active/passive volume & controller pedal

[Michael Tuminello <m1cha3l@earthlink.net>]

Hi -

one more question for the collective musical overmind known as
Loopers-Delight.  well, maybe 3.

What is the difference between a passive and active volume pedal.   I heard
one goes before effects and one after, or somethign like that, but the
passive one is described in Musician's Friend as if it is only meant for
keyboard.

Does a volume pedal work as a controller/expression pedal generally, or is
that a separate thing altogether (and in which case why do I never see any
in the catalogs).  I need a controller for midi parameter change with my QV
GT.

third, and final (for now) question - anyone recommend a nice stageworthy
tuner.  Is that boss pedal tuner any good?

Thanks,

MT