Meyer Sound MM-10 - Manual (Page 13)

MM-10 OPERATING INSTRUCTIONS
13
MM-10XP Temperature and Limiting
The Limit LED turns solid yellow when its heat sink tempera-
ture reaches 65° C (145° F), indicating the unit is reaching its
maximum heat dissipation and a reduction in SPL is recom-
mended. While the MM-10XP will continue to operate while
the LED is yellow, the limiter threshold is lowered to a safe
level (causing the output level to be lowered by 6 dB) to pre-
vent the subwoofer from overheating. When the temperature
of the heat sink cools to 50°C (122°F), the LED changes
from yellow to green and the limiter threshold returns to nor-
mal.
Clipping (Red)
The Limit LED flashes red when its input signal causes the
amplifier to overload. If the LED flashes red continuously, the
subwoofer is severely overloaded and a reduction in the
input level is recommended.
CAUTION: If the Limit LED turns solid red and
the subwoofer continues to output audio,
though at reduced levels, the subwoofer’s voltage
may have dropped below 25 V DC. When these con-
ditions are encountered, operation of the subwoofer
should cease and its power supply and cabling
should be verified.
MM-10XP CURRENT DRAW AND CABLE
REQUIREMENTS
Each MM-10XP subwoofer draws a maximum current of
3.31 A average and 3.45 A peak from the 48 V DC output of
the MPS-488HP. The current draw for the MM-10XP is
dynamic and fluctuates as operating levels change. The
cabling between the MM-10XP and the MPS-488HP adds
resistance and hence causes a voltage drop at the sub-
woofer. Because lower DC voltages compromise amplifier
performance (peak SPL), and in some cases frequency
response, cable resistance should be kept to a minimum.
NOTE: For long cable runs, you can use a large
cable gauge for DC power and a separate bal-
anced audio cable for audio.
Cable Lengths and Cable Gauges for
MM-10XPs
When connecting an MM-10XP to an MPS-488HP channel
output, you can use cable lengths of up to 150 feet with only
1 dB of peak SPL loss using 18 AWG wire. Longer cable
lengths are possible with heavier wire gauges (see Table 1
and Table 2).
NOTE: When connecting an MM-10XP to an
MPS-488HP channel output, the total cable
resistance should not exceed 2 ohms.
Calculating the Maximum Cable Length
The maximum cable length for an MM-10XP can be calcu-
lated with the following formula:
maximum length = 2 ohms / 2 * cable resistance
For example, the maximum length of an 18 AWG cable with
a resistance of 0.00636 is 157.2 feet (2 / 2 * 0.00636).
!
Table 1: MM-10XP Loudspeaker Cable Lengths (AWG)
Cable Gauge Resistance
(
/ft)
Approximate
Max. Length
12 AWG 0.0016 600 ft
14 AWG 0.00253 375 ft
16 AWG 0.00402 237 ft
18 AWG 0.00636 150 ft
20 AWG 0.01008 87 ft
Table 2: MM-10XP Loudspeaker Cable Lengths (European)
Cable Gauge Resistance
( /m)
Approximate
Max. Length
2.50 mm 2 0.0052 157 m
1.50 mm 2 0.01076 87 m
1.00 mm 2 0.02087 45 m
0.75 mm 2 0.03307 27 m