Audio Engineering

770 Chapter 27

27.3 Standard Operating Levels and Line-Up Tones ....................................................

Irrespective of the type of meter employed, it should be pretty obvious that a meter is
entirely useless unless it is calibrated in relation to a particular signal level (think about it
if rulers had different centimeters marked on them!).

Three important line-up levels exist (see Figure 27.6 ):

PPM4  0 dBu  0.775 V rms, used by United Kingdom broadcasters.

0VU   4 dBu  1.23 V rms, used in commercial music sector.

0VU   10 dBV  316 mV rms, used in consumer and “ prosumer ” equipment.

Pro VU BBC

PPM

Pro

digital

meter

Semi-pro

VU (dbV)

Semi-pro

digital

meter

Semi-pro

0 VU line-up

approx8 dBu

BBC line-up

(PPM  4)

Pro-audio

line-up

Unrecorded

peaks to

14 dBu

Unrecorded

peaks to

2 dBu

dBU

18

10

0

 10

 3

0

 10

1

2

3

4  18

0

 30

 10

 3

0  18

0

5

6

 6

8

4

 18

Figure 27.6 : Standard levels compared.