[sdiy] I need a 909 kick circuit analysis

[Dave Magnuson]

I highly recommend you look here:

http://members.tripod.de/raf909/bassdrum.htm

this is the circuit description for the kick... all the other analog
portions are here as well.

Dave Magnuson




At 06:11 AM 9/9/01 -0700, you wrote:
>Hi All,
>
>I looked through the archives and I can't seem to find
>much detail on the 909 kick.  I have a schematic of
>the kick (sidenote, none of the 909 schematics links
>work, are they on line somewhere?) and I'm trying to
>make some sense of it.
>
>In  particular, how is the VCO working, and what is
>the role of Q11? I see that it bridges C4 with R51 on
>what appears to be the start of the trigger. I'm
>assuming the trigger is a positive going pulse.  Also
>is the "Attack" circuit simmilar to other drum synths.
> What I mean is, I see that they are injecting noise
>into the "Attack" circuit, does "Attack" just control
>the level of a noise blip.  I haven't touched my 909
>in a while and it's not sitting in front of me.
>
>Any general explanation of the various components of
>the 909 kick would be appreciated.
>
>Thanks
>Daryl
>
>
>
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Resonant Frequency:
resfreq at hoohahrecords.com
http://www.hoohahrecords.com/resfreq/index.html