# Wow & Flutter Meter Measure wow and flutter of tape and vinyl transfers: weighted RMS per AES6/IEC 60386/DIN 45507, 2-sigma peak, and drift / wow / flutter / scrape band breakdown. > Canonical page: https://elysiatools.com/en/tools/audio-wow-flutter-measure - **Category:** Media - **Keywords:** wow and flutter, wrms, tape speed, turntable, cassette deck, aes6, iec 60386, din 45507, fm demodulation, pitch instability, drift, scrape flutter, analog transfer, vinyl transcription ## Overview The standard way to quantify speed stability of analog transports, done the way AES6-2008, IEC 60386, IEEE Std-193, CCIR 409-2 and DIN 45507 define it. Feed a recording of a 3150 Hz test tone (3 kHz works too - the carrier is auto-detected between 2 and 5 kHz) and the meter performs FM demodulation: it mixes the signal to complex baseband around the carrier, low-passes the result, and reads the instantaneous frequency deviation. The deviation series is then perceptually weighted - the AES6 curve peaks at 4 Hz where the ear is most sensitive to pitch wobble, falling to 0.5 at 0.8 Hz, 0.508 at 20 Hz and about 0.03 at 0.2 Hz (anchors published in AES6; log-log interpolated between them, extrapolated to 200 Hz at the 4-20 Hz slope). Reported numbers: weighted RMS (WRMS, the JIS-style headline figure), weighted and unweighted 2-sigma peak (the AES method: the deviation exceeded only 5 percent of the time, so a single scratch does not fake the reading), and band breakdown per the classic definitions - drift below 0.5 Hz (unweighted), wow 0.5-6 Hz, flutter 6-100 Hz, scrape flutter above 100 Hz. For reference: the best studio machines measure around 0.02 percent weighted, a very good cassette deck around 0.08 percent, and typical consumer decks land at 0.1-0.3 percent. Program-material mode is offered for transfers where no test tone exists: it pitch-tracks sustained tonal content (200-2000 Hz) with autocorrelation and treats the relative pitch deviation as the flutter signal - clearly an estimate, since vibrato and intentional pitch expression count too; a test tone is always the trustworthy measurement. At least 5 seconds of audio is required so that 0.2 Hz modulation is representable; analysis covers the first 3 minutes of longer files. ## Inputs - **Audio recording** (file) - **Analysis mode** (select) ## When to use - Calibrating tape transport mechanisms, capstan belts, or turntable motor speeds using standard 3150 Hz or 3000 Hz test media. - Auditing vinyl rips and cassette deck digitizations for pitch instability, wow, and high-frequency scrape flutter. - Evaluating speed consistency on legacy tape transfers where no calibration tone is present by running program material pitch estimation. ## How it works - Upload an audio recording of at least 5 seconds containing a 3150 Hz test tone or sustained program audio. - The tool automatically detects carrier frequencies between 2 kHz and 5 kHz, mixes the signal down to complex baseband, and calculates instantaneous frequency deviations via FM demodulation. - Deviations are weighted against the perceptual AES6 curve (peaking at 4 Hz) and categorized into drift (<0.5 Hz), wow (0.5–6 Hz), flutter (6–100 Hz), and scrape flutter (>100 Hz). - An interactive HTML report renders WRMS, 2-sigma peak figures, band energy distributions, and modulation spectra. ## Use cases - Turntable maintenance: Verifying plinth isolation, belt tension, and direct-drive speed consistency using a 3150 Hz vinyl test record. - Cassette deck servicing: Diagnosing worn pinch rollers, motor cogging, and capstan runout across wow and scrape flutter bands. - Archival audio quality assurance: Quantifying mechanical pitch stability in digitized reel-to-reel and vinyl master captures prior to restoration. ## Frequently asked questions ### What audio length and file size are supported? Recordings must be at least 5 seconds long to capture low-frequency drift down to 0.2 Hz, can be up to 100 MB, and the tool evaluates up to the first 3 minutes of audio. ### Which test tone frequencies can I use? Standard 3150 Hz tones are recommended, but 3000 Hz tones and any steady carrier between 2000 Hz and 5000 Hz are automatically detected in test-tone mode. ### What is the difference between WRMS and 2-sigma peak readings? WRMS measures perceptually weighted root-mean-square instability, while the AES 2-sigma peak represents deviation exceeded only 5 percent of the time to avoid outlier skewing from tape dropouts or vinyl clicks. ### How does program material mode work without a calibration tone? Program mode tracks sustained tonal material between 200 Hz and 2000 Hz using autocorrelation, treating relative pitch shifts as an estimated flutter signal. ### What are typical wow and flutter benchmarks for analog gear? High-end studio tape recorders generally register around 0.02% WRMS, high-grade cassette decks land near 0.08% WRMS, and typical consumer decks range from 0.1% to 0.3% WRMS. ## Related tools - [Analog Tape Saturation](https://elysiatools.com/en/tools/audio-analog-tape-saturation): Run audio through a simulated tape machine: tanh magnetic soft clipping, speed-dependent head bump and HF rolloff, wow & flutter, and tape hiss — with 3.75/7.5/15/30 IPS presets. - [Audio Wow Flutter Corrector](https://elysiatools.com/en/tools/audio-wow-flutter-corrector): Reduce mild tape speed wobble and compensate known speed offset in audio recordings. - [Mastering Before/After Report](https://elysiatools.com/en/tools/audio-mastering-before-after-report): Compare a source mix against its master: integrated LUFS, true peak, LRA, DR dynamic range, crest, spectral balance and waveform strips, with every delta spelled out. - [Ultrasonic Content Scanner](https://elysiatools.com/en/tools/audio-ultrasonic-content-scanner): Scan the inaudible band of your recordings for hidden high-frequency tones: tracking beacons, flyback whine, aliasing images - with frequencies, durations and classifications. - [Audio Chipmunk Effect](https://elysiatools.com/en/tools/audio-chipmunk-effect): Increase pitch and speed for a chipmunk effect - [Forensic Speech Enhancer](https://elysiatools.com/en/tools/audio-forensic-enhancer): Speech-focused cleanup for noisy evidence and interview recordings: documented FFmpeg filter chains with presets for evidence clarity, broadcast, telephone band and transcription prep. - [Audio Radio Effect](https://elysiatools.com/en/tools/audio-radio-effect): Simulate the sound of an old AM radio - [Audio Tape Hiss](https://elysiatools.com/en/tools/audio-tape-hiss): Add tape hiss noise for a vintage feel ## Samples - [Copyright-Free FLAC Audio Samples](https://elysiatools.com/en/samples/flac-samples): Lossless FLAC audio samples for testing and development, mirrored from MP3 set with nature sounds and meditation music - [Copyright-Free MP3 Audio Samples](https://elysiatools.com/en/samples/mp3-samples): Collection of royalty-free audio samples for testing and development purposes including nature sounds, meditation music, and ambient audio - [Copyright-Free WAV Audio Samples](https://elysiatools.com/en/samples/wav-samples): Uncompressed PCM WAV audio samples for testing and development, mirrored from MP3 set with nature sounds and meditation music - [Copyright-Free Raw PCM Audio Samples](https://elysiatools.com/en/samples/pcm-samples): Raw PCM s16le audio samples featuring nature ambience and relaxing music for waveform, playback, and conversion workflows