Wah — effect atlas

12 effects · 1,390 captures. Swept band-pass filters: auto-wah (LFO driven), touch wah (envelope driven) and wah chains. The stepped-transients probe shows how much louder playing opens the filter.

Part of the Motif ES effects teardown; the method and the cross-effect findings are in the main analysis (notebook).

How to read a card

Each effect gets one card, then a written breakdown.

• Header band. The effect's name, category, how many recordings exist, and a one-sentence summary written from the measurements.
• Tiles. The handful of numbers that matter most for this type of effect, at default settings. A dash means the value could not be measured, and the small caption says why.
• The knob console. One knob per control. Click a knob to select it and move the slider under the knobs to turn it. A knob's ring is its own travel, coloured stretch by stretch: green where turning it barely changes the sound, red where a small turn changes it a lot, grey where nothing measurable happens. A knob outlined in cyan was also recorded together with the selected one, and its ring changes as the slider moves; every other ring shows that knob with the rest at their defaults. Controls that showed no measurable change at all are listed under the console, not drawn.
• What each knob does. One bar per control, longest first. Bar length is the size of the change the knob makes, in multiples of the smallest change that matters in practice (1 dB of level, 20% of decay time, 10% of LFO rate…), on a log scale. Colour says what kind of change. ◆ marks readings taken with a test sound designed for that knob. Grey dots are knobs that did nothing with the other controls at default.
• Signature panel. The view that best explains this kind of effect: decay curves for a reverb, echo taps for a delay, the input/output curve for a compressor, harmonics against input level for a distortion, the LFO for a modulation effect.
• Knob × frequency. Each row is one knob at one tested setting; red means louder than default at that frequency, blue quieter. Modulation effects get a what the knobs touch matrix instead, because a running LFO has no single frequency response.
• Stereo. How the left and right inputs reach the outputs.

The breakdown under each card notes the structure the measurements reveal, flags caveats, and names the tests in TESTS_NEEDED.md that would complete the picture. Below it, every knob is charted with the range tested and what it does; hover a bar for the detail.

Show code

import warnings; warnings.filterwarnings("ignore")
import sys; sys.path.insert(0, "..")
import os; os.chdir("..")                   # the cache lives in the project root
import matplotlib.pyplot as plt
from IPython.display import HTML, Markdown, display
import load, knobs, cards, plots, iviz, gapfill, knobviz, vizstyle as V
V.setup()
from matplotlib_inline.backend_inline import set_matplotlib_formats
set_matplotlib_formats("svg")           # figures embed as vector, not PNG
display(iviz.page_css())
df, curves = load.load()
noise = knobs.noise_table(df, curves)
g = gapfill.load()

def show(fig):
    display(fig)
    plt.close(fig)

def show_card(effect):
    show(cards.effect_card(df, curves, effect, noise)[0])

def show_knobs(effect):
    board = knobviz.console(df, curves, effect, noise)
    if board is not None:
        display(board)
    _, main, rh = cards.merged_knobs(df, curves, effect, noise)
    for h in iviz.knob_plots(effect, main, rh):
        display(h)

def show_parts(parts):
    for f, note in parts:           # each chart, then its own explanation directly under it
        f.show()
        display(Markdown(note))

def show_gapfill(effect, stimuli=None, drives_only=False):
    parts = iviz.gf_effect_parts(g, effect, stimuli, drives_only)
    if parts:
        display(Markdown(iviz.GF_INTRO))
    show_parts(parts)

The family at a glance

Every effect in the category on the same few numbers, then all of them on one chart — drag the slider to bring one forward, hover for exact values.

Show code

knob_counts = {'Auto Wah': (9, 0), 'Auto Wah+Dist': (13, 0), 'Auto Wah+Odrv': (14, 0), 'Touch Wah': (6, 2), 'Touch Wah+Dist': (11, 2), 'Touch Wah+Odrv': (11, 1), 'Vintage Auto Wah 1': (11, 0), 'Vintage Auto Wah 2': (12, 0), 'Vintage Touch Wah 1': (10, 3), 'Vintage Touch Wah 2': (10, 2), 'Wah+Dist+Dly': (11, 1), 'Wah+Odrv+Dly': (11, 0)}
show(cards.family_overview(df, 'Wah', knob_counts, curves))

Show code

iviz.family_fig(df, curves, 'Wah').show()

Recap. Why: to compare the tone of every effect in the family on one chart. How to read it: each line is one effect's frequency response, centred on its own median; drag the slider to bring one forward, hover for exact values.

Technical explanation. Each effect's frequency response at the capture baseline — how much each frequency is boosted or cut on its way through — measured by log-sweep deconvolution, smoothed to 1/6 octave, averaged over repeat captures, and shifted to its own median so the chart compares tone shape, not loudness. Drag the slider to bring one effect forward. The chart below this text reads each curve off as three numbers: its peak, the range within 6 dB of the peak, and the span from peak to deepest cut.

Identical curves (under 0.5 dB apart), so the same processing at these settings — a shared tone stage, or, for an EQ left flat, no shaping beyond the capture chain: Vintage Touch Wah 1 = Vintage Touch Wah 2. A presence peak between 2 and 8 kHz with a steep cut above it (a speaker-cabinet shape): Auto Wah+Dist, Auto Wah+Odrv, Touch Wah+Dist, Touch Wah+Odrv, Wah+Dist+Dly, Wah+Odrv+Dly. Less reliable in detail (repeat captures differ by over 3 dB, usually a running LFO): Vintage Auto Wah 1, Vintage Auto Wah 2. Not shown: level (each curve is centred on its own median), anything that changes over time.

Plain explanation: this is the effect's tone — which parts of the sound it makes louder or quieter. Curves that overlap exactly mean those effects do the same thing to your tone at these settings. A bump in the upper mids followed by a steep drop is what a guitar speaker does: it adds bite and removes harsh fizz. Auto Wah, Auto Wah+Dist, Auto Wah+Odrv, Vintage Auto Wah 1 and Vintage Auto Wah 2 roll off the top end early, so they sound darker.

In other words, the main points:

• Most shaping: Wah+Odrv+Dly, 40 dB from peak to deepest cut.
• Same tone curve (within 0.5 dB): Vintage Touch Wah 1 = Vintage Touch Wah 2.
• Speaker-cabinet shape (presence peak, steep cut above it): Auto Wah+Dist, Auto Wah+Odrv, Touch Wah+Dist, Touch Wah+Odrv, Wah+Dist+Dly, Wah+Odrv+Dly.
• Darkest (top end rolled off early): Auto Wah, Auto Wah+Dist, Auto Wah+Odrv, Vintage Auto Wah 1, Vintage Auto Wah 2.
• Least repeatable in detail (usually a running LFO): Vintage Auto Wah 1, Vintage Auto Wah 2.

Show code

iviz.tone_bands(df, curves, 'Wah')

Playing dynamics: how effects answer loud, soft and decaying notes

Recap · Why: sweeps and steady tones cannot show how an effect responds to playing dynamics, or to a note that dies away. The pink-pluck probe plays noise bursts at three levels 18 dB apart, then three plucked notes.
How to read it: one bar per effect. First, how much brighter the loud burst comes out than the quiet one, in octaves; second, how much of the 18 dB level difference is removed; third, how long a pluck takes to fall 20 dB.

Technical explanation. Touch Wah's spectral centroid rises 2.0 octaves from the quiet burst to the loud one and the Vintage Touch Wahs' by 0.9; Auto Wah's does not follow level (-0.7 octaves), its filter being driven by an LFO. The distortions remove a median 17 dB of the 18 dB level difference and hold a plucked note within 20 dB of its peak for 1.49 s, essentially the whole 1.5 s note, against 1.02 s through bypass; the Compressor removes 12 dB and holds it for 1.48 s.

Plain explanation: play harder into a Touch Wah and its filter opens by about 2 octaves; an Auto Wah sweeps on its own and ignores how hard you play. Distortion evens out your dynamics almost completely, so loud and soft come out at nearly the same volume, and notes ring at least 1.5 times as long.

In other words, the main points:

• Touch Wah opens 2.0 octaves between quiet and loud playing; Auto Wah does not follow level.
• Distortions remove 17 of 18 dB of level difference; the Compressor 12 dB.
• A plucked note stays within 20 dB of its peak for at least 1.49 s through the distortions, 1.02 s through bypass.

Show code

show_parts(iviz.probe_parts(g, 'pluck'))

What it shows. How much brighter the loud noise burst comes out than the quiet one, 18 dB apart, for each effect at its default settings.

How to read it. Bars above zero mean the effect opens up as you play harder; near zero means it ignores playing dynamics.

What it found.

• Touch Wah brightens by 2.0 octaves and the Vintage Touch Wahs by 0.9; Auto Wah does not follow level.

What it shows. How much of the 18 dB level difference between the quiet and loud bursts each effect removes.

How to read it. Zero means loud stays loud and quiet stays quiet; 18 would mean both come out at the same volume.

What it found.

• The distortions remove a median 17 dB, the Compressor 12 dB.

What it shows. How long a plucked note stays within 20 dB of its peak through each effect.

How to read it. Taller means more sustain. The note itself lasts 1.5 s, so bars at that height held it for its whole length; no bar means it was still ringing when the note ended.

What it found.

• Through bypass the pluck falls 20 dB in 1.02 s; through the distortions it lasts at least 1.49 s.

How fast the filter opens and closes

A touch wah is a filter that the playing level opens. These charts follow it moment by moment after the level jumps and after it drops.

