JBL S7150 - Manual (Page 9)

Quiet Cooling
The S7150 utilizes a fan to cool the amplifier channels,
ensuring long-term reliability. To reduce fan noise to an
absolute minimum, a thermal sensing and control
circuit has been incorporated in the Synthesis S7150
that senses increases in temperature within the
amplifier and powers a fan at a speed proportional to
that temperature increase. When the S7150 is
"loafing", the fan turns very slowly – and quietly. At
high listening levels (and the higher operating
temperatures this creates within any amplifier), the
sensing circuitry causes the fan to turn faster,
producing increased cooling. As a result, the fan is
never turning faster than necessary, and most of the
noise that is generated is masked by the program
being listened to.
Comprehensive and Isolated Circuit Protection
The S7150 amplifier employs a sophisticated protective
circuit (one for each channel) that senses many possible
fault conditions, such as shorted loudspeaker wires or
excess power demand, and turns the affected
channel(s) and their blue front panel indicators off
until the fault condition is removed, at which time
normal operation is automatically restored. While
protection of this sort is not uncommon in today’s
well-designed amplifiers, a remarkable feature of the
Synthesis S7150’s protective circuits is that they are
optically-coupled to the signal circuit; there is no direct
electrical connection between the signal path and the
protective circuitry.
As a result, there can be no coloration of the
music, no interaction between protection and
amplification, until certain thresholds are
exceeded, at which point the channel(s) turn
off completely.
9
2.0
INTRODUCTION
AND FEATURES
2.0
INTRODUCTION
AND FEATURES