Why do some Fuzz pedals increase sutain whene not on the bridge pup?

[PurpleStrat]

Is this an impedence thing with the pedal or guitar? Some pedals don't change but some do in a big way. Take the Bazz Fuzz as an example. It sounds much better when not played on the bride pup. I have found when bread boarding that even if a Fuzz is not biased right and cuts out or decays on the lower strings it seems to do better when not using the bridge pup.

I mainly use single coils, Start and Tele's. I could also use any links to good articles on inpendence in guitar and pedals!

[John Lyons]

Bridge PU = more bass and a stronger signal. More string movement etc etc.
The more signal the more gain, more compression, more sustain.
Lower the neck and or middle pickup and it will balance this out with the bridge PU.

john

[PurpleStrat]

Bridge PU = more bass and a stronger signal. More string movement etc etc.
The more signal the more gain, more compression, more sustain.
Lower the neck and or middle pickup and it will balance this out with the bridge PU.

john

So it's just a matter of positioning not inpendence or anything? I notice some pedals don't change much but some do.

[Mark Hammer]

What we hear as fuzz is as much a function of time as it is of level.

Huh?

What your guitar provides as fuel/fodder for a distortion pedal is the sum total of the fundamental and the various harmonics produced by the string and sensed by the pickup.  The most harmonic information is provided at the outset of the note, and very quickly thereafter, your signal consists principally of the fundamental and a few small lower-order ahrmonic components as the string vibrations die out. 

The question you have to ask is "For what period of that note's entire 'lifespan' will the signal be at or above the needed level to generate clipping in the pedal?".  The answer is usually that this critical period will be longer at the neck pickup than at the bridge pickup simply because the string wiggles more near its middle and generates a higher amplitude signal.  This is the very reason why you will see "matched" or "balanced" sets of pickups that wind the bridge  PU hotter than the neck - to compensate for their inherent difference in signal strength.

The illusion of sustain arises because the neck pickup continues to be at the clipping threshold for a longer period of time than the bridge pickup.  For as long as it is clipping it seems tobe at the same constant volume, hence "sustaining".

[PurpleStrat]

Here I was thinking it was something more technical! Thanks guys!