Hello, today I looked at the circuit for the Analogic Logic modules.
Here are my first impressions, in order:
1) Cool idea, but won't the signal be distorted because the diodes are
exponential amplifiers?
2) Ah right, the diode in the feedback path takes care of that.
3) Wait, the feedback loop won't do the exact same thing as the signal path.
I fully understand the rationale behind the -/+10 V virtual reference
points that are used with the 100k pull resistors to keep the circuit
in a neutral state when nothing is connected. What I don't understand
however is why the resistor on the feedback side of each element is
chosen to be 100k and connected to the same -/+10 V. I'm assuming that
if you wanted the least possible distorsion, you'd go for a 10k
resistor connected to -/+ 15 V, to come as close as you can to the
connection on the summing bus.
Of course I'm sure the current design is "good enough", especially for
CV (Although I'm planning to use this module for audiorate signals as
well) but isn't my suggestion slightly more "correct"?
If I'll build this module, I'll build it the way I described. If
there's a really good reason not to, let me know.
/Ove
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Here are my first impressions, in order:
1) Cool idea, but won't the signal be distorted because the diodes are
exponential amplifiers?
2) Ah right, the diode in the feedback path takes care of that.
3) Wait, the feedback loop won't do the exact same thing as the signal path.
I fully understand the rationale behind the -/+10 V virtual reference
points that are used with the 100k pull resistors to keep the circuit
in a neutral state when nothing is connected. What I don't understand
however is why the resistor on the feedback side of each element is
chosen to be 100k and connected to the same -/+10 V. I'm assuming that
if you wanted the least possible distorsion, you'd go for a 10k
resistor connected to -/+ 15 V, to come as close as you can to the
connection on the summing bus.
Of course I'm sure the current design is "good enough", especially for
CV (Although I'm planning to use this module for audiorate signals as
well) but isn't my suggestion slightly more "correct"?
If I'll build this module, I'll build it the way I described. If
there's a really good reason not to, let me know.
/Ove
-----BEGIN 2ROT13 MESSAGE-----
Low Bitrate Netlabel: <http://flb.gg8.se/>
Blog:
<http://gameboygenius.8bitcollective.com/>
SKRIVA på Lysator. Ditt Ahrvid-fria alternativ:
<http://lists.lysator.liu.se/mailman/listinfo/korkek?SKRIVA?>
Sätt på ett par flipflops, vippa på rumpan
och gör det här till en minnesvärd sommar!
-----END 2ROT13 MESSAGE-----