So here's an interesting analysis - what's actually happening with the "gain boost" (formerly "bass boost") push-push on the 2019 Music Man Stingray Short-scale? In playing with it at the store, I arrived at the conclusion that the best description for what it does is "in the down position, it's the 'sounds like a stingray' setting. In the up position, it's the "MORE." setting."
After playing around with it some more with my Ampeg BA-108v2 practice amp, I realized I've heard the effect before - I made a high-pass box to help with biamping between a bass rig and a guitar amp that cuts at 200hz. I believe my parts for that included an 8K resistor, but I don't know for sure... I just know I calculated what to throw together based on what's in my crap drawer. Anyway, I figured "there's probably an RC network in here and they probably set it up so that the down position does actually sound close to a standard two-band Stingray with the controls flat" I'm surprised to see something a bit more complicated than that on the circuit board, but we'll start with what I did get right - the RC network on the right side of the board. The components are marked RBST and CBST - presumably Resistor BooST and Capacitor BooST respectively, as they're attached to the push-push. The resistor is 15K, which if my memory from a while ago is correct, would filter below about 105Hz if connected to a .1uF cap. .047 puts it closer to 225Hz. (aside: 15K is quite a high load, which is why the output drops significantly when the circuit is engaged. Solid state preamps seem to be finicky about this and will give a huge difference in output volume, while tube preamps seem to be much more forgiving in dealing with the extra signal) The spec sheet for the instrument says that the tone pot uses a .1uF cap, which is marked out on the left side. There has to be a significant difference between the two values, otherwise in engaged mode with the tone knob turned down, all signal would go away (which is what happens if you use the strangle switch on a Bass VI along with the tone knob).
I haven't done any further reverse engineering as I'm not interested in taking apart a brand new instrument, but it does make me wonder if a similar tactic couldn't be applied to the Mustang PJ to get a "sounds like a P-bass" mode. I may experiment with this on an external breadboard just to see what happens; that could be a cool pedal project someday, though, as it doesn't particularly need to be inside the instrument to work correctly, and I'm not interested in changing out the JINSUNG marked pots in there, as they feel really good, while push-push and push-pull pots decidedly do not.
It also probably would have made a great restraining circuit for the DiMarzio Model P+J set I had in my short scale Jaguar bass, but those pickups ended up back in their box as I decided the push-push pots were too awful for me to continue using.
Hey uh... CTS? Yeah, CTS... you guys want to make some decent-feeling switching pots?
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