Lo-Fi — effect atlas¶

5 effects · 569 captures. Deliberate degradation: sample-rate and bit-depth reduction, noise, and filtering.

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

In [1]:

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

In [2]:

knob_counts = {'Attack Lo-Fi': (15, 0), 'Digital Turntable': (8, 0), 'Lo-Fi': (9, 0), 'Low Resolution': (7, 0), 'Noisy': (11, 1)}
show(cards.family_overview(df, 'Lo-Fi', knob_counts, curves))

No description has been provided for this image

Show code

In [3]:

iviz.family_fig(df, curves, 'Lo-Fi').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.

Less reliable in detail (repeat captures differ by over 3 dB, usually a running LFO): Attack Lo-Fi, Lo-Fi, Noisy. 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. Lo-Fi rolls off the top end early, so it sounds 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: Lo-Fi, 28 dB from peak to deepest cut.
Darkest (top end rolled off early): Lo-Fi.
Least repeatable in detail (usually a running LFO): Attack Lo-Fi, Lo-Fi, Noisy.

Show code

In [4]:

iviz.tone_bands(df, curves, 'Lo-Fi')

Out[4]:

Lo-Fi in pictures¶

What the Lo-Fi effect adds to a sound, shown against what was played.

Show code

In [5]:

import kinetics, kviz, wviz, rviz
show_parts(wviz.staircase_parts(g) + kviz.lofi_parts(g))

What it shows. A steady 1 kHz note through Lo-Fi, drawn sample by sample (44,100 samples a second) with nothing averaged, at each tested Sampling Freq setting. Use the slider to change the setting.

How to read it. A smooth wave means the effect is passing every sample. Flat steps mean it is holding one sample and repeating it: the longer each step, the lower the effect's own sample rate, and the less the result looks like the note that went in. The flat top and bottom at about ±0.45 are the effect's clipping ceiling at its default Word Length.

What it found.

The steps are a whole number of samples long at every setting, and at 8 of 8 settings above 0 the step is exactly the setting plus one: setting 15 holds 16 samples (0.36 ms, a rate of 2,756 Hz), setting 31 holds 32 samples (0.73 ms, a rate of 1,378 Hz), setting 47 holds 48 samples (1.09 ms, a rate of 919 Hz), setting 63 holds 64 samples (1.45 ms, a rate of 689 Hz), setting 79 holds 80 samples (1.81 ms, a rate of 551 Hz), setting 95 holds 96 samples (2.18 ms, a rate of 459 Hz), setting 111 holds 112 samples (2.54 ms, a rate of 394 Hz), setting 127 holds 128 samples (2.90 ms, a rate of 345 Hz).
That is 44,100 Hz divided by (setting + 1), which matches Yamaha's value table.
At setting 0 nothing is held.

What it shows. A single note sliding up from 20 Hz to 20 kHz over three seconds through Lo-Fi, at each Sampling Freq setting. For every moment of the slide the chart marks the frequencies present in the output: cyan where it is the note itself, violet for its harmonics, amber for anything else.

How to read it. The frequency being played runs left to right, what comes out runs upward, both on musical (log) scales. A clean effect would draw only the cyan diagonal. Violet lines parallel to it are ordinary harmonics. Amber lines that fall as the note rises are images: copies reflected off the reduced sampling rate, which is why a rising melody through Lo-Fi is accompanied by tones that descend. The dotted curves are where images of the note must fall if the rate is 44.1 kHz ÷ (setting + 1). Drag the slider through the settings.

What it found.

At Sampling Freq 0 (the full 44.1 kHz) there are no falling lines, but 294 harmonic points: Lo-Fi adds odd harmonics of its own before any rate reduction.
At the reduced rates, between 86% and 90% of the stronger amber points (within 30 dB of the loudest, while the note is still below half the rate) sit within two-thirds of a semitone of an image of the note or of its 3rd or 5th harmonic at the predicted rate.
The rate is what the division says, and nothing filters the images out afterwards.
By Sampling Freq 127 (345 Hz) the note can only be followed to about 172 Hz before images take over, and only 54 of the marked points are the note at all.
Only lines within 42 dB of the loudest at each moment are marked, read from 93 ms slices.