Show code

import kinetics, kviz, wviz, rviz
show_parts(wviz.notch_parts(g, 'Wah') + kviz.wah_parts(g))

What it shows. Steady pink noise through each effect at its default settings. Every 10 ms the effect's frequency response is worked out against the same noise recorded with no effect, and each peak in it is marked with a dot.

How to read it. Time runs left to right, pitch (frequency) bottom to top. Each trail of dots is one peak travelling up and down the spectrum. How far a trail travels is the depth of the sweep; how often it repeats is the speed; trails that keep the same spacing as they move are stages locked together. Use the slider to change effect.

What it found.

• Auto Wah: about 1 peak at a time; the lowest moves between 1,054 and 3,577 Hz (1.8 octaves).
• Vintage Auto Wah 1: about 1 peak at a time; the lowest moves between 646 and 1,550 Hz (1.3 octaves).
• Vintage Auto Wah 2: about 1 peak at a time; the lowest moves between 646 and 1,550 Hz (1.3 octaves).
• Holding still on steady noise: Touch Wah, Vintage Touch Wah 1, Vintage Touch Wah 2 (these follow the playing level, and the noise here is one steady level).
• Not drawn: Auto Wah+Dist, Auto Wah+Odrv, Touch Wah+Dist, Touch Wah+Odrv, Wah+Dist+Dly, Wah+Odrv+Dly.
• Their distortion stage adds overtones of its own, so the response cannot be read by comparing output with input.

What it shows. Pink noise that jumps 30 dB louder, through every wah at its default settings. The line is the output's spectral centroid (the frequency at which half the energy lies either side), a single number for how bright it sounds, read every 12.5 ms after the jump.

How to read it. Time after the jump runs left to right, brightness upward. A line that leaps up is a filter the louder signal has opened; a flat line is a filter that does not follow level. Only effects whose brightness moves by more than 0.3 octave are drawn.

What it found.

• Wah+Dist+Dly opens furthest, from 1,304 Hz to 6,963 Hz (2.4 octaves).
• The touch wahs without a delay stage are already open at the first 12.5 ms reading, so their lines start high and stay flat; the chains that include a delay change late, by the length of that delay.
• Touch Wah+Dist, Touch Wah+Odrv, Wah+Odrv+Dly get darker when the level jumps, not brighter: the centroid follows what their distortion stage does to the noise as much as where the filter sits.
• Not drawn because their brightness does not follow level: Auto Wah, Auto Wah+Dist, Auto Wah+Odrv, Vintage Auto Wah 1, Vintage Auto Wah 2 (the auto-wahs sweep on an LFO).

What it shows. The same effects after the noise drops back by 30 dB: the filter closing.

How to read it. As above. The longer a line takes to come down, the longer the wah stays open after a loud note.

What it found.

• Touch Wah takes 588 ms to close 90% of the way; Vintage Touch Wah 1 takes 250 ms to close 90% of the way; Vintage Touch Wah 2 takes 238 ms to close 90% of the way; Wah+Dist+Dly takes 38 ms to close 90% of the way.
• Where there is no delay in the chain, the opening is too fast to time and the closing takes tenths of a second: these filters snap open and ease shut.

---

Auto Wah

Show code

show_card('Auto Wah')

Auto Wah: what the measurements say

Recap. A filter effect with 9 tested controls, 9 of which measurably change the sound. Beyond mix and level, the biggest lever is LFO Depth: amplitude modulation depth 0.00 → 3.49. Measured with 94 captures: 46 on the main sweep + tone probe (one control at a time), 20 on matched probes (spectralSweep ×15, sustainedStereo ×5), 28 two-control pairs.

Technical explanation. At default settings: output -25.1 dBFS RMS (crest 20.9 dB); stereo width 0.23, L/R correlation +0.90; spectral tilt -0.61 dB/octave; 99% of the impulse response's energy in its first 5 ms; harmonics H2 -81 dB, H3 -40 dB re the linear response.

Two-control pairs captured: Cutoff Offset×Low Gain, LFO Depth×Cutoff Offset, LFO Depth×Low Gain, LFO Speed×Cutoff Offset, LFO Speed×LFO Depth, LFO Speed×Low Gain, Low Frequency×Resonance (interaction analysis in the main notebook).

Plain explanation: The control to reach for first is LFO Depth: amplitude modulation depth 0.00 → 3.49. After that, LFO Speed, Cutoff Offset and Low Gain make the next biggest differences. DryWet sets how much of the effect you hear and how loud it is. At default it has a moderate stereo spread.

In other words, the main points:

• 9 of 9 tested controls measurably change the sound.
• Biggest lever beyond mix and level: LFO Depth, 69.8× the smallest change that matters (amplitude modulation depth 0.00 → 3.49).
• At default: stereo width 0.23, output -25.1 dBFS RMS.
• Still to measure: T1 (see TESTS_NEEDED.md).

Show code

show_knobs('Auto Wah')

barely changes the soundchanges it a lot■no measurable changeall to default

Click a knob to select it, then move the slider to turn it. A ring is that knob's own travel: green stretches barely change the sound, red stretches change it a lot. Rings show each knob with the others at their defaults; a knob outlined in cyan was also recorded together with the selected one, and its ring follows the slider.

Gap Fill: each control in physical units

Every control stepped on a probe matched to what it does (17 steps for time and rate controls, 9 for the rest), read as the physical quantity it sets: how far a delay tap moves, level or treble lost per repeat, LFO rate and pitch swing, gate length, THD, intermodulation, compressor ratio, knee, attack and release, and where a gate opens and closes. Times are read inside one capture (channel against channel) because Gap Fill runs fully wet and file starts wander by about ±50 ms.

Show code

show_gapfill('Auto Wah')

How to read these charts. Each chart is one control. Left to right is the control's raw value as sent to the Motif (low to high setting); the height of the line is the physical quantity that control sets, measured from the recording. The title names the control, then the test signal used.

LFO-Depth · sustainedStereo. Played: a held chord, one note per channel. The line is cents pitch swing: how far the pitch bends, peak to peak (100 cents = one semitone); here it barely moves (about 0.00624 throughout).

---

Auto Wah+Dist

Show code

show_card('Auto Wah+Dist')

Auto Wah+Dist: what the measurements say

Recap. A filter effect with 14 tested controls, 13 of which measurably change the sound. Beyond mix and level, the biggest lever is Drive: gain compression across the input range 1.2 → -17.5 dB. Measured with 132 captures: 71 on the main sweep + tone probe (one control at a time), 29 on matched probes (harmonicTwoTone ×29), 32 two-control pairs.

Technical explanation. At default settings: output -23.3 dBFS RMS (crest 8.1 dB); stereo width 0.08, L/R correlation +0.99; spectral tilt -0.02 dB/octave; 99% of the impulse response's energy in its first 5 ms; harmonics H2 -51 dB, H3 -11 dB re the linear response.

Two-control pairs captured: Cutoff Offset×Low Gain, Drive×Cutoff Offset, Drive×LFO Speed, Drive×Low Gain, LFO Speed×Cutoff Offset, LFO Speed×LFO Depth, LFO Speed×Low Gain, Low Frequency×Resonance (interaction analysis in the main notebook).

Caveats:

• some long settings decay more slowly than the recording allows; their T30 is a lower bound

Plain explanation: The control to reach for first is Drive: gain compression across the input range 1.2 → -17.5 dB. After that, LFO Speed, Cutoff Offset and Low Gain make the next biggest differences. DryWet and Output Level set how much of the effect you hear and how loud it is. At default the output is close to mono.

In other words, the main points:

• 13 of 14 tested controls measurably change the sound.
• Biggest lever beyond mix and level: Drive, 18.7× the smallest change that matters (gain compression across the input range 1.2 → -17.5 dB).
• At default: stereo width 0.08, output -23.3 dBFS RMS.
• Main caveat: some long settings decay more slowly than the recording allows; their T30 is a lower bound.
• Still to measure: T1, T3, T4 (see TESTS_NEEDED.md).

Show code

show_knobs('Auto Wah+Dist')

barely changes the soundchanges it a lot■no measurable changeall to default

Click a knob to select it, then move the slider to turn it. A ring is that knob's own travel: green stretches barely change the sound, red stretches change it a lot. Rings show each knob with the others at their defaults; a knob outlined in cyan was also recorded together with the selected one, and its ring follows the slider.

Gap Fill: each control in physical units

Every control stepped on a probe matched to what it does (17 steps for time and rate controls, 9 for the rest), read as the physical quantity it sets: how far a delay tap moves, level or treble lost per repeat, LFO rate and pitch swing, gate length, THD, intermodulation, compressor ratio, knee, attack and release, and where a gate opens and closes. Times are read inside one capture (channel against channel) because Gap Fill runs fully wet and file starts wander by about ±50 ms.

Show code

show_gapfill('Auto Wah+Dist')

How to read these charts. Each chart is one control. Left to right is the control's raw value as sent to the Motif (low to high setting); the height of the line is the physical quantity that control sets, measured from the recording. The title names the control, then the test signal used.

Cutoff-Offset · pinkPluck. Played: pink-noise bursts at three levels, then plucked notes. The line is Hz spectral centroid: the spectrum's centre of gravity, a measure of brightness; higher means brighter; here it goes from 1,276 at raw 0 to 4,056 at raw 127.

