Modulation — effect atlas

14 effects · 1,601 captures. Tremolo, auto-pan and the rotary-speaker family. Amplitude modulation is read from the envelope; auto-pan shows up as anti-phase between the channels.

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 = {'Amp+Rotary SP 1': (10, 0), 'Amp+Rotary SP 2': (14, 0), 'Auto Pan': (6, 5), 'Auto Pan 2': (7, 0), 'Dist+Rotary SP 1': (9, 0), 'Dist+Rotary SP 2': (12, 1), 'Dual Rotor SP 1': (14, 0), 'Dual Rotor SP 2': (13, 0), 'Dual Rotor SP 3': (15, 0), 'Odrv+Rotary SP 1': (9, 0), 'Odrv+Rotary SP 2': (12, 0), 'Rotary SP 1': (10, 0), 'Rotary SP 2': (10, 0), 'Tremolo': (12, 0)}
show(cards.family_overview(df, 'Modulation', knob_counts, curves))

Show code

iviz.family_fig(df, curves, 'Modulation').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.

A presence peak between 2 and 8 kHz with a steep cut above it (a speaker-cabinet shape): Amp+Rotary SP 2, Dist+Rotary SP 1, Odrv+Rotary SP 1. Less reliable in detail (repeat captures differ by over 3 dB, usually a running LFO): Amp+Rotary SP 1, Amp+Rotary SP 2, Dist+Rotary SP 1, Dist+Rotary SP 2, Dual Rotor SP 1, Dual Rotor SP 2, Dual Rotor SP 3, Odrv+Rotary SP 1, Odrv+Rotary SP 2, Rotary SP 1, Rotary SP 2, Tremolo. These effects move while they are measured, so each curve is one snapshot of a response that sweeps back and forth; read the overall tilt, not individual notches. The LFO maps in the cards and in §14 of the main analysis show the movement itself. 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. A bump in the upper mids followed by a steep drop is what a guitar speaker does: it adds bite and removes harsh fizz. Amp+Rotary SP 1, Amp+Rotary SP 2, Dist+Rotary SP 1, Dist+Rotary SP 2, Dual Rotor SP 1, Dual Rotor SP 2, Odrv+Rotary SP 1 and Odrv+Rotary SP 2 roll off the top end early, so they sound darker. Because these effects sweep constantly, think of each line as a single frame of a moving picture.

In other words, the main points:

• Most shaping: Dist+Rotary SP 2, 33 dB from peak to deepest cut.
• Speaker-cabinet shape (presence peak, steep cut above it): Amp+Rotary SP 2, Dist+Rotary SP 1, Odrv+Rotary SP 1.
• Darkest (top end rolled off early): Amp+Rotary SP 1, Amp+Rotary SP 2, Dist+Rotary SP 1, Dist+Rotary SP 2, Dual Rotor SP 1, Dual Rotor SP 2, Odrv+Rotary SP 1, Odrv+Rotary SP 2.
• Least repeatable in detail (usually a running LFO): Amp+Rotary SP 1, Amp+Rotary SP 2, Dist+Rotary SP 1, Dist+Rotary SP 2, Dual Rotor SP 1, Dual Rotor SP 2, Dual Rotor SP 3, Odrv+Rotary SP 1, Odrv+Rotary SP 2, Rotary SP 1, Rotary SP 2, Tremolo.

Show code

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

The stereo LFO as an orbit

A chorus, flanger or phaser is defined as much by how its left and right channels move against each other as by its rate and depth. This chart draws that relationship directly.

Show code

import kinetics, kviz, wviz, rviz
show_parts(wviz.motion_parts(g) + kviz.orbit_parts(df, curves, 'Modulation'))

What it shows. Steady noise, the same in both speakers, through each effect at its default settings. Every 10 ms the size of what comes out of each side is compared with the same moment of the noise recorded with no effect.

How to read it. Time runs left to right. A line at 100 is that side at its average size; above is louder, below quieter. Cyan is the left side, amber the right. Lines that rise and fall together are a tremolo; lines that take turns are a pan; the shape of the wave (smooth, pointed, lopsided) is the shape of the effect's modulator. Use the slider to change effect.

What it found.

• Amp+Rotary SP 1: 2.69 times a second, the left side swinging between 61% and 132% of its average; the two sides rise and fall together.
• Auto Pan: 2.69 times a second, the left side swinging between 41% and 161% of its average; the two sides take turns (one is up when the other is down).
• Auto Pan 2: 2.69 times a second, the left side swinging between 44% and 176% of its average; the two sides take turns (one is up when the other is down).
• Dual Rotor SP 2: 3.03 times a second, the left side swinging between 47% and 165% of its average; the two sides rise and fall together.
• Dual Rotor SP 3: 3.31 times a second, the left side swinging between 45% and 153% of its average; the two sides rise and fall together.
• Tremolo: 2.69 times a second, the left side swinging between 40% and 160% of its average; the two sides rise and fall together.
• Not drawn: Amp+Rotary SP 2, Dist+Rotary SP 1, Dist+Rotary SP 2, Dual Rotor SP 1, Odrv+Rotary SP 1, Odrv+Rotary SP 2, Rotary SP 1, Rotary SP 2.
• They move, but no regular rise and fall could be read; a moving delay (as in a rotary speaker) changes the noise in ways this comparison cannot separate from loudness.

What it shows. The pitch of the left channel plotted against the pitch of the right, traced over ten seconds of a held chord (a different note in each channel, so each can be followed separately) at default settings. Time is not an axis: the LFO draws the same figure once per cycle.

How to read it. A line along the rising diagonal means both channels go sharp and flat together (one LFO for both). A line along the falling diagonal means they move in opposite directions. A loop that encloses area means one channel leads the other; a circle or square is a quarter cycle apart, which is what makes a chorus seem to rotate. Corners mean a triangle-wave LFO, rounded figures a sine. Use the slider to step through the effects.

What it found.

• Left and right move together: Amp+Rotary SP 1 (+26°), Odrv+Rotary SP 1 (+26°), Rotary SP 1 (+29°).
• Left and right move a quarter cycle apart: Amp+Rotary SP 2 (−95°), Dual Rotor SP 1 (−56°), Dual Rotor SP 2 (−57°), Dual Rotor SP 3 (−58°), Odrv+Rotary SP 2 (−95°).
• Left and right move without a fixed relation: Rotary SP 2 (−44°).
• The angle is the lead of the left channel over the right, averaged over the recording.
• The tracker follows one partial in a ±100 cent band, so swings beyond about ±60 cents are flattened and multi-voice effects, whose voices beat against each other, draw a tangle rather than a clean figure.

