Articles

DSP and music-production tutorials, each with its calculator in the body of the text.

Core series

• Published

  dB conversion, from dBFS to dB SPL

  All five reference levels, the 0.775 V history behind dBu, and the five conversion mistakes that survive a decade of experience.

• Published

  IEEE 754 floats and hex, decoded field by field

  Sign, exponent and mantissa by hand, subnormals, ULP, and reading a 32-bit capture from a logic analyser.

• Published

  Dither and quantisation: what 16 bits actually buys you

  The 6 dB rule derived from the rounding step, the difference between RPDF and TPDF, noise shaping, and the level dependence that decides whether 16 bits is enough.

• Published

  Window functions: leakage, resolution and sidelobes

  Why the window is not optional, how to pick between Hann, Hamming, Blackman and flat-top, and the two corrections that depend on what you are measuring.

• Published

  FFT, RMS and peak levels in practice

  Why the tallest bin is not the amplitude, how far parabolic interpolation gets you, and how to turn a floor into a density.

• Published

  Magnitude-squared coherence between two channels

  How many averages a trustworthy coherence needs, why one average always reads 1.0, and what the cross-spectrum phase says that coherence cannot.

• Published

  FIR design with the windowed-sinc method

  Choosing tap count from transition width, predicting the passband ripple from the stopband attenuation, and why the group delay is not optional.

Extended series

Follow-ups that take one of the core subjects further, usually because the practical question turns out to be subtler than the theory.

• Published

  THD, THD+N, SINAD and ENOB

  Five distortion figures that are not interchangeable, the bandwidth caveat, and why harmonic percentages add in quadrature.

• Published

  Biquad design: the RBJ cookbook explained

  Eight filter types from one transfer function, why A = 10^(dB/40), and the Q-versus-bandwidth difference that no one mentions.

• Published

  Sensitivity, power and distance

  How loud a system really plays: the inverse square law, the two sensitivity conventions, and the crest factor that decides the amplifier.

• Published

  Adding decibels: +3, +6, or nothing

  Powers add, amplitudes add as vectors, and the answer depends on correlation — with the noise-floor correction table and the averaging bias.

• Published

  LUFS and true peak: what the meter measures

  The K-weighting filter, the two-stage gate, loudness range, and why every sample can be below full scale while the true peak is 3 dB above it.

• Published

  Weighting networks and Leq: two conventions that decide the number

  The A, C and Z curves derived from their poles, why A-weighting is a convention rather than a correction, and the exchange rate behind a dose.

• Published

  Room modes and the Schroeder frequency

  Axial, tangential and oblique modes, the coincidences that make a room sound wrong, and where the modal region ends.

• Published

  Reverberation time: Sabine, Eyring, and where the formula stops working

  Both energy balances, the mean free path, why absorption is not one number, and the Schroeder frequency that divides the room in two.

• Published

  SBIR: the reflection you cannot treat, only move

  The image source and one subtraction, the frequency a wall puts a null at, and why the side wall's path difference is not twice the distance.

• Published

  Loudspeaker impedance, reflection and return loss

  Why the number on the cabinet is a convention, what the reflection coefficient costs you, and the DCR tolerance test that catches a dead driver.

• Published

  Speaker cable: what resistance actually costs

  Two conductors make one loop, damping factor is a ratio rather than a specification, and the loss turns out to be a plain voltage divider.

• Published

  Closed-box alignment: Qtc decides everything, volume is the only control

  The one parameter a sealed box adds, the -3 dB point solved properly, the cost of the lift, and where the data sheet stops being true.

• Published

  Passive crossover design

  Butterworth and Linkwitz-Riley ladders with the response measured off the values, and the corner shift a real driver introduces.

• Published

  Subwoofer alignment: delay, distance and polarity

  Three controls that are not interchangeable, the crossover's own group delay, and why a half-period delay is not a substitute for reversing polarity.

• Published

  Band-pass level loss: two filters, two answers

  The same low-pass and high-pass sum to unity across two drivers and lose 12 dB in series on one. The closed form, why a steeper slope costs less, and the headroom the correction needs.

Music production

The everyday units of playing and producing: tempo, pitch and delivery level. Same approach as the rest of the site — the ratio behind the number, and a tool that runs in your browser. The three are collected on the music calculators page.

• Published

  BPM to ms Calculator

  Every note value, dotted and triplet, with the reverse lookup and a tap tempo that ignores a fumbled tap.

• Published

  Cents & Tuning Calculator

  How far off a pitch is in cents, what your A4 means, and where the reference has moved over the centuries.

• Published

  LUFS Normalisation Calculator

  The gain that hits a delivery target, and whether the true peak still fits under the ceiling afterwards.

Supporting calculators

• Published

  CRC calculator: parameter sets that actually match

  Poly, init, refin and refout — the settings that make two CRC-16 implementations disagree, and the check value that settles it.

• Published

  Nyquist, oversampling and alias folding

  Working out where an out-of-band tone lands before you spend a day chasing it on a scope.

• Published

  Acoustic delay, distance and temperature

  Speed of sound as a function of temperature, and why a five-degree error moves a five-metre alignment by four centimetres.

• Published

  Audio file size: three multiplications and nothing else

  Frames, channels and bytes per sample, what the container adds, and why the compression ratio depends on the material rather than the settings.