Jazz Bass pickup with plenty of rich, clear, deep bottom end.

The Physics of how magnetic pickups work is interesting - they all have good, uncolored bass (and low mid) response. The differences occur in the high mids and above. The impression of more or less bass is a relative thing - if a pickup has a lot of treble content, that grabs your attention, and you perceive less lows. In reality, the lows are always there in conventional magnetic pickups.

 

Maybe it's this bass's body, neck and fretboard, not its strings and/or electronics.

You cite "some of" you other basses. What physical makeup do those have in common that the other of your bass do not? Now, which is the phyiscal makeup of this bass more like: those of your other basses that have the sound you want, or those that don't?

Did you try swapping the very pickups and strings from one of your basses whose sound you like onto this bass? If you try that and the desireable sound transfers to this bass, then you know it's the strings and/or pickups; but if it does not, then it's this bass's body, neck and fretboard.

 

Is the JZ3 a a 3 band with balance or two volumes?

 

I love the Bart B-Axis Jazz p/u. That's what I have in my mod MIM Jazz along with an Audere 4-band pre. The combo is full, rich, and very articulate.

 

You should cycle through every variation of Barts and Duncans and even some vintage stock Fenders. Then when you're really ready to answer your own question you have 2 choices that will kick your bass in the jewels.
Jason Lollar, Lindy Fralin.

Or go ahead and mess around. Time is money. You can do Lindys or Lollars now or pee away your time and money on whatever. That preamp of yours will marry very well with either.

 

Have you experimented with different string types?

 

+1 for Lindys
Also take a look into your capacitor. Changing the value on that can do wonderful things.

 

The V-Mod pickups that I replaced with CS60’s have the crisp high end and tight, deep low end that you want. The higher end was TOO crisp for me, which is why I swapped the pickups. But it sounds like it may be what you’re after.

My experience using them was also on an Ash body, maple neck/board. I gigged the V-Mods for a year before swapping them. They are nice pickups, just not what I am after, tonally.

 

So, you want scooped mids pickups? I would go for Seymour Duncan Quarter Pounders.
Quarter Pound™ Jazz Bass - Guitar Pickups, Bass Pickups, Pedals

 

I have the same bass material as yours (it’s a Squier) and I get the tone you’re looking for on my bass with DR Lo-Riders Stainless Steel strings.

 

He wants more low end and high end - I assume he's playing with the tone turned all the way up. If that assumption is right (I admit there is an if there), the value of tone capacitor at that setting is meaningless.

 

Based on the description, you might like DiMarzio's Ultra Jazz. I've never tried them, but they're known for deep, clear lows, scooped mids, and clear highs. Not too expensive, and noiseless too:

Ultra Jazz™ Pair | DiMarzio

 

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If you aren't getting that with those pickups you used, I'm not sure there's anything that's really going to get it for you. A pickup surely makes a difference, but I can't imagine something that'll make a drastic difference compared to what you've already tried. I've had really great experiences with the Custom Shop 60s and JVX. MAYBE overwound pickups from Fralin?