Drive · transferSine. Played: a 100 Hz sine at −6 dBFS. The line is dB THD: total harmonic distortion: how loud the added overtones are against the note itself. −40 dB is clean, 0 dB would be overtones as loud as the note; higher on the chart means more distortion; here it goes from -75.1 at raw 0 to -7.41 at raw 127.

Drive · twoToneLadder. Played: two notes together (220 and 697 Hz), stepped from very quiet to loud. The line is dB intermodulation: how loud the extra tones created between two notes are against the notes themselves, which is what makes chords sound harsh; higher means harsher; here it goes from -76.6 at raw 0 to -14.5 at raw 127.

LFO-Depth · sustainedStereo. Played: a held chord, one note per channel. The line is cents pitch swing: how far the pitch bends, peak to peak (100 cents = one semitone); here it goes from 3.17 at raw 0 to 5.36 at raw 127, peaking at 28.8.

LFO-Speed · sustainedStereo. Played: a held chord, one note per channel. The line is Hz LFO rate: how many times a second the modulation cycles; here it goes from 4.84 at raw 23 to 9.1 at raw 127, peaking at 9.87, dipping to 3.28.

LPF-Cutoff · pinkPluck. Played: pink-noise bursts at three levels, then plucked notes. The line is Hz spectral centroid: the spectrum's centre of gravity, a measure of brightness; higher means brighter; here it goes from 1,355 at raw 0 to 4,165 at raw 60.

Resonance · pinkPluck. Played: pink-noise bursts at three levels, then plucked notes. The line is Hz spectral centroid: the spectrum's centre of gravity, a measure of brightness; higher means brighter; here it goes from 2,469 at raw 0 to 2,868 at raw 120, peaking at 2,914.

---

Auto Wah+Odrv

Show code

show_card('Auto Wah+Odrv')

Auto Wah+Odrv: what the measurements say

Recap. A filter effect with 14 tested controls, 14 of which measurably change the sound. Beyond mix and level, the biggest lever is Drive: gain compression across the input range 1.2 → -18.3 dB. Measured with 134 captures: 71 on the main sweep + tone probe (one control at a time), 31 on matched probes (spectralSweep ×19, harmonicTwoTone ×7, sustainedStereo ×5), 32 two-control pairs.

Technical explanation. At default settings: output -23.2 dBFS RMS (crest 8.0 dB); stereo width 0.08, L/R correlation +0.99; spectral tilt +0.04 dB/octave; 99% of the impulse response's energy in its first 5 ms; harmonics H2 -51 dB, H3 -10 dB re the linear response.

Two-control pairs captured: Drive×Cutoff Offset, Drive×LFO Depth, Drive×LPF Cutoff, LFO Depth×Cutoff Offset, LFO Speed×LFO Depth, LPF Cutoff×Cutoff Offset, LPF Cutoff×LFO Depth, Low Frequency×Resonance (interaction analysis in the main notebook).

Caveats:

• some long settings decay more slowly than the recording allows; their T30 is a lower bound

Plain explanation: The control to reach for first is Drive: gain compression across the input range 1.2 → -18.3 dB. After that, LPF Cutoff, LFO Depth and Cutoff Offset make the next biggest differences. DryWet and Output Level set how much of the effect you hear and how loud it is. At default the output is close to mono.

In other words, the main points:

• 14 of 14 tested controls measurably change the sound.
• Biggest lever beyond mix and level: Drive, 19.5× the smallest change that matters (gain compression across the input range 1.2 → -18.3 dB).
• At default: stereo width 0.08, output -23.2 dBFS RMS.
• Main caveat: some long settings decay more slowly than the recording allows; their T30 is a lower bound.
• Still to measure: T1, T3, T4 (see TESTS_NEEDED.md).

Show code

show_knobs('Auto Wah+Odrv')

barely changes the soundchanges it a lot■no measurable changeall to default

Click a knob to select it, then move the slider to turn it. A ring is that knob's own travel: green stretches barely change the sound, red stretches change it a lot. Rings show each knob with the others at their defaults; a knob outlined in cyan was also recorded together with the selected one, and its ring follows the slider.

Gap Fill: each control in physical units

Every control stepped on a probe matched to what it does (17 steps for time and rate controls, 9 for the rest), read as the physical quantity it sets: how far a delay tap moves, level or treble lost per repeat, LFO rate and pitch swing, gate length, THD, intermodulation, compressor ratio, knee, attack and release, and where a gate opens and closes. Times are read inside one capture (channel against channel) because Gap Fill runs fully wet and file starts wander by about ±50 ms.

Show code

show_gapfill('Auto Wah+Odrv')

How to read these charts. Each chart is one control. Left to right is the control's raw value as sent to the Motif (low to high setting); the height of the line is the physical quantity that control sets, measured from the recording. The title names the control, then the test signal used.

Cutoff-Offset · pinkPluck. Played: pink-noise bursts at three levels, then plucked notes. The line is Hz spectral centroid: the spectrum's centre of gravity, a measure of brightness; higher means brighter; here it goes from 1,267 at raw 0 to 3,534 at raw 127, peaking at 3,670.

Drive · transferSine. Played: a 100 Hz sine at −6 dBFS. The line is dB THD: total harmonic distortion: how loud the added overtones are against the note itself. −40 dB is clean, 0 dB would be overtones as loud as the note; higher on the chart means more distortion; here it goes from -75.1 at raw 0 to -7.43 at raw 127.

Drive · twoToneLadder. Played: two notes together (220 and 697 Hz), stepped from very quiet to loud. The line is dB intermodulation: how loud the extra tones created between two notes are against the notes themselves, which is what makes chords sound harsh; higher means harsher; here it goes from -72.5 at raw 0 to -14.6 at raw 127.

LFO-Depth · sustainedStereo. Played: a held chord, one note per channel. The line is cents pitch swing: how far the pitch bends, peak to peak (100 cents = one semitone); here it goes from 6.87 at raw 0 to 4.57 at raw 127, peaking at 27.7.

LFO-Speed · sustainedStereo. Played: a held chord, one note per channel. The line is Hz LFO rate: how many times a second the modulation cycles; here it goes from 3.14 at raw 15 to 9.1 at raw 127, peaking at 9.88.

LPF-Cutoff · pinkPluck. Played: pink-noise bursts at three levels, then plucked notes. The line is Hz spectral centroid: the spectrum's centre of gravity, a measure of brightness; higher means brighter; here it goes from 1,305 at raw 0 to 3,978 at raw 60.

Resonance · pinkPluck. Played: pink-noise bursts at three levels, then plucked notes. The line is Hz spectral centroid: the spectrum's centre of gravity, a measure of brightness; higher means brighter; here it goes from 2,207 at raw 0 to 2,820 at raw 120, peaking at 2,854.

---

Touch Wah

Show code

show_card('Touch Wah')

Touch Wah: what the measurements say

Recap. A filter effect with 8 tested controls, 6 of which measurably change the sound. Beyond mix and level, the biggest lever is High Gain: how much louder plucks brighten the sound 0.92 → 0.26 oct per 10 dB. 2 do nothing with the others at default. Measured with 86 captures: 41 on the main sweep + tone probe (one control at a time), 17 on matched probes (steppedTransients ×17), 28 two-control pairs.

Technical explanation. At default settings: output -26.1 dBFS RMS (crest 20.2 dB); stereo width 0.11, L/R correlation +0.98; spectral tilt +0.87 dB/octave; 100% of the impulse response's energy in its first 5 ms; decay T30 2.56 s, EDT 13.78 s; harmonics H2 -69 dB, H3 -53 dB re the linear response.

Structure:

• brightening 0.53 octaves per 10 dB of pluck level; centroid 3755–10104 Hz

Two-control pairs captured: High Gain×Low Gain, High Gain×Resonance, High Gain×Sensitivity, Low Frequency×Resonance, Resonance×Low Gain, Sensitivity×Low Gain, Sensitivity×Resonance (interaction analysis in the main notebook).

Caveats:

• High Frequency, Low Frequency did nothing because the matching gain sits at 0 dB in the one-at-a-time design

Plain explanation: The control to reach for first is High Gain: how much louder plucks brighten the sound 0.92 → 0.26 oct per 10 dB. After that, Sensitivity, Resonance and Low Gain make the next biggest differences. DryWet sets how much of the effect you hear and how loud it is. High Frequency and Low Frequency made no measurable difference with the other controls at default. At default the tail takes about 2.6 s to die away. At default it has a moderate stereo spread.

In other words, the main points:

• 6 of 8 tested controls measurably change the sound; 2 do nothing with the others at default.
• Biggest lever beyond mix and level: High Gain, 6.5× the smallest change that matters (how much louder plucks brighten the sound 0.92 → 0.26 oct per 10 dB).
• At default: stereo width 0.11, decay T30 2.56 s, output -26.1 dBFS RMS.
• Main caveat: High Frequency, Low Frequency did nothing because the matching gain sits at 0 dB in the one-at-a-time design.
• Still to measure: T1, T13 (see TESTS_NEEDED.md).

Show code

show_knobs('Touch Wah')

barely changes the soundchanges it a lot■no measurable changeall to default

Click a knob to select it, then move the slider to turn it. A ring is that knob's own travel: green stretches barely change the sound, red stretches change it a lot. Rings show each knob with the others at their defaults; a knob outlined in cyan was also recorded together with the selected one, and its ring follows the slider.

Not shown, because these recordings show no measurable change from them: High Frequency, Low Frequency.

