ECE4893A: Analog Circuits for Music Synthesis (Spring 2015)

ECE4893A: Analog Circuits for Music Synthesis (Spring 2015)

Analog Circuits for Music Synthesis (Spring 2016)

When: TuTh 1:35-2:55 PM;
Where: Van Leer 241C

Instructor: Aaron

Office: Van Leer W431
Phone: 404-385-2548 (but it’s better to try reaching me through
(the best way to reach me; please include “ACMS”
somewhere in the subject of class-related
e-mail so I can find it quickly)

Classroom decorum:
In general, please do not instant message, websurf, Facebook (can I use
it as a verb?), e-mail, play games, etc. during class. It can be quite
distracting. Unless told otherwise, the preferred position for laptops
during class is in your backpack.
The Twitter exception: If
Prof. Lanterman says something particularly brilliant
and clever during lecture, you are allowed to use your phone to Tweet it
and/or post it to Facebook.

Course description: Circuits from classic analog synthesizers:
voltage-controlled oscillators, filters, and amplifiers;
nonlinear waveshapers.
Operational transconductance amplifiers. Exploitation of dynamic resistance
of semiconductors. Hands-on projects.
Prerequisites: (ECE3043
or ECE3741) and ECE3084.
Basically, you need some
familiarity with op amps, diodes, transistors, poles and zeros of
transfer functions, frequency response, and you need to know how to use
a scope.

Website for previous offering:
ACMS (Spring 2015)
will help give you a feel for what the class is like

Aaron’s SDIY Pages

  • Synth
    DIY Datasheet and Ap Note Collection
  • Music synthesis
    patents collection
    , with some brief commentary

  • Current
    modular synth manufacturers
    – look through these to get ideas for your
    own new designs, ideas for packaging, etc.<!–


    • Homework 1 (due Thursday, Jan. 29,
      at the start of class)
    • Homework 2 (due Tuesday, Feb. 10, at
      the start of class)
    • Homework 3 (due Tuesday, Feb. 24, at
      the start of class)
    • Homework 4 (due Friday, March 13, at
      4:30 PM)
    • Homework 5 (due Tuesday, April 14, at
      7:30 PM)



    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.


  • –>


    We will draw material from numerous sources: book, articles, patents,
    and particularly schematics and descriptions posted on websites. Think of
    google as the main class text. Here’s some
    good ones:

  • Hal Chamberlin, Musical Applications of Microprocessors, 2nd
    Edition, Hayden, 1982.
    Although it has
    “microprocessors” in the title, it has a superb section on analog circuits.
    NOS (New Old Stock – meaning old, but unused) copies are available for
    purchase from
    Jeff Dec ($50 + shipping)
  • Barry Klein, Electronic Music Circuits, SAM, 1982. Long out
    of print, but photocopies can be purchased directly from
  • V. Valimaki and A. Huovilainen,
    Oscillator and Filter Algorithms for Virtual
    Analog Synthesis
    , Computer Music Journal, Vol. 30, No. 2, 2006,
    pp. 19-31.
  • T. Stilson,
    Efficiently-Variable Non-Oversampled Algorithms in Virtual-Analog
    Music Synthesis
    , PhD Thesis, Standford University, June 2006.


    Final letter grades
    will be based on a series of written homeworks,
    two in-class quizzes, and
    the quality of a final project in
    which you will design and build a module for a modular synthesizer. The
    final project will permit (and encourage) you to make extensive use of
    various existing schematics you might find on the web, in textbooks, or
    elsewhere. Details about the final project will be posted at a later date.
    A project “team” may consist of 1 or 2 students.
    class this semester is much larger than it has been in the past,
    so I may allow teams of 2 or 3 people. Projects with two people
    will be
    expected to be somewhat more ambitious than projects with smaller teams.

    The homeworks
    are intended to be instructive and enlightening, and in particular
    get you looking at schematics of real synthesizers that have been
    in production
    , and not “textbook” problems. I try to avoid giving
    anything resembling “busywork.”

    <!–The labs will be brief (less than an hour), fun, and not
    have lengthy 3041/3042 style reporting requirements. We will not do many
    of these; probably just two, or three at the most. They will be intended
    to help you get your “feet wet,” so you will have some more hand-on hardware
    experience before jumping into the final project. (Previous versions of
    the class just had the final project without any earlier labs. One of the
    most common suggestions I received from students was to put in some small
    lab components earlier in the semester
    so students would feel more confident going into the final
    project.) –>
    The first quiz
    will be given about 1/3
    through the class, and the second will be given about 2/3 of the way through
    the class. Both will be closed book. The first quiz
    will focus on basic
    facts about circuits and electronic facts that a designer needs to have
    “at their fingertips,” without having to stop and look up, in order facilitate
    a smooth creative workflow. I will provide extremely detailed
    information about
    what I will ask on that quiz. The second quiz will probe what kind of
    intuition you have developed concerning the class material; the
    questions will be more qualitative in nature (for instance: if the value
    of resistor X is increased, will the frequency of this oscillator go up
    or down?), in the sense that they will not require tedious calculations with
    precise numeric results.
    (I used to do
    only one quiz, but, curiously enough, students told me
    I should give more quizzes!) There will be no usual written final exam given
    during final exam week.

    I consider the final project
    to be the most important thing in the class;
    hence, your course grade will max out at whatever your project grade
    e.g., if you do B work on the homeworks, etc., but turn in an A project,
    you might get an A for the class, or you might get a B;
    but if you do A work on everything else but turn in B level project,
    your grade won’t be an A.

    I will work with you very closely in helping you
    with your final project. By the end of the semester, I will have a pretty
    accurate feel for what concepts you understand and what concepts you

    T-square usage:
    In spite of its awfulness, I will use T-square for posting grades.

    Honor code:
    This course will be conducted under the rules and guidelines of the Georgia
    Tech Honor Code; infractions will be reported to the Dean of Students. The
    “ground rules” for each assignment, which may vary from assignment to
    assignment, will be given in each assignment description. Please ask
    for clarification if any
    aspects of the given “ground rules” seem unclear.

    Major emergencies:
    If you have some sort of major life emergency – serious illness or injury,
    death in the family, house burns down or is flooded, etc. – that seriously
    impedes your progress in the class, please let me know as soon as possible so
    we can work something out. You will find professors can be quite reasonable
    if you keep us in the loop. Please don’t disappear with no warning half way
    through, making me think that you dropped the class, and then reappear out of
    nowhere the week before finals asking what you can do to make things up.
    (Yes, this has happened quite a bit, in both undergrad and grad classes.)

    Topical Outline

    • Historical perspective
    • Demonstration of a modular synthesizer
    • Circuit theory review (emphasis on operational amplifiers)
    • Operational transconductance amplifiers (OTAs)
      • Voltage-controlled amplifiers
      • Linear current sources
    • Voltage-controlled oscillators
      • Sawtooth cores (comparators with resettable integrators)
      • Triangle cores (comparators and integrators with current switches)
      • Temperature-compensated exponential current sources
      • Basic waveshaping circuits
      • Complex waveshaping circuits for generating time-varying spectra
    • Voltage controlled filters (VCFs)
      • Single-pole OTA-C VCFs (resistor replacement and “systems” viewpoints)
      • Four-pole VCFs with feedback (pole migration and resonance peaks)
      • Transistor-ladder and diode-ladder VCFs (dynamic resistance)
      • Second-order filter properties
      • State-variable VCFs
      • Sallen-Key VCFs