MUS206: Hardware Synthesis Syllabus

Hardware Synthesis Syllabus

Topics for Fall 2018

  • Patching and Signals: Control Voltage, Audio, AC, DC, Gates, Triggers (Strange: Chapter 5)
  • Slope, Envelope and LFO (Strange: Chapter 6, Maths Manual – Make Noise Website)
  • Oscillators: Sine, Square, Triangle and Ramp; Sync; Linear & Log Frequency; Vibrato & Gliss; Subharmonics; Additive; Noise; Multiple Oscillators; ASR (Strange: Chapter 3)
  • Amplifiers: Tremolo; Envelope and LFO; Amplitude and Ring Modulation, Envelope Tracking, Types of VCAs (Strange: Chapter 4)
  • Modulation: More Amplitude and Ring Mod, Wave Folding, Frequency Modulation, Chaotic Oscillation, Feedback Networks (Strange: Chapter 7-8)
  • Sequencing and Variation, Structure, Rhythmic Patching, Clocking (Rene Manual – Make Noise Website)
  • Computer Interface: MIDI, Control Voltage, Gates; Recording Material
  • Reverb and Echo; External Processing (Strange: Chapter 12)
  • Musique Concrete Techniques

Readings from Allan Strange: Electronic Music; Make Noise Website

Listening Assignments

Pieces Presented on Week 5 and Week 10

MUS271A (Max w4) – Modulation 1 (Amplitude)

The next two lessons will focus on techniques which involve reshaping waveforms by modulating a simple (often sinusoidal) waveform. These modulation techniques include:

  • Ring Modulation (aka Balanced Modulation, Amplitude Modulation)
  • Waveshaping
  • Frequency Modulation
  • Phase Distortion

Each type of modulation creates a new waveform that has more harmonic content than the original. The modulating oscillator (or modulator) is connected to either the frequency or amplitude of the audible oscillator (or carrier). Varying the amplitude or frequency changes the slope of the carrier waveform continuously, and this creates new harmonics in the resultant waveform. These new harmonics are called sidebands, as they appear on both “sides” of the carrier frequency – both lower and higher.

Ring Modulation

This technique is called ring modulation because of the ring of diodes used in the analog implementation of this technique.

Digitally, the technique is much simpler, one simply needs to multiply the amplitude of the carrier oscillator by the output of the modulating oscillator. Here is a simple example:

Screen Shot 2018-07-16 at 12.50.14 PMThe carrier is at a fairly high frequency (8372 Hz), and the modulator is at 987.8 Hz. Note that the output consists of two harmonics – one is at C – M (~7384) and the other at C + M (~9360 Hz). These two sidebands are created by the sum and difference of the slopes of the two oscillators. The carrier oscillator is completely absent (this is referred to as “carrier suppression”). One can bring back the carrier by adding an offset to the modulating waveform as in the following patch:Screen Shot 2018-07-16 at 1.00.49 PM

Here a signal of value 1.0 is added to the modulating waveform. This signal is multiplied by the carrier. The carrier then appears in the sonogram in the middle of the two sidebands.

Different signals can be used for the carrier or modulator. In this patch a radio button and selector~ object is used to change the modulator waveform. All the harmonics of the Screen Shot 2018-07-16 at 1.14.46 PMmodulator are now applied to the carrier, giving a much denser waveform. For example, choose the 3rd radio button to use a square waveform. Here one can see all of the harmonics of the square wave on either side of the carrier. Also notice that low sideband harmonics wrap-around 0 Hz, and proceed back upward.Screen Shot 2018-07-16 at 1.21.20 PM

 

Most of the time, ring modulation creates rather dissonant or non-harmonic timbres. This can be limited by relating the frequencies of the carrier and modulator by integers or simple ratios. In this example the carrier is 5/3 the frequency of the modulator.