What it shows. A 1 kHz tone rising smoothly from −69 to −4 dBFS through Lo-Fi, with Sampling Freq at its full rate so that only Word Length is acting: everything in the output that is not the 1 kHz note (harmonics, aliases and noise together), relative to the note. One line per Word Length setting.

How to read it. Input level left to right; lower is cleaner. A line falling steadily to the right is a fixed noise floor being left behind as the note gets louder. A sudden jump upward is the moment the note hits the ceiling.

What it found.

Until the ceiling every setting follows the bypass line down to about −59 dB (bypass reaches −62 dB): no quantisation noise is added, which is what reducing word length from the bottom would do.
Past the ceiling the residue jumps to between −24 and −9 dB at −6 dBFS in, the level of a hard-clipped wave.
The lower the Word Length, the earlier the jump: the setting is a ceiling on the output (−4 dBFS at 15, −0 dBFS at 31, +3 dBFS at 47, +6 dBFS at 63, +7 dBFS at 79, +7 dBFS at 95, +8 dBFS at 111, +8 dBFS at 127, where 0 dBFS is the level a full-scale tone returns at through bypass), above +24 dB of plain gain.
At Word Length 0 nothing comes out at all.
A shorter word does not make quiet sounds grainy here; it takes headroom away from the top.

Attack Lo-Fi¶

Show code

In [6]:

show_card('Attack Lo-Fi')

Attack Lo-Fi: what the measurements say¶

Recap. An effect with 16 tested controls, 15 of which measurably change the sound. Beyond mix and level, the biggest lever is Peak Freq: modulation depth 0.89 → 0.34 by raw 34, then modulation depth 0.34 → 0.82 by raw 54. Measured with 146 captures: 81 on the main sweep + tone probe (one control at a time), 33 on matched probes (steppedTransients ×33), 32 two-control pairs.

Technical explanation. At default settings: output -23.2 dBFS RMS (crest 15.6 dB); stereo width 0.53, L/R correlation +0.44; spectral tilt +1.49 dB/octave; 95% of the impulse response's energy in its first 5 ms; decay T30 2.70 s, EDT 0.08 s; harmonics H2 -28 dB, H3 -26 dB re the linear response.

Two-control pairs captured: Flanger Delay×Flanger Feedback, Flanger Mix×Flanger Depth, Flanger Speed×Flanger Depth, LPF Freq×Flanger Depth, LPF Freq×Flanger Mix, Peak Freq×Flanger Depth, Peak Freq×Flanger Mix, Peak Freq×LPF Freq (interaction analysis in the main notebook).

Plain explanation: The control to reach for first is Peak Freq: modulation depth 0.89 → 0.34 by raw 34, then modulation depth 0.34 → 0.82 by raw 54. After that, LPF Freq, Flanger Mix and Flanger Depth make the next biggest differences. DryWet sets how much of the effect you hear and how loud it is. At default the tail takes about 2.7 s to die away. At default left and right are largely independent, so it sounds wide.

In other words, the main points:

15 of 16 tested controls measurably change the sound.
Biggest lever beyond mix and level: Peak Freq, 12.2× the smallest change that matters (modulation depth 0.89 → 0.34 by raw 34, then modulation depth 0.34 → 0.82 by raw 54).
At default: stereo width 0.53, decay T30 2.70 s, output -23.2 dBFS RMS.
Still to measure: T1 (see TESTS_NEEDED.md).

Show code

In [7]:

show_knobs('Attack Lo-Fi')

barely changes the soundchanges it a lot■no measurable change

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

In [8]:

show_gapfill('Attack Lo-Fi')

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

Delay-Offset-R · sweepTail. Played: a sweep followed by silence. The line is s T30: the reverb decay time (extrapolated to 60 dB of decay); here it goes from 2.34 at raw 0 to 2.05 at raw 884, peaking at 2.43, dipping to 1.98.

