7
Minimum
Recommended
Amperage Service
115V
15 Amps
20 Amps
230V
10 Amps
16 Amps
AC sags, or lack of current can be au-
dible. When running into this type of
problem, the anomaly generally encoun-
tered is similar to that of a processor
compressing the input signal very hard.
This is caused by the inability of the toroid
transformer to recharge the amplifier ca-
pacitors fast enough. As a result, the audio
performance gets very thin sounding and
you must lower the input level in order for
the system to recuperate. This is a very com-
mon problem for the pro-audio industry in
general. When you begin talking about am-
plifier systems that deliver high power
levels (more than 1,000 watts), the limita-
tions of 115V AC service create problems.
Here are some basic calculations for
some high power amplifiers:
Amp
Output
Required
Power
AC Service
Amps
1000 watts
115V
8.7 Amps
1500 watts
115V
13 Amps
2000 watts
115V
17.4 Amps
2500 watts
115V
21.7 Amps
3000 watts
115V
26 Amps
If the signal reproduced were a full band-
width sine wave, then the above data would
be true at full output with an absolutely flat
signal. An audio signal presents a distinct
problem when it comes to the reproduction
of transient signals found in the typical pro-
grams. For a very short time, the amplifier’s
power supply could require up to four times
the amperage as it tries to reproduce a 6 dB
peak. This is especially true of subwoofer
amplifier systems trying to reproduce fre-
quencies below 50 Hz, which is the frequency
that AC power usually travels at. The
SA1232 amplifiers have extremely robust
toroidal transformers and use a large num-
ber of capacitors. Toroidal power supplies
have one huge advantage over other types
of supplies, which is their ability to provide
higher output beyond their nominal rating.
For a very short period of time, a well designed
2500 watt transformer can deliver up to
AC POWER
Be sure the SA1232 is plugged into an
outlet that is able to supply the correct volt-
age specified for your model. If the voltage
should drop below 97% of the specified line
voltage, the built-in amplifiers will no
longer be able to supply rated power. (They
will continue to operate down to 80% of
the rated line voltage, but won’t reach full
power, resulting in lower headroom.)
Be sure the electrical service can supply
enough amperage for all the components
connected to it.
We recommend that a stiff (robust) sup-
ply of AC power be used because the
amplifiers place high current demands on
the AC line. The more power that is avail-
able on the line, the louder the speakers will
play and the more peak output power will
be available for cleaner, punchier bass. A
suspected problem of “poor bass perfor-
mance” is often caused by a weak AC
supply to the amplifiers.
CAUTION
: Never re-
move the ground pin on
the power cord of the
SA1232 or any other
component. This is very
dangerous.
SA1232 systems are available in 115V
and 230V AC configurations. Mackie De-
signs specifies a specific amount of
amperage service availability for individual
active cabinets. It is a good rule of thumb,
especially in countries using 115V AC
power, to know precisely the amount of
voltage/amperage service available to oper-
ate your active speaker systems safely and
to their full output capacity. We have pro-
vided specifications relative to minimum
amperage requirements that should be used
as a general guideline. Additionally, it is
necessary to comprehend the demands put
upon the AC service when running the
cabinets for prolonged periods of time at
maximum output levels. Depending on the
source material and level, cabinets running
on 115V AC can demand as much as 20
amps of peak amperage service. Depending
on the type of service available, this could
be beyond the capability of your AC system
and produce unwanted audible by-products.
