Filter Frequency Modulation

[Harry Bissell]

When you say "FM" modulation from an Audio signal... that can mean several
things...

1) You CAN route audio signals (preamplified and possibly filtered if you
like) to CV inputs... the effect is like "cross-modulation" or "ring
modulation"

(Disclaimer : Math Types... I know this isn't correct... I'm referring to
what synth maunfacturers have called this as a trade name... not the
physical principle)

2) If you take the Amplitude envelope from the audio, you can get auto-wah
Mutron III type effects.

3) If you break the audio into many bands first, take the amplitude of each
band and control a separate filter... Its a Vocoder

4) An audio to CV converter could convert Amplitude to CV (envelope
follower) or
Frequency to CV (aka Pitch to CV)...  or harmonic structure to CV (the heart
of the Vocoder).

There are many Amplitude converters... There are a few Pitch converters

(ahem... including the NOT SOLD OUT ... PV-1 ptich to voltage converter
designed by
(ahem) ...me from a Bob Moog design used by permission....  enquire to
efm at xavax.com.  or contact me and I'll fill you in on what it does and
doesn't...)

Hope this helps you warp your Wayne Newton records you twisted puppy...
H^)  harry


Rob Rickner wrote:

> I'm building a few of Tomg's filters and I'm wondering if I can add FM
> modulation from an audio signal to replace a CV input.  Also would it be
> possible to do one big audio to CV converter that I could build one of
> and use to modulate anything I wanted to.
> Rob Rickner