[sdiy] I need a 909 kick circuit analysis

[TooManySynths]

Hi All,

Rofs site was linked in several places but the links
were broken and it didn't show up on search engines.
That was EXACTLY What I was looking for.

>From that site, I gather that there is nothing really
special in the 909 circuit.  It is a triangle wave VCO
converted into a sine wave (plus click). What I mean,
is, there is nothing like in the 808 where filter
points are changed on the fly.   The detail and
significance of the 909 sound really comes from the
flat topped vca envelope and the VCO sync.  I would
guess that the sloped attack on the "Attack" sound
envelope also contributes to the quality of the sound.
This gives me several new ideas for modifying the
TS306 kick sound.  Although several people on AH claim
the Techstars do a good job of emulating the 909 kick,
I don't really think they do.  The VCA envelope in the
TS doesn't have that nice flat top, nor do they sync
the VCO.  Both of these items can be added to the TS
with just a few passive components, however, and with
the additional controls on the TS, you will have a
very nice kick drum generator indeed.  

Thanks
Daryl



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