PART 2

Misconceptions and Misnomers
Vacuum Cleaners were once globally referred to as "Hoovers", despite "Hoover" manufacturing many different products, not just "cleaners".

In modern music, Modulation is sometimes misconceived as a collective term for "an effect", most notably a "Chorus Type" effect. There's nothing surprising or irksome about this, it is understandable.

But, this common misconception only serves to befuddle those wishing to understand Modulation, because they will be constantly trying to equate everything to a "Chorus Effect".

To reiterate, Modulation encompasses everything that modifies any aspect of a source "sound" over time.

LFO's, Envelope's, Macro's, CV/Expression Pedals, Effects Pedals etc are all just electronic means by which Modulation is automated. Musically, "Modulation" actually refers to which aspect of the sound is being changed e.g. Pitch, Delay, Phase, Volume, Timbre, EQ, even Musical Key, Tempo or Meter.

In truth, multiple aspects may be modulated simultaneously, and frequently are. An LFO may be configured to modulate multiple aspects at once. An LFO is just a robotic hand. Take the Violinist as an example, with just one bowing hand, he can simultaneously vary Volume, Timbre and to some extent Pitch. These three forms of Modulation contribute, in part, to what we recognise as a Violin Sound.

To equate this to "Electronic Modulation" we would use an ADSR Envelope on Volume (Amp), Timbre (Filter) and Pitch (Pitch) to mimic, or "synthesise" the sound of a String being "bowed". Obviously, one would also need to synthesise other aspects, but the Envelope is at least a necessary component.

The point here is, though perhaps not often recognised as such, an Envelope Generator (ADSR) is a means of Modulation, no less than an LFO or a "Chorus Pedal".

There is no law that states that Modulation must be cyclic, symmetrical, geometric and repetitively consistent. In fact, these are the qualities of "a machine", and arguably undesirable from a musical perspective. "Natural" or "Manual" Modulation is far more random, inconsistent and unpredictable, and therefore more "musical".

The common misconception and misnomer here is that the "Electronic Means" is the "Modulation". It is not. The means (LFO, Envelope etc) is the "Modulator". It is analogous to a Human Hand. The Human Hand does not make any sound, but is used to manipulate the sound from an instrument.

Modulation is descriptive of the aspect of the sound or music that is being changed. As in "What aspect of the sound is being Modulated?"

It may seem pedantic, but it is key to understanding Modulation in general.

To illustrate, regarding Chorus or Vibrato.

To this day, no effective electronic means has been discovered to directly vary the fundamental Pitch of an Input electronic Source Signal.

By effective, we mean instantaneous, and without noticeable or undesirable changes in Timbre, i.e. natural sounding. The usual problem is "lag", an audible Processing Delay, between the note being played, and it's pitch shifted version being heard. The more accurate the "shifted version" the greater the Lag.

You can directly vary the Source frequency (voltage controlled oscillator), but that's not what we need. We require that the "Pitch Modulation" is done "downstream".

Over the decades, many Musical Instrument companies have attempted to produce a "Pitch Shifter" or "Harmoniser" with varying, yet limited success. It is presumed that extremely fast, as yet unavailable technology, will be required to achieve a musically satisfactory result.

But for decades, it is has been well known that by modulating an Audio Signal in Time, you can vary it's Pitch, without changing its "signature" Timbre.

So, from a single sound source, we can create a Chorusing effect, by splitting the signal, and Modulating a short delay time (less than 25ms) on one or more of the "splits".

The distinction being made here is, in your common Chorus Effect, the Modulator (LFO) is Modulating Delay Time, not Frequency/Pitch.

Chorus is not the "Modulation". The LFO is not the Modulation. The modulation not even Pitch.

It is Time that is being Modulated. We are modulating Time.

PART 3

Pulling Back the Veil

In Part 2, we made a distinction between what is being modulated (Pitch, Amplitude, Timbre, Time etc), in the Audio Signal/Sound (the Modulation) and the external force (the Modulator) that is executing the Modulation (Violinists Hands, Flautist's Lips, Electronic LFO, Envelope etc).

You can maybe see there a many forms of Modulation, and also separately, many forms of Modulators.

This is apparent on most any Synthesiser in the so called "Modulation Matrix". You select a Source (Modulator) and a Target/Destination (Form/Aspect of Modulation).

