Toa A-724 - Manual (Page 6)

6
unintentional inputs such as background noise
and noise sound, it is recommended to cut the
audio signal at the input equipment (such as a
microphone with talk switch).
14. Function switches
(1) Phantom power ON/OFF switch
[PHANTOM ON, OFF]
Turns on or off the phantom power for the
corresponding input. This switch is valid only
when the LINE/MIC selector switch is set to the
MIC position.
(2) LINE/MIC selector switch [LINE, MIC]
Selects the input sensitivity of LINE or MIC as
follows:
LINE: –10 dB
MIC: –70 to –50 dB, adjustable with the
Microphone gain trimmer (15).
15. Microphone gain trims [MIC TRIM]
Adjust the microphone input gain for the inputs
set to MIC.
16. Input 1 – 6 connectors [INPUT 1 – 6]
–10 dB (LINE) or –70 to –50 dB (MIC)
selectable, 600 Ω, balanced, removable terminal
blocks.
Either LINE or MIC level can be selected by the
Function switch (14).
When MIC level is selected, the input sensitivity
can be adjusted from –70 to –50 dB with the
Microphone gain trim (15).
The inputs 2 and 3, which are electronically
balanced, can be converted into transformer-
balanced type by using optional transformers IT-
455.
17. Module input slot
Accepts TOA's 900 series module.
18. Functional ground terminal
Hum noise may be generated when external
equipment is connected to the unit. Connecting
this terminal to the functional ground terminal of
the external equipment may reduce the hum
noise.
Note: This terminal is not for protective earth.
19. Speaker output terminals [SP OUT]
4 Ω, 25 V and 70 V outputs, removable terminal
block. Connects to speakers.
20. Recording output jacks [REC OUT]
0 dB, 600 Ω, unbalanced RCA jacks. Output all
input signals before they enter the master
volume control. Connect a cassette deck, etc.
when recording the broadcast contents.
21. Power amplifier input jack [PWR AMP IN]
0 dB, 600 Ω, unbalanced RCA jack. Accepts
output signals from the signal processor
connected to the Preamplifier output jack (12).
(Refer to p. 7.)
Inserting an RCA plug disconnects the internal
power amplifier section from the preamplifier
section.
22. Input 7 and 8 jacks [INPUT 7, 8]
–20 dB, 10 kΩ, unbalanced RCA jacks. Accept
output signals from external equipment.
6. CONNECTIONS
6.1. Input Connections
70 V LINE
Total impedance
83
Ω (A-706)
42 Ω (A-712)
21
Ω (A-724)
4 – 16 Ω
COM 4 Ω 25 V 70 V
70 V Line
COM 4 Ω 25 V 70 V
25 V LINE
Total impedance
10
Ω (A-706)
5.2 Ω (A-712)
2.6
Ω (A-724)
25 V Line
COM 4 Ω 25 V 70 V
Notes
• Do not use both the 4 Ω, 25 V and 70 V terminals at the same time.
• Impedances indicated in the figures represent the total speaker system (load) impedances.
6.2. Speaker Connections
HOT COLD EARTH
C
E
H
MIC
HOT COLD EARTH
C
E
H
[MIC] [LINE] [AUX]
Input
source
Input
source H
E
Input
source H
E