The best mods to do on a NYC RI IMO is to swap the 3 470pF caps to 100pF and add a tone bypass switch. Takes about 15 minutes, costs about $3. As a result it really opens up the muff, you can gain a ton of volume in bypass mode and it just sounds better in regular mode IMO with more definition.

hi everyone
i just found this old thread cause i recently bought a supposed-not-to-be-working nyc 3003 muff which turned out to be 100% functionnal and decided to try to modify the hell out of it.
i spent a good deal of time online, trying to find what does what, found kitrae’s review on all the different circuits and clones + list of mods (and tried a few), found lots of different sites and thread proposing pretty much always the same stuff (mentionned above) and didn’t quite found “it”.

so far, i tried jack orman’s version 2 of the AMZ tone control, bypassed emitter resistor of clipper #2 stage, replaced the first pair of diodes with ultrabright LEDs and the second pair with standard red LEDs.
i tried asymetrical clipping with 1 LED and 1 stock diode but it didn’t sound any different. i didn’t try germanium diodes since i read that the smaller Vr, the more compressed the muff.
it opened the sound, made it much less compressed and brighter (which is what i was looking for) but i’m still looking for something “different”, something wild and crazy.
i also tried the feedback mods on kitrae’s list, just made the pedal buzz.

i wanted to replace the tone section with a 3-band baxandall active eq but didn’t find any satisfying circuit so far, most of the circuits are for bass and treble only, and nowhere i can find how to design a circuit with my own frequencies and Qs. i could use the Xotic RC booster’s tone section with added mid control if i knew how to calculate the values, for instance.

i was thinking of changing the 3 470pF caps in the feedback of the first three stages but i’m not sure it will take me a lot further.

i’ve been a DIYist for a few years now so i can solder well, but everything i learnt at the college i lost with the years of not practicing, so i’m absolutely not able to take a circuit and find mods myself because i probably won’t understand anything i’m doing, so i’m asking you guys if you would know of a site/page/thread somewhere where i could find ideas to wilderness.
i’m not specially looking for ready-made mods, but hints or explanations of what such changes would do.
i want to learn but i need a little push, i believe.

if anyone has any idea, i would be happy to hear and discuss it
cheers