Gap Fill: each control in physical units

Every control stepped on a probe matched to what it does (17 steps for time and rate controls, 9 for the rest), read as the physical quantity it sets: how far a delay tap moves, level or treble lost per repeat, LFO rate and pitch swing, gate length, THD, intermodulation, compressor ratio, knee, attack and release, and where a gate opens and closes. Times are read inside one capture (channel against channel) because Gap Fill runs fully wet and file starts wander by about ±50 ms.

Show code

show_gapfill('Touch Wah')

---

Touch Wah+Dist

Show code

show_card('Touch Wah+Dist')

Touch Wah+Dist: what the measurements say

Recap. A filter effect with 13 tested controls, 11 of which measurably change the sound. Beyond mix and level, the biggest lever is Resonance: how much louder plucks brighten the sound 2.48 → 0.11 oct per 10 dB. 2 do nothing with the others at default. Measured with 121 captures: 66 on the main sweep + tone probe (one control at a time), 27 on matched probes (steppedTransients ×27), 28 two-control pairs.

Technical explanation. At default settings: output -24.2 dBFS RMS (crest 9.2 dB); stereo width 0.09, L/R correlation +0.99; spectral tilt +3.16 dB/octave; 99% of the impulse response's energy in its first 5 ms; harmonics H2 -50 dB, H3 -11 dB re the linear response.

Structure:

• brightening 0.08 octaves per 10 dB of pluck level; centroid 2515–4909 Hz

Two-control pairs captured: Cutoff Offset×Dist Low Gain, Cutoff Offset×LPF Cutoff, Dist Low Gain×LPF Cutoff, Low Frequency×Resonance, Resonance×Cutoff Offset, Resonance×Dist Low Gain, Resonance×LPF Cutoff (interaction analysis in the main notebook).

Caveats:

• some long settings decay more slowly than the recording allows; their T30 is a lower bound
• High Frequency, Low Frequency did nothing because the matching gain sits at 0 dB in the one-at-a-time design

Plain explanation: The control to reach for first is Resonance: how much louder plucks brighten the sound 2.48 → 0.11 oct per 10 dB. After that, Cutoff Offset, Dist Low Gain and LPF Cutoff make the next biggest differences. DryWet and Output Level set how much of the effect you hear and how loud it is. High Frequency and Low Frequency made no measurable difference with the other controls at default. At default the output is close to mono.

In other words, the main points:

• 11 of 13 tested controls measurably change the sound; 2 do nothing with the others at default.
• Biggest lever beyond mix and level: Resonance, 23.7× the smallest change that matters (how much louder plucks brighten the sound 2.48 → 0.11 oct per 10 dB).
• At default: stereo width 0.09, output -24.2 dBFS RMS.
• Main caveat: some long settings decay more slowly than the recording allows; their T30 is a lower bound.
• Still to measure: T1, T13, T3, T4 (see TESTS_NEEDED.md).

Show code

show_knobs('Touch Wah+Dist')

barely changes the soundchanges it a lot■no measurable changeall to default

Click a knob to select it, then move the slider to turn it. A ring is that knob's own travel: green stretches barely change the sound, red stretches change it a lot. Rings show each knob with the others at their defaults; a knob outlined in cyan was also recorded together with the selected one, and its ring follows the slider.

Not shown, because these recordings show no measurable change from them: High Frequency, Low Frequency.

Gap Fill: each control in physical units

Every control stepped on a probe matched to what it does (17 steps for time and rate controls, 9 for the rest), read as the physical quantity it sets: how far a delay tap moves, level or treble lost per repeat, LFO rate and pitch swing, gate length, THD, intermodulation, compressor ratio, knee, attack and release, and where a gate opens and closes. Times are read inside one capture (channel against channel) because Gap Fill runs fully wet and file starts wander by about ±50 ms.

Show code

show_gapfill('Touch Wah+Dist')

How to read these charts. Each chart is one control. Left to right is the control's raw value as sent to the Motif (low to high setting); the height of the line is the physical quantity that control sets, measured from the recording. The title names the control, then the test signal used.

Cutoff-Offset · pinkPluck. Played: pink-noise bursts at three levels, then plucked notes. The line is Hz spectral centroid: the spectrum's centre of gravity, a measure of brightness; higher means brighter; here it goes from 291 at raw 0 to 4,049 at raw 127.

Drive · transferSine. Played: a 100 Hz sine at −6 dBFS. The line is dB THD: total harmonic distortion: how loud the added overtones are against the note itself. −40 dB is clean, 0 dB would be overtones as loud as the note; higher on the chart means more distortion; here it goes from -71.3 at raw 0 to -7.3 at raw 127, dipping to -88.7.

Drive · twoToneLadder. Played: two notes together (220 and 697 Hz), stepped from very quiet to loud. The line is dB intermodulation: how loud the extra tones created between two notes are against the notes themselves, which is what makes chords sound harsh; higher means harsher; here it goes from -63.6 at raw 0 to -13.9 at raw 127.

LPF-Cutoff · pinkPluck. Played: pink-noise bursts at three levels, then plucked notes. The line is Hz spectral centroid: the spectrum's centre of gravity, a measure of brightness; higher means brighter; here it goes from 924 at raw 0 to 7,647 at raw 60.

Resonance · pinkPluck. Played: pink-noise bursts at three levels, then plucked notes. The line is Hz spectral centroid: the spectrum's centre of gravity, a measure of brightness; higher means brighter; here it goes from 2,959 at raw 0 to 4,526 at raw 120.

---

Touch Wah+Odrv

Show code

show_card('Touch Wah+Odrv')

Touch Wah+Odrv: what the measurements say

Recap. A filter effect with 13 tested controls, 11 of which measurably change the sound. Beyond mix and level, the biggest lever is Resonance: how much louder plucks brighten the sound 2.33 → 0.10 oct per 10 dB. 1 does nothing with the others at default. Measured with 121 captures: 66 on the main sweep + tone probe (one control at a time), 27 on matched probes (steppedTransients ×27), 28 two-control pairs.

Technical explanation. At default settings: output -24.3 dBFS RMS (crest 9.2 dB); stereo width 0.09, L/R correlation +0.99; spectral tilt +0.76 dB/octave; 99% of the impulse response's energy in its first 5 ms; harmonics H2 -52 dB, H3 -11 dB re the linear response.

Structure:

• brightening 0.03 octaves per 10 dB of pluck level; centroid 2320–4697 Hz

Two-control pairs captured: Dist Low Gain×High Gain, Dist Low Gain×LPF Cutoff, LPF Cutoff×High Gain, Low Frequency×Resonance, Resonance×Dist Low Gain, Resonance×High Gain, Resonance×LPF Cutoff (interaction analysis in the main notebook).

Caveats:

• some long settings decay more slowly than the recording allows; their T30 is a lower bound
• High Frequency did nothing because the matching gain sits at 0 dB in the one-at-a-time design

Plain explanation: The control to reach for first is Resonance: how much louder plucks brighten the sound 2.33 → 0.10 oct per 10 dB. After that, Dist Low Gain, LPF Cutoff and High Gain make the next biggest differences. Output Level and DryWet set how much of the effect you hear and how loud it is. High Frequency made no measurable difference with the other controls at default. At default the output is close to mono.

In other words, the main points:

• 11 of 13 tested controls measurably change the sound; 1 does nothing with the others at default.
• Biggest lever beyond mix and level: Resonance, 22.3× the smallest change that matters (how much louder plucks brighten the sound 2.33 → 0.10 oct per 10 dB).
• At default: stereo width 0.09, output -24.3 dBFS RMS.
• Main caveat: some long settings decay more slowly than the recording allows; their T30 is a lower bound.
• Still to measure: T1, T13, T3, T4 (see TESTS_NEEDED.md).

Show code

show_knobs('Touch Wah+Odrv')

barely changes the soundchanges it a lot■no measurable changeall to default

Click a knob to select it, then move the slider to turn it. A ring is that knob's own travel: green stretches barely change the sound, red stretches change it a lot. Rings show each knob with the others at their defaults; a knob outlined in cyan was also recorded together with the selected one, and its ring follows the slider.

Not shown, because these recordings show no measurable change from them: High Frequency.

Gap Fill: each control in physical units

Every control stepped on a probe matched to what it does (17 steps for time and rate controls, 9 for the rest), read as the physical quantity it sets: how far a delay tap moves, level or treble lost per repeat, LFO rate and pitch swing, gate length, THD, intermodulation, compressor ratio, knee, attack and release, and where a gate opens and closes. Times are read inside one capture (channel against channel) because Gap Fill runs fully wet and file starts wander by about ±50 ms.

Show code

show_gapfill('Touch Wah+Odrv')

How to read these charts. Each chart is one control. Left to right is the control's raw value as sent to the Motif (low to high setting); the height of the line is the physical quantity that control sets, measured from the recording. The title names the control, then the test signal used.

Cutoff-Offset · pinkPluck. Played: pink-noise bursts at three levels, then plucked notes. The line is Hz spectral centroid: the spectrum's centre of gravity, a measure of brightness; higher means brighter; here it goes from 234 at raw 0 to 3,537 at raw 127.

Drive · transferSine. Played: a 100 Hz sine at −6 dBFS. The line is dB THD: total harmonic distortion: how loud the added overtones are against the note itself. −40 dB is clean, 0 dB would be overtones as loud as the note; higher on the chart means more distortion; here it goes from -71.4 at raw 0 to -7.7 at raw 127, dipping to -87.7.