---

Amp+Rotary SP 1

Show code

show_card('Amp+Rotary SP 1')

Amp+Rotary SP 1: what the measurements say

Recap. A modulation effect with 10 tested controls, 10 of which measurably change the sound. Beyond mix and level, the biggest lever is AMP Drive: gain compression across the input range 0.3 → -18.2 dB. Measured with 101 captures: 50 on the main sweep + tone probe (one control at a time), 23 on matched probes (spectralSweep ×13, harmonicTwoTone ×5, sustainedStereo ×5), 28 two-control pairs.

Technical explanation. At default settings: output -20.1 dBFS RMS (crest 11.6 dB); stereo width 0.16, L/R correlation +0.95; spectral tilt -1.46 dB/octave; 99% of the impulse response's energy in its first 5 ms; harmonics H2 -47 dB, H3 -11 dB re the linear response.

Structure:

• pitch LFO 2.68 Hz, 8 cents peak-to-peak, L/R phase -13°
• amplitude LFO 2.70 Hz, depth 0.44
• crosstalk L→R -0 dB, R→L 0 dB

Two-control pairs captured: AMP Drive×AMP LPF Cutoff, AMP Drive×AMP Type, AMP Drive×LFO Depth, AMP Drive×LFO Speed, LFO Depth×AMP LPF Cutoff, LFO Speed×AMP LPF Cutoff, LFO Speed×LFO Depth (interaction analysis in the main notebook).

Caveats:

• the LFO runs during the sweep, so the frequency-response features are averages over LFO phase, not a fixed response
• some long settings decay more slowly than the recording allows; their T30 is a lower bound
• at least one setting mutes the output; those captures are excluded from spectral analysis

Plain explanation: The control to reach for first is AMP Drive: gain compression across the input range 0.3 → -18.2 dB. After that, LFO Depth, LFO Speed and AMP LPF Cutoff make the next biggest differences. AMP Output Level 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:

• 10 of 10 tested controls measurably change the sound.
• Biggest lever beyond mix and level: AMP Drive, 18.6× the smallest change that matters (gain compression across the input range 0.3 → -18.2 dB).
• At default: stereo width 0.16, output -20.1 dBFS RMS.
• Main caveat: the LFO runs during the sweep, so the frequency-response features are averages over LFO phase, not a fixed response.
• Still to measure: T1, T4, T6, T7 (see TESTS_NEEDED.md).

Show code

show_knobs('Amp+Rotary SP 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('Amp+Rotary SP 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.

AMP-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 -33.8 at raw 0 to -7.58 at raw 127.

AMP-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 -57.9 at raw 0 to -10.2 at raw 127.

AMP-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 346 at raw 0 to 2,071 at raw 60.

AMP-Type · 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 -7.58 at raw 0 to -13.4 at raw 3.

AMP-Type · 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 -10.3 at raw 0 to -12.7 at raw 3, dipping to -13.3.

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 0.324 at raw 0 to 7.89 at raw 95.

LFO-Speed · longSine. Played: a steady 440 Hz sine. The line is Hz LFO rate: how many times a second the modulation cycles; here it goes from 0.299 at raw 7 to 1.3 at raw 31.

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 1.29 at raw 31 to 8.07 at raw 95.

---

Amp+Rotary SP 2

Show code

show_card('Amp+Rotary SP 2')

Amp+Rotary SP 2: what the measurements say

Recap. A modulation effect with 14 tested controls, 14 of which measurably change the sound. Beyond mix and level, the biggest lever is AMP Drive: gain compression across the input range 0.0 → -18.4 dB. Measured with 130 captures: 70 on the main sweep + tone probe (one control at a time), 32 on matched probes (spectralSweep ×15, harmonicTwoTone ×9, sustainedStereo ×5, rhythmicGrid ×3), 28 two-control pairs.

Technical explanation. At default settings: output -27.9 dBFS RMS (crest 18.2 dB); stereo width 0.65, L/R correlation +0.16; spectral tilt -0.52 dB/octave; 91% of the impulse response's energy in its first 5 ms; harmonics H2 -40 dB, H3 -11 dB re the linear response.

Structure:

• pitch LFO — Hz, — cents peak-to-peak, L/R phase —°
• amplitude LFO 8.41 Hz, depth 0.67
• crosstalk L→R — dB, R→L — dB

Two-control pairs captured: AMP Drive×AMP LPF Cutoff, AMP Drive×Mic Angle, AMP Drive×Rotor Speed, Drive Low×AMP Type, Mic Angle×AMP LPF Cutoff, Rotor Speed×AMP LPF Cutoff, Rotor Speed×Mic Angle (interaction analysis in the main notebook).

Caveats:

• the LFO runs during the sweep, so the frequency-response features are averages over LFO phase, not a fixed response
• some long settings decay more slowly than the recording allows; their T30 is a lower bound
• at least one setting mutes the output; those captures are excluded from spectral analysis

Plain explanation: The control to reach for first is AMP Drive: gain compression across the input range 0.0 → -18.4 dB. After that, Rotor Speed, Mic Angle and AMP LPF Cutoff make the next biggest differences. AMP Output Level sets how much of the effect you hear and how loud it is. At default left and right are largely independent, so it sounds wide.

In other words, the main points:

• 14 of 14 tested controls measurably change the sound.
• Biggest lever beyond mix and level: AMP Drive, 18.4× the smallest change that matters (gain compression across the input range 0.0 → -18.4 dB).
• At default: stereo width 0.65, output -27.9 dBFS RMS.
• Main caveat: the LFO runs during the sweep, so the frequency-response features are averages over LFO phase, not a fixed response.
• Still to measure: T1, T3, T4, T6, T7 (see TESTS_NEEDED.md).

Show code

show_knobs('Amp+Rotary SP 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('Amp+Rotary SP 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.

AMP-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 -59.3 at raw 0 to -11.9 at raw 127.

AMP-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 -44.9 at raw 0 to -13.3 at raw 127.

AMP-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 353 at raw 0 to 2,679 at raw 60.

AMP-Type · 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 -12.3 at raw 0 to -15.2 at raw 3.

AMP-Type · 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 -13.3 at raw 0 to -13.2 at raw 3, dipping to -17.8.

Divide-Frequency · 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 1,020 at raw 0 to 863 at raw 54, peaking at 1,053.

Drive-High · 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 -4.07 at raw 0 to -16 at raw 127, dipping to -16.8.

Drive-High · 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 -11.4 at raw 0 to -11.3 at raw 127, dipping to -13.

