Most patches don't sound like the real 808/909, because they need some/much
more tweaking. Feel free to improve the patches.
I'm now trying to decipher the original schematics of the TR-909, my aim is to
write a separate 909 softsynth (clone), because Alsa Modular Synth is too
limiting (difficult/impossible to create drum maps, difficult to handle
multiple instances of AMS, etc)