Tape plugins give you knobs called wow, flutter, saturation and hiss, and almost nobody explains what they are or what a realistic amount looks like. Here is what each one is physically, and the numbers to aim at.
Useful whether you are using a tape plugin, sampling a real deck, or building the effect by hand.
Both are speed variation, which the ear hears as pitch variation. The only difference is how fast the variation happens, and they come from different parts of the machine.
| Rate | Comes from | Sounds like | |
|---|---|---|---|
| Wow | below about 6 Hz | Eccentric or warped spool, slipping reel, worn bearing | Slow drifting and seasick, most obvious on held notes and piano |
| Flutter | about 6 Hz to 100 Hz | Capstan, pinch roller, tape scraping across guides | A shimmer or graininess, more texture than pitch |
The practical point: wow you notice, flutter you feel. If you want the listener to clock that this is tape, you need wow. If you want it to just sit slightly wrong in a nice way, that is flutter.
A working cassette deck in reasonable condition manages roughly 0.1 to 0.3 percent wow and flutter. A tired one, or a cheap portable, might be double that. A well maintained reel to reel is an order of magnitude better and is nearly inaudible.
So if a plugin's wow control goes to something wild, the top of the range is a broken machine, not a vintage one. Most of the sound people actually want lives in the bottom quarter of that knob. Past about half, the listener stops hearing nostalgia and starts hearing a fault.
Wow and flutter on a sustained pad is obvious and lovely. The same setting on a piano or a clean vocal sounds like a mistake, because the ear knows exactly what pitch those should be. Automate it down under anything with clear pitch, or apply it to a bus that excludes them.
Magnetic tape cannot record an arbitrarily loud signal. As you push level, the medium starts to run out of headroom gradually rather than clipping abruptly. Two things happen at once.
The peaks get squashed. Transients come back rounder. This is why a drum kit through tape sounds glued and thick without a compressor being anywhere near it.
Harmonics appear. Tape adds mostly odd harmonics as it saturates, which reads as warmth and thickness at low levels and as grit at high ones. Push further and you also lose high frequency content, because the top end saturates first.
The mistake is treating a saturation control like a distortion control and turning it up until you hear it. Tape saturation working properly is barely audible as an effect. You notice it when you bypass it and everything sounds thin and spiky.
This one is rarely explained and it matters more than the rest. The geometry of a tape head creates a low frequency resonance, a broad bump of a few dB somewhere in the bass. On a cassette it typically sits somewhere around 50 to 100 Hz.
That bump is a large part of why tape recordings feel bigger and rounder than the source. When people describe tape as warm, they are often describing head bump plus the gentle high frequency loss above it, which together tilt the whole balance downward.
If your tape plugin has no head bump control, you can add one: a broad bell of 2 to 3 dB around 80 Hz with a wide Q, and a gentle shelf taking a dB or two off above 8 kHz. That alone gets you a surprising distance.
An order that works, and roughly where to start:
SILT is a tape loop instrument rather than a tape emulation. The wow, the flutter, the saturation and the dropouts are how the thing behaves rather than knobs bolted onto a clean signal, so the sound moves on its own the way a real loop does.
It is a different job from a tape plugin on a bus. If what you need is to make an existing mix sound like tape, everything above will get you there in any DAW. If what you need is something to play that already lives in that world, that is what SILT is for.
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