Drive-Low · 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 -7.75 at raw 0 to -6.18 at raw 127, dipping to -15.7.

Drive-Low · 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 -11 at raw 0 to -12.1 at raw 127, dipping to -13.1.

Low-High-Balance · 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 105 at raw 0 to 45.7 at raw 127.

Mic-Angle · sustainedStereo. Played: a held chord, one note per channel. The line is ° L/R LFO phase: how far the right channel's modulation runs ahead of or behind the left's; here it goes from -8.71 at raw 0 to 173 at raw 60.

Rotor-Speed · longSine. Played: a steady 440 Hz sine. The line is Hz LFO rate: how many times a second the modulation cycles; here it goes from 0.299 at raw 7 to 1.3 at raw 31.

---

Auto Pan

Show code

show_card('Auto Pan')

Auto Pan: what the measurements say

Recap. A modulation effect with 11 tested controls, 6 of which measurably change the sound. Beyond mix and level, the biggest lever is High Gain: raises everything above ~165 Hz by up to 24 dB. 5 do nothing with the others at default. Measured with 112 captures: 57 on the main sweep + tone probe (one control at a time), 23 on matched probes (stereoRouting ×23), 32 two-control pairs.

Technical explanation. At default settings: output -32.4 dBFS RMS (crest 14.2 dB); stereo width 0.39, L/R correlation +0.69; spectral tilt +0.37 dB/octave; 100% of the impulse response's energy in its first 5 ms; harmonics H2 -78 dB, H3 -55 dB re the linear response.

Two-control pairs captured: High Gain×Left Right Depth, High Gain×Low Gain, High Gain×Mid Gain, LFO Speed×Left Right Depth, Left Right Depth×Low Gain, Left Right Depth×Mid Gain, Low Gain×Mid Gain, Mid Width×Left Right Depth (interaction analysis in the main notebook).

Caveats:

• the LFO runs during the sweep, so the frequency-response features are averages over LFO phase, not a fixed response
• High Frequency, Low Frequency, Mid Frequency, Mid Width 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: raises everything above ~165 Hz by up to 24 dB. After that, Left Right Depth, Low Gain and Mid Gain make the next biggest differences. Front Rear Depth, High Frequency, Low Frequency, Mid Frequency and Mid Width made no measurable difference with the other controls at default. At default it has a moderate stereo spread.

In other words, the main points:

• 6 of 11 tested controls measurably change the sound; 5 do nothing with the others at default.
• Biggest lever beyond mix and level: High Gain, 10.7× the smallest change that matters (raises everything above ~165 Hz by up to 24 dB).
• At default: stereo width 0.39, output -32.4 dBFS RMS.
• Main caveat: the LFO runs during the sweep, so the frequency-response features are averages over LFO phase, not a fixed response.
• Still to measure: T1, T13, T6, T7 (see TESTS_NEEDED.md).

Show code

show_knobs('Auto Pan')

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: Front Rear Depth, High Frequency, Low Frequency, Mid Frequency, Mid Width.

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 Pan')

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.

Front-Rear-Depth · stereoRouting. Played: bursts sent left only, right only, both in phase and both out of phase. The line is dB L/R isolation: how well left and right are kept apart; higher means less bleed; here it goes from -0.457 at raw 0 to -0.46 at raw 127, peaking at -0.407.

Left-Right-Depth · stereoRouting. Played: bursts sent left only, right only, both in phase and both out of phase. The line is dB L/R isolation: how well left and right are kept apart; higher means less bleed; here it goes from -0.273 at raw 0 to -0.596 at raw 127.

Pan-Direction · stereoRouting. Played: bursts sent left only, right only, both in phase and both out of phase. The line is dB L/R isolation: how well left and right are kept apart; higher means less bleed; here it goes from -0.418 at raw 0 to -0.473 at raw 5, peaking at -0.269.

---

Auto Pan 2

Show code

show_card('Auto Pan 2')

Auto Pan 2: what the measurements say

Recap. A modulation effect with 12 tested controls, 7 of which measurably change the sound. Beyond mix and level, the biggest lever is Input Mode: side-signal survival -53 → -0 dB. Measured with 116 captures: 59 on the main sweep + tone probe (one control at a time), 25 on matched probes (stereoRouting ×25), 32 two-control pairs.

Technical explanation. At default settings: output -33.4 dBFS RMS (crest 14.7 dB); stereo width 0.48, L/R correlation +0.53; spectral tilt +0.29 dB/octave; 100% of the impulse response's energy in its first 5 ms; harmonics H2 -78 dB, H3 -55 dB re the linear response.

Two-control pairs captured: High Gain×Left Right Depth, High Gain×Low Gain, High Gain×Pan Direction, LFO Speed×Left Right Depth, Low Gain×Left Right Depth, Low Gain×Pan Direction, Mid Width×Left Right Depth, Pan Direction×Left Right Depth (interaction analysis in the main notebook).

Caveats:

• the LFO runs during the sweep, so the frequency-response features are averages over LFO phase, not a fixed response

Plain explanation: The control to reach for first is Input Mode: side-signal survival -53 → -0 dB. After that, High Gain, Low Gain and Pan Direction make the next biggest differences. At default it has a moderate stereo spread.

In other words, the main points:

• 7 of 12 tested controls measurably change the sound.
• Biggest lever beyond mix and level: Input Mode, 17.8× the smallest change that matters (side-signal survival -53 → -0 dB).
• At default: stereo width 0.48, output -33.4 dBFS RMS.
• Main caveat: the LFO runs during the sweep, so the frequency-response features are averages over LFO phase, not a fixed response.
• Still to measure: T1, T6, T7 (see TESTS_NEEDED.md).

Show code

show_knobs('Auto Pan 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('Auto Pan 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.

Front-Rear-Depth · stereoRouting. Played: bursts sent left only, right only, both in phase and both out of phase. The line is dB L/R isolation: how well left and right are kept apart; higher means less bleed; here it barely moves (about -59.6 throughout).

Left-Right-Depth · stereoRouting. Played: bursts sent left only, right only, both in phase and both out of phase. The line is dB L/R isolation: how well left and right are kept apart; higher means less bleed; here it goes from -62.7 at raw 0 to -58.1 at raw 127.

Pan-Direction · stereoRouting. Played: bursts sent left only, right only, both in phase and both out of phase. The line is dB L/R isolation: how well left and right are kept apart; higher means less bleed; here it goes from -59.6 at raw 0 to -61.1 at raw 5, peaking at -58.2.

