quadrature audio

[Sean Costello]

Martin Czech wrote:
> 
> By the way:
> 
> what could be usefull applications for a wideband audio quadrature
> circuit?  Ie. a circuit that offers some delayed versions of the input
> and where the outputs have (allmost) 90 DEG phase difference?
> 
> So far I only know about one application : Single Sideband Modulation
> a la Weaver.

Hilbert transformers (i.e. wideband audio quadrature circuits) have also
been used for producing more accurate amplitude followers. Bernie
Hutchins has also used them in a pitch-extracting scheme, in one of the
later Electronotes. There are probably lots of other uses we haven't
figured out yet. 

Sean Costello (who finally made that Weaver-style frequency shifter in
Csound, and WOW! it sounds GREAT!!!!!!!)