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Cajón bass: fleshy palm impact + thuddy box resonance

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Added hand-on-wood transient (lowpassed noise for soft palm feel)
before the box resonance kicks in. Deeper sub, longer air cavity
thump. You hear the hand, then the box.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
This commit is contained in:
Kenneth Reitz
2026-03-29 16:53:00 -04:00
parent d771117d5c
commit 8a07be23e6
2 changed files with 27 additions and 16 deletions
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@@ -2792,32 +2792,43 @@ def _synth_doumbek_ka(n_samples):
def _synth_cajon_bass(n_samples):
"""Cajón bass — palm strike on center of the face.
"""Cajón bass — open palm slaps the center of the plywood face.
You're hitting a wooden box. The front panel flexes, the air
inside resonates, and the whole thing booms with a hollow,
boxy midrange character.
Two sounds happening at once: the fleshy THUD of the palm
hitting wood, then the box resonating. The hand sound is
a soft, round impact — skin on plywood — followed by the
hollow chamber boom.
"""
t = numpy.arange(n_samples, dtype=numpy.float32) / SAMPLE_RATE
# Box body resonance — hollow wooden chamber tone
body = numpy.sin(2 * numpy.pi * 80 * t) * _exp_decay(n_samples, 6) * 0.7
# Box resonance modes — the boxy character
box1 = numpy.sin(2 * numpy.pi * 180 * t) * _exp_decay(n_samples, 12) * 0.4
box2 = numpy.sin(2 * numpy.pi * 320 * t) * _exp_decay(n_samples, 18) * 0.2
# Palm thump on plywood
thump_len = min(int(SAMPLE_RATE * 0.08), n_samples)
# HAND IMPACT — fleshy palm on wood, round and thuddy
hand_len = min(int(SAMPLE_RATE * 0.015), n_samples)
hand_raw = _noise(hand_len)
if hand_len > 10:
# Lowpassed — palm is soft, not bright
bl, al = scipy.signal.butter(2, 1500 / (SAMPLE_RATE / 2), btype='low')
hand = scipy.signal.lfilter(bl, al, numpy.pad(hand_raw, (0, max(0, n_samples - hand_len))))[:hand_len].astype(numpy.float32)
else:
hand = hand_raw
hand *= _exp_decay(hand_len, 100) * 1.0
# BOX RESONANCE — hollow chamber thud
body = numpy.sin(2 * numpy.pi * 75 * t) * _exp_decay(n_samples, 5) * 0.7
box1 = numpy.sin(2 * numpy.pi * 170 * t) * _exp_decay(n_samples, 10) * 0.4
box2 = numpy.sin(2 * numpy.pi * 300 * t) * _exp_decay(n_samples, 16) * 0.2
# Panel flex — deep sub thud
sub = _sine_f32(45, n_samples) * _exp_decay(n_samples, 6) * 0.5
# Broader thump from the air cavity
thump_len = min(int(SAMPLE_RATE * 0.1), n_samples)
thump_raw = _noise(thump_len)
if thump_len > 20:
bl, al = scipy.signal.butter(2, [60, 400], btype='band', fs=SAMPLE_RATE)
bl, al = scipy.signal.butter(2, [40, 350], btype='band', fs=SAMPLE_RATE)
thump = scipy.signal.lfilter(bl, al, numpy.pad(thump_raw, (0, max(0, n_samples - thump_len))))[:thump_len].astype(numpy.float32)
else:
thump = thump_raw
thump *= _exp_decay(thump_len, 14) * 0.7
# Panel flex — low thud
sub = _sine_f32(50, n_samples) * _exp_decay(n_samples, 8) * 0.4
thump *= _exp_decay(thump_len, 12) * 0.6
result = body + box1 + box2 + sub
result[:thump_len] += thump
return numpy.tanh(result * 1.4).astype(numpy.float32)
result[:hand_len] += hand
return numpy.tanh(result * 1.5).astype(numpy.float32)
def _synth_cajon_slap(n_samples):