[sdiy] simple "level separator"?

[VINTVOLT]

Hi,
I'm in need of a simple circuit that would be used to separate high and 
low
levels from a signal. It's transfer function should be like this:


    ^out
    |         /
    |        /
    |       /1:1
    |      |
    |      |
    |      |
sym  ======---------->in
          thr


where the threshold should be adjustable, so very similar to a noise 
gate,
but without any time constants. It should be instantaneous.
I searched the web, but could not find any simple circit. I thought 
about
using a fet in the audio-path with the gate connected to the output of a
comparator. would that work?

--
Carles Vila Deutschbein
Departament d'Acústica -Engingeria La Salle