Macro-Tech 24x6 Reference Manual - page 16
Page 16
Macro-Tech 24x6 & 36x12 Power Amplifiers
Note: The components shown in Figure 3.12 are com-
monly available from most electronic supply stores.
Typical fuses help prevent damage due to prolonged
overload, but provide essentially no protection against
damage from large transients. To minimize this prob-
lem, use high-speed instrument fuses such as the
Littlefuse 361000 series. If the loudspeaker is only sus-
ceptible to damage caused by prolonged overload
(such as overheating), use a fuse or circuit breaker
having the same slow thermal response as the loud-
speaker itself (such as a slow-blow fuse).
3.4 AC Power Requirements
All
Macro-Tech amplifiers are shipped with an appro-
priate line cord. When possible, use a power recep-
tacle on a dedicated circuit and always make sure that
it can supply the correct voltage and current. We do
not recommend operating your amplifier on voltages
greater than 10% above or below the unit’s rated volt-
age. For example, if your amplifier is rated for 120 VAC,
the line voltage should not exceed 132 VAC. See Sec-
tion 7 for power requirements under a variety of condi-
tions.
All specifications in this manual were measured using
120 VAC, 60 Hz power, unless otherwise noted. Speci-
fications were derived using a voltage that is accurate
to within 0.5% with THD less than 1.0% under all test-
ing conditions. Performance variations can occur at
other AC voltages and frequencies. In addition, line
regulation problems directly affect the output power
from the amplifier.
1.0
1.2
1.4
1.6
2.5
3
4
5
6
7
8
9
10
12
14
16
20
25
30
20
15
10
8
6
5
4
3
2
1.5
1
.8
.6
.5
.4
.3
.2
.15
.1
.08
3000
2000
1500
1000
800
600
400
300
200
150
100
80
60
40
30
20
15
10
8
6
4
3
2
1.5
1
LOUDSPEAKER IMPEDANCE
(ohms)
FUSE
(amps)
LOUDSPEAKER RATING
PEAK MUSIC POWER
(watts)
(Typically 4 times the continuous average power)
Answer: Fuse = 1.5 A
2
40
Example:
Impedance = 8 ohms.
Peak Power = 75 W
Fig. 3.13 Loudspeaker Fuse Selector Nomograph
3.3.3 Additional Load Protection
Because the amplifier generates enormous power, it
may be desirable to protect loudspeakers (or other
sensitive loads) from damage due to excessive power.
A common way to do this is to put a fuse in series with
the load. This may be accomplished by using a single
fuse to protect all drivers connected to an output, or
each driver may be fused individually. The nomograph
in Figure 3.13 shows fuse size versus loudspeaker
peak power rating. It can be used to determine what
size fuse to use.
4-ohm, 20-watt
Resistor
590 to 708
µ
f Capacitor
120 VAC, N.P.
+
–
Inductive
Load
+
–
From
Amplifier
Output
Fig. 3.12 Inductive Load (Transformer) Network