[sdiy] simple nasty clipping?

[Harry Bissell Jr]

> This might be a dumb question, but most of the
> schemos are built
> around a single +9V supply; if they'd be modified to
> accomodate
> the usual +-12V or +-15V of a modular, would the
> sound effects
> remain unchanged ?
> 
> Thanks,
> JB
> 

They would be different, but in most cases not
terribly
so.  All 9V effects have some form of biasing to get
bipolar (AC) signals to pass through. Usually this is
a
4.5V bias point... in effect (lol) the circuit is
running on a +/-4.5V supply.

This pseudo-ground requires a lot of coupling caps
which
introduce frequency response variations of their own.
In
some poorly designed circuits the pseudo-ground is
less so than others, these might have ghostly
interactions between stages that could color the sound
as well.

You could always generate the 9V from +15V and ground
with a simple regulator and the sound should be the
same.

Or you could make the 4.5V supply = ground and make
ground = -15V and +9 = +15V... and eliminate a bunch
of
extra components...

One more point - some effects suffer (benefit) from
the
saggy power supply of a dying battery... you might
need to allow for this as well...

H^) harry