Meyer Sound MPS-488HP Manual Do Utilizador

25

When powering up the MM-10AC subwoofer, the following 
startup events occur and are indicated by the Limit LED:

1. The LED flashes green and then yellow during power up.

2. The LED turns solid green indicating the subwoofer is 

ready to reproduce audio.

If the Limit LED turns red and stays 

solid red after powering up and the audio is 

muted, the subwoofer has encountered a failure and 
may need to be serviced. Contact Meyer Sound 
Technical Support.

If the Limit LED turns solid red and 

the MM-10AC continues to output audio, 

though at reduced levels, the subwoofer’s voltage 
may have dropped below 90 V AC. When these con-
ditions are encountered, operation of the subwoofer 
should cease and its power supply and cabling 
should be verified.

Limiting activity is indicated when the Limit LED turns yel-
low. When engaged, the limiter protects the subwoofer’s 
driver and prevents signal peaks from causing excessive 
distortion in the subwoofer’s amplifier, thereby preserving 
headroom and maintaining smooth frequency responses at 
high levels. When the level returns to normal, below the lim-
iter’s threshold, the LED turns green and limiting ceases.

The MM-10AC performs within its acoustical specifications 
at normal temperatures when the Limit LED is green, or if the 
LED turns yellow for two seconds or less and then returns to 
green for at least one second. If the LED remains yellow for 
longer than three seconds, the subwoofer enters hard limit-
ing where:

■

Increases to the input level have no effect.

■

Distortion increases due to clipping and nonlinear driver 
operation.

■

The drivers are subjected to excessive heat and excur-
sion, which will compromise their life span and may 
eventually lead to damage over time.

The Limit LED turns yellow when 

the subwoofer’s signal rises 2 dB above the 

limiting threshold, and indicates a safe, optimum level 
has been exceeded. If the MM-10AC subwoofers in a 
system begin to limit before reaching the desired 
SPL, consider adding more subwoofers to the sys-

tem to achieve the desired SPL without exposing the 
subwoofers to excessive levels and possible over-
heating.

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-10AC 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.

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.

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 90 V AC. When these con-
ditions are encountered, operation of the subwoofer 
should cease and its power supply and cabling 
should be verified.