Depth-Offset-R · 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 0.676 at raw 0 to 1.55 at raw 127, peaking at 50.5.

Feedback-Offset-R · sweepTail. Played: a sweep followed by silence. The line is dB per repeat: how much quieter each repeat is than the one before; closer to 0 means more repeats; here it goes from -0.248 at raw 0 to -0.673 at raw 127, peaking at -0.0338.

Flanger-Delay · sweepTail. Played: a sweep followed by silence. The line is s T30: the reverb decay time (extrapolated to 60 dB of decay); here it goes from 2.76 at raw 0 to 2.36 at raw 6500, peaking at 2.89, dipping to 1.94.

Flanger-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 0.0663 at raw 0 to 1.03 at raw 127, peaking at 91.

Flanger-Feedback · sweepTail. Played: a sweep followed by silence. The line is dB per repeat: how much quieter each repeat is than the one before; closer to 0 means more repeats; here it goes from -0.998 at raw 0 to -1.06 at raw 127, peaking at -0.195.

Flanger-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 0.305 at raw 7 to 6.14 at raw 119, peaking at 8.42.

Digital Turntable¶

Show code

In [9]:

show_card('Digital Turntable')

Digital Turntable: what the measurements say¶

Recap. An effect with 11 tested controls, 8 of which measurably change the sound. Beyond mix and level, the biggest lever is Noise Level: 2nd harmonic -55 → -23 dB. Measured with 110 captures: 59 on the main sweep + tone probe (one control at a time), 23 on matched probes (silenceNoise ×23), 28 two-control pairs.

Technical explanation. At default settings: output -30.1 dBFS RMS (crest 28.4 dB); stereo width 0.38, L/R correlation +0.71; spectral tilt -0.34 dB/octave; 98% of the impulse response's energy in its first 5 ms; harmonics H2 -30 dB, H3 -41 dB re the linear response.

Two-control pairs captured: Dry Level×Dry Send to Noise, Dry Level×Noise Level, Dry Level×Noise Tone, Noise Level×Dry Send to Noise, Noise Level×Noise Tone, Noise Mod Speed×Noise Mod Depth, Noise Tone×Dry Send to Noise (interaction analysis in the main notebook).

Caveats:

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

Plain explanation: The control to reach for first is Noise Level: 2nd harmonic -55 → -23 dB. After that, Noise Tone, Noise LPF Q and Noise LPF Freq make the next biggest differences. Dry Level, Dry Send to Noise and Dry LPF Freq set 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:

8 of 11 tested controls measurably change the sound.
Biggest lever beyond mix and level: Noise Level, 10.9× the smallest change that matters (2nd harmonic -55 → -23 dB).
At default: stereo width 0.38, output -30.1 dBFS RMS.
Main caveat: some long settings decay more slowly than the recording allows; their T30 is a lower bound.
Still to measure: T1, T4 (see TESTS_NEEDED.md).

Show code

In [10]:

show_knobs('Digital Turntable')

barely changes the soundchanges it a lot■no measurable change

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

In [11]:

show_gapfill('Digital Turntable')

Lo-Fi¶

Show code

In [12]:

show_card('Lo-Fi')

Lo-Fi: what the measurements say¶

Recap. An effect with 10 tested controls, 9 of which measurably change the sound. Beyond mix and level, the biggest lever is Input Mode: side-signal survival -55 → 2 dB. Measured with 98 captures: 48 on the main sweep + tone probe (one control at a time), 22 on matched probes (spectralSweep ×19, stereoRouting ×3), 28 two-control pairs.

Technical explanation. At default settings: output -12.0 dBFS RMS (crest 8.6 dB); stereo width 0.44, L/R correlation +0.62; spectral tilt -3.05 dB/octave; 44% of the impulse response's energy in its first 5 ms.

