[sdiy] amateur question about modifying the ms-20 ota filter

Roman Sowa modular at go2.pl
Mon Dec 12 12:17:06 CET 2022


Try replacing 10k in emitter followers with 1k

Roman

W dniu 2022-12-12 o 11:14, Emily Straight via Synth-diy pisze:
> i'm tweaking the rene schmitz <https://www.schmitzbits.de/ms20.html> 
> implementation of the ms-20 filter for a project, and i was hoping to 
> use the emitter followers on the 13700 rather than separate op amps if 
> possible, it seems, like, vaguely wasteful not to or something. in 
> simulation this is resulting in killing the resonance on the negative 
> side of the waveform, however. is this because of a mistake i made 
> setting it up, or is the 13700 buffer fundamentally unsuited for the 
> purpose? i found one schematic 
> <https://aisynthesis.com/wp-content/uploads/2020/05/MS20v2.5.pdf> that 
> appears to do the same thing so i'm guessing the former, though idk 
> maybe theirs sucks too lol. i also put a vca in the feedback path rather 
> than a potentiometer, maybe that's causing problems? i have essentially 
> zero experience in analog electronics if you couldn't tell
> 
> thanks <3
> -emily
> 
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