 


Single Sideband Ring Modulation (AKA Frequency Shifting)

With a little more effort the upper or lower sideband from ring modulation can be suppressed. This technique requires a sine and cosine oscillator pair for the modulating oscillator, and a 90 degree phase shifted version of the carrier.
Screen Shot 2018-07-18 at 12.47.10 PMA multiply of sin x sin and cos x cos will create a 180 degree and 0 degree phase shifted components. Adding the two products will leave only the upper sideband. In Max one can use the hilbert~ object to create sin and cos components from any sound source. In this example, a triangle wave is being processed by hilbert~. The frequency of the modulator is the frequency shift of the upper sideband. As the triangle wave is shifted upward, you can hear the harmonics go out of tune, One can also apply SSB ring-modulation/frequency shifting to sound files or live sound sources. At small settings there is still some harmonic integrity, but this soon disappears.

Screen Shot 2018-07-18 at 1.20.47 PMAnother variant of this technique is to use feedback to create a series of harmonics. If the carrier and modulator are related by simple ratios, a consonant timbre is created. Also, as feedback is increased – the gain is increased, so output volume may need to be adjusted to avoid  clipping distortion

 

 

 


Wave Shaping

And speaking of clipping distortion, another form of amplitude processing is wave shaping, a technique in which the original waveform is reshaped by a transfer function. The function is used to map input values to output values and will change the harmonic content of the original waveform.

Screen Shot 2018-07-18 at 3.44.47 PMA very typical transfer function is one which produces clipping when the input reaches a limit. In this transfer function, the input value is mapped to the x-axis, and the output on the y-axis. One can think of the input coming in the bottom of the function and the output proceeding out of the right of the function. You can see that when the input goes above 1.0, the output is clipped to 1.0, and similarly the output is clipped to -1.0 for input signals below -1.0. This transfer function is similar to simple amplifier distortion, much like what you would find in a two transistor fuzz pedal. The clipping in this case will add a great number of harmonics to the input signal (aka harmonic distortion). Also note that a steeper slope will produce gain equivalent to the slope.

MUS174C – Editing and Mixing Assignments

Present rough mix/edit week 7 Tuesday
  • 2A: Kjell Nordeson: Farley, D’Agostini
  • 2B: Mari Kawamura: Greenwood, Hess
  • 3A: Madison Greenstone: Bari, Bahn
  • 3B: Kyle Adam Blair: Jiao, Loree
  • 4A: Ben Rempel:  Richardson, Chumakov
Present rough mix/edit week 7 Thursday
  • 4B: Barbara Byers: Levick, Galang
  • 5A: Tim McNalley: Zamora, Reid
  • 5B: Anthony Vine: Abid, Kim
  • 6B: Jordan Morton: Hovander, Jiron

MUS174C – session requirements

Look at the course calendar to see which session you are assigned to.

1) If you are the first person listed in bold, you are responsible for the mic setup, sending me a mic plot and listing the day before the session, checking out microphones, stands, headphones, cables, etc. and setting up the microphones.

2) If you are the second person listed in bold, you are responsible for setting up ProTools before the session (all channels should be created, labelled, and correspond to the mic list from 1. You are also responsible for logging the session.

3) If you are listed for the session, you are helping out in setup and breakout. Also, 1 and 2 can assign you duties (fix the headphones, move the mic, do the log, run the session for a while, make sure no one lets the door slam, etc.)

4) After the session gets started, I will split off with the people who have a session next week to plan that session (in 268). Next week is Greenstone (Tues.) and Blair (Thurs.). If you are listed for either session, you are required to be at the planning meeting.

