you can generally find perfectly nice PU's on ebay much cheaper, particularly for bass and especially if you're patient. I've bought brand new and/or like new PU's for like 30% of retail (and I'm saying 30%, not 30% off) on more than one occasion.
 
There's nothing wrong with or superior about either active or passive and there are both good and bad implementations of each. It's a "there's more than one right answer" kind of thing. All electric instruments are ultimately active, so it's just a matter of where the preamp/buffering/EQ is done - it can be done in the PU's and/or the on-board EQ as well as at the amp or direct input.

if those are J-bass retrofits,
i'd suggest these:
 

J-45's
http://www.wildepickups.com/Bass_Pickups.html

Thanks Drew, the CTB3BN is the model. For me this is my first experience with anything active, so I was more trying to make sure the controls were doing what I thought they did. It seems that they do, but the active part of it was throwing me at first.
 
I checked with SPAN last night and the bass EQ is a straight-up +/- 6 dB boost cut, which is useful since the signal is uniform in that region. The treble EQ also seems to be a +/- 6 dB but that region is not uniform so this wildly exacerbates harmonics - this part caught me off guard since the discrete harmonics thrown in that region rival my guitar. The treble EQ swung fully pulls harmonics from the floor (totally hidden) to well over the bass component. I can see its use for pre-processing signals prior to hitting an amp since it will mask a lot of improper technique. I honestly wasn't expecting a "big fat string" to throw such wild harmonics even on an open string thumb-plucked.
 
Unplugged it sounds fine, and a lot of the fretting (I tend to fret hard) doesn't get to the amp with the treble EQ at unity or less. I tend to leave the amp at lower volumes so was actually hearing my fingers over the amp previously, but jacked the amp up last night and the fret hits do not come through. I am slowly creeping the treble EQ up as I go since it is a good litmus test for getting proper technique down. Through the amp it does well, so I think a major portion is getting more familiar with it. I want to get some recording done with it this weekend, but overall I think there is nothing wrong or bad with it... just the player is a bit clueless so fumbling around .
 
The upside to this whole venture is that it builds up hand strength big time, and with strength comes speed, so this is actually rather interesting for its "guitar application" as well.
 
 

I found the missing piece of the "puzzle"... Ibanez got back to me, and they did dredge up the diagrams (still no board details) for the CTB5, which they said was identical electronics. I got the rug yanked out from under me, since I had the balancer and treble pots confused. The treble pot is very slight, which led me to believe it was the balancer, but the balancer knob is wired correctly... the dull (very bassy) pickup is the bridge (J-type), and the screaming hot harmonic one if the neck (P-type). So, I went digging for info on these...
 
I found a set on Seymour-Duncan's web site which is probably very close to the set in this bass. I could search specifically by "active" and see the J/P side-by-side. What I did not realize is that the J-types are bass-heavy, and the P-types are more treble-heavy. Whatever is on that board just makes the P-type even more pronounced (so much so that the P-type full on cannot be tamed by the treble pot!). This was counter-intuitive for me, since the heavy harmonic puller is at the bridge on a guitar. Even on mine those two pickups are so close in performance that harmonics will naturally be more pronounced at the bridge, but on this bass the difference in the pickup designs is the complete opposite of expectation.
 
I definitely learned something from refurbishing that bass! It seems that P-type is hard-wired even hotter on the board which makes it very sensitive to noise, feedback, string-zings, etc., so I am having a hard time seeing a use for that guy full-on at the moment, but a smidge of it is definitely needed for slap bass styles.