Wow - tough one, but I'll try. Single coil is the easiest to describe; the pickup is in the 'Ray position and it's the bridge side that is active in single coil mode, so it pretty much sounds like a hyped up J bass bridge pickup. The Big Single is (imo) pretty much "more" of everything that a standard J single coil pickup brings. Parallel is basically Stingray. Kinda scooped with plenty of lows and highs. The ebony board probably adds some brightness, but you can tell the pickup ain't hurting in that department either. Series is bigger and bolder than Parallel, with more mids and less extended high end. Kind of angry sounding if that makes any sense, but the overall bridge positioning/fretless thing makes for a good amount of growl as well. More gain in Series too, so I have to roll volume a hair down to match parallel or single coil.
Does any of that make any sense?
Describing parallel and series is where I don't have an equivalent.
I'll grab my Stingray to A/B to the $$, and yeah the BMs are really big in everyway. There is a bite to the BM, with definition that is very complex bc there's so much of it.
The Ray is easy, you know what they sound like.
The $$ I'm using both BMs a lot.
Take it into a gear shop and everyone looks over like "*** is that?".
Parallel is nice, I specifically wandered into a place that had an old Mesa 215 with EV 15l's. I used the new Fender tube head and a Genzler 800. The 90's warm mid thing was there. Big attack was there when I switched heads.
I tried out a heritage 810 with a GK fusion 500 and an SVT heritage in series. Holy rock explosion. Series is loud and satisfyingly scooped. It's an Alnico pair of pickups so the permanent edgy ceramic sound that's hard to shape isn't a problem.
BMs have made amp and cab matching more of a priority.
I'm trying to find the edge of them, bc they seem to have a way higher toque curve than what I've used or installed in the past.
People talk about passive pickups having essentially unlimited headroom compared to an active setup.
Well, I might have to go try a poweramp and see how deep the BMs can dig before they flatten out.
I already know that in parallel the "gobs of golden compression" thing is the richest and most complex I've tried so far.