Archive of the former Yahoo!Groups mailing list: MOTM

A lot of early analog drum circuits used cheapie filters with high
resonance. The effect you're describing is a damped oscillation caused by
the filter 'ringing,' and by tweaking the filter component values, you can
get all sorts of drum sounds.

I think PAIA had/has a board that lets you play with this kind of thing.


-----Original Message-----

For drums, the TR-808 uses a "bridged T-network" in order to create a
waveform similar to an oscillator decaying in amplitude. Rather than using
the trigger to trigger EG's controlling separate VCO's and VCA's as in the
606 and 909, it seems the trigger itself is transformed into the sound. In
my limited understanding, it's like a VCO that runs out of steam. Like the
skin of a drum, it oscillates after being hit, then tapers off into
silence. For the 808 toms, this circuit is modified with diodes such that
the frequency decays as well. Perhaps this technology could be rolled into
a MOTM module with increased flexibility such that it could produce more
than just drum sounds.