---

Dist+Rotary SP 1

Show code

show_card('Dist+Rotary SP 1')

Dist+Rotary SP 1: what the measurements say

Recap. A modulation effect with 9 tested controls, 9 of which measurably change the sound. Beyond mix and level, the biggest lever is Dist Drive: gain compression across the input range 0.3 → -18.0 dB. Measured with 93 captures: 46 on the main sweep + tone probe (one control at a time), 19 on matched probes (harmonicTwoTone ×19), 28 two-control pairs.

Technical explanation. At default settings: output -17.8 dBFS RMS (crest 12.9 dB); stereo width 0.19, L/R correlation +0.93; spectral tilt -1.79 dB/octave; 99% of the impulse response's energy in its first 5 ms; harmonics H2 -47 dB, H3 -9 dB re the linear response.

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

Caveats:

• the LFO runs during the sweep, so the frequency-response features are averages over LFO phase, not a fixed response
• some long settings decay more slowly than the recording allows; their T30 is a lower bound
• at least one setting mutes the output; those captures are excluded from spectral analysis

Plain explanation: The control to reach for first is Dist Drive: gain compression across the input range 0.3 → -18.0 dB. After that, LFO Speed, Low Gain and High Frequency make the next biggest differences. Dist Output Level 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: Dist Drive, 18.3× the smallest change that matters (gain compression across the input range 0.3 → -18.0 dB).
• At default: stereo width 0.19, output -17.8 dBFS RMS.
• Main caveat: the LFO runs during the sweep, so the frequency-response features are averages over LFO phase, not a fixed response.
• Still to measure: T1, T4, T6, T7 (see TESTS_NEEDED.md).

Show code

show_knobs('Dist+Rotary SP 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('Dist+Rotary SP 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.

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 -34.8 at raw 0 to -6.21 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 -58 at raw 0 to -10.5 at raw 127.

Dist-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 483 at raw 0 to 1,250 at raw 60.

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 0.207 at raw 0 to 7.83 at raw 95.

LFO-Speed · longSine. Played: a steady 440 Hz sine. The line is Hz LFO rate: how many times a second the modulation cycles; here it goes from 0.299 at raw 7 to 1.3 at raw 31.

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 1.29 at raw 31 to 8.07 at raw 95.

---

Dist+Rotary SP 2

Show code

show_card('Dist+Rotary SP 2')

Dist+Rotary SP 2: what the measurements say

Recap. A modulation effect with 13 tested controls, 12 of which measurably change the sound. Beyond mix and level, the biggest lever is Dist Drive: gain compression across the input range 0.0 → -18.4 dB. 1 does nothing with the others at default. Measured with 122 captures: 66 on the main sweep + tone probe (one control at a time), 28 on matched probes (harmonicTwoTone ×25, rhythmicGrid ×3), 28 two-control pairs.

Technical explanation. At default settings: output -21.8 dBFS RMS (crest 15.8 dB); stereo width 0.58, L/R correlation +0.32; spectral tilt -2.57 dB/octave; 48% of the impulse response's energy in its first 5 ms.

Two-control pairs captured: Dist Drive×Dist LPF Cutoff, Dist Drive×Low High Balance, Dist Drive×Mic Angle, Dist LPF Cutoff×Low High Balance, Mic Angle×Dist LPF Cutoff, Mic Angle×Low High Balance, Rotor Speed×Drive Low (interaction analysis in the main notebook).

Caveats:

• the LFO runs during the sweep, so the frequency-response features are averages over LFO phase, not a fixed response
• some long settings decay more slowly than the recording allows; their T30 is a lower bound
• Low Frequency did nothing because the matching gain sits at 0 dB in the one-at-a-time design
• at least one setting mutes the output; those captures are excluded from spectral analysis

Plain explanation: The control to reach for first is Dist Drive: gain compression across the input range 0.0 → -18.4 dB. After that, Mic Angle, Dist LPF Cutoff and Low High Balance make the next biggest differences. Dist Output Level sets how much of the effect you hear and how loud it is. Low Frequency made no measurable difference with the other controls at default. At default left and right are largely independent, so it sounds wide.

In other words, the main points:

• 12 of 13 tested controls measurably change the sound; 1 does nothing with the others at default.
• Biggest lever beyond mix and level: Dist Drive, 18.4× the smallest change that matters (gain compression across the input range 0.0 → -18.4 dB).
• At default: stereo width 0.58, output -21.8 dBFS RMS.
• Main caveat: the LFO runs during the sweep, so the frequency-response features are averages over LFO phase, not a fixed response.
• Still to measure: T1, T13, T3, T4, T6, T7 (see TESTS_NEEDED.md).

Show code

show_knobs('Dist+Rotary SP 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: 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('Dist+Rotary SP 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.

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 -59.1 at raw 0 to -7.93 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 -47.4 at raw 0 to -11.5 at raw 127.

Dist-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 407 at raw 0 to 721 at raw 60.

Divide-Frequency · 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 471 at raw 0 to 548 at raw 54, peaking at 661, dipping to 454.

Drive-High · 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 -3.07 at raw 0 to -11.8 at raw 127.

Drive-High · 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 -12.7 at raw 0 to -10.9 at raw 127, peaking at -10.8.

Drive-Low · 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 -10.7 at raw 0 to -6.08 at raw 127.

Drive-Low · 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 -10.6 at raw 0 to -14 at raw 127.

Low-High-Balance · 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 105 at raw 0 to 45.6 at raw 127.

Mic-Angle · sustainedStereo. Played: a held chord, one note per channel. The line is ° L/R LFO phase: how far the right channel's modulation runs ahead of or behind the left's; here it goes from -0.48 at raw 0 to -179 at raw 60, peaking at 150.

Rotor-Speed · longSine. Played: a steady 440 Hz sine. The line is Hz LFO rate: how many times a second the modulation cycles; here it goes from 0.299 at raw 7 to 1.3 at raw 31.

Rotor-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 0.306 at raw 7 to 8.07 at raw 95.

---

Dual Rotor SP 1

Show code

show_card('Dual Rotor SP 1')

Dual Rotor SP 1: what the measurements say

Recap. A modulation effect with 15 tested controls, 14 of which measurably change the sound. Beyond mix and level, the biggest lever is Horn Speed Fast: amplitude-LFO rate 2.66 → 39.69 Hz. Measured with 133 captures: 73 on the main sweep + tone probe (one control at a time), 32 on matched probes (sustainedStereo ×27, harmonicTwoTone ×5), 28 two-control pairs.

Technical explanation. At default settings: output -29.7 dBFS RMS (crest 20.4 dB); stereo width 0.58, L/R correlation +0.33; spectral tilt -0.77 dB/octave; 67% of the impulse response's energy in its first 5 ms; harmonics H2 -78 dB, H3 -41 dB re the linear response.