Tom

MUS174C – Recording Schedule

week 2
4/10: Kjell Nordeson – percussion/vibes set up (Farley, Richardson, Galang, Levick, Loree, Bahn, Zamora)
4/12: Mari Kawamura, piano (Greenwood,ChumakovBahn, Hovander,  Kim, Jiron, Jiao)
week 3
4/17: Madison Greenstone, clarinet  (Hess, Bari, Galang, Loree, D’Agostini, Greenwood,  Zamora, Abid)
4/19: Kyle Adam Blair – musical (Jiao, Loree, Hovander, Richardson, Bari, Jiron, D’Agostini, Hess)
week 4
4/24: Ben Rempel – 4 piece brazilian band   (Kim, Bahn, Galang, Chumakov, Farley, Reid, Zamora, Abid)
4/26: Barbara Byers – voice, koto, percussion, and double bass  (Galang, Zamora, Jiron, Chumakov, Levick, Jiao, Bahn, Greenwood )
week 5
5/1: Tim McNalley – slide guitar trio thingy, guitar/bass/drums (ReidD’Agostini, Hess, Hovander, Bari, Levick, Loree, Greenwood, Abid)
5/3: Anthony Vine – ambient electric guitar and clarinet (Levick, Abid, Reid, Hovander, Chumakov, Richardson, Farley, Kim, Jiron, Jiao)
week 6
5/10: Jordan Morton, voice and bass stuff (Jiron, Hovander, Farley, D’Agostini, Richardson, Bari, Kim, Reid, Hess)

MUS 174C – Syllabus

mus 174c - audio studio techniques - spring 2018
cpmc 269/203 - tuesday, thursday 11:00 - 12:20
instructor - tom erbe - tre@ucsd.edu - cpmc 254
teaching assistant - jordan morton - jmmorton@ucsd.edu

advanced projects – studio design

topics

  • projects in class – working with grad students and faculty guests
  • room acoustics
  • building a studio
  • audio electronics

texts

  1.  tape op magazine www.tapeop.com
  2.  bartlett & bartlett – practical recording techniques

class requirements

  • 25% – attendance, participation, quiz
  • 75% – final project

project requirements

  • tracked in class, each person has specific tasks for tracking session
  • edited as group
  • each person mixes and masters their own version
  • you must help on 4 tracking sessions
  • you must plan and setup a solo session alone, or plan and setup a multiple instrument session with another student
  • must attend planning session before each of 4 selected tracking session
  • show respect to diverse music

MUS 174C – Schedule

week 1
4/3: Introduction: Review of general micing techniques/session planning and process
4/5: Planning for week 2 – 6 sessions
week 2
4/10: Kjell Nordeson – percussion/vibes set up
4/12: Mari Kawamura, piano (s)
week 3
4/17: Madison Greenstone, clarinet – extended technique 20′ long piece, very beautiful and interesting and will be a good challenge to mic (s)
4/19: Kyle Adam Blair – demo of a new musical he is writing, w/singers
week 4
4/24: Ben Rempel – 4 piece brazilian band
4/26: Barbara Byers – trio of original music, voice, koto, percussion, and double bass
week 5
5/1: Tim McNalley – alum returning in style with a slide guitar trio thingy, guitar/bass/drums
5/3: Anthony Vine – ambient electric guitar and clarinet, long-form meditative stuff
week 6
5/8: Lecture: Studio Acoustics/Treatment/Room Design
5/10: Jordan Morton, voice and bass stuff, probably live (s)
week 7
5/12: Listening: week 2, 3, 4 play edited rough mixes with critique
5/14: Listening: week 4, 5, 6 play edited rough mixes with critique
week 8
Lecture: Designing a studio of any size (1)
Lecture: Designing a studio of any size (2)
week 9
Lecture: Studio electronics (1)
Lecture: Studio electronics (2)
week 10
Tuesday/Thursday: present final pieces

MUS271A (Max w10) – digital reverb

This class is not about fully understanding digital reverb – but just enough to get comfortable with some of the ideas. The patches can be downloaded from here: 09max-reverb.

Screen Shot 2018-03-06 at 6.53.08 PMFirst I would like you to listen to a chain of allpass~ fillters. This allpass filter is a specially configured delay with feedback that is designed to have a flat frequency response. Though it has a flat frequency over it’s entire decay, at any moment it is pitched. Note how the combination of different delay times and gain will sound more noise-like or more metallic. We include the allpass~ filter in most reverb designs because it adds a dense group of many short echoes.

