IEC 60386: Magnetic Tape Recorder Speed Stability — Measuring Wow and Flutter in the Analogue Audio Era

“Wow and Flutter” — The Most Annoying Sound Distortion of the Analogue Era and Its Measurement

IEC 60386:1972 specifies magnetic tape recorder speed stability measurement. Flutter (>10 Hz) and Wow (<10 Hz) are the most annoying distortions in analogue recording — flutter makes sound “tremble,” wow makes it “drift.” High-quality open-reel recorders achieve weighted Wow&Flutter <0.05%; typical cassette decks ~0.1–0.3%.

TNLab — Digital audio eliminated Wow&Flutter — and also erased the history of analogue-era engineers battling mechanical precision.