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CHAPTER 3: THE MM-4XP LOUDSPEAKER
16
MM-4XP Current Draw and Cable Require-
ments
Each MM-4XP loudspeaker draws a maximum current of
0.7 A rms and 2.2 A peak from the 48 V DC output of the
MPS-488. The current draw for the MM-4XP is dynamic and
fluctuates as operating levels change. The cabling between
the MM-4XP and the MPS-488 adds resistance and hence
causes a voltage drop at the loudspeaker. Because lower
voltages compromise peak SPL, and in some cases fre-
quency response, cable resistance should be minimized.
NOTE: When connecting an MM-4XP to an
MPS-488 Channel Output, the total cable
resistance should not exceed 4 ohms.
Cable Lengths and Cable Gauges for MM-4XPs
When connecting an MM-4XP to an MPS-488 Channel Out-
put, you can use cable lengths of up to 300 feet with only
1 dB of peak SPL loss using 18 AWG wire. Longer cable
lengths are possible with heavier wire gauges (see Table 3
and Table 4).
NOTE: For music playback at moderate levels
(when the MM-4XP is not driven to maximum
output), cable lengths of up to 500 feet with 18 AWG
wire are acceptable.
The maximum cable length for an MM-4XP can be calcu-
lated with the following formula:
maximum length = 4 ohms / 2 * cable resistance
For example, the maximum length of an 18 AWG cable with
a resistance of 0.00636 is 314.4 feet (4 / 2 * 0.00636).
NOTE: For long cable runs, you can use large
cable gauges for most of the run and then ter-
minate with the included EN3-to-pigtail cable.
THE MM-4XP LED
The MM-4XP has a three-color LED on its rear panel that
changes color to indicate the loudspeaker’s status.
Powering On (Green)
When powering up the MM-4XP loudspeaker, the following
startup events occur and are indicated by the LED:
1. The LED flashes green and then yellow during power up.
2. The LED turns solid green indicating the loudspeaker is
ready to reproduce audio.
CAUTION: If the MM-4XP LED turns red and
stays solid red after powering up and the audio
is muted, the loudspeaker has encountered a failure
and may need to be serviced. Contact Meyer Sound
Technical Support.
CAUTION: If the MM-4XP LED turns solid red
and the loudspeaker continues to output audio,
though at reduced levels, the loudspeaker’s voltage
may have dropped below 25 V DC. Operation of the
loudspeaker under these conditions is not recom-
mended and the loudspeaker’s power supply and
cabling should be verified.
Limiting (Yellow)
Limiting activity is indicated when the MM-4XP LED turns
yellow. When engaged, the limiter protects the loud-
speaker’s driver and prevents signal peaks from causing
excessive distortion in the loudspeaker’s amplifier, thereby
preserving headroom and maintaining smooth frequency
response at high levels. When the level returns to normal,
below the limiter’s threshold, the LED turns green and limit-
ing ceases.
Table 3: MM-4XP Loudspeaker Cable Lengths (AWG)
Cable Gauge Resistance
(Ω/ft)
Approximate
Max. Length
12 AWG 0.0016 1200 ft
14 AWG 0.00253 750 ft
16 AWG 0.00402 475 ft
18 AWG 0.00636 300 ft
20 AWG 0.01008 175 ft
Table 4: MM-4XP Loudspeaker Cable Lengths (European)
Cable Gauge Resistance
(Ω/m)
Approximate
Max. Length
2.50 mm
2
0.0052 365 m
1.50 mm
2
0.01076 175 m
1.00 mm
2
0.02087 90 m
0.75 mm
2
0.03307 55 m
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