Drive · twoToneLadder. Played: two notes together (220 and 697 Hz), stepped from very quiet to loud. The line is dB intermodulation: how loud the extra tones created between two notes are against the notes themselves, which is what makes chords sound harsh; higher means harsher; here it goes from -63.1 at raw 0 to -13.9 at raw 127.

LPF-Cutoff · pinkPluck. Played: pink-noise bursts at three levels, then plucked notes. The line is Hz spectral centroid: the spectrum's centre of gravity, a measure of brightness; higher means brighter; here it goes from 925 at raw 0 to 7,163 at raw 60.

Resonance · pinkPluck. Played: pink-noise bursts at three levels, then plucked notes. The line is Hz spectral centroid: the spectrum's centre of gravity, a measure of brightness; higher means brighter; here it goes from 2,589 at raw 0 to 4,158 at raw 120.

---

Vintage Auto Wah 1

Show code

show_card('Vintage Auto Wah 1')

Vintage Auto Wah 1: what the measurements say

Recap. A filter effect with 12 tested controls, 11 of which measurably change the sound. Beyond mix and level, the biggest lever is Speed: amplitude-LFO rate 0.23 → 20.01 Hz. Measured with 116 captures: 57 on the main sweep + tone probe (one control at a time), 27 on matched probes (spectralSweep ×19, sustainedStereo ×5, harmonicTwoTone ×3), 32 two-control pairs.

Technical explanation. At default settings: output -29.8 dBFS RMS (crest 14.7 dB); stereo width 0.30, L/R correlation +0.82; spectral tilt +1.11 dB/octave; 100% of the impulse response's energy in its first 5 ms; harmonics H2 -94 dB, H3 -35 dB re the linear response.

Two-control pairs captured: Bottom×Resonance Offset, Bottom×Top, Low Frequency×Resonance Offset, OverDrive×Type, Speed×Bottom, Speed×Resonance Offset, Speed×Top, Top×Resonance Offset (interaction analysis in the main notebook).

Plain explanation: The control to reach for first is Speed: amplitude-LFO rate 0.23 → 20.01 Hz. After that, Output, Bottom and Top make the next biggest differences. At default it has a moderate stereo spread.

In other words, the main points:

• 11 of 12 tested controls measurably change the sound.
• Biggest lever beyond mix and level: Speed, 46.8× the smallest change that matters (amplitude-LFO rate 0.23 → 20.01 Hz).
• At default: stereo width 0.30, output -29.8 dBFS RMS.
• Still to measure: T1 (see TESTS_NEEDED.md).

Show code

show_knobs('Vintage Auto Wah 1')

barely changes the soundchanges it a lot■no measurable changeall to default

Click a knob to select it, then move the slider to turn it. A ring is that knob's own travel: green stretches barely change the sound, red stretches change it a lot. Rings show each knob with the others at their defaults; a knob outlined in cyan was also recorded together with the selected one, and its ring follows the slider.

Gap Fill: each control in physical units

Every control stepped on a probe matched to what it does (17 steps for time and rate controls, 9 for the rest), read as the physical quantity it sets: how far a delay tap moves, level or treble lost per repeat, LFO rate and pitch swing, gate length, THD, intermodulation, compressor ratio, knee, attack and release, and where a gate opens and closes. Times are read inside one capture (channel against channel) because Gap Fill runs fully wet and file starts wander by about ±50 ms.

Show code

show_gapfill('Vintage Auto Wah 1')

How to read these charts. Each chart is one control. Left to right is the control's raw value as sent to the Motif (low to high setting); the height of the line is the physical quantity that control sets, measured from the recording. The title names the control, then the test signal used.

Bottom · pinkPluck. Played: pink-noise bursts at three levels, then plucked notes. The line is Hz spectral centroid: the spectrum's centre of gravity, a measure of brightness; higher means brighter; here it goes from 923 at raw 0 to 3,193 at raw 127.

OverDrive · transferSine. Played: a 100 Hz sine at −6 dBFS. The line is dB THD: total harmonic distortion: how loud the added overtones are against the note itself. −40 dB is clean, 0 dB would be overtones as loud as the note; higher on the chart means more distortion; here it goes from -74.8 at raw 0 to -34 at raw 80.

OverDrive · twoToneLadder. Played: two notes together (220 and 697 Hz), stepped from very quiet to loud. The line is dB intermodulation: how loud the extra tones created between two notes are against the notes themselves, which is what makes chords sound harsh; higher means harsher; here it goes from -87.3 at raw 0 to -47.4 at raw 80.

Resonance-Offset · pinkPluck. Played: pink-noise bursts at three levels, then plucked notes. The line is Hz spectral centroid: the spectrum's centre of gravity, a measure of brightness; higher means brighter; here it goes from 1,214 at raw 0 to 1,016 at raw 88.

Top · pinkPluck. Played: pink-noise bursts at three levels, then plucked notes. The line is Hz spectral centroid: the spectrum's centre of gravity, a measure of brightness; higher means brighter; here it goes from 621 at raw 0 to 1,548 at raw 127.

Type · sustainedStereo. Played: a held chord, one note per channel. The line is cents pitch swing: how far the pitch bends, peak to peak (100 cents = one semitone); here it goes from 0.158 at raw 0 to 1.08 at raw 3.

---

Vintage Auto Wah 2

Show code

show_card('Vintage Auto Wah 2')

Vintage Auto Wah 2: what the measurements say

Recap. A filter effect with 12 tested controls, 12 of which measurably change the sound. Beyond mix and level, the biggest lever is Speed: amplitude-LFO rate 0.23 → 20.01 Hz. Measured with 116 captures: 57 on the main sweep + tone probe (one control at a time), 27 on matched probes (spectralSweep ×19, sustainedStereo ×5, harmonicTwoTone ×3), 32 two-control pairs.

Technical explanation. At default settings: output -29.7 dBFS RMS (crest 14.7 dB); stereo width 0.29, L/R correlation +0.83; spectral tilt +0.66 dB/octave; 100% of the impulse response's energy in its first 5 ms; harmonics H2 -93 dB, H3 -34 dB re the linear response.

Two-control pairs captured: Bottom×High Frequency, Bottom×Top, Low Frequency×Resonance Offset, OverDrive×Type, Speed×Bottom, Speed×High Frequency, Speed×Top, Top×High Frequency (interaction analysis in the main notebook).

Plain explanation: The control to reach for first is Speed: amplitude-LFO rate 0.23 → 20.01 Hz. After that, Output, Bottom and Top make the next biggest differences. At default it has a moderate stereo spread.

In other words, the main points:

• 12 of 12 tested controls measurably change the sound.
• Biggest lever beyond mix and level: Speed, 46.8× the smallest change that matters (amplitude-LFO rate 0.23 → 20.01 Hz).
• At default: stereo width 0.29, output -29.7 dBFS RMS.
• Still to measure: T1 (see TESTS_NEEDED.md).

Show code

show_knobs('Vintage Auto Wah 2')

barely changes the soundchanges it a lot■no measurable changeall to default

Click a knob to select it, then move the slider to turn it. A ring is that knob's own travel: green stretches barely change the sound, red stretches change it a lot. Rings show each knob with the others at their defaults; a knob outlined in cyan was also recorded together with the selected one, and its ring follows the slider.

Gap Fill: each control in physical units

Every control stepped on a probe matched to what it does (17 steps for time and rate controls, 9 for the rest), read as the physical quantity it sets: how far a delay tap moves, level or treble lost per repeat, LFO rate and pitch swing, gate length, THD, intermodulation, compressor ratio, knee, attack and release, and where a gate opens and closes. Times are read inside one capture (channel against channel) because Gap Fill runs fully wet and file starts wander by about ±50 ms.

Show code

show_gapfill('Vintage Auto Wah 2')

How to read these charts. Each chart is one control. Left to right is the control's raw value as sent to the Motif (low to high setting); the height of the line is the physical quantity that control sets, measured from the recording. The title names the control, then the test signal used.

Bottom · pinkPluck. Played: pink-noise bursts at three levels, then plucked notes. The line is Hz spectral centroid: the spectrum's centre of gravity, a measure of brightness; higher means brighter; here it goes from 952 at raw 0 to 3,193 at raw 127.

OverDrive · transferSine. Played: a 100 Hz sine at −6 dBFS. The line is dB THD: total harmonic distortion: how loud the added overtones are against the note itself. −40 dB is clean, 0 dB would be overtones as loud as the note; higher on the chart means more distortion; here it goes from -74.4 at raw 0 to -34 at raw 80.

OverDrive · twoToneLadder. Played: two notes together (220 and 697 Hz), stepped from very quiet to loud. The line is dB intermodulation: how loud the extra tones created between two notes are against the notes themselves, which is what makes chords sound harsh; higher means harsher; here it goes from -83 at raw 0 to -47.4 at raw 80.

Resonance-Offset · pinkPluck. Played: pink-noise bursts at three levels, then plucked notes. The line is Hz spectral centroid: the spectrum's centre of gravity, a measure of brightness; higher means brighter; here it goes from 1,170 at raw 0 to 1,032 at raw 88, dipping to 1,018.

Top · pinkPluck. Played: pink-noise bursts at three levels, then plucked notes. The line is Hz spectral centroid: the spectrum's centre of gravity, a measure of brightness; higher means brighter; here it goes from 621 at raw 0 to 1,454 at raw 127.

