MACKIE M3000 - Manual (Page 17)

17
Owner’s Manual
Owner’
s Manual
AC Power Distribution
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 a different AC circuit than the one
powering the audio equipment. This will help minimize
noise from the lights coupling into the audio (particu-
larly if SCRs are used).
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 making an unbalanced connection,
use a high-quality 2-conductor shielded cable. Your
Mackie Dealer can recommend a suitable cable for your
application.
Refer to “Inputs” [9] on page 13 for more information
about making the input connections.
When connecting a balanced line-level signal using
XLR plugs, they’re wired thusly, per AES (Audio Engi-
neering Society) standards:
Pin 2 = Hot (+)
Pin 3 = Cold (–)
Pin 1 = Shield (Ground)
2
2
3 1
1
SHIELD
COLD
HOT
SHIELD
COLD
HOT
3
SHIELD
COLD
HOT
3
2
1
Balanced XLR Connectors
Balanced TRS (tip-ring-sleeve) plugs can be con-
nected to the combination jacks as well. They are wired
as follows:
Tip = Hot (+)
Ring = Cold (–)
Sleeve = Shield (Ground)
SLEEVE
TIP SLEEVE
TIP
RING
RING
TIP
SLEEVE RING
Balanced TRS Connectors
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, punch-
ier bass.
Under typical conditions, reproducing rock music
where musical peaks are just below the clipping point,
you can safely connect one or more amplifiers to an AC
service. Use the table below as a guideline:
The M-Series amplifiers are equipped with an in-rush
limiting circuit to minimize startup current and pre-
vent tripping the breakers when two or more amplifiers
are turned on at the same time, on the same breaker.
Sequencing is not required.
If you use an extension cord to supply power to the
“amp rack,” it should have a third wire safety ground to
avoid presenting a safety hazard. We also recommend
using a cord that has conductors large enough to avoid
severely limiting the amplifier’s ability to supply high
currents on transients.
Power amplifiers can have momentary peak current
requirements many times above the nominal average
current draw. According to Ohm’s Law, the greater the
resistance of the linecord, the more input power is lost
between the AC outlet and the power amplifier (across
the linecord). And to further aggravate the matter,
this relationship is nonlinear. The amount of power
lost across the linecord increases exponentially as the
current demand increases. So if the current demand
doubles momentarily because of an exceptionally loud
bass note, the amount of AC input power lost across
the linecord increases four times. You can see that it
is very important to keep the resistance of the line-
cord to a minimum. That’s why we recommend using a
heavy gauge extension cord (like 14 gauge or bigger).
Remember, wire gets thicker as the gauge number gets
smaller (10 gauge is thicker than 14 gauge).
Maximum Number of Amplifiers
on a 120V/15A Service
M•2000 Amplifier Loading (or 240V/7.5A Service)
2 ohms per side or 4 ohms bridged 2
4 ohms per side or 8 ohms bridged 3
8 ohms per side or 16 ohms bridged 4
M•3000 Amplifier Loading
2 ohms per side or 4 ohms bridged 1
4 ohms per side or 8 ohms bridged 2
8 ohms per side or 16 ohms bridged 3
M•4000 Amplifier Loading
2 ohms per side or 4 ohms bridged 1
4 ohms per side or 8 ohms bridged 1
8 ohms per side or 16 ohms bridged 2