From obxwindsurf@yahoo.com Mon Oct 13 08:09:37 2003
Subject:Re: Leslie Mics

Since the shape of the lower rotor and thus the bass is not as
directional as the horn and the treble, the lower rotor has less of
an FM (frequency modulation) component - although it's there - than
an AM (amplitude modulation) component which is more dominant.

Contrast that with the horn which has both an AM and FM component
which pretty much coincide unless you remove the diffusers. When you
do that the apparent position of the sound source moves from the bell
down into the throat of the driver inversely with frequency.

The audible effect in this case has been described as "beaming".
Thus the horn in the non-diffuser configuration has more of an AM
component (or content in the context of the message in question)
which becomes dominant.

Regards,
Kevin

>
> what is the AM content?
>