Module 6 · Lesson 4 of 5

Comb, Vowel and Resonator

Three filters are tuned rather than set: the Comb rings at a pitch like a plucked string, the Vowel shapes a sound into A, E, I, O and U, and the Resonator turns any sound into a chord.

18 minHeadphones or studio monitorsKiMiA and your keyboard

In this lesson you will

Turn a burst of noise into a plucked string with the Comb
Make a sound talk, and choose its singer
Tune the Resonator’s four bands to a chord

01The Comb: a string made of echoes

The comb filter is a very short echo fed back into itself. An echo every 3.8 ms repeats 262 times a second, which is the pitch of middle C, so the Comb rings at a note. Its curve has a tooth at that note and at every multiple of it, like the teeth of a comb.

That makes the Cutoff a pitch, and KiMiA shows it as one: choose Comb and the Cutoff reads a note name, C4 or A2 +12¢. Two more knobs set how it rings. Resonance sets how long, and damping, beside it, how fast the high harmonics die away. Feed it a short burst of noise and you hear a plucked string:

Figure 6.4.1

One burst of noise through the Comb, three settings of Damping

Comb · tuned to C3 by Key tracking 100% · Resonance 85%

Damping 0%: metallic

Damping 50%: a plucked string

Damping 100%: palm-muted

The Comb’s curve at C3: a tooth at the note and at every multiple of it

Switch while it plays: same moment, different sound Audio example — listen in the online course

The noise lasts about 29 ms; everything after it is the Comb ringing. Each horizontal line is one harmonic of C3. With Damping 0% every harmonic rings alike: the highs above 2 kHz last 2.7 s, as long as the fundamental (2.8 s, both to 40 dB down), bright and metallic. At 50% the highs die in 0.16 s while the fundamental rings on for 2.7 s, like a string. At 100% even the fundamental stops in 0.31 s: palm-muted. Below, the Comb’s curve: a tooth at the note and at every multiple of it, which is why it rings at a pitch.

KiMiA’s Filter 1 panel with 06 · Comb Pluck loaded and playing, its controls numbered — Filter 1 on Comb: the curve is a row of peaks at the harmonics of its Cutoff, which the Comb shows as a note (C4). Key tracking 100% moves the peaks with every key, so the burst of noise rings at the note you play; Damping softens the higher ones.

With Key tracking at 100% the pitch follows the keys, so the Comb plays in tune. In our measurement, from C2 to C6 it stayed within 0.3 cents. Set the Cutoff to the note C4 and every key plays its own pitch. 06 · Comb Pluck is built that way: no oscillator, only 29 ms of noise and the Comb.

Pro tip

Feed the Comb an oscillator instead of noise and it adds a metallic, flanged color, strongest when its pitch and the note’s don’t match. Set Key tracking to 0 and the Cutoff to a fixed note, then play: the Comb’s pitch rings through every note like a drone.

02The Vowel: a filter that talks

Your vocal cords make a buzz rich in harmonics, much like a saw wave. Your mouth and throat then boost a few regions of that buzz, the formants, and where they sit tells the listener which vowel you are singing, whatever the note. Lesson 5.3 built two of them with two band-passes. The Vowel type puts five on a sound, placed as a singer’s:

Figure 6.4.3

The Vowel filter’s five shapes (the tenor)

Voice type Tenor · Resonance 36% · the dots are each vowel’s formants

A saw through each vowel Audio example — listen in the online course

Each row is the filter’s curve for one vowel: five formant peaks of a tenor’s voice, the first two strongest. “A” has its first two at 650 Hz and 1.1 kHz; “I” keeps its first one low, at 290 Hz, and its second high, at 1.9 kHz. Your ear recognizes a vowel by where these peaks sit, whatever note is sung.

On the Vowel the Cutoff moves through the vowels, and the knob shows the letter: A, E, I, O and U, gliding between them. Resonance sharpens the formants: low, the vowel is soft and breathy; high, it is clear and nasal. Sweep it and the sound talks:

Figure 6.4.4

The cutoff swept from A to U

Saw · C3 · Vowel · Cutoff 30 Hz → 18 kHz in 5 s

Two different examples Audio example — listen in the online course

Moving the cutoff walks the filter through the vowels. The bright bands are the formants, gliding from one vowel’s place to the next. Anything that moves the cutoff, a modulator, the filter envelope or your touch, makes the sound talk.

