Meyer Sound Self-Powered Studio Monitor HM-1S - Manual (Page 16)

16
Cooling and Fan Installation
The HM-1S depends on natural convection to cool the
heatsinks that absorb heat from the amplifiers and radiate
the heat into the surrounding air space. Natural convection
requires free air in back of, and underneath the HM-1S to
allow air to flow up over the heatsinks. The HM-1S reaches
an equilibrium temperature in approximately 15 minutes
at a steady operating level.
In free air, at a typical room temperature of 25°C, the HM-
1S reaches an equilibrium temperature of
• 40°C in a quiescent state (no audio signal);
• 60°C at a moderate operating level (occasional
limiting);
• 75°C at the maximum operating level (continuous
limiting), or at a moderate level with a subwoofer.
If the temperature reaches 85°C, the thermal limiters
activate (see Protection and Limiting) to prevent high
source levels from further increasing the temperature
and damaging the drivers and electronics. The thermal
limiters provide 30 dB of muting until the temperature
decreases to 75°C.
The HM-1S can be cooled by two fans, available as an
accessory kit. The fans should be used if:
• the HM-1S is enclosed in a soffit or ceiling mount
without adequate space for natural convection;
• the HM-1S is used in hot ambient temperatures or
direct sunlight;
• the user wishes to avoid accidental contact with the
heatsinks if the rear of the HM-1S is exposed.
Installed fans blow air over the heatsink
The fans attach easily to the two bottom rear corners of
the HM-1S. Use a 5 /
32
” Allen wrench to remove the bottom
screws and install the left and right fans according to the
diagram below. The fans are shipped with a terminal plug
keyed for insertion into the 2-pin fan output connector in
the proper orientation only.
The fan speed is temperature controlled. At a heatsink
temperature of 25°C, the fans turn on at half speed and
increase speed linearly until reaching full speed at
75°C.
Protection and Limiting
The front of the HM-1S has two LEDs that indicate power and
limiter activity. The right LED is green when power is ap-
plied. This LED turns red if thermal limiting occurs (de-
scribed in the section Cooling and Fan Installation) until the
temperature decreases to 75°C.
The left LED indicates driver limiter activity with a vari-
able intensity red color; full illumination occurs at thermal
limiting.
Rigging
! Do not drill into the HM-1S Cabinet.
The HM-1S is not designed for use with rigging systems.
For rigging needs, Use the Standard Contractors version
HM-1 cabinets which can be easily fitted for omni- mounts,
and other rigging options.