Tape fluxivity ↔ level
Convert magnetic tape fluxivity in nWb/m to dB relative to a reference level.
nWb/m
dB
nWb/m
| Fluxivity | re 320 nWb/m | Commonly used as |
|---|---|---|
| 185 nWb/m | −4.76 dB | Ampex operating level (US, older standard) |
| 200 nWb/m | −4.08 dB | NAB / MRL 200 (US) |
| 250 nWb/m | −2.14 dB | MRL 250, +3 dB over 185 (common studio level) |
| 320 nWb/m | +0.00 dB | DIN / IEC reference, 38 cm/s and 19 cm/s |
| 355 nWb/m | +0.90 dB | +6 dB over 185 (high-output tape) |
| 510 nWb/m | +4.05 dB | DIN stereo reference (full-track equivalent) |
Analogue tape machines are aligned to a reference fluxivity in nanowebers per metre of track width. Calibration tapes and standards use different references, and measurement methods (ANSI vs. DIN) differ by about 0.8 dB, so check which one your tape and machine documentation mean.
How it works
The recorded level on analogue tape is measured as magnetic flux per metre of track width. Tape machines are aligned so that a reference fluxivity reads 0 VU; hotter tapes use higher references.
Formulas
- L = 20 · log₁₀( Φ / Φ_ref )
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