Structure:

• pitch LFO — Hz, — cents peak-to-peak, L/R phase —°
• amplitude LFO 14.79 Hz, depth 0.51
• crosstalk L→R — dB, R→L — dB

Two-control pairs captured: Horn Speed Fast×Horn Speed Slow, Horn Speed Fast×Horn Transition Time, Horn Speed Fast×Speed Control, Horn Transition Time×Horn Speed Slow, Rotor Speed Slow×Horn Speed Slow, Speed Control×Horn Speed Slow, Speed Control×Horn Transition Time (interaction analysis in the main notebook).

Caveats:

• the LFO runs during the sweep, so the frequency-response features are averages over LFO phase, not a fixed response

Plain explanation: The control to reach for first is Horn Speed Fast: amplitude-LFO rate 2.66 → 39.69 Hz. After that, Speed Control, Horn Transition Time and Horn Speed Slow make the next biggest differences. At default left and right are largely independent, so it sounds wide.

In other words, the main points:

• 14 of 15 tested controls measurably change the sound.
• Biggest lever beyond mix and level: Horn Speed Fast, 28.4× the smallest change that matters (amplitude-LFO rate 2.66 → 39.69 Hz).
• At default: stereo width 0.58, output -29.7 dBFS RMS.
• Main caveat: the LFO runs during the sweep, so the frequency-response features are averages over LFO phase, not a fixed response.
• Still to measure: T1, T3, T6, T7 (see TESTS_NEEDED.md).

Show code

show_knobs('Dual Rotor SP 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('Dual Rotor SP 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.

Drive-High · 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 barely moves (about -94 throughout).

Drive-High · 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 -78.6 at raw 0 to -45.1 at raw 127.

Drive-Low · 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 -106 at raw 0 to -91.1 at raw 127.

Drive-Low · 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 -64.6 at raw 0 to -56.3 at raw 127.

Horn-Speed-Fast · longSine. Played: a steady 440 Hz sine. The line is Hz LFO rate: how many times a second the modulation cycles; here it goes from 5.72 at raw 0 to 5.72 at raw 31, dipping to 2.69.

Horn-Speed-Fast · 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 barely moves (about 8.41 throughout).

Horn-Speed-Slow · longSine. Played: a steady 440 Hz sine. The line is Hz LFO rate: how many times a second the modulation cycles; here it barely moves (about 6.39 throughout).

Horn-Speed-Slow · 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 barely moves (about 8.41 throughout).

Horn-Transition-Time · longSine. Played: a steady 440 Hz sine. The line is Hz LFO rate: how many times a second the modulation cycles; here it barely moves (about 6.4 throughout).

Horn-Transition-Time · 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 barely moves (about 8.41 throughout).

Low-High-Balance · 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 71.2 throughout).

Mic-Angle · sustainedStereo. Played: a held chord, one note per channel. The line is ° L/R LFO phase: how far the right channel's modulation runs ahead of or behind the left's; here it goes from -0.343 at raw 0 to 111 at raw 60.

Rotor-Speed-Fast · longSine. Played: a steady 440 Hz sine. The line is Hz LFO rate: how many times a second the modulation cycles; here it barely moves (about 17.5 throughout).

Rotor-Speed-Slow · longSine. Played: a steady 440 Hz sine. The line is Hz LFO rate: how many times a second the modulation cycles; here it barely moves (about 6.39 throughout).

Rotor-Transition-Time · longSine. Played: a steady 440 Hz sine. The line is Hz LFO rate: how many times a second the modulation cycles; here it barely moves (about 6.39 throughout).

---

Dual Rotor SP 2

Show code

show_card('Dual Rotor SP 2')

Dual Rotor SP 2: what the measurements say

Recap. A modulation effect with 15 tested controls, 13 of which measurably change the sound. Beyond mix and level, the biggest lever is Rotor Speed Fast: amplitude-LFO rate 2.68 → 39.70 Hz. Measured with 133 captures: 73 on the main sweep + tone probe (one control at a time), 32 on matched probes (sustainedStereo ×27, harmonicTwoTone ×5), 28 two-control pairs.

Technical explanation. At default settings: output -26.7 dBFS RMS (crest 20.1 dB); stereo width 0.54, L/R correlation +0.41; spectral tilt -1.67 dB/octave; 49% of the impulse response's energy in its first 5 ms.

Structure:

• pitch LFO — Hz, — cents peak-to-peak, L/R phase —°
• amplitude LFO 8.41 Hz, depth 1.07
• crosstalk L→R — dB, R→L — dB

Two-control pairs captured: Rotor Speed Fast×Drive Low, Rotor Speed Fast×Rotor Transition Time, Rotor Speed Fast×Speed Control, Rotor Speed Slow×Horn Speed Slow, Rotor Transition Time×Drive Low, Speed Control×Drive Low, Speed Control×Rotor Transition Time (interaction analysis in the main notebook).

Caveats:

• the LFO runs during the sweep, so the frequency-response features are averages over LFO phase, not a fixed response

Plain explanation: The control to reach for first is Rotor Speed Fast: amplitude-LFO rate 2.68 → 39.70 Hz. After that, Speed Control, Rotor Transition Time and Drive Low make the next biggest differences. At default left and right are largely independent, so it sounds wide.

In other words, the main points:

• 13 of 15 tested controls measurably change the sound.
• Biggest lever beyond mix and level: Rotor Speed Fast, 28.3× the smallest change that matters (amplitude-LFO rate 2.68 → 39.70 Hz).
• At default: stereo width 0.54, output -26.7 dBFS RMS.
• Main caveat: the LFO runs during the sweep, so the frequency-response features are averages over LFO phase, not a fixed response.
• Still to measure: T1, T3, T6, T7 (see TESTS_NEEDED.md).

Show code

show_knobs('Dual Rotor SP 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('Dual Rotor SP 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.

Drive-High · 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 barely moves (about -91.8 throughout).

Drive-High · 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 -64.8 at raw 0 to -65.6 at raw 127, peaking at -62.4.

Drive-Low · 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 -86.7 at raw 0 to -89.8 at raw 127, dipping to -95.6.

Drive-Low · 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 -79.1 at raw 0 to -62.1 at raw 127.

Horn-Speed-Fast · longSine. Played: a steady 440 Hz sine. The line is Hz LFO rate: how many times a second the modulation cycles; here it barely moves (about 8.42 throughout).

