Playground · research instrument
DSP · AudioAudio & Acoustics Toolbox
Eight instruments for when air, electricity, and mechanics have to agree. Each is a bench, not a demo — built to make invisible physics visible: how a box stiffens a resonance, how a coil leaves a gap, how a cone forgets it is a piston, how a room piles bass into corners, how heat turns into compression, how a pole-zero pair sings.
Independent research instrument — not claimed as MakerPortal shipped product code. Methods, equations, assumptions, and limitations are disclosed so you can inspect what the page does and does not establish.
Choose a tool
Each tool opens as its own page with shareable URLs, focused controls, and detailed method notes. Nothing runs in the background — open only what you need.
Acoustics Calculators
Wavelength, SPL, RT60, delay — the numbers you reach for daily
Bench-ready math: wavelength, SPL summation, RT60 Sabine vs Eyring, critical distance, port tuning, Helmholtz resonance, speed of sound vs temperature. No fluff — just formulas turned into sliders.
Open toolRT60 Calculator
Sabine and Eyring side by side, and where they part
Reverberation time from room size and average absorption, both formulas at once, plus the Schroeder frequency that says which half of the spectrum the number applies to and the critical distance where the room beats the source.
Open toolHelmholtz Resonator Calculator
A spring made of air — cavity, neck, one frequency
Resonant frequency from cavity volume and neck geometry, with the flanged end correction that moves the answer about 10% and that most calculators silently omit. Corrected and uncorrected shown side by side.
Open toolSpeaker Port Length Calculator
Tuning frequency in, length to cut out
Port length for a vented box from volume, diameter and target tuning, end correction removed. Prints port air velocity so you know whether it will chuff, and names the minimum diameter when the port is too narrow to reach the tuning at all.
Open toolRoom Mode Calculator
Where bass piles up and why your room lies
Rectangular eigenfrequencies, axial/tangential sorting, Schroeder frequency, pressure anti-nodes. Modal density collapses below Schroeder — you hear the room, not the speaker.
Open toolPole-Zero Plot Tool
Drag poles, hear the math bite
Z-plane is destiny: poles inside unit circle stable. Drag pairs → magnitude, phase, group-delay. RBJ export, Web Audio audition.
Open toolSpeaker Box Calculator
Box as spring, port as mass — Thiele-Small alignment
Compliance ratio sets Qtc and fc. Butterworth 0.707, Bessel 0.577. QB3/SBB4/SC4 via Small 1973. Hoffman Iron Law: small, deep, loud — pick two.
Open toolDriver Nonlinearity Lab
Bl(x), Kms(x), Le(x) — why sine out ≠ sine in
Motor force, suspension stiffness, inductance modulation. Even vs odd harmonics from Taylor expansion, THD, Klippel-style visualization.
Open toolSpeaker Power Compression
Power in, heat stays, SPL sags
Thermal RC: coil tau vs magnet tau. Resistance rises with temperature, current falls, SPL compresses. Copper turns into a limiter.
Open toolAcoustic Horn Calculator
Webster flare — exponential, conical, oblate spheroidal
Horn profile from the 1D Webster equation. Cutoff follows the flare rate; mouth circumference sets the frequency below which the horn stops loading and starts radiating like an open pipe.
Open toolSpeaker Cone Breakup Simulator
Piston to chaos — bending waves win
Bending stiffness, dispersive wave speed, modal patterns with Bessel functions, breakup scales with sqrt(E/ρ)/diameter.
Open toolFrontier instruments, not demos
Loudspeaker design is multiphysics. Electrical current makes force, force fights suspension and air load, cone bends, room stores energy, copper heats and fights back. This toolbox splits that chain into eight focused benches where you can turn one knob and see consequence instantly — no background simulation, no hidden state.
Electrical ↔ Mechanical
Pole-Zero + Nonlinearity Lab
Every filter is a pole-zero placement:
Drag a pair, magnitude and group-delay tilt. Then meet the motor: droop clips force, cubes displacement, modulates current. Taylor , . One bench shows linear dream, the next why it fails at power.
Volume ↔ Mass
Speaker Box Calculator + Acoustics Calculators
Thiele-Small: two springs, one mass. Compliance sets and . Vented adds Helmholtz .
Hoffman → small / deep / loud — pick two. Calculators give , Sabine , port .
Piston ↔ Breakup
Cone Breakup + Acoustic Horn Calculator
Low → piston. Bending stiffness sets .
Modes . Breakup . Waveguide mouth must hold pattern: OSWG CD, exponential beams.
Energy storage
Room Modes + Thermal Compression
Room . Below Schroeder modes isolated — you hear room.
Thermal: , drop . Heat is final compressor.
How to use — 3 rules
1. Start frozen.
Each tool opens at a known-good state. Watch 5 seconds. See default , , coherence, bell.
2. One knob, one effect.
Move and . Change and shifts . Add and 2nd harmonic rises. Causal chain is lesson.
3. Read the bottom.
Every tool has 4–5 frontier notes: hook, intuition, math, playbook, honesty. Honesty tells where model stops — no FEA, no BEM, no Klippel rig. That boundary is part of instrument.
Shareable still
The instrument, captured—not illustrated.
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