Tape Recording Calibration and Metering: Difference between revisions
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* [http://walkman-archive.com/articles/guide-excellent-recordings_05.html Walkman Archive] | * [http://walkman-archive.com/articles/guide-excellent-recordings_05.html Walkman Archive] | ||
* [[Media:Marantz Reference.jpg|Marantz Reference]] | * [[Media:Marantz Reference.jpg|Marantz Reference]] | ||
* [[Media: | * BASF "The Inventor's Notebook" | ||
**[[Media:BASF_Bias.pdf|Bias]] | |||
**[[Media:BASF_Chrome.pdf|The Technical Argument for Chromium Dioxide]] | |||
**[[Media:BASF_EQ.pdf|EQ]] | |||
**[[Media:BASF_Housing.pdf|The Cassette Housing]] | |||
**[[Media:BASF_Meters.pdf|Meters and Measurement]] | |||
*[[Media:BASF_Calibration.pdf|BASF Calibration Mechanism]] | |||
* [https://en.wikipedia.org/wiki/Compact_Cassette_tape_types_and_formulations Wikipedia - Tape Formulations] | * [https://en.wikipedia.org/wiki/Compact_Cassette_tape_types_and_formulations Wikipedia - Tape Formulations] | ||
Latest revision as of 14:06, 20 July 2025
Accurate calibration of a tape based recording is necessary to match record and replay levels, and is critical for Dolby tracking.
Reference:
- Walkman Archive
- Marantz Reference
- BASF "The Inventor's Notebook"
- BASF Calibration Mechanism
- Wikipedia - Tape Formulations
Recorded Flux
- 3% distortion is generally considered maximum acceptable.
- MOL (Maximum Output Level):
- Level that produces 3rd harmonic distortion of 3%
- Frequency dependent. At high frequencies can't be used as harmonics won't be reproduced.
- SOL (Saturated Output Level):
- The level which produces the maximum output. More record level reduces playback output.
- Measurement of flux can be open circuit or closed circuit
- 200 nWb/m closed circuit = 220 nWb/m open circuit (Dolby Level)
Metering
Three standards:
- DIN
- 0 dB is 250 nWb/m
- Dolby level shown at -1.2 dB (voltage factor: 0.871)
- Used by Marantz, Sony, TEAC
- Nakamichi
- 0 dB is 200 nW/m
- Dolby level shown at 0 dB
- "Old" Philips
- 0 dB is 160 nWb/m
- Dolby level shown at 2.8 dB (voltage factor: 1.380)
- Most common, used by Aiwa, Akai, Pioneer, Technics, etc
True VU Meters have a tightly controlled professional definition of response, but are more approximate in consumer grade equipment. They show an average signal level over time, and smooth out sharp peaks.
- 3% distortion level is usually around +6 to +8 VU
Peak Meters have fast response, showing peak levels. Better for use on cassette decks with their lower headroom compared to faster tape speeds of Open Reel decks.
- Generally 0 dB on a VU meter is a lower flux level than 0 dB on a peak meter, by about 3 dB.