JBL S7150 user manual Introduction And Features, Quiet Cooling

2.0 INTRODUCTION AND FEATURES

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

2INTRODUCTION.0 AND FEATURES

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.

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