ACMS Lectures

Spring 2018

Since this is a lecture/lab class, I will only lecture for 2/3 of the class periods, and that lecturing will mostly be “front loaded,” i.e. I will lecture for the first 2/3 of the class, and the last 1/3 of the class you will be just working on your final projects, with me dropping by the lab to help out as much as I can. Any time we are not having class (for whatever reason) you should be thinking about or working on your projects.

• 1/8: Campus closed; class cancelled due snow
• 1/10, Session 1: 50 Years of Music Synthesis, Part 1
• 1/12, Session 2: 50 Years of Music Synthesis, Part 2
• 1/15, Martin Luther King holiday
• 1/17, Campus classed; class cancelled due to snow
• 1/19, Session 3: Demo of a Modular
• 1/22, Session 4: Review of Op-Amp Circuits
• 1/24, Session 5: Operational Transconductance Amplifiers, VCAs
• 1/26, Session 6: OTA Internals, Linear Voltage-to-Current Converters
• 1/29, Session 7: Sawtooth Core VCOs
• 1/31, Session 8: Exponential Voltage-to-Current Converters
  • A tutorial on exponential convertors and temperature compensation, by Rene Schmitz (this is the description my lecture was based on)
  • Tempo Equations, by Ian Fritz (a much more detailed analysis)
• 2/1, Session 9: Triangle Core VCOs
  • Buchla 259 Vintage Modular Oscillator youtube demo
  • Buchla 259 schematics, on 4 pages: 1, 2, 3, 4.
  • The Buchla 258 is an older, simpler oscillator with a similar triangle core: 258C, 258A.
  • The new Buchla 261e is quite similar to the Buchla 259. Here’s a youtube demo of the 261e: Simple 261e Melody
  • Buchla 259 vs. 261e Audio Comparisons on electro-music
  • Alessandro Cortini, who used to play synths for Nine Inch Nails, sold his Buchla 259 a while back. Alessandro has been making music on his Buchla 200e system under the name blindoldfreak. I find this piece particularly hypnotic.
• 2/5, Session 10: Simple Waveshaping (Sawtooth-to-Triangle, Triangle-to-Sawtooth, Triangle-to-Sine)
  • Related to circuits discussed in class:
    • R. Williams, Triangle to Sine Conversion with OTAs
    • R.G. Meyer, W.M.C. Sansen, S. Lui, S. Peeters, The Differential Pair as a Triangle-Sine Wave Converter, IEEE J. of Solid-State Circuits, June 1976, pp. 418-420.
    • G. Klein, Accurate Triangle-Sine Converter, IEEE International Solid-State Circuits Conference, Digest of Technical Papers, Volume X, Feb. 1967, pp. 120-121.
  • Other ideas:
    • H. Hassan, FET Differential Amplifier as a Tri-Wave to Sine Converter, Proc. 36th Southeastern Symposium on System Theory, 2004, pp. 427-430.
    • Z. Tang, O. Ishizuka, H. Matsumoto, MOS Triangle-to-Sine Wave Convertor Based on Subthreshold Operation, Electronics Letters, Vol. 26, No. 23, Nov. 8, 1990, pp. 1983-1985.
• 2/7, Session 11: Complex Waveshaping, Part 1
  • Demo: Adaptation of the timbre circuit from the Buchla Music Easel (fun part starts at around 2:20)
  • Page 3 of Buchla 259 schematics, with five “diodeless deadband” circuits
  • Page from the Buchla Music Easel schematics, with five more “diodeless deadband” circuits
• 2/9, Session 12: Complex Waveshaping, Part 2
  • Ken Stone’s page on the Serge Wave Multiplier (see the “middle section“)
  • Ken Stone’s Wave Multiplier (Ken was inspired by Serge, but independently came up with a similar design)
• 2/12, Session 13: Single-Pole OTA-C filter
  • Oberheim/Rossum patent, Circuit for Dynamic Control of Phase Shift
  • ARP patent, Frequency Sensitive Circuit Employing Variable Transconductance Circuit
• 2/14, Session 14: 4-Pole Cascade with Feedback
  • Note that most of the linear analysis on the Moog ladder filter, as presented in papers and webpages listed under Session 16, applies to 4-pole-with-feedback filters built with OTA-C sections. (An analysis of the nonlinearities would show differences.)
• 2/16, Session 15: OTA-C filter examples
  • N-Pole Filter Circuit Having Cascaded Filter Sections – careful, the resonance feedback path drawn on the first page is in error! It should be going to the negative terminal of the first OTA on the left.
• 2/19, Session 16: Transistor & Diode Ladder Filters, Part 1
  • Moog patent, Electronic High-Pass and Low-Pass Filters Employing the Bass to Emitter Diode Resistance of Bipolar Transistors
  • T. Stilson and J. O. Smith, Analyzing the Moog VCF with Considerations for Digital Implementation, Proceedings of the 1996 International Computer Music Conference, pp. 398-401.
  • A. Huovilainen, Non-Linear Digital Implementation of the Moog Ladder Filter, Proc. of the 7th Int. Conf. on Digital Audio Effects (DAFx’04), Naples, Italy, Oct. 5-8, 2004.
  • T.E. Stinchcombe, Analysis of the Moog Transistor Ladder and Derivative Filters, Oct. 25, 2008
  • M. Civolani and F. Fontana, A Nonlinear Digital Model of the EMS VCS3 Voltage-Controlled Filter, Proc. of the 11th Int. Conf. on Digital Audio Effects (DAFx’08), Espoo, Finland, Sept. 1-4, 2008.
  • T.E. Stinchcombe’s page on Diode Ladder Filters
  • T.E. Stinchcombe’s Filter pole animations
• 2/21, Session 17: Transistor & Diode Ladder Filters, Part 2
• 2/23, Session 18: General properties of second-order filters
  • T.E. Stinchcombe’s
    Filter pole animations (see the bottom of the page for second-order examples)
• 2/26, Quiz 1
• 2/28, Session 19: State Variable Filters
  • MIT 2.161 Signal Processing notes, Op-Amp Implementation of Analog Filters (see Section 2)
  • R. Johnson, Programmable State-Variable Filter Design For a Feedback Systems Web-Based Laboratory
  • Daycounter, Inc. Engineering Services, State Variable Filter Design Equations
• 3/2, Session 20: State Variable Filters (examples)
• 3/5, Session 21: Sallen-Key Filters (theory)
• 3/7, Session 22: Sallen-Key Filters (OTA-based examples)
  • T.E. Stinchcombe’s page on The Korg35 Chip, the MS-10 & MS-20 Filters, Clones and Links
  • T.E. Stinchcombe, A Study of the Korg MS10 & MS20 Filters, August 30, 2006
• 3/9, Session 23: Korg MS-20 Demo
• 3/12, Session 24: Buchla Lowpass Gate
  • J. Parker and S. D’Angelo, A Digital Model of the Buchla Lowpass-Gate, Proc. of the 16th Int. Conference on Digital Audio Effects (DAFx-13), Maynooth, Ireland, Sept. 2-5, 2013.
  • Demo: Thomas White’s Buchla Lopass Gate 292 Clone

Old Lecture Videos

“Analog Circuits for Music Synthesis” is the latest name the version of the class I’ve taught since Spring 2015. In previous years it’s gone under names like “Theory and Design of Music Synthesizers” and “Electronics for Music Synthesis.”