Handbook for Sound Engineers

Grounding and Interfacing 1209

Figure 32-46. Measured hum rejection versus source impedance, active differential amplifier versus input transformer
isolator.

Figure 32-47. Using an audio ground isolator to break the loop.

Figure 32-48. Using a CATV ground isolator to break the loop.

Transformer

ISO-Max® CI-2RR

Consumer Zo range

Differential amplifier

Sonance AGI-1

(now discontinued)

CMRR Rejection—dB versus Source impedance—^7

1 10 100 1k

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

AGI-1

ISO-MAX

TV receiver

CD player

Cassette player

Preamplifier

Crossover and

subwoofer

power amplifier

Main

power

amplifier

ac power safety ground

Entry

lightning

ground

CATV

3' 20' 15'

3'

3'

Isolator

TV receiver

CD player

Cassette player

Preamplifier

Crossover and

subwoofer

power amplifier

Main

power

amplifier

ac power safety ground

Entry

lightning

ground

CATV 3'

20' 15'

3'

3'

Isolator