Type · sustainedStereo. Played: a held chord, one note per channel. The line is cents pitch swing: how far the pitch bends, peak to peak (100 cents = one semitone); here it goes from 0.161 at raw 0 to 1.08 at raw 3.

---

Vintage Touch Wah 1

Show code

show_card('Vintage Touch Wah 1')

Vintage Touch Wah 1: what the measurements say

Recap. A filter effect with 13 tested controls, 10 of which measurably change the sound. Beyond mix and level, the biggest lever is OverDrive: 3rd harmonic -42 → -14 dB. 3 do nothing with the others at default. Measured with 121 captures: 62 on the main sweep + tone probe (one control at a time), 27 on matched probes (steppedTransients ×27), 32 two-control pairs.

Technical explanation. At default settings: output -29.6 dBFS RMS (crest 15.7 dB); stereo width 0.29, L/R correlation +0.83; spectral tilt +0.48 dB/octave; 100% of the impulse response's energy in its first 5 ms; harmonics H2 -86 dB, H3 -35 dB re the linear response.

Structure:

• brightening 0.41 octaves per 10 dB of pluck level; centroid 3071–6402 Hz

Two-control pairs captured: Direction×Sensitivity, Direction×Top, Low Frequency×Resonance Offset, OverDrive×Direction, OverDrive×Sensitivity, OverDrive×Top, OverDrive×Type, Top×Sensitivity (interaction analysis in the main notebook).

Caveats:

• High Frequency, Low Frequency did nothing because the matching gain sits at 0 dB in the one-at-a-time design

Plain explanation: The control to reach for first is OverDrive: 3rd harmonic -42 → -14 dB. After that, Direction, Top and Sensitivity make the next biggest differences. Attack Offset, High Frequency and Low Frequency made no measurable difference with the other controls at default. At default it has a moderate stereo spread.

In other words, the main points:

• 10 of 13 tested controls measurably change the sound; 3 do nothing with the others at default.
• Biggest lever beyond mix and level: OverDrive, 9.1× the smallest change that matters (3rd harmonic -42 → -14 dB).
• At default: stereo width 0.29, output -29.6 dBFS RMS.
• Main caveat: High Frequency, Low Frequency did nothing because the matching gain sits at 0 dB in the one-at-a-time design.
• Still to measure: T1, T13 (see TESTS_NEEDED.md).

Show code

show_knobs('Vintage Touch Wah 1')

barely changes the soundchanges it a lot■no measurable changeall to default

Click a knob to select it, then move the slider to turn it. A ring is that knob's own travel: green stretches barely change the sound, red stretches change it a lot. Rings show each knob with the others at their defaults; a knob outlined in cyan was also recorded together with the selected one, and its ring follows the slider.

Not shown, because these recordings show no measurable change from them: Attack Offset, High Frequency, Low Frequency.

Gap Fill: each control in physical units

Every control stepped on a probe matched to what it does (17 steps for time and rate controls, 9 for the rest), read as the physical quantity it sets: how far a delay tap moves, level or treble lost per repeat, LFO rate and pitch swing, gate length, THD, intermodulation, compressor ratio, knee, attack and release, and where a gate opens and closes. Times are read inside one capture (channel against channel) because Gap Fill runs fully wet and file starts wander by about ±50 ms.

Show code

show_gapfill('Vintage Touch Wah 1')

How to read these charts. Each chart is one control. Left to right is the control's raw value as sent to the Motif (low to high setting); the height of the line is the physical quantity that control sets, measured from the recording. The title names the control, then the test signal used.

Bottom · pinkPluck. Played: pink-noise bursts at three levels, then plucked notes. The line is Hz spectral centroid: the spectrum's centre of gravity, a measure of brightness; higher means brighter; here it goes from 2,028 at raw 0 to 3,193 at raw 127.

OverDrive · transferSine. Played: a 100 Hz sine at −6 dBFS. The line is dB THD: total harmonic distortion: how loud the added overtones are against the note itself. −40 dB is clean, 0 dB would be overtones as loud as the note; higher on the chart means more distortion; here it goes from -75.3 at raw 0 to -34.1 at raw 80.

OverDrive · twoToneLadder. Played: two notes together (220 and 697 Hz), stepped from very quiet to loud. The line is dB intermodulation: how loud the extra tones created between two notes are against the notes themselves, which is what makes chords sound harsh; higher means harsher; here it goes from -85 at raw 0 to -45.9 at raw 80.

Resonance-Offset · pinkPluck. Played: pink-noise bursts at three levels, then plucked notes. The line is Hz spectral centroid: the spectrum's centre of gravity, a measure of brightness; higher means brighter; here it goes from 2,139 at raw 0 to 1,594 at raw 88.

Top · pinkPluck. Played: pink-noise bursts at three levels, then plucked notes. The line is Hz spectral centroid: the spectrum's centre of gravity, a measure of brightness; higher means brighter; here it goes from 621 at raw 0 to 3,193 at raw 127.

Type · sustainedStereo. Played: a held chord, one note per channel. The line is cents pitch swing: how far the pitch bends, peak to peak (100 cents = one semitone); here it goes from 0.0119 at raw 0 to 0.0125 at raw 3, dipping to 0.0115.

---

Vintage Touch Wah 2

Show code

show_card('Vintage Touch Wah 2')

Vintage Touch Wah 2: what the measurements say

Recap. A filter effect with 13 tested controls, 10 of which measurably change the sound. Beyond mix and level, the biggest lever is OverDrive: 3rd harmonic -42 → -14 dB. 2 do nothing with the others at default. Measured with 121 captures: 62 on the main sweep + tone probe (one control at a time), 27 on matched probes (steppedTransients ×27), 32 two-control pairs.

Technical explanation. At default settings: output -29.7 dBFS RMS (crest 15.7 dB); stereo width 0.29, L/R correlation +0.83; spectral tilt +0.48 dB/octave; 100% of the impulse response's energy in its first 5 ms; harmonics H2 -88 dB, H3 -35 dB re the linear response.

Structure:

• brightening 0.41 octaves per 10 dB of pluck level; centroid 3054–6447 Hz

Two-control pairs captured: Direction×Sensitivity, Direction×Top, Low Frequency×Resonance Offset, OverDrive×Direction, OverDrive×Sensitivity, OverDrive×Top, OverDrive×Type, Top×Sensitivity (interaction analysis in the main notebook).

Caveats:

• Low Frequency did nothing because the matching gain sits at 0 dB in the one-at-a-time design

Plain explanation: The control to reach for first is OverDrive: 3rd harmonic -42 → -14 dB. After that, Direction, Top and Sensitivity make the next biggest differences. Attack Offset and Low Frequency made no measurable difference with the other controls at default. At default it has a moderate stereo spread.

In other words, the main points:

• 10 of 13 tested controls measurably change the sound; 2 do nothing with the others at default.
• Biggest lever beyond mix and level: OverDrive, 9.1× the smallest change that matters (3rd harmonic -42 → -14 dB).
• At default: stereo width 0.29, output -29.7 dBFS RMS.
• Main caveat: Low Frequency did nothing because the matching gain sits at 0 dB in the one-at-a-time design.
• Still to measure: T1, T13 (see TESTS_NEEDED.md).

Show code

show_knobs('Vintage Touch Wah 2')

barely changes the soundchanges it a lot■no measurable changeall to default

Click a knob to select it, then move the slider to turn it. A ring is that knob's own travel: green stretches barely change the sound, red stretches change it a lot. Rings show each knob with the others at their defaults; a knob outlined in cyan was also recorded together with the selected one, and its ring follows the slider.

Not shown, because these recordings show no measurable change from them: Attack Offset, Low Frequency.

Gap Fill: each control in physical units

Every control stepped on a probe matched to what it does (17 steps for time and rate controls, 9 for the rest), read as the physical quantity it sets: how far a delay tap moves, level or treble lost per repeat, LFO rate and pitch swing, gate length, THD, intermodulation, compressor ratio, knee, attack and release, and where a gate opens and closes. Times are read inside one capture (channel against channel) because Gap Fill runs fully wet and file starts wander by about ±50 ms.

Show code

show_gapfill('Vintage Touch Wah 2')

How to read these charts. Each chart is one control. Left to right is the control's raw value as sent to the Motif (low to high setting); the height of the line is the physical quantity that control sets, measured from the recording. The title names the control, then the test signal used.

Bottom · pinkPluck. Played: pink-noise bursts at three levels, then plucked notes. The line is Hz spectral centroid: the spectrum's centre of gravity, a measure of brightness; higher means brighter; here it goes from 2,029 at raw 0 to 3,194 at raw 127.

OverDrive · transferSine. Played: a 100 Hz sine at −6 dBFS. The line is dB THD: total harmonic distortion: how loud the added overtones are against the note itself. −40 dB is clean, 0 dB would be overtones as loud as the note; higher on the chart means more distortion; here it goes from -74.6 at raw 0 to -34.1 at raw 80.

OverDrive · twoToneLadder. Played: two notes together (220 and 697 Hz), stepped from very quiet to loud. The line is dB intermodulation: how loud the extra tones created between two notes are against the notes themselves, which is what makes chords sound harsh; higher means harsher; here it goes from -80.6 at raw 0 to -46 at raw 80.

Resonance-Offset · pinkPluck. Played: pink-noise bursts at three levels, then plucked notes. The line is Hz spectral centroid: the spectrum's centre of gravity, a measure of brightness; higher means brighter; here it goes from 2,139 at raw 0 to 1,594 at raw 88.

