Fundamental concept: Harmonics and sound - Modular V Tutorial

(gentle, quiet synthesizer tune) - [Voiceover: Josh Meyer] As you probably know, the notes that make up a chord affect the sound of that chord. For example, a "C minor" triad (plays "C minor" triad on piano) sounds different than a "C major" triad. (plays "C major" triad on piano) This is true even though they share the same root note, "C". (plays "C" note on piano) Even if I hold the three bottom notes the same, (plays "C major" chord on piano) which notes I had on top still change the sound of the chord. (plays altered "C major" chord on piano) (plays original "C major" chord on piano) Well it's the same with harmonics and sound. Each harmonic that makes up a sound is like the notes (plays three different keys on piano) that make up a chord. Different combinations of harmonics produce different tone colors, just like different notes produce different sounds of chords. (plays original "C major" chord on piano) Here I've created a patch in the Modular V software where I've tuned the first six oscillators to match the tunings of the first six harmonics that make up a sound. There's a few rules of harmonics, one: the wave form of each harmonic is a sine wave. That's the purest wave form that sounds only one harmonic and no additional overtones. In this case, I've tuned the first oscillator to the 32-foot mark, that's like the longest pipe on this pipe organ, if I play an "A" on the keyboard (plays an "A" note on the pipe organ synthesizer) I get a pure tone. You can see my oscilloscope. There's our pure sine wave, and down here in the spectrograph is our first harmonic. If I measure it, its frequency is right around 110 hertz, two octaves below "A" 440. Each harmonic is an integer multiple of the frequency of that fundamental, or lowest, harmonic: the root harmonic. For example, the second harmonic is tuned to a pitch twice that of the first harmonic. In this case, I've merely tuned it up an octave. It's at the 16-foot mark which is one octave above the 32-foot mark on this old recreation of a Moog synthesizer. So I'll play my "A" again. (plays first "A" harmonic on Moog synthesizer) Fade up that second harmonic. (adds second "A" harmonic on Moog synthesizer) Now if I measure its frequency, you'll see that harmonic is right around 220 hertz, double that of the first harmonic. Now there's some variation going on in the wave form because a Modular V software is built to have some de-tuning between the oscillators to create a fatter sound. We typically think of harmonics as being perfectly tuned to each other, although in real acoustic instruments there may be some de-tuning. So, here's that fundamental. (plays first "A" harmonic on Moog synthesizer) Here's the second harmonic, (plays second "A" harmonic on Moog synthesizer) and here's a mixture of the two. (plays both "A" harmonics together on Moog synthesizer) The third harmonic is tuned to a pitch that's exactly three times that of the fundamental harmonic. In other words, an octave and a fifth above the fundamental. Let's bring it into our mix. (plays all three "A" harmonics together on Moog synthesizer) And we go measure its pitch, and you'll see it's right around 330 hertz, three times that of our 110 hertz fundamental. So... (speaker pauses) Third harmonic in isolation, (plays third "A" harmonic note on Moog synthesizer) the second mixed in, (adds second "A" harmonic note on Moog synthesizer) with the fundamental first harmonic mixed in. (adds first "A" harmonic note on Moog synthesizer) It keeps going up the scale. The fourth harmonic is at four times the pitch of the fundamental. In other words, two octaves above. I have this one tuned to the eight-foot mark which is two octaves above the 32-foot on this old Moog-style wave tuning. I'll bring that in, (adds fourth "A" harmonic note on Moog synthesizer) and again....this pitch is right around 440, four times of our fundamental, and so forth. The fifth harmonic is five times the pitch of the fundamental. So, two octaves above plus a major third, (adds fifth "A" harmonic note on Moog synthesizer) and the sixth harmonic is six times that of the fundamental. Two octaves and a fifth. (adds sixth "A" harmonic note in Moog synthesizer) As you can hear, as I brought in each harmonic, the tone character of our sound changed, and different mixtures of harmonics create different wave forms and different tones. (plays all six "A" harmonic notes on Moog synthesizer) I'm going to take out the odd harmonics, (plays fundamental, second, fourth, and sixth "A" harmonics) So I'm going to have the fundamental and even harmonics, that's one sound. Or I can take out the even harmonics and add in the odd harmonics. (plays fundamental, third, and fifth "A" harmonics) Very different tone character even though I'm still playing the same note, this "A", and I still have my fundamental present. Different wave forms in a synthesizer produce different mixtures of harmonics. For example, square waves tend to have odd harmonics, sawtooth waves have all the harmonics present, (plays all harmonic "A" notes on Moog synthesizer) but in a ratio where the higher harmonics are not as strong as the lower harmonics, (plays all harmonic "A" notes, with louder lower tones) a lot of synthesis is all about choosing a wave form that has the basic harmonic mixture that you want, and then removing some of those harmonics with filters in a synthesizer. For example, if I turn all of these harmonics back up again, (plays all harmonic "A" notes together on Moog synthesizer) watch what happens to the roll of height of the spikes in the spectrograph display as I use a low-pass filter to remove some of the high harmonics. (uses filter to silence higher "A" harmonics) You see those higher spikes gets lower in amplitude as the sound grows duller, and we're just down to our fundamental. (fades to playing only the fundamental "A" note) And that is the fundamental concept of synthesizing sounds. Starting with a rich mixture of harmonics with different mixtures producing different "A" sounds, and then selectively removing some of the harmonics to further shape the tone of the sound. If you understand this concept, all of the controls in here will start to make a lot more sense as we start creating different sounds.