Horn-Speed-Slow · longSine. Played: a steady 440 Hz sine. The line is Hz LFO rate: how many times a second the modulation cycles; here it barely moves (about 8.42 throughout).

Horn-Transition-Time · longSine. Played: a steady 440 Hz sine. The line is Hz LFO rate: how many times a second the modulation cycles; here it barely moves (about 8.42 throughout).

Low-High-Balance · 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 74.3 at raw 111 to 82.5 at raw 127.

Rotor-Speed-Fast · longSine. Played: a steady 440 Hz sine. The line is Hz LFO rate: how many times a second the modulation cycles; here it barely moves (about 2.69 throughout).

Rotor-Speed-Slow · longSine. Played: a steady 440 Hz sine. The line is Hz LFO rate: how many times a second the modulation cycles; here it barely moves (about 8.42 throughout).

Rotor-Speed-Slow · 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 8.36 at raw 55 to 3.44 at raw 63.

Rotor-Transition-Time · longSine. Played: a steady 440 Hz sine. The line is Hz LFO rate: how many times a second the modulation cycles; here it barely moves (about 8.42 throughout).

Rotor-Transition-Time · 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 8.34 at raw 95 to 3.27 at raw 127.

---

Dual Rotor SP 3

Show code

show_card('Dual Rotor SP 3')

Dual Rotor SP 3: what the measurements say

Recap. A modulation effect with 15 tested controls, 15 of which measurably change the sound. Beyond mix and level, the biggest lever is Rotor Speed Fast: amplitude-LFO rate 2.68 → 39.69 Hz. Measured with 133 captures: 73 on the main sweep + tone probe (one control at a time), 32 on matched probes (sustainedStereo ×27, harmonicTwoTone ×5), 28 two-control pairs.

Technical explanation. At default settings: output -29.7 dBFS RMS (crest 16.6 dB); stereo width 0.48, L/R correlation +0.54; spectral tilt -0.25 dB/octave; 71% of the impulse response's energy in its first 5 ms; harmonics H2 -76 dB, H3 -47 dB re the linear response.

Structure:

• pitch LFO 8.41 Hz, 71 cents peak-to-peak, L/R phase +56°
• amplitude LFO 8.41 Hz, depth 0.49
• crosstalk L→R -0 dB, R→L 0 dB

Two-control pairs captured: Drive Low×Rotor Speed Slow, Rotor Speed Fast×Drive Low, Rotor Speed Fast×Rotor Speed Slow, Rotor Speed Fast×Speed Control, Rotor Speed Slow×Horn Speed Slow, Speed Control×Drive Low, Speed Control×Rotor Speed Slow (interaction analysis in the main notebook).

Caveats:

• the LFO runs during the sweep, so the frequency-response features are averages over LFO phase, not a fixed response

Plain explanation: The control to reach for first is Rotor Speed Fast: amplitude-LFO rate 2.68 → 39.69 Hz. After that, Speed Control, Drive Low and Rotor Speed Slow make the next biggest differences. At default it has a moderate stereo spread.

In other words, the main points:

• 15 of 15 tested controls measurably change the sound.
• Biggest lever beyond mix and level: Rotor Speed Fast, 28.3× the smallest change that matters (amplitude-LFO rate 2.68 → 39.69 Hz).
• At default: stereo width 0.48, output -29.7 dBFS RMS.
• Main caveat: the LFO runs during the sweep, so the frequency-response features are averages over LFO phase, not a fixed response.
• Still to measure: T1, T3, T6, T7 (see TESTS_NEEDED.md).

Show code

show_knobs('Dual Rotor SP 3')

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('Dual Rotor SP 3')

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.

Drive-High · 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 barely moves (about -94.2 throughout).

Drive-High · 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 -70.4 at raw 0 to -51.1 at raw 127.

Drive-Low · 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 -101 at raw 0 to -91.8 at raw 127, dipping to -103.

Drive-Low · 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 -75.2 at raw 0 to -57.2 at raw 127.

Horn-Speed-Fast · longSine. Played: a steady 440 Hz sine. The line is Hz LFO rate: how many times a second the modulation cycles; here it barely moves (about 8.42 throughout).

Horn-Speed-Fast · 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 barely moves (about 8.41 throughout).

Horn-Speed-Slow · longSine. Played: a steady 440 Hz sine. The line is Hz LFO rate: how many times a second the modulation cycles; here it barely moves (about 8.42 throughout).

Horn-Speed-Slow · 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 barely moves (about 8.41 throughout).

Horn-Transition-Time · longSine. Played: a steady 440 Hz sine. The line is Hz LFO rate: how many times a second the modulation cycles; here it barely moves (about 8.42 throughout).

Horn-Transition-Time · 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 barely moves (about 8.41 throughout).

Low-High-Balance · 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 71.7 at raw 79 to 67.8 at raw 95.

Mic-Angle · sustainedStereo. Played: a held chord, one note per channel. The line is ° L/R LFO phase: how far the right channel's modulation runs ahead of or behind the left's; here it goes from -0.686 at raw 0 to 114 at raw 60.

Rotor-Speed-Fast · longSine. Played: a steady 440 Hz sine. The line is Hz LFO rate: how many times a second the modulation cycles; here it barely moves (about 20.2 throughout).

Rotor-Speed-Slow · longSine. Played: a steady 440 Hz sine. The line is Hz LFO rate: how many times a second the modulation cycles; here it barely moves (about 8.42 throughout).

Rotor-Speed-Slow · 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 8.41 at raw 23 to 2.4 at raw 63.

Rotor-Transition-Time · longSine. Played: a steady 440 Hz sine. The line is Hz LFO rate: how many times a second the modulation cycles; here it barely moves (about 8.42 throughout).

Rotor-Transition-Time · 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 8.41 at raw 71 to 2.59 at raw 127.

---

Odrv+Rotary SP 1

Show code

show_card('Odrv+Rotary SP 1')

Odrv+Rotary SP 1: what the measurements say

Recap. A modulation effect with 9 tested controls, 9 of which measurably change the sound. Beyond mix and level, the biggest lever is Dist Drive: gain compression across the input range 0.3 → -18.1 dB. Measured with 91 captures: 46 on the main sweep + tone probe (one control at a time), 21 on matched probes (spectralSweep ×9, harmonicTwoTone ×7, sustainedStereo ×5), 24 two-control pairs.

Technical explanation. At default settings: output -15.8 dBFS RMS (crest 11.5 dB); stereo width 0.20, L/R correlation +0.92; spectral tilt -2.10 dB/octave; 99% of the impulse response's energy in its first 5 ms; harmonics H2 -46 dB, H3 -9 dB re the linear response.

