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It is recommended that a
stiff supply of AC power be
used because the amplifier
places high current demands
on the AC line. The more
power that is available on the line, the louder
the amplifier 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 amplifier.
The M•2600 has an in-rush limiting circuit
and relay that will prevent popping the house
circuit breakers during turn-on. You should still
avoid turning on all of your amplifiers at the
same time. Rather, turn them on one at a time.
AC Power Distribution
The majority of AC outlets encountered in
homes and clubs (in the U.S.) are served by a
240VAC center-tapped service entrance trans-
former. This provides two phases of AC power
on either side of the center tap, at 120V each.
In order to minimize ground loops, the safety
grounds for all the outlets should be connected
to a common (“star”) grounding point, and the
distance between the outlets and the common
grounding point should be as short as possible.
If lighting is used in a show, it is preferable
to power the lights from one leg of the service,
and power the audio equipment from the other
leg. This will help minimize noise from the
lights coupling into the audio (particularly if
SCRs are used).
When setting up for a show, oftentimes you
are plugging into an AC power distribution sys-
tem you know nothing about. You may even be
faced with 2-wire outlets that are missing the
third safety ground pin. It’s a good idea to have
a three-wire AC outlet tester in your toolbox so
you can check the outlets yourself to make
sure they are wired correctly. These testers will
tell you if the polarity of the hot and neutral
wires is reversed and if the safety ground is
disconnected. Don’t use an outlet if it is wired
improperly! This is to protect yourself as well
as your equipment.
INPUT WIRING
Use a high-quality 3-conductor shielded
cable to connect the signal between the signal
source (mixing console, equalizer, etc.) and
the balanced inputs to the amplifier. If you’re
using the unbalanced inputs, use a high-quality
2-conductor shielded cable. Your Mackie
Dealer can recommend a suitable cable for
your application.
If you want to roll your own, refer to the
“Connectors” section in Appendix B.
OUTPUT WIRING
Use heavy gauge, CLASS 1, stranded wire for
connecting speakers to the M•2600
amplifier’s
SPEAKER OUTPUT
terminals. As
the distance between the amplifier and the
speakers increases, the thickness of the wire
should also increase. Speaker wire has resis-
tance, and when electricity passes through a
resistor, power is lost. The thicker the wire,
the less resistance it offers and the more power
actually gets to the speakers.
The wire thickness is rated in gauges. Use
the chart below to determine the correct gauge
of wire to use according to the distance between
the speakers and the amplifier, and the imped-
ance of the load the amplifier is driving. This
ensures that the power lost across the speaker
wire is less than 0.5 dB.
Load Gauge of
Wire Length Impedance Wire
Up to 25 ft. 2Ω 14 gauge
4Ω 14 gauge
8Ω 14 gauge
Up to 40 ft. 2Ω 12 gauge
4Ω 12 gauge
8Ω 14 gauge
Up to 60 ft. 2Ω 10 gauge
4Ω 12 gauge
8Ω 14 gauge
Up to 100 ft. 2Ω 8 gauge
4Ω 10 gauge
8Ω 14 gauge
Up to 150 ft. 2Ω 6 gauge
4Ω 8 gauge
8Ω 12 gauge
Up to 250 ft. 2Ω 4 gauge
4Ω 6 gauge
8Ω 10 gauge
TRANSFORMER
120V
120V
240V
HIGH VOLTAGE POWER LINE
EARTH
GROUND
(NEUTRAL)
PRIMARY
WINDING
SECONDARY
WINDING
240V Center-Tapped Secondary