Top · pinkPluck. Played: pink-noise bursts at three levels, then plucked notes. The line is Hz spectral centroid: the spectrum's centre of gravity, a measure of brightness; higher means brighter; here it goes from 621 at raw 0 to 3,191 at raw 127.

Type · sustainedStereo. Played: a held chord, one note per channel. The line is cents pitch swing: how far the pitch bends, peak to peak (100 cents = one semitone); here it goes from 0.0118 at raw 0 to 0.0124 at raw 3, dipping to 0.0115.

---

Wah+Dist+Dly

Show code

show_card('Wah+Dist+Dly')

Wah+Dist+Dly: what the measurements say

Recap. A filter effect with 12 tested controls, 11 of which measurably change the sound. Beyond mix and level, the biggest lever is Wah Cutoff: gain compression across the input range -19.0 → -7.6 dB. 1 does nothing with the others at default. Measured with 115 captures: 61 on the main sweep + tone probe (one control at a time), 26 on matched probes (harmonicTwoTone ×21, steppedTransients ×5), 28 two-control pairs.

Technical explanation. At default settings: output -22.8 dBFS RMS (crest 8.9 dB); stereo width 0.09, L/R correlation +0.99; spectral tilt +1.29 dB/octave; 97% of the impulse response's energy in its first 5 ms; decay T30 0.53 s, EDT 2.45 s; harmonics H2 -38 dB, H3 -12 dB re the linear response.

Structure:

• brightening 0.12 octaves per 10 dB of pluck level; centroid 2176–7844 Hz

Two-control pairs captured: Delay Mix×Dist Low Gain, Delay Time×Delay Feedback Level, Dist Drive×Delay Mix, Dist Drive×Dist Low Gain, Wah Cutoff×Delay Mix, Wah Cutoff×Dist Drive, Wah Cutoff×Dist Low Gain (interaction analysis in the main notebook).

Caveats:

• some long settings decay more slowly than the recording allows; their T30 is a lower bound

Plain explanation: The control to reach for first is Wah Cutoff: gain compression across the input range -19.0 → -7.6 dB. After that, Dist Drive, Delay Mix and Dist Low Gain make the next biggest differences. DryWet and Dist Output Level set how much of the effect you hear and how loud it is. Wah Release made no measurable difference with the other controls at default. At default the tail takes about 0.5 s to die away. At default the output is close to mono.

In other words, the main points:

• 11 of 12 tested controls measurably change the sound; 1 does nothing with the others at default.
• Biggest lever beyond mix and level: Wah Cutoff, 11.4× the smallest change that matters (gain compression across the input range -19.0 → -7.6 dB).
• At default: stereo width 0.09, decay T30 0.53 s, output -22.8 dBFS RMS.
• Main caveat: some long settings decay more slowly than the recording allows; their T30 is a lower bound.
• Still to measure: T1, T4 (see TESTS_NEEDED.md).

Show code

show_knobs('Wah+Dist+Dly')

barely changes the soundchanges it a lot■no measurable changeall to default

Click a knob to select it, then move the slider to turn it. A ring is that knob's own travel: green stretches barely change the sound, red stretches change it a lot. Rings show each knob with the others at their defaults; a knob outlined in cyan was also recorded together with the selected one, and its ring follows the slider.

Not shown, because these recordings show no measurable change from them: Wah Release.

Gap Fill: each control in physical units

Every control stepped on a probe matched to what it does (17 steps for time and rate controls, 9 for the rest), read as the physical quantity it sets: how far a delay tap moves, level or treble lost per repeat, LFO rate and pitch swing, gate length, THD, intermodulation, compressor ratio, knee, attack and release, and where a gate opens and closes. Times are read inside one capture (channel against channel) because Gap Fill runs fully wet and file starts wander by about ±50 ms.

Show code

show_gapfill('Wah+Dist+Dly')

How to read these charts. Each chart is one control. Left to right is the control's raw value as sent to the Motif (low to high setting); the height of the line is the physical quantity that control sets, measured from the recording. The title names the control, then the test signal used.

Delay-Feedback-Level · sweepTail. Played: a sweep followed by silence. The line is dB per repeat: how much quieter each repeat is than the one before; closer to 0 means more repeats; here it goes from -0.00906 at raw 0 to 0.000552 at raw 127, dipping to -18.1.

Delay-Time · sweepTail. Played: a sweep followed by silence. The line is s T30: the reverb decay time (extrapolated to 60 dB of decay); here it goes from 3.58 at raw 0 to 6.58 at raw 16383, dipping to 3.03.

Dist-Drive · transferSine. Played: a 100 Hz sine at −6 dBFS. The line is dB THD: total harmonic distortion: how loud the added overtones are against the note itself. −40 dB is clean, 0 dB would be overtones as loud as the note; higher on the chart means more distortion; here it goes from -74.2 at raw 0 to -7.73 at raw 127.

Dist-Drive · twoToneLadder. Played: two notes together (220 and 697 Hz), stepped from very quiet to loud. The line is dB intermodulation: how loud the extra tones created between two notes are against the notes themselves, which is what makes chords sound harsh; higher means harsher; here it goes from -35.8 at raw 0 to -13.8 at raw 127.

Wah-Cutoff · pinkPluck. Played: pink-noise bursts at three levels, then plucked notes. The line is Hz spectral centroid: the spectrum's centre of gravity, a measure of brightness; higher means brighter; here it goes from 3,750 at raw 0 to 6,963 at raw 127, dipping to 181.

Wah-Resonance · pinkPluck. Played: pink-noise bursts at three levels, then plucked notes. The line is Hz spectral centroid: the spectrum's centre of gravity, a measure of brightness; higher means brighter; here it goes from 6,312 at raw 0 to 7,077 at raw 120.

---

Wah+Odrv+Dly

Show code

show_card('Wah+Odrv+Dly')

Wah+Odrv+Dly: what the measurements say

Recap. A filter effect with 12 tested controls, 11 of which measurably change the sound. Beyond mix and level, the biggest lever is Delay Feedback Level: first left echo 20 → 400 ms. Measured with 113 captures: 61 on the main sweep + tone probe (one control at a time), 28 on matched probes (harmonicTwoTone ×9, impulseTail ×7, spectralSweep ×7, steppedTransients ×5), 24 two-control pairs.

Technical explanation. At default settings: output -23.4 dBFS RMS (crest 8.9 dB); stereo width 0.09, L/R correlation +0.98; spectral tilt +2.10 dB/octave; 99% of the impulse response's energy in its first 5 ms; decay T30 0.53 s, EDT 2.44 s; harmonics H2 -44 dB, H3 -11 dB re the linear response.

Structure:

• brightening 0.09 octaves per 10 dB of pluck level; centroid 1537–6371 Hz

Two-control pairs captured: Delay Feedback Level×Delay Mix, Delay Feedback Level×Dist Drive, Delay Time×Delay Feedback Level, Delay Time×Delay Mix, Dist Drive×Delay Mix, Dist Drive×Delay Time (interaction analysis in the main notebook).

Caveats:

• some long settings decay more slowly than the recording allows; their T30 is a lower bound

Plain explanation: The control to reach for first is Delay Feedback Level: first left echo 20 → 400 ms. After that, Dist Drive, Delay Time and Delay Mix make the next biggest differences. DryWet and Dist Output Level set how much of the effect you hear and how loud it is. At default the tail takes about 0.5 s to die away. At default the output is close to mono.

In other words, the main points:

• 11 of 12 tested controls measurably change the sound.
• Biggest lever beyond mix and level: Delay Feedback Level, 31.4× the smallest change that matters (first left echo 20 → 400 ms).
• At default: stereo width 0.09, decay T30 0.53 s, output -23.4 dBFS RMS.
• Main caveat: some long settings decay more slowly than the recording allows; their T30 is a lower bound.
• Still to measure: T1, T4 (see TESTS_NEEDED.md).

Show code

show_knobs('Wah+Odrv+Dly')

barely changes the soundchanges it a lot■no measurable changeall to default

Click a knob to select it, then move the slider to turn it. A ring is that knob's own travel: green stretches barely change the sound, red stretches change it a lot. Rings show each knob with the others at their defaults; a knob outlined in cyan was also recorded together with the selected one, and its ring follows the slider.

Gap Fill: each control in physical units

Every control stepped on a probe matched to what it does (17 steps for time and rate controls, 9 for the rest), read as the physical quantity it sets: how far a delay tap moves, level or treble lost per repeat, LFO rate and pitch swing, gate length, THD, intermodulation, compressor ratio, knee, attack and release, and where a gate opens and closes. Times are read inside one capture (channel against channel) because Gap Fill runs fully wet and file starts wander by about ±50 ms.

Show code

show_gapfill('Wah+Odrv+Dly')

How to read these charts. Each chart is one control. Left to right is the control's raw value as sent to the Motif (low to high setting); the height of the line is the physical quantity that control sets, measured from the recording. The title names the control, then the test signal used.

Delay-Feedback-Level · sweepTail. Played: a sweep followed by silence. The line is dB per repeat: how much quieter each repeat is than the one before; closer to 0 means more repeats; here it goes from -0.0604 at raw 0 to -0.0944 at raw 127, dipping to -11.8.

Delay-Time · sweepTail. Played: a sweep followed by silence. The line is s T30: the reverb decay time (extrapolated to 60 dB of decay); here it goes from 4.31 at raw 0 to 7.53 at raw 16383, dipping to 3.45.

