Meyer Sound MSL-4

longer than two seconds, and off for at least one second. If either

LED remains on for longer than three seconds, that channel is

hard limiting with these negative consequences:

• Increasing the input level will not increase the vol-

ume.

• The system distorts due to clipping and nonlinear driver

operation.

• Unequal limiting between the low and high frequency

drivers alters the frequency response.

• Driver and ampliﬁer life-span is reduced because they

are subje cted to excessive heat.

NOTE: Although the TPL limiters exhibit smooth sonic char-

acteristics, we do not recommend using them for intenti onal

compression effects. Use an outboard compressor/limiter to

compress a mixed signal.

The TPL LEDS can indicate an imbalance in a conﬁguration of

loudspeakers by functioning like a spectrum analyzer. If the

loudspeakers in a subwoofer, mid-bass, or mid-hi subsy stem

begin to limit before reaching the required operating level for

the entire system, then that subsystem needs to be supplemented

with additional loudspeakers.

Fans and Cooling System

The MSL-4 uses a forced-air cooling system with two fans to

prevent the ampliﬁers from overheating. The fans draw air in

through ducts on the front of the cabinet, over the heatsinks, and

out the rear of the cabinet. Since dust does not accumulate in

the ampliﬁer circuitry, its life-span is increased signiﬁcantly.

A foam insert ﬁlter, in combination with the entire front grill

surface, acts as an air ﬁlter for the cooling system. Despite the

ﬁltering, extensive use or a dusty operating environment can al-

low dust to accumulate along the path of the airﬂow, preventing

normal cooling . We recommend periodically removing the

grill, ﬁlter, and ampliﬁer module and using compressed air to

clear dust from the grill, ﬁlter, fans, and heatsinks. Make sure

that the air ducts are clear and that there is at least six inches

clearance for exhaust behind the cabinet.

air

intake

power supply

air filter

heatsinks

amplifier

cooling

fans

A variable-speed primary fan runs continuously with an inaudible

operating noise of 22dBA at 1 m at its slowest speed. The speed

of the primary fan begins increasing when the temperature

of the heatsinks reaches 42°C. The fan reaches full speed at

62°C and is barely audible near the cabinet, even without an

audio signal.

In the unusual event that the heatsink temperature reaches 74°C,

the secondary fan turns on; it turns off when the temperature

decreases to 68°C. The secondary fan is audible at close prox-

imity without an audio signal and turns on in response to

• primary fan failure (check its status immediately);

• a prolonged period of high source levels in hot tempera-

tures or direct sunlight;

• accumulation of dust in the cooling system path;

• driver failure.

TROUBLESHOOTING NOTE: In the highly unlikely event

that the secondary fan does not keep the temperature below

85°C, the MSL-4 automatically shuts down until AC power is

removed and reapplied. If the MSL-4 shuts down again after

cooling and reapplying AC power, contact Meyer Sound for

repair information.