Source/Modulator = Mod Wheel, Knob, Foot Pedal, LFO, Ribbon etc.

Destination/Modulation = Volume, Pitch, Delay Time, Filter Cutoff etc.

Behind "the veil" it may be difficult to equate what you actually hear, to what is actually being modulated.

The Chorus Effect is a great example.

In the "Human world", Pitch Modulation is a direct application of Human Hands on a physical Musical Instrument... for example "shaking" a bowed violin string.

In the "Electronic World", you can't do that. Instead you have to vary the Delay Time [see Edit Note 1 below], on an already delayed Signal. The audible result is a "shaking" Pitch.

Flip it over once more, no Human Hand can delay or manipulate Delay Time on a physical Musical Instrument.

Different methods, same end (audible) result. In the Human world, it is easy to equate the audible result, with the visible (shaking) method. In the Electronic world it is not so apparent, and it would be easy to conclude that the electronics are directly "shaking" the frequency of the note. Except, now you know, they aren't.

What is an LFO?
We've mentioned, but skipped over this. Since it is the most frequently used method (Modulator) for electronic automated Modulation, we need to know what it is.

It is basically an Oscillator Circuit (Google it), but designed to output Low Frequencies. Low Frequencies in this case means "Below the Human Hearing Range". That is, it operates below the "Audio" Frequency Spectrum i.e. from 0Hz up to around 20Hz.

LFO is an acronym for Low Frequency Oscillator.

[In case you don't know:-

Hz = Hertz, Frequency aka Pitch is measured in Hertz. 1 Hertz = 1 Wave Cycle per second.

Above 20Hz, the Human Ear starts to perceive Sound Frequency as a Pitch or "Continuous Tone"... a "Low Hum". Below 20Hz, it is perceived as an intermittent "throb" or beat... not a continuous sound. It depends on the Human, everyone hears differently]

If the Modulator (LFO) Frequency goes higher than 20Hz, then it's (audio range) Frequency starts to have an audible influence on the actual Timbre (Harmonic Spectrum) of the sound being modulated. Depending on what aspect of the "target" sound the LFO is modulating (Amplitude, Frequency, Phase etc), you enter the realms of FM (Frequency Modulation), AM (Amplitude Modulation aka Ring Modulation) or PM (Phase Modulation).

Here is a bizarre thought. If a Violinist was physically capable of "shaking" his fretting finger more than 40 times per second (that's once up and once down, 20 times per second) he could turn his Violin into an FM Synth. 🙂

Back on track, typically LFO's are used operating at Fractions of Hertz (Less than 1Hz) since this most resembles the human/musical capability of musical "vibrato" that we are used to hearing. Equally, any audible rhythmic impact (throbbing, pulsing, beating) is in line with typical Musical Tempos (BPM/Beats Per Minute).

In Part 4, we will take a look at "Modulation" Effects.... Chorus, Flanger, Tremolo, Phaser etc. I use inverted commas here, with chagrin, because these effects do not "define" Modulation, which is the common misnomer/misconception.

EDIT:-
Note 1: A Synthesiser, being entirely Electronic, has a few more "options" up its sleeve. For Vibrato, it is possible to just vary the Pitch, directly, at Source. That is, vary the pitch of the Voltage Controlled Oscillator (VCO Saw, Triangle, Square etc). However, since the LFO is a separate "circuit" that may also be called upon to vary other aspects (such as Filter, Amplitude), logistically, it could better placed further down the Signal Path (nearer the output). In which case the "Delay Time Method" becomes the more versatile option. The advent of the "BBD" Audio Delay chip facilitated this design approach. A classic example of where this was exploited was in the "String Machines", a Single Oscillator output could multiplied and divided to produce Polyphony, with BBDs producing enough Pitch variation to create an "Ensemble" effect. These days, we'd call it a "Unison" effect... but technology allows for multiple oscillators, all slightly detuned from each other, at Source.

You any good at video production?

@Andrew... nope. Old School. Blackboard and Chalk.

The best vids on Javascript were unedited: a guy in front of a static camera with a whiteboard behind him.

The script you've got.

Maybe start with Oscillation, then Modulation. Then Filtration.

Sponsored by... Yamaha?

Do they do that kind of thing?