Dist-Drive · transferSine. Played: a 100 Hz sine at −6 dBFS. The line is dB THD: total harmonic distortion: how loud the added overtones are against the note itself. −40 dB is clean, 0 dB would be overtones as loud as the note; higher on the chart means more distortion; here it goes from -74.7 at raw 0 to -8.33 at raw 127.

Dist-Drive · twoToneLadder. Played: two notes together (220 and 697 Hz), stepped from very quiet to loud. The line is dB intermodulation: how loud the extra tones created between two notes are against the notes themselves, which is what makes chords sound harsh; higher means harsher; here it goes from -35.9 at raw 0 to -14 at raw 127.

Wah-Cutoff · pinkPluck. Played: pink-noise bursts at three levels, then plucked notes. The line is Hz spectral centroid: the spectrum's centre of gravity, a measure of brightness; higher means brighter; here it goes from 3,218 at raw 0 to 5,192 at raw 127, dipping to 215.

Wah-Resonance · pinkPluck. Played: pink-noise bursts at three levels, then plucked notes. The line is Hz spectral centroid: the spectrum's centre of gravity, a measure of brightness; higher means brighter; here it goes from 3,366 at raw 0 to 5,792 at raw 120.

---

Revision 36 · 2026-10-15

Revision history

• Rev 36 · 2026-10-15: The Distortion drive ladders are re-recorded in the current setup (80 takes) and replace those of 2026-09-28, whose flat-topped waves came from the levels of the setup at the time, not from the effects: with the drive up, each distortion gives a square wave whose tops sag, and its Output Level only scales it.
• Rev 35 · 2026-10-12: The main page folds by topic and each family's detail page folds by effect: every section is closed until opened, with one control to open or close them all.
• Rev 34 · 2026-10-12: Every sheet: a play button steps through each control's settings; every recorded pair of controls drawn, with whether they simply add or one changes the other; EQ frequency and width controls drawn with their band at full boost. New detailed charts on every board: which controls depend on each other; the EQ bands moving; the ring modulator's pitch against its controls.
• Rev 33 · 2026-10-12: Every control on every effect's sheet: all its tested settings overlaid in one cell, and its measured law in physical units where a probe reads one. Misc board: the equalisers' bands at full cut and boost.
• Rev 32 · 2026-10-12: Headline findings set apart with larger titles; a note under the three whose graphic shows less than the headline says (Lo-Fi rate, delay feedback, repeats).
• Rev 31 · 2026-10-12: Main page: a graphic under each of the eight headline findings (the delay feedback one animated), each with a plain-terms line.
• Rev 30 · 2026-10-12: Main page opens with a chart of where every capture went and the central technique in pictures: the sweep, and the spikes the matched filter turns a recording of it into.
• Rev 29 · 2026-10-12: Misc board: the ring modulator's carrier pitch against OSC Freq Coarse and Fine, read from the sine takes.
• Rev 28 · 2026-10-11: Fifth capture batch in: the Reverb board gains the gap before the reverb starts against Initial Delay, the Chorus and Flanger boards gain the delay length against the delay knob.
• Rev 27 · 2026-10-11: Waves: a third page, what the instrument and effect waves measure: the note each one plays, where it starts repeating and how long the loop is, how long it rings, and the harmonics of each pitched wave.
• Rev 26 · 2026-10-11: Waves: the instrument and effect tiles now show the opening of the note (its first 8 cycles) instead of the whole take, so the individual waves can be seen.
• Rev 25 · 2026-10-11: Waves: a second page for the 955 instrument and effect waves, each drawn as the whole take of one note with one cycle of the sound under it where the wave holds a steady pitch.
• Rev 24 · 2026-10-08: Reverb knob pairs recorded (288 takes over the 12 distinct reverbs), so the reverb consoles' rings follow each other too; 799 knob pairs measured in all.
• Rev 23 · 2026-10-08: Every family page now opens with a comparison board (one row per effect, shared scales down each column) and control sheets with all tested settings side by side; each family's detailed charts are folded in beneath and the earlier pages are kept as detail pages.
• Rev 22 · 2026-10-08: Knob consoles: 2,120 new recordings of knob pairs, so within each effect's four strongest controls every knob's ring now follows every other (679 pairs measured, up from 155). A Waves page shows the 904 drum and percussion waves.
• Rev 21 · 2026-10-07: Delay page rebuilt the same way: every delay's echoes side by side, and each control's tested settings next to each other as echo patterns.
• Rev 20 · 2026-10-07: Reverb page rebuilt for comparison: one board with every distinct reverb as a row and every measure as a column on a shared scale, then each reverb's controls with all tested settings side by side. The detailed charts are folded in beneath; the earlier page is kept as the detail page. Knob consoles now use a slider for the selected knob, and controls with nothing measurable are listed, not drawn.
• Rev 19 · 2026-10-07: A knob console on every effect: each ring shows where along the knob's travel the sound changes, and turning a knob shows how the knobs captured together with it respond.
• Rev 18 · 2026-10-07: Reverb taken apart in time: how fast separate reflections merge into a wash; the tail's colour through time; how alike left and right are at each pitch and through the decay; how smooth each tail is against noise of the same tone; the Reverb Time control against Yamaha's table; and the twenty reverb names compared pair by pair.
• Rev 17 · 2026-10-07: Charts that only compared output level or gain are removed from every page except the compressors and gates, where level is what the effect does.
• Rev 16 · 2026-10-07: Capture set finished and audited (14,635 takes; the takes recorded through a reverb are all replaced). Corrections: Celeste 1's control shown as Delay is its Feedback Level, and Symphonic's shown as Feedback is its Delay Offset; two Symphonic controls that do not exist on the effect are removed. New charts in time and wave shape rather than level: Delay, where every echo lands as each time control is turned; Distortion, the wave that comes out as the drive rises; Lo-Fi, the output wave sample by sample at each Sampling Freq setting; Chorus and Flanger, the delay line followed as it sweeps; Phaser and Wah, where each notch or peak sits in Hz from moment to moment; Reverb, the separate early reflections in the first quarter second after one click; Modulation and Tech, each side turned up and down from moment to moment.
• Rev 15 · 2026-10-06: Pitch Change: a click train in, and when each click comes out.
• Rev 14 · 2026-10-06: Distortion: output and distortion against input level on a smooth ramp, harmonics against the pitch of the note, high-note harmonics folding back off 44.1 kHz (no oversampling), a bass note modulating a treble note, input-against-output loops, and the amp and cabinet filters' level and phase.
• Rev 13 · 2026-10-06: Lo-Fi on a smoothly rising tone: Word Length sets a clipping ceiling and adds no quantisation noise; the five Lo-Fi effects compared on the same ramp.
• Rev 12 · 2026-10-06: Lo-Fi: a rising note against everything that comes out with it, at each sampling-rate setting. Pitch Change: the cluster of lines a shifted note returns as, and the splice window read from it (about 35 ms and 28 ms).
• Rev 11 · 2026-10-06: The same routing fault is confirmed for the 1,835 re-takes of 2026-09-30/10-01 (the dry-plus-wet timing takes and the full-rate Lo-Fi takes). No published chart used them; they are withdrawn from the counts and are being re-recorded.
• Rev 10 · 2026-10-06: Correction: the all-effects comparison (section 17 of the main report), added earlier today, is withdrawn. Its 625 recordings were made with the Motif's System Reverb left in the signal path and are being re-recorded. New: compressor timing inside the distortion chains, wah filter sweeps, reverb decay per octave band.
• Rev 9 · 2026-10-06: Follow-up captures analysed: compressor attack and release against step size, MultiBand Comp 2 band by band, Noise Gate opening, hold and closing times, and distortion on level steps (no sag: the clippers act instant by instant). Release times now require the level to stay recovered for 50 ms, which fixes readings fooled by ringing or by a delay's echo. Capture counts include the overnight batches.
• Rev 8 · 2026-10-05: Beyond level curves: gain-reduction speed, release shape, phase-space orbits, harmonic matrices, intermodulation maps, parallel coordinates, a behaviour map and loudness in phon and sone on the Dynamic atlas; harmonic-against-drive matrices (Distortion), stereo LFO orbits (Chorus, Flanger, Phaser, Modulation), an echo map (Delay) and a decay-rate matrix (Reverb).
• Rev 7 · 2026-10-04: All figures vector and stacked one per row; control tables replaced by interactive charts; every section in four parts (recap, professional, plain, main points); capture counts include Gap Fill; six more Gap Fill probes analysed (dynamics timing, band staircase, gate ramp, two-tone ladder, tone triplet, pink pluck).
• Rev 6 · 2026-10-04: Complete 13-category analysis with detail ladders; all notebooks rebuilt with executed cells and interactive charts.
• Rev 5 · 2026-10-01: T28/T29 re-take analysis (dry/wet time references, Lo-Fi full-rate captures); Reverb detail ladders.
• Rev 4 · 2026-09-30: Reverb analysis from full 9,876 Gap Fill run; two-voice explanations added to main page sections 1–15.
• Rev 3 · 2026-09-29: Gap Fill captures: delay and feedback time laws, LFO maps, drive transfer curves, Lo-Fi rate, early reflections; Gate/Reverse Gate relabelled; interactive charts, atlas links, dark theme.
• Rev 2 · 2026-09-28: Gate Reverb time origin fixed; Auto Pan phase and Distortion harmonics computed from data.
• Rev 1 · 2026-09-27: First complete report: main analysis and 13 atlas notebooks.