KiMiA’s Filter 1 panel with 06 · Vowel Talker loaded and playing, its controls numbered — Filter 1 on Vowel, Voice type Tenor: Cutoff chooses the vowel (here I) and reads it as a letter, and the curve shows its formant peaks, a low one and a cluster between 2 and 3 kHz.

Four voices

Different singers have different formants: shorter vocal tracts put them higher. The Vowel’s Voice type buttons, in the Slope row’s place, choose Soprano, Alto, Tenor (the default) or Bass. A soprano’s “A” has its first two formants at 800 Hz and 1.2 kHz; a bass’s at 600 Hz and 1 kHz. Play the same note through both and the same vowel sounds younger or older, lighter or darker:

Switch while it plays: same moment, different sound Audio example — listen in the online course

In KiMiA

With Unison above 1, each unison voice sings through its own slightly different formants, as the singers of a section do. 06 · Vowel Choir uses four unison voices on the soprano: hold a chord and it sounds like a group, not a single synth voice.

03The Resonator: a chord in a filter

The Resonator is a bank of four band-passes. The first sits at the Cutoff; the Spread knob, in the Slope row’s place, stacks the other three above it, each the same interval above the last. The knob names the musical intervals as it passes them:

Spread shows	The four bands	Sounds like
Unison	All four on the Cutoff	One strong, ringing band
Minor 3rds	A diminished chord	Dark, tense
Major 3rds	An augmented chord	Dreamy, unresolved
4ths	Stacked fourths	Open, modern
5ths	Stacked fifths	Bright, open, bell-like
Octaves	Four octaves	Pure, organ-like

Figure 6.4.6

The Resonator: four bands, a fifth apart

Resonator · Cutoff 220 Hz · Spread 7/12 (fifths) · Resonance 70%

Measured from the engine

Two different examples Audio example — listen in the online course

The Resonator is a bank of four band-passes. The first sits at the Cutoff, and Spread stacks the others above it, from all four on one note at 0 to octaves at 100%; on the way it passes minor thirds, major thirds, fourths and, here, fifths: measured at 219 Hz, 327 Hz, 489 Hz, 748 Hz. Resonance sharpens the bands until they ring like struck glass. A burst of noise then plays a chord; a saw is reduced to the harmonics that fall in the bands.

KiMiA’s Filter 1 panel with 06 · Resonator Fifths loaded and playing, its controls numbered — Filter 1 on the Resonator: four narrow peaks, a fifth apart from the Cutoff (262 Hz) up. Spread reads the interval, here 5ths; Key tracking 100% moves the chord with the key you play.

Resonance decides how much the bands ring. Low, the Resonator colors a sound with a chord’s worth of peaks. High, a burst of noise or a short pluck makes the bands sing on their own, like struck glass. With Key tracking at 100% the chord moves with the keys.

Watch out

A saw through narrow bands keeps only the harmonics that land in them. If the bands fall between the note’s harmonics, the sound gets thin and quiet. Lower the Resonance or move the Cutoff until a band meets the note.

04Try it

Tune a string. Load 06 · Comb Pluck and play a melody. Turn Damping to 0%, then 100%. Then lower Resonance to 60%: what happens to the length of each note?
Drone through the comb. Load 06 · Course Init. Set Type Comb, Cutoff to the note A2, Resonance 70%, Key tracking 0. Play chords in A minor, then in C major.
Make it talk. Load 06 · Vowel Talker and play a slow melody. Set the Cutoff to A, then U, and try each Voice type.
A choir in a filter. Load 06 · Vowel Choir, hold a chord, and set Unison to 1, then back to 4.
Change the chord. Load 06 · Resonator Fifths. Play a few notes, then turn Spread to Minor 3rds, Major 3rds and Octaves.

Your notes · which vowel and voice type you liked best

05Check yourself

Q1Why does a burst of noise through the Comb sound like a plucked string?

The echo’s repeat rate is the note’s frequency. Each pass through the loop loses a little, so the ring dies away like a string’s.

Q2Your comb pluck sounds metallic. Which knob makes it sound more like a guitar?

Damping makes the highs die away before the fundamental, as on a real string. At 0% every harmonic rings alike, which sounds metallic.

Q3On the Vowel type, what does the Cutoff knob change?

The Cutoff moves the five formants together from one vowel’s place to the next. The voice type is chosen with its own buttons.

Q4You want every note to ring a stack of fifths. Which type and setting?

The Resonator’s four bands sit a Spread apart. At 5ths they stack fifths above the Cutoff, and Key tracking moves the stack with the keys.