Tape Recording Calibration and Metering: Difference between revisions

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:

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.

@@ Line 4: / Line 4: @@
 * [http://walkman-archive.com/articles/guide-excellent-recordings_05.html Walkman Archive]
 * [[Media:Marantz Reference.jpg|Marantz Reference]]
-* [[Media:BASF Meters and Measurement.pdf|BASF Reference]]
+* 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]
@@ Line 24: / Line 30: @@
 * DIN
 ** 0 dB is 250 nWb/m
-** Dolby level shown at -1.2 dB
+** Dolby level shown at -1.2 dB (voltage factor: 0.871)
-** Used by Sony, TEAC
+** Used by Marantz, Sony, TEAC
 * Nakamichi
 ** 0 dB is 200 nW/m
 ** Dolby level shown at 0 dB
-* Old Philips
+* "Old" Philips
 ** 0 dB is 160 nWb/m
-** Dolby level shown at 2.8 dB
+** 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.
+True [https://en.wikipedia.org/wiki/VU_meter 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
+* 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.