[sdiy] Chorus unit

[Mike I.]

Hi Paul,
Take a look at the Korg Polysix schematics - the board labelled KLM-368 
is a fairly standard (but well-implemented) 3-phase chorus complete with 
companders. It can be operated in chorus - "phase" - ensemble modes. The 
typical 3-phase ensemble circuit uses 3 parallel BBD's - left output is 
composed of BBD1 out + BBD 2 out, while right output is composed of BBD 
2 out + BBD 3 out. The direct signal is not mixed in. Some Roland stereo 
choruses use two parallel BBD's, BBD 1 out going to left, BBD 2 out 
going to right, again, with no direct signal. Simple one BBD choruses 
such as the CE-1 produce a pseudo-stereo output by feeding the direct 
signal to one output, and the delayed signal to the other output. 
Another possibility is to use the sum and difference technique used in 
phasers.
Mike