Music Man sound and pickups
I feel there are 3 main attributes that contribute to the tone of a Music Man.
1. The larger humbucking (or dual coil) style pickup
2. The ‘sweet spot’ placing of that pickup
3. The EBMM preamp
I am a retired electronics technician, two degrees and over 50 years experience modifying basses and amps. I have also been playing bass for over 50 years. The bass I have owned the longest is a 1977 Stingray. My most recent purchase is a 2020 BFR Stingray Special fretless 5 string.
To fill the gap left by companies who used to market versions of the original pre-EB Stingray preamp, I had circuit boards professionally made and use high quality components, including a clone of the original (60+ year old) 4250 opamp. I sell these preamps on the usual sites, including the Talkbass classifieds.
The old 2-band preamp is unique. As Tony P accurately described above, the sound comes from the combination of pickup and preamp. One or the other will NOT do the job. Leo designed the pickup/preamp combination by trial and error, which explains why the controls have no center detent and why some people think the preamp only provides boost. I go into more detail and explain all this in my ad for the preamp.
I specialize, mostly for fun and some minor profit, in upgrading Sterling by MusicMan (SBMM) Ray4 and Ray5 basses by upgrading the pickup and preamp, defretting the bass, and "murdering" them by changing the chrome hardware to black. I generally defret the bass because there are no high quality fretless MM-style basses under $600. Depending upon model and style, I usually resell these for anywhere between $499 and $599. I sell the preamp, fully wired and tested, with all controls and battery clip for $99 (free shipping).
I started doing this because my own 2013 Ray4 was light and fun to play, but had awful tone. The pickup was WAY too hot and the preamp prone to distortion. Replacing pickup and preamp turned it into a great sounding, great playing bass.
A while ago, LowEndLobster, my favorite YouTube bass reviewer, had a shootout to determine which drop-in replacement pickup recreated the sound of the original Stingray Alnico pickup most accurately. He came up with two, and I have since found another one.
He found, and I completely agree, that the two best are the Aguilar 4M (for Ray4s) and the Nordstrand MM4.2 (Ray4s) and 5.2 (Ray5s). Recently Guitar Fetish got their excellent KP - GFS MM Pro Plus pickup (Ray4s only) with Alnico magnet which comes in at $38 plus shipping, less than half the cost of either the Aguilar and Nordstrand.
I have been doing these mods in one form or another since 2013 and have had nothing but excellent reviews.
I will be glad to answer any questions on any of these things. Just PM me. - Bud