Structure:

• pitch LFO 2.68 Hz, 8 cents peak-to-peak, L/R phase -13°
• amplitude LFO 2.70 Hz, depth 0.44
• crosstalk L→R -0 dB, R→L 0 dB

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

Caveats:

• the LFO runs during the sweep, so the frequency-response features are averages over LFO phase, not a fixed response
• some long settings decay more slowly than the recording allows; their T30 is a lower bound
• at least one setting mutes the output; those captures are excluded from spectral analysis

Plain explanation: The control to reach for first is Dist Drive: gain compression across the input range 0.3 → -18.1 dB. After that, LFO Depth, LFO Speed and Low Gain make the next biggest differences. Dist Output Level 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: Dist Drive, 18.5× the smallest change that matters (gain compression across the input range 0.3 → -18.1 dB).
• At default: stereo width 0.20, output -15.8 dBFS RMS.
• Main caveat: the LFO runs during the sweep, so the frequency-response features are averages over LFO phase, not a fixed response.
• Still to measure: T1, T4, T6, T7 (see TESTS_NEEDED.md).

Show code

show_knobs('Odrv+Rotary SP 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('Odrv+Rotary SP 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.

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 -18.5 at raw 0 to -8.4 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 -57.1 at raw 0 to -10.3 at raw 127.

Dist-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 340 at raw 0 to 1,577 at raw 60.

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 0.342 at raw 0 to 7.88 at raw 95.

LFO-Speed · longSine. Played: a steady 440 Hz sine. The line is Hz LFO rate: how many times a second the modulation cycles; here it goes from 0.299 at raw 7 to 1.3 at raw 31.

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 1.29 at raw 31 to 8.07 at raw 95.

---

Odrv+Rotary SP 2

Show code

show_card('Odrv+Rotary SP 2')

Odrv+Rotary SP 2: what the measurements say

Recap. A modulation effect with 13 tested controls, 12 of which measurably change the sound. Beyond mix and level, the biggest lever is Dist Drive: gain compression across the input range 0.0 → -18.4 dB. Measured with 124 captures: 66 on the main sweep + tone probe (one control at a time), 30 on matched probes (harmonicTwoTone ×11, spectralSweep ×11, sustainedStereo ×5, rhythmicGrid ×3), 28 two-control pairs.

Technical explanation. At default settings: output -21.4 dBFS RMS (crest 17.3 dB); stereo width 0.64, L/R correlation +0.17; spectral tilt -1.02 dB/octave; 89% of the impulse response's energy in its first 5 ms; harmonics H2 -42 dB, H3 -9 dB re the linear response.

Structure:

• pitch LFO — Hz, — cents peak-to-peak, L/R phase —°
• amplitude LFO 8.41 Hz, depth 0.54
• crosstalk L→R — dB, R→L — dB

Two-control pairs captured: Dist Drive×Divide Frequency, Dist Drive×Mic Angle, Dist Drive×Rotor Speed, Mic Angle×Divide Frequency, Rotor Speed×Divide Frequency, Rotor Speed×Drive Low, Rotor Speed×Mic Angle (interaction analysis in the main notebook).

Caveats:

• the LFO runs during the sweep, so the frequency-response features are averages over LFO phase, not a fixed response
• some long settings decay more slowly than the recording allows; their T30 is a lower bound
• at least one setting mutes the output; those captures are excluded from spectral analysis

Plain explanation: The control to reach for first is Dist Drive: gain compression across the input range 0.0 → -18.4 dB. After that, Rotor Speed, Mic Angle and Divide Frequency make the next biggest differences. Dist Output Level sets how much of the effect you hear and how loud it is. At default left and right are largely independent, so it sounds wide.

In other words, the main points:

• 12 of 13 tested controls measurably change the sound.
• Biggest lever beyond mix and level: Dist Drive, 18.4× the smallest change that matters (gain compression across the input range 0.0 → -18.4 dB).
• At default: stereo width 0.64, output -21.4 dBFS RMS.
• Main caveat: the LFO runs during the sweep, so the frequency-response features are averages over LFO phase, not a fixed response.
• Still to measure: T1, T3, T4, T6, T7 (see TESTS_NEEDED.md).

Show code

show_knobs('Odrv+Rotary SP 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('Odrv+Rotary SP 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.

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 -37.7 at raw 0 to -11.7 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 -44.6 at raw 0 to -13.2 at raw 127.

Dist-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 390 at raw 0 to 1,108 at raw 60.

Divide-Frequency · 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 706 at raw 0 to 592 at raw 54, peaking at 796.

Drive-High · 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 -4.15 at raw 0 to -16.5 at raw 127.

Drive-High · 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 -11.8 at raw 0 to -11.8 at raw 127, dipping to -13.4.

Drive-Low · 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 -7.24 at raw 0 to -5.36 at raw 127, dipping to -15.

Drive-Low · 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 -11.2 at raw 0 to -12.3 at raw 127, dipping to -13.3.

Low-High-Balance · 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 105 at raw 0 to 45.6 at raw 127.

Mic-Angle · sustainedStereo. Played: a held chord, one note per channel. The line is ° L/R LFO phase: how far the right channel's modulation runs ahead of or behind the left's; here it goes from -8.98 at raw 0 to 173 at raw 60.

Rotor-Speed · longSine. Played: a steady 440 Hz sine. The line is Hz LFO rate: how many times a second the modulation cycles; here it goes from 0.299 at raw 7 to 1.3 at raw 31.

---

Rotary SP 1

Show code

show_card('Rotary SP 1')

Rotary SP 1: what the measurements say

Recap. A modulation effect with 10 tested controls, 10 of which measurably change the sound. Beyond mix and level, the biggest lever is LFO Depth: pitch wobble 0 → 77 cents. Measured with 101 captures: 51 on the main sweep + tone probe (one control at a time), 22 on matched probes (spectralSweep ×17, sustainedStereo ×5), 28 two-control pairs.

Technical explanation. At default settings: output -22.5 dBFS RMS (crest 14.4 dB); stereo width 0.31, L/R correlation +0.81; spectral tilt +0.35 dB/octave; 65% of the impulse response's energy in its first 5 ms; harmonics H2 -60 dB, H3 -46 dB re the linear response.

Structure:

• pitch LFO 2.68 Hz, 73 cents peak-to-peak, L/R phase -22°
• amplitude LFO 2.68 Hz, depth 0.47
• crosstalk L→R -3 dB, R→L 0 dB

Two-control pairs captured: High Gain×Low Gain, LFO Depth×High Gain, LFO Depth×Low Gain, LFO Speed×High Gain, LFO Speed×LFO Depth, LFO Speed×Low Gain, Mid Width×LFO Depth (interaction analysis in the main notebook).