Two-control pairs captured: Pre LPF Cutoff×Output Gain, Pre LPF Cutoff×Word Length, Sampling Freq×Output Gain, Sampling Freq×Pre LPF Cutoff, Sampling Freq×Pre LPF Resonance, Sampling Freq×Word Length, Word Length×Output Gain (interaction analysis in the main notebook).

Caveats:

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

Plain explanation: The control to reach for first is Input Mode: side-signal survival -55 → 2 dB. After that, Sampling Freq, Pre LPF Cutoff and Word Length make the next biggest differences. DryWet sets how much of the effect you hear and how loud it is. At default it has a moderate stereo spread.

In other words, the main points:

9 of 10 tested controls measurably change the sound.
Biggest lever beyond mix and level: Input Mode, 18.8× the smallest change that matters (side-signal survival -55 → 2 dB).
At default: stereo width 0.44, output -12.0 dBFS RMS.
Main caveat: some long settings decay more slowly than the recording allows; their T30 is a lower bound.
Still to measure: T1, T4 (see TESTS_NEEDED.md).

Show code

In [13]:

show_knobs('Lo-Fi')

barely changes the soundchanges it a lot■no measurable change

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.

In the weeds: sample-and-hold and quantisation¶

The wave going in against what comes out at every Sampling Freq setting, the alias images against the 44.1 kHz ÷ (raw + 1) prediction, the level ladder (each spike is one quantisation level), and a 60 dB fade at full rate. The full discussion is in section 14 of the main analysis.

Show code

In [14]:

iviz.lofi_destruction(g).show()

Show code

In [15]:

iviz.lofi_alias_spectra(g).show()

Show code

In [16]:

iviz.lofi_levels(g, 'Word-Length').show()

Show code

In [17]:

iviz.lofi_fade(g).show()

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

In [18]:

show_gapfill('Lo-Fi')

Low Resolution¶

Show code

In [19]:

show_card('Low Resolution')

Low Resolution: what the measurements say¶

Recap. An effect with 7 tested controls, 7 of which measurably change the sound. Beyond mix and level, the biggest lever is Resolution: 3rd harmonic -47 → -10 dB. Measured with 83 captures: 37 on the main sweep + tone probe (one control at a time), 18 on matched probes (impulseTail ×5, spectralSweep ×5, sustainedStereo ×5, stereoRouting ×3), 28 two-control pairs.

Technical explanation. At default settings: output -23.6 dBFS RMS (crest 16.9 dB); stereo width 0.30, L/R correlation +0.82; spectral tilt +1.17 dB/octave; 98% of the impulse response's energy in its first 5 ms; decay T30 2.58 s, EDT 0.91 s; harmonics H2 -32 dB, H3 -17 dB re the linear response.

Two-control pairs captured: Mod Delay Offset×Mod Feedback, Mod Depth×Mod Mix, Phase Inverse R×Mod Delay Offset, Phase Inverse R×Mod Feedback, Resolution×Mod Delay Offset, Resolution×Mod Feedback, Resolution×Phase Inverse R (interaction analysis in the main notebook).

Plain explanation: The control to reach for first is Resolution: 3rd harmonic -47 → -10 dB. After that, Phase Inverse R, Mod Delay Offset and Mod Feedback make the next biggest differences. DryWet sets how much of the effect you hear and how loud it is. At default the tail takes about 2.6 s to die away. At default it has a moderate stereo spread.

In other words, the main points:

7 of 7 tested controls measurably change the sound.
Biggest lever beyond mix and level: Resolution, 12.4× the smallest change that matters (3rd harmonic -47 → -10 dB).
At default: stereo width 0.30, decay T30 2.58 s, output -23.6 dBFS RMS.
Still to measure: T1 (see TESTS_NEEDED.md).

Show code

In [20]:

show_knobs('Low Resolution')

barely changes the soundchanges it a lot■no measurable change

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

In [21]:

show_gapfill('Low Resolution')

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.

