Sidni writes –
Dr. Aaron Lanterman of Georgia Tech covers the analysis of several modules used in analog modular synthesis as well as digital synthesis techniques. All lectures posted online for free!
Definitely a class that would’ve greatly increased my interest in math back in school – very cool!
Just take a look at homework assignment #1 –
Moog (east coast) and Buchla (west coat) developed their ideas about voltage controlled synthesizers independently. Moog used a pitch control standof of 1 volt/octave, which works out to 0.08333… volts/semitone (the pitch difference between to adjacent notes on the piano is a semitone; there are twelve semitones per octave). Buchla preferred to use 0.1 volts/semitone, which works out to 1.2 volts/octave.
Hence, if to try to directly drive a Moog oscillator from a Buchla pitch control source, or vice-versa, everything will be horribly out of tune.
a) Design an circuit with a single op amp that will covert pitch control voltages from the Moog standard to the Buchla standard. You may assume that your conversion module is given an input from a voltage source with zero output impedance and is being fed to a module with an infinite input impedance; you also do not need worry about input and output protection (assume nobody will be abusing your module). For this part of the exercise, assume you have perfect “zero-tolerance” resistors.
b) Off-the-shelf resistors never exactly match their listed values. Let’s do a “worst case” analysis for the case where your circuit is given a one volt input. If you use 5% resistors, assuming the true resistance is uniformly distributed, what is the highest voltage you might get out? What is the lowest voltage? How many semitones above and below the desired value are these voltages in the Buchla pitch standard?
c) Repeat the above analysis for 1% resistors.
Head over to the site to take the course yourself (well, virtually at least) – Electronics for Music Synthesis