Definitions
Wow and flutter describe unwanted variations in playback speed. Wow usually refers to slower changes; flutter to faster ones. Measurement standards use defined weighting and test methods, so a percentage from one method is not automatically comparable with a figure from another.
On tape equipment, transport mechanics can vary speed. On a turntable, an off-centre record or speed instability can create pitch changes. A digital effect can imitate aspects of that movement without reproducing the original mechanical cause.
What they do to music
Changing playback speed changes pitch. A sustained piano note can reveal this as drift or a tremor. A single modulated signal is closer to vibrato; chorus normally involves combining differently timed or pitched versions. The terms should not be treated as interchangeable.
Small amounts can be an artistic choice. Larger amounts can make tuning unstable or be unpleasant. Neither is inherently more accurate than the original recording.
Recreating it
MP95 provides wow and flutter controls in its sound tools. Start with both low, listen to a sustained sound and change one control at a time. Compare at the same comfortable volume with the analog processing bypassed.
A control amount in the app should not be presented as a measured wow-and-flutter specification of real hardware.
The rest of the tape sound
- Saturation and drive: tape compresses softly and adds harmonics when pushed. It makes loud things rounder.
- Head bump and roll-off: a gentle lift in the low mids and a soft top. MP95's tone and sub knobs cover this.
- Hiss: the noise floor. MP95 keeps it low, because a whisper of hiss reads as tape and a lot reads as a bad copy.
Comparing measurements
For a hardware comparison, use the manufacturer’s stated measurement method and the condition of the particular machine. This article does not assign a universal percentage to every cassette deck, portable player or reel-to-reel.
For MP95, the useful test is whether you like the effect on the recording you are playing. You can leave it off for ordinary listening.
Frequently asked questions
Is wow and flutter a defect?
In a transport specification, it describes deviation from stable speed. An imitation of that deviation can also be used deliberately as an audio effect. Tape warmth should not be reduced to this one factor.
Can I add wow and flutter to a digital file?
Yes. MP95 renders it in real time on any file you play, with the amount on a knob, and a switch to bypass it.