Audio Engineering

168 Chapter 7

source, which gives an output voltage of 1 mV for each 1000 ohms of load impedance,
such that a unit with a 100-K input impedance would see an input signal voltage of
100 mV, or the line output standard, designed to drive a load of 600 ohms or greater, at a
mean signal level of 0.775 V rms, often referred to in tape recorder terminology as OVU.

Generally, but not invariably, units having DIN type interconnections, of the styles shown
in Figure 7.1 , will conform to the DIN signal and impedance level convention, whereas
those having “ phono ” plug/socket outputs, of the form shown in Figure 7.2 , will not. In
this case, the permissible minimum load impedance will be within the range 600 to 10,000
ohms, and the mean output signal level will commonly be within the range 0.25–1 V rms.

An exception to this exists regarding compact disc players, where the output level is most
commonly 2 V rms.

Figure 7.2 : The phono connector.

Plugs

3

8

76

5 4

2

1

7-way 8-way

3

76

5 4

2

1

5-way

3

5 4

2

1

3-way

3

2

1

Electrical connections

(viewed from rear of socket)

For 5-spin

connector

LH input  1

RH input  4

LH output  3

RH output  5

0 V line (chassis)  2

3

5 4

2

1

Figure 7.1 : Common DIN connector confi gurations.