mick, are you the guy that modded that mrbillyhill's pedal? if so, nice job, that thing sounds excellent- very close to the freq response and richness of the nice originals.
either way, here we go:
modding a 100k pot down to 25k via limiting resistors does not do the correct job in a boomer circ. i found this on my own thru hundreds of experiments/measurements, but also had this independently verified by the man who designed the BG2, richard mintz ( he commented on this without any prompting from me as i was asking about other aspects of the boomer).
his exact words about the taper of the original BG2 centralab pots were " they were reverse audio taper, but slightly modified". keep in mind, in the late 60s or early 70s, if gibson, inc asked for a spec; ial pot taper, you as a mfgr would provide said taper. he later told me that the volume pedal or wah function would be compromised if a correct taper pot was not used in that circ, as the biasing and the whole circ was tuned exactly for that pot spec. he also said that the original centralabs would vary from 22k up to 28k. every vintage unit i have tested hits very near 30k with original pot.
i think the stagg might be similar to the washsburn/lyons wah unit i have here. however, it had a similar gear mech to a crybaby, so there may have been different versions. the pot in that thing looked like cheap chinese crap, i would not have trusted it for a gig, even if the the gig was only one song long. (every chinese 25mm pot i have seen made for wah is short life, including propot, the recent dunlop chinese made wahs, etc etc.)
to your Q about a standard 25k audio doing the job, if you do this, go back to the crybaby rotation, this will be more correct to the original sweep direction.
just saw the pics of your re-work. very nice. unfortunately, that pot looks like one of he ones that will last about 4 to 7 songs before going scratchy. hop i am wrong tho.
paul, no, just switching the direction of the pot by changing wiring does not do it. mick was correct in actually physically making this pot go the other way. in my experiments, the hump is totally in the wrong place if simply reversing the wiring, hence the dozens of hours making 'cam gears' to make hotpotz sound correct in these ( 33k limiting Rs included). we got close, but when zac came over and watched my foot movement and listened to the frequencies, " close" was still not as good as a real 72 boomerang we were AB'ing to. i have a vid showing this. will post it.