Bass detection calibration etude

A ~41-second exercise that stresses every bass weak-spot in the detector: open low strings (weak fundamentals), a chromatic walk (pitch precision across the low range), long sustains, a fast eighth-note run (onset density), octave jumps, and an optional 5-string low-B section.

Play it locked to click.wav so your notes line up with the reference chart — the scorer only corrects a single start-offset, not tempo drift.

Recording setup (please follow these)

Clean DI only. Bass → interface, before any amp sim / NAM / pedals / EQ. This is what the detector taps.
Play to the click in headphones. Open click.wav in your DAW/player and monitor it in headphones; keep it out of the recorded DI (a tiny bit of bleed is harmless — the click is high-pitched and won't match any bass note).
Tempo: 90 BPM, 4/4. The click has a 4-beat count-in; the first note lands on the next downbeat (≈2.67 s into click.wav).
Record two passes, same etude, so I can tune for both attacks:
- bass_finger.wav — fingerstyle
- bass_pick.wav — with a pick
Format: WAV, 16-bit PCM, 48 kHz preferred (44.1/96 fine), mono or stereo.
Let sustained/ringing notes ring fully — don't mute early.
4-string bass: stop after Section D (~35 s). 5-string: continue into Section E.

When done, drop the WAV(s) anywhere and tell me the path — I'll run the bench.

The etude

Notation: bass tab, one digit = fret on that string. · = that string silent. "q" = quarter note (one per click), "8th" = two per click. Let ring unless noted.

Section A — open strings (bars 2–3, quarter notes)

Pluck each open string twice; let every note ring.

Bar 2:  E(open)  E(open)  A(open)  A(open)
Bar 3:  D(open)  D(open)  G(open)  G(open)

Section B — chromatic walk, frets 0–3 (bars 4–7, quarter notes)

One note per click, up each string:

E string:  0  1  2  3
A string:  0  1  2  3
D string:  0  1  2  3
G string:  0  1  2  3

Section C — sustains (bars 8–11, whole notes — let ring the full bar)

One open string per bar, held for all 4 beats:

E (open) ——ring—— | A (open) ——ring—— | D (open) ——ring—— | G (open) ——ring——

Section D — fast eighth notes (bars 12–14, two notes per click)

Bar 12 — open E eighths ×8 (steady, even):

E| 0 0 0 0 0 0 0 0

Bar 13 — A-string walk eighths (A B C# D E D C# B):

A| 0 2 4 · · · 4 2
D| · · · 0 2 0 · ·

Bar 14 — octave jumps E1↔E2 eighths (alternate, ×8):

D| · 2 · 2 · 2 · 2
E| 0 · 0 · 0 · 0 ·

Section E — low B (5-STRING ONLY — 4-string players skip)

Open low B ring, then a B-string chromatic 0–3 (B C C# D):

B (open) ——ring—— ,  B(0) ,  B: 0  1  2  3

What I do with it

cd tests/chordscorer
cmake --build build --target cs_bench
./build/cs_bench <bass_finger.wav> calibration/chart.txt bass 4   # or "bass 5"
./build/cs_bench <bass_pick.wav>   calibration/chart.txt bass 5

The chart (chart.txt) is "<time_s> <midi> <sustain_s>" per line, generated by make_calibration.py. I sweep fundamentalRatio / onset profile / cents against your real take, then re-run the guitar bench on di-take.wav to prove zero guitar regression.

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