http://www.guitarboomer.com/2008/04/how-to-choose-correct-signal-chain.htmli found this with a quick search. i have always heard 'before everything else, after a wah ONLY'. the reasoning is supposed to be that the germanium or silicon transistor in a fuzz doesn't like buffers.
i don't use a lot of pedals usually. when i use my fuzz face, i find that any pedal i have got anywhere around the dang thing changes its sound. so i use it by itself. this seems to be more prevalent with tube amps than digital...and i scratch my head. i dunno.
i think, given the variety of manufacturing methods, range of 'acceptability' (not iso 9000, i think) in components and general 'on the ground' changes for every guitarist, guitar, amp and cable....everything is somewhat subjective about fuzz. one 'too long with the soldering gun on one connection', and everything changes in the line. do they do a qa check on the finished product at dunlop or fulltone? i dunno....
if they aren't using a scope, but just their ears, does that count as a random qa check? no, guai lo...throw it in the box and ship it to dam yankees! (i think that's what i would hear in china on the manufacturing floor, eh?)
and deming taught these people using our money, too. they are doing a lot better, so i have my tongue in my cheek some.
