PROFESSIONAL AUDIO & SOUND
®
TM
DIGITAL MUSIC SERIES
DIGITAL MUSIC AMPLIFIERS
INSTALLATION AND WIRING
PAGE 23
SPECIFICATIONS ARE SUBJECT TO CHANGE WITHOUT NOTICE
T3015/3030DMA
OUTPUT CONNECTIONS
25 VOLT AND 70 VOLT CONSTANT VOLTAGE DISTRIBUTION SYSTEMS - In applications requiring a large number of speakers that
are located at a far distance from the amplifier a 25 Volt or a 70 Volt Constant Voltage method is most widely used.
MAIN ADVANTAGES IN USING THE HIGH IMPEDANCE METHOD
1) All speakers are connected in parallel usually on to a single speaker line.
2) The Amplifier Output Voltage is constant over a very wide range of load impedance.
3) The Amplifier Output Voltage remains practically constant if loudspeakers are connected or disconnected from the line.
4) Different acoustic power can be allocated in each area as required by using the power taps on the speaker line transformer.
5) Since the system provides a higher voltage at a lower current, resistive loss in the cable is reduced resulting in a higher efficiency.
6) Calculations of the output power needed and the speaker power requirements are simple and easily accomplished.
CONSTANT VOLTAGE DISTRIBUTION SYSTEMS
3015B spkout05
0.6
5
0
2.5
1.25
0.6
5
0
2.5
1.25
0.6
5
0
2.5
1.25
0.6
5
0
2.5
1.25
spk 1
spk 2
spk 3
spk 4
70 Volt
Transformer
70 Volt
Transformer
70 Volt
Transformer
70 Volt
Transformer
Total Speaker Load Calculation
TL = SPK1+SPK2+SPK3+SPK4
TL =1.25+1.25+2.5+5 = 10 Watt
0 8 25V 70V
Fig. 23 - 70 Volt Constant Voltage System Diagram
INSTALLATION TIPS
1) Determine the amount of speakers required for the
installation and their location.
2) Choose the power output needed for each speaker
(typically 1.25 Watt for background music applications
and 5-10 Watt for paging horns).
3) Add all the speaker taps wattage (see Fig. 23) and be
sure that the total power needed does not exceed the
Rated RMS Power Output of the Amplifier
4) Procure a jacketed, two conductor cable of at least 18
gauge.
5) Carefully route cable starting with the farthest speaker
in the system and until all speakers are reached by the
cable and terminating at the Amplifier location. The best
cable route is determined by the individual application.
6) Connect each speaker in accordance to the power out-
put required by selecting the corresponding Power Tap.
IMPORTANT NOTE: Make sure that the unused stripped
power tap wires are INDIVIDUALLY INSULATED and do
not touch each other or an amplifier overload will occur.
7) Connect the speakers cable to the
25 Volt or 70 Volt
and
COM output terminals of the Amplifier, turn the sys-
tem on and balance the various speakers accordingly.
The selection of the Constant Voltage (25 Volt or 70 Volt)
is determined by the speakers used. All speakers must
operate at the same constant voltage and cannot be
mixed.
LINE ATTENUATORS
In installation requiring that one or a group of speakers
have an independent level control a Line Attenuator can
be utilized. The Fig. 23A shows the use of a PASO model
VC20 - 20 Watt Attenuator used to control two speakers
simultaneously. The wire colors pertain to the VC20, if
other types are used follow the directions supplied with
the unit.
By turning the stepped switch of the VC20 the level of
speakers SPK 1 and SPK 2 can be adjusted, up or down,
from 0 (no output) to the maximum output determined by
the tap utilized on the speakers (in this example 2.5 Watt
max.). Speakers SPK 3 and SPK 4 are not affected.
NOTE: The total power required for all the speaker or
speakers to be controlled should not exceed the Power
Handling rating of the Attenuator. Example: the maximum
load for the VC20 is 20 Watt.
WIRING
0.6
5
0
2.5
1.25
0.6
5
0
2.5
1.2
5
spk 3
spk 4
70 Volt
Transformer
70 Volt
Transformer
Total Speaker Load Calculation
T
L
= SPK1+SPK2+SPK3+SPK4
T
L
= 2.5+2.5+2.5+2.5 = 10 Watt MAX.
0.6
5
0
2.5
1.25
spk
1
70 V
o
lt
T
ransf
ormer
0.6
5
0
2.5
1.25
spk
2
70 V
o
lt
T
ransf
ormer
RED
BLUE
BLA
CK
PASO VC20 ATTENUATOR
3015B spkout06
0 8 25V 70V
Fig. 23A - Using a Line Attenuator Diagram