Mod-Delay-Offset · sweepTail. Played: a sweep followed by silence. The line is s T30: the reverb decay time (extrapolated to 60 dB of decay); here it goes from 2.57 at raw 1 to 2.56 at raw 127, peaking at 2.61, dipping to 2.55.

Mod-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 0.06 at raw 0 to 0.0395 at raw 127, dipping to 0.0366.

Mod-Feedback · sweepTail. Played: a sweep followed by silence. The line is dB per repeat: how much quieter each repeat is than the one before; closer to 0 means more repeats; here it goes from -0.591 at raw 1 to -0.453 at raw 127, dipping to -18.6.

Phase-Inverse-R · 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 -39.8 throughout).

Noisy¶

Show code

In [22]:

show_card('Noisy')

Noisy: what the measurements say¶

Recap. An effect with 13 tested controls, 11 of which measurably change the sound. Beyond mix and level, the biggest lever is Drive: gain compression across the input range -2.3 → -34.2 dB. 1 does nothing with the others at default. Measured with 132 captures: 66 on the main sweep + tone probe (one control at a time), 30 on matched probes (spectralSweep ×13, sustainedStereo ×11, harmonicTwoTone ×3, impulseTail ×3), 36 two-control pairs.

Technical explanation. At default settings: output -15.4 dBFS RMS (crest 11.9 dB); stereo width 0.38, L/R correlation +0.71; spectral tilt -0.28 dB/octave; 97% of the impulse response's energy in its first 5 ms; decay T30 2.51 s, EDT 0.06 s; harmonics H2 -48 dB, H3 -30 dB re the linear response.

Two-control pairs captured: AM Depth×Mod Feedback, AM Depth×Mod Mix, Drive×AM Depth, Drive×Mod Feedback, Drive×Mod Mix, EQ Width×Mod Depth, LPF Freq×LPF Resonance, Mod Feedback×Mod Mix, Mod Speed×Mod Depth (interaction analysis in the main notebook).

Caveats:

EQ 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 Drive: gain compression across the input range -2.3 → -34.2 dB. After that, AM Depth, Mod Feedback and Mod Mix make the next biggest differences. DryWet sets how much of the effect you hear and how loud it is. EQ Width made no measurable difference with the other controls at default. At default the tail takes about 2.5 s to die away. At default it has a moderate stereo spread.

In other words, the main points:

11 of 13 tested controls measurably change the sound; 1 does nothing with the others at default.
Biggest lever beyond mix and level: Drive, 32.0× the smallest change that matters (gain compression across the input range -2.3 → -34.2 dB).
At default: stereo width 0.38, decay T30 2.51 s, output -15.4 dBFS RMS.
Main caveat: EQ Width did nothing because the matching gain sits at 0 dB in the one-at-a-time design.
Still to measure: T1, T13, T3 (see TESTS_NEEDED.md).

Show code

In [23]:

show_knobs('Noisy')

barely changes the soundchanges it a lot■no measurable change

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: EQ 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

In [24]:

show_gapfill('Noisy')

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 goes from 2.71 at raw 0 to 1.72 at raw 95.

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 -15.8 at raw 0 to -20.9 at raw 127, dipping to -31.3.

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 -21.7 at raw 0 to -59.1 at raw 127, peaking at -14.3.

LPF-Freq · 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 516 at raw 34 to 1,487 at raw 60, peaking at 2,208.

LPF-Resonance · pinkPluck. Played: pink-noise bursts at three levels, then plucked notes. The line is Hz spectral centroid: the spectrum's centre of gravity, a measure of brightness; higher means brighter; here it goes from 1,276 at raw 10 to 5,626 at raw 120.

Mod-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 0.0763 at raw 0 to 6.09 at raw 10.

Mod-Feedback · sweepTail. Played: a sweep followed by silence. The line is dB per repeat: how much quieter each repeat is than the one before; closer to 0 means more repeats; here it goes from -4.54 at raw 1 to -13.1 at raw 127.

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.