Screen Shot 2018-03-06 at 7.19.43 PM


Our first reverb in this collection is the classic Manfred Schroeder reverb. This is just one of his designs, a combination of 4 delays with feedback (aka comb filters) and 2 allpass~ filters. In this example, I combined 2 of these reverbs in a matrix to create a stereo reverb. One innovation of this reverb is that the gain on each comb~ filter is set so that they all decay at the same time. You can adjust the delay time (500 in patch) to make a longer reverb. This reverb design is the basis of the free
verb~ 
object.

 

Screen Shot 2018-03-06 at 7.27.14 PM


 

The next reverb is based on the design of Christopher Moore’s Ursa Major Spacestation. This reverb is notable for it’s use of multitap delay, time modulation, and separate delay taps for early reflections. I should note, my patch sounds similar, but nowhere near as warm and rich as the actual hardware.

 

Screen Shot 2018-03-06 at 7.24.51 PM

 

 

This reverb starts to feedback and resonate when the gain is set too high. In this image, the gain is set to 3.2 (the maximum allowed by the patch).

 

 

 

 


 

Next we have Miller Puckette and John Stautner’s feedback delay network reverb. I implemented the 16 x 16 matrix reverb in this example. There are no allpass filters in this design. Instead, the diffusion comes from the feedback matrix connecting the 16 delay lines. The matrix has a unitary gain, and the reverb will nicely feedback indefinitely if the gain is set to 1.0. Many reverb designs have been based on the FDN including IRCAM’s Spat, and possibly several of the Eventide reverb designs (my guess).Screen Shot 2018-03-06 at 7.33.49 PM


 

The last reverb patch in this collection is Jon Dattorro’s emulation of a famous commercial reverb. This reverb design features a circle of allpass filters and delays, with many early reflection taps in the loop. Two of the allpass filters are modulated with varying time, and the sound enters the network after being diffused by a chain of allpass filters. Like the Puckette FDN, the gain can be set to 1.0 for “infinite” reverb.

Screen Shot 2018-03-06 at 7.43.12 PM

MUS271A (Max w9) – ambisonics tools

Screen Shot 2018-03-06 at 6.39.52 PMHead on over to Zurich University of the Arts – Institute fo Computer Music and Sound Technology (aka ZHdK – ICST) to download some very usable tools for ambisonic encoding and decoding (the URL is https://www.zhdk.ch/en/5381). ambipanning~ can encode a signal and place it in a set speaker array. ambiencode~ will encode a number of signals at different positions into ambisonic format. ambidecode~ can take that ambisonic set of channels and decode it into a set speaker format. There are many details and sub patchers to look into and understand in each of the help files, but this is a fairly easy and powerful system to work with. To start, you need to know the location of each of your speakers, and learn the message format to specify that location.

MUS271A (Max w9) – granular with phasor and poly~

Download the patch and abstraction here: 09-phasorgrainScreen Shot 2018-03-06 at 6.12.32 PM

To enable faster granular modulation we can use phasor~ to clock the grains at audio rate rather than metro. The signal from phasor~ is multiplied by the number of voices outside of the patch to create a ramp the rises from 0 to almost 8. Also, each message to the poly~ voices is preceded by the message target 0 so that the message (a list of parameters) is passed to all voices.
Screen Shot 2018-03-06 at 6.13.08 PM

Inside of each voice, the input from phasor~ * 8.0 is shifted down by the voice number. If the result of this is less than 0.0, 8.0 is added. The intention here is to open the cos~ window whenever between 0.0 and 1.0, and have each voice’s window offset an amount based on the voice number.

Finally, random numbers are generated quickly with a metro, and a gate stops frequency updates when the voice is active. That is, parameters are only updated when the grain is silent.