Reference level (sound engineering)

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The term reference level has two different meanings in sound engineering :

  • On the one hand, a level is referred to as a reference level if it relates to a specific level specification; this is then the reference value . For example, the reference level for the level unit dBu can be 0 dBu = 775 mV ( effective ).
  • On the other hand, the reference level can be a level for which a certain device, an input, an output or an entire device chain is designed; here the reference level is the same as the nominal level.

International reference values

Level unit Ref.value Physical size comment field of use
0 dBu U 0 = 0.775 V eff tension Voltage that converts 1 mW eff power into 600 ohms Audio, technology, telecommunications
0 dBV U 0 = 1 V eff tension corresponds to 2.22 dBu Audio, technology, USA
0 dBm P 0 = 1 mW eff power Reference value at R = 600 Ohm Telecommunication technology
Reference value at R = 50 Ohm HF technology
Reference value at R = 75 Ohm HF technology (television)

Comparison of important sound levels

For radio and television, the analog reference level or nominal level was set at +6 dBu according to an ARD agreement, corresponding to 1.55 V (effective). It refers to a level of 0 dBu at 0.775 V (rms value) and is measured with a standardized level meter.

In the area of ​​the EBU (European Broadcasting Union) and the ARD (working group of the public broadcasters of the Federal Republic of Germany), this corresponds to the scale value −9  dBFS (FS = full scale) in digital signal processing . Analog-to-digital converters and digital-to-analog converters for audio signals are adjusted accordingly. The equation +6 dBu = −9 dBFS = 0 dBr ( relative to the studio level or full scale) is not a general rule, but is based solely on an agreement between the members of the ARD broadcasters. A different setting (leveling) of AD and DA converters and especially the use of non-standard level meters lead to completely different dB values.

The analog reference level of +4 dBu comes from the USA , corresponding to 1.228 V (rms value) for the sound engineering and the sound reinforcement .

There is also the reference level of 0 dBV, corresponding to exactly 1 V (effective) and the home device level (USA) with −10 dBV, corresponding to 0.3162 V (effective).

dB ( sound pressure level ) dBV (consumer electronics) dBu (TV BRD ) dBu (TV USA ) dBr (studio level) dBFS (digital level)
Clip border ( Pain threshold ) ( Distortion ) +15 dBu ( distortion ) +22 dBu ( distortion ) ( Distortion ) 0 dBFS
Full scale - -10 dBV
(= -7.78 dBu
= 0.3162 V eff )
+6 dBu
(= 1.55 V eff )
+13 dBu 0 dBr -9 dBFS
standardized test tone - -19 dBV -3 dBu +4 dBu
(= 1.228 V eff )
-9 dBr -18 dBFS
Reference value Hearing threshold
(2 · 10 −5 Pa ) = 0 dB
0 dBV = 1 V eff 0 dBu = 0.775 V eff Full scale Clipping

See also


  • Michael Dickreiter, Volker Dittel, Wolfgang Hoeg, Martin Wöhr (eds.), "Handbuch der Tonstudiotechnik", 8th, revised and expanded edition, 2 volumes, publisher: Walter de Gruyter, Berlin / Boston, 2014, ISBN 978-3- 11-028978-7 or e- ISBN 978-3-11-031650-6 .
  • Thomas Görne: Microphones in theory and practice. 8th new, revised and expanded edition. Elektor-Verlag, Aachen 2007, ISBN 978-3-89576-189-8 .
  • Thomas Görne: Sound engineering. Fachbuchverlag Leipzig by Carl Hanser Verlag, Munich a. a. 2006, ISBN 3-446-40198-9 .
  • Roland Enders: The home recording manual. The way to optimal recordings. 3rd, revised edition, revised by Andreas Schulz. Carstensen, Munich 2003, ISBN 3-910098-25-8 .

Web links

Individual evidence

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