← Revision 7 as of 2021-04-26 22:15:17
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Rhythm Wolf Snare Drum
This is very similar to the 808 snare (can't compare the pinged filters too much without the capacitor values), except the noise VCA is a common base amplifier stage, which doesn't work at all. The envelope pretty much acts as a gate for 90% of the time, and then does decay for the last 10%. Also, this topology has a higher voltage to operate since the emitter is higher (they could have biased it to -12V to eliminate this), so the envelope cuts out sooner for lower accent levels. Its close to twice as long between low and high accents. It would be pretty straightforward to convert this back to an 808 style VCA.
I didn't mod this part too heavily, mostly because i was running out of steam on this project. I set it back to mostly an 808 style snare.
- Removed C82 and jumpered from the noise source side pad to the Q24 base with a 33nF capacitor.
- Removed R182 and C96, which makes it the standard VCA.
- Changed R157 to 100ohms.
- Changed R47 (typo on schematic - shown as R147) to 12k to make the decay not shut the noise off completely.