ISP Technologies Reference Line 4215 - Manual (Page 6)

THERMAL CONDITIONS
The ISP REFERENCE LINE 4215 Series is capable of producing in excess of 2000 watts at
full power. This generates heat that must be dissipated in order to maintain reliability and
insure the amplifier components stay within their operating temperature specs. To
accomplish this, the amplifier is mounted on a heatsink that is internal to the cabinet. Airflow
is forced through a port near the internal heatsink.
In addition, the amplifiers are thermally protected internally via a thermal switch, which will
attenuate the signal 40db if the heatsink temperature exceeds a certain temperature. When
the temperature drops below a certain point, full signal will be restored. Tests have shown
under extreme conditions that cycling will occur approx. (40 sec. ON, 20 sec. OFF)
It should also be noted that a separate internal thermal breaker also protects the power
transformers. If one power transformer temperature reaches a critical point, the internal
thermal breaker will open. If this condition occurs, simply reduce the signal level of the
system. This will only occur if the REFERENCE LINE 4215 is continually pushed into heavy
distortion.