Yes and no. I also have two of the Charvel San Dimas P basses, and they come with Dimarzio Model P and Model J pickups in them. Those basses also have a (cheap) preamp and 3 band EQ, whereas my Relentless J loaded bass is a traditional passive JJ setup. All three of these have roasted maple necks, with Jazz-spec nut widths.
It's not really an apples-apples comparison, but I'll share my thoughts/feelings anyway. Also, I just don't think I'm a fan of the preamp and grounding on these basses. Both are noisy, and oppressively so when not touching strings or grounded hardware. I have an Audere pre sitting here beside me that I'm going to drop into one and see how that changes things, which will inform my opion on what to do with the other as well. I'm planning to end up with one wearing rounds, the other flats, and tailor the pickups and preamps to each string type.
OK... with that background info out of the way, I THINK that even after accounting for the preamp, the Relentless J is the clearer, more balanced pickup vs he Model J. I won't comment about output levels between the active Charvels and the passive Relentless bass, but comparing the Relentless bass vs some Fender Japan and a MIM I have around, and I'll say that the Relentless pickups have a slightly stronger output than any of these stock Fenders, but they're not ridiculously hot. The Model J is also a great pickup, but I do think it's a little more focused/voiced to do a certain thing.
The Relentless set has really nice presence and clarity, with a bit of "air" and crispness, even when amp is EQ is set flat. You can roll that right out with the tone knob if you like, but I appreciate having it there naturally in the tonal spectrum vs trying to brighten up an inherently dull pickup with artificial/amp EQ. More and more, I'd rather have a full-spectrum signal up front and then cut what I don't want, vs getting a strongly-flavored tone at the instrument jack and then trying to heavy-handedly boost or cut EQ at pedals or amp to fit the room/song/situation. The Relentless set is not overly-voiced, imho. I think the Relentless Middle (P pickup) and Relentless Neck pickups really sound like Billy, but the J set is different. I mean.... he's not known for playing a J. I don't feel that there's a strong tonal relationship between the P set and the J set of pickups at all. I think the J set just makes for a really fantastic, full-spectrum Jazz with great output that looks hekkin awesome. It could easily be advertised as that on its own without Billy's name. I don't mean that as a diss. I know Billy and love him, and completely understand that the marketing with his name is helping sales. I'm just saying these pickups are good enough that they can stand on their own without a celeb endorsement, imho.
My experience with the Model J pickup (please realize, I am playing this with a model P in the neck, not a JJ setup) in the Charvels is also positive. I like it as a rock pickup. Very punchy in the mid and upper-mid range. Controlled in the lows but not woofy or sloppy. I won't say it's AS tight and defined in the lowest lows as the Relentless J, but it DOES have more resonance/output down there. It's not such a big difference that a smol twist of the bass EQ at our amps won't make it disappear, but it's there. Ah... that's a point I should have made in the previous paragraph. The Relentless J might ALMOST seem thin in the lows at first listen, but I think that's because we are used to so many pickups being heavily/artificially boosted there. The Relentless set, to me, is ALL ABOUT clarity and balance at the pickups, then adjust to taste downstream. OK, back to Model J. Plenty of lows and low-mids right there, and almost a pre-dialed in punch in the Charvel suit, though I wonder if some of that exaggeration is coming from the preamp. It makes for a great rock bass pickup, and it has a brightness that really makes pick-playing stand out as well, but it's got a different feeling top end than the Relentless. It almost feels a little.... artificial isn't a good work, but maybe "processed" on the upper end. While the Relentless upper end simply sounds like what your brain might imagine the actual string movement sounds like... the Model J sounds like what I think it'd sound like after running through some EQ to highlight the upper end... which could totally just be the preamp coloring this opinion. Anywho, hi-cut (what would be tone roll-off on a passive bass) can get you into warmer sounds that are good for smoother clean playing, but again... I only have the Model J bridge and not the J neck pickup to go with it, so I can't speak to the full J experience. I will say that I don't think this humbucking J design quite gives me that idyllic J snap and growl/burp-ish kinda stuff when you're down attacking at the bridge.
Oof. Hope you like this book.
With my experience so far, I definitely wouldn't yank out a set of Model Js to put in a Relentless set... but I would absolutely yank some stock stuff out of an MIM Fender or even some MIA and drop some Relentless Js in there.
Charvel needs to do an updated San Dimas line with the Relentless pickups. My ONLY BEEF with ALL the Relentless stuff is that they are NICKEL, and not chrome. Really hard to match hardware to them, as most good bridges (Hipshot, Babicz, etc) have more chrome options than nickel. Tuners, knobs, strap buttons, etc... Chrome options outnumber nickel like 10 to 1 or worse. I also simply prefer the bluish of chrome to the yellowish of nickel.
….Yeah pass lol