Caveats:

• the LFO runs during the sweep, so the frequency-response features are averages over LFO phase, not a fixed response

Plain explanation: The control to reach for first is LFO Depth: pitch wobble 0 → 77 cents. After that, LFO Speed, High Gain 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:

• 10 of 10 tested controls measurably change the sound.
• Biggest lever beyond mix and level: LFO Depth, 15.4× the smallest change that matters (pitch wobble 0 → 77 cents).
• At default: stereo width 0.31, output -22.5 dBFS RMS.
• Main caveat: the LFO runs during the sweep, so the frequency-response features are averages over LFO phase, not a fixed response.
• Still to measure: T1, T6, T7 (see TESTS_NEEDED.md).

Show code

show_knobs('Rotary SP 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('Rotary SP 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.

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 0.0101 at raw 0 to 77.5 at raw 127.

LFO-Speed · longSine. Played: a steady 440 Hz sine. The line is Hz LFO rate: how many times a second the modulation cycles; here it goes from 0.299 at raw 7 to 1.3 at raw 31.

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 0.589 at raw 7 to 9.11 at raw 127.

---

Rotary SP 2

Show code

show_card('Rotary SP 2')

Rotary SP 2: what the measurements say

Recap. A modulation effect with 10 tested controls, 10 of which measurably change the sound. Beyond mix and level, the biggest lever is Rotor Speed: amplitude modulation depth 0.00 → 0.85. Measured with 99 captures: 51 on the main sweep + tone probe (one control at a time), 24 on matched probes (spectralSweep ×11, harmonicTwoTone ×5, sustainedStereo ×5, rhythmicGrid ×3), 24 two-control pairs.

Technical explanation. At default settings: output -30.7 dBFS RMS (crest 19.1 dB); stereo width 0.68, L/R correlation +0.09; spectral tilt +0.70 dB/octave; 29% of the impulse response's energy in its first 5 ms.

Structure:

• pitch LFO — Hz, — cents peak-to-peak, L/R phase —°
• amplitude LFO 8.41 Hz, depth 0.66
• crosstalk L→R — dB, R→L — dB

Two-control pairs captured: Divide Frequency×Low High Balance, Drive Low×Divide Frequency, Drive Low×Low High Balance, Rotor Speed×Divide Frequency, Rotor Speed×Drive Low, Rotor Speed×Low High Balance (interaction analysis in the main notebook).

Caveats:

• the LFO runs during the sweep, so the frequency-response features are averages over LFO phase, not a fixed response

Plain explanation: The control to reach for first is Rotor Speed: amplitude modulation depth 0.00 → 0.85. After that, Drive Low, Divide Frequency and Low High Balance make the next biggest differences. At default left and right are largely independent, so it sounds wide.

In other words, the main points:

• 10 of 10 tested controls measurably change the sound.
• Biggest lever beyond mix and level: Rotor Speed, 17.0× the smallest change that matters (amplitude modulation depth 0.00 → 0.85).
• At default: stereo width 0.68, output -30.7 dBFS RMS.
• Main caveat: the LFO runs during the sweep, so the frequency-response features are averages over LFO phase, not a fixed response.
• Still to measure: T1, T3, T6, T7 (see TESTS_NEEDED.md).

Show code

show_knobs('Rotary SP 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('Rotary SP 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.

Divide-Frequency · 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 2,346 at raw 0 to 2,329 at raw 54, peaking at 2,853, dipping to 2,236.

Drive-High · 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 barely moves (about -86.2 throughout).

Drive-High · 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 -64.8 at raw 0 to -60.2 at raw 127.

Drive-Low · 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 -96.4 at raw 0 to -73.7 at raw 127.

Drive-Low · 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 -77.1 at raw 0 to -40.2 at raw 127.

Low-High-Balance · 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 119 at raw 0 to 54.4 at raw 127.

Rotor-Speed · longSine. Played: a steady 440 Hz sine. The line is Hz LFO rate: how many times a second the modulation cycles; here it goes from 0.299 at raw 7 to 1.3 at raw 31.

---

Tremolo

Show code

show_card('Tremolo')

Tremolo: what the measurements say

Recap. A modulation effect with 12 tested controls, 12 of which measurably change the sound. Beyond mix and level, the biggest lever is AM Depth: amplitude modulation depth 0.00 → 2.01. Measured with 113 captures: 58 on the main sweep + tone probe (one control at a time), 27 on matched probes (spectralSweep ×15, sustainedStereo ×9, stereoRouting ×3), 28 two-control pairs.

Technical explanation. At default settings: output -29.7 dBFS RMS (crest 12.5 dB); stereo width 0.34, L/R correlation +0.77; spectral tilt -0.33 dB/octave; 79% of the impulse response's energy in its first 5 ms; decay T30 6.86 s, EDT 0.03 s; harmonics H2 -76 dB, H3 -52 dB re the linear response.

Structure:

• pitch LFO — Hz, — cents peak-to-peak, L/R phase —°
• amplitude LFO 2.68 Hz, depth 1.21
• crosstalk L→R — dB, R→L — dB

Two-control pairs captured: AM Depth×Low Gain, AM Depth×Phase Difference, LFO Speed×AM Depth, LFO Speed×Low Gain, LFO Speed×Phase Difference, Mid Width×AM Depth, Phase Difference×Low Gain (interaction analysis in the main notebook).

Caveats:

• the LFO runs during the sweep, so the frequency-response features are averages over LFO phase, not a fixed response

Plain explanation: The control to reach for first is AM Depth: amplitude modulation depth 0.00 → 2.01. After that, LFO Speed, Input Mode and Phase Difference make the next biggest differences. At default the tail takes about 6.9 s to die away. 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: AM Depth, 40.3× the smallest change that matters (amplitude modulation depth 0.00 → 2.01).
• At default: stereo width 0.34, decay T30 6.86 s, output -29.7 dBFS RMS.
• Main caveat: the LFO runs during the sweep, so the frequency-response features are averages over LFO phase, not a fixed response.
• Still to measure: T1, T6, T7 (see TESTS_NEEDED.md).

Show code

show_knobs('Tremolo')

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('Tremolo')

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.

AM-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 43.1 throughout).

LFO-Speed · longSine. Played: a steady 440 Hz sine. The line is Hz LFO rate: how many times a second the modulation cycles; here it goes from 0.299 at raw 7 to 1.3 at raw 31.

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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.