JBL Synthesis S5165 User Manual page 9

S7165.S5165.S820.OM.qxd 4/16/09
F
EATURES
• Quiet Cooling
The S7165/S5165/S820 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 that senses increases in temperature within
the amplifier and powers a fan at a speed proportional to that temperature increase has been incorporated in the
S7165/S5165/S820. When the S7165/S5165/S820 is used at lower volume levels, 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 S7165/S5165/S820 amplifier employs sophisticated protection circuitry (one for each channel) that senses
many possible fault conditions, such as shorted loudspeaker wires or excess power demand, and turns the affect-
ed 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 S7165/S5165/S820's protection circuitry is that it is optically coupled to
the signal circuit; there is no direct electrical connection between the signal path and the protection 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) will turn off completely.
• Balanced and Single-Ended Inputs
Both balanced on XLR and single-ended (unbalanced) on RCA inputs are available for each channel input.
This allows the amplifier to be used with preamplifiers such as the SDP-5 with RCA outputs and SDP-40HD
preamplifiers with XLR outputs.
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