No431 & No432 Owner's Manual - Mark Levinson
No431 & No432 Owner's Manual - Mark Levinson
No431 & No432 Owner's Manual - Mark Levinson
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
Extensive Protection<br />
The Nº432/431 is designed to shut itself down if it senses any of a<br />
number of fault conditions that could cause damage to itself or to<br />
associated loudspeakers.<br />
These fault conditions include:<br />
• the presence of DC (direct current) at the output<br />
• demand for excessive current at the output, indicating a shortcircuit<br />
• over-voltage or under-voltage conditions (+5% to -10%) at the<br />
~ac mains connector<br />
• unsafe operating temperatures in any of several critical areas<br />
within the amplifier<br />
In the case of either significant DC offset or an over-current<br />
condition, the amplifier will shut down to protect itself and the<br />
associated loudspeakers. The front panel indicator LED will blink<br />
rapidly, remaining lit about half of the time. To restore normal<br />
operation, remove the cause of the fault and power cycle the<br />
amplifier with the power button.<br />
12<br />
If the ~ac mains connector voltage is too high or too low for safe<br />
operation, the amplifier will automatically enter sleep mode and<br />
the front panel indicator LED will blink rapidly, remaining on<br />
most of the time. The amplifier will not come out of sleep mode<br />
until the ~ac mains connector voltage is again within the normal<br />
operating range. For example, a 120V amplifier will operate<br />
between approximately 108-132VAC; a 230V amplifier will operate<br />
between approximately 207-253VAC. Outside of these generous<br />
limits, the amplifier will enter sleep mode. Once the fault condition<br />
is removed, the amplifier can be taken out of sleep mode.<br />
If the amplifier overheats despite its innovative heat sinking and<br />
cooling system, it will enter and remain in sleep mode until the<br />
temperature at the output heat sinks drops below 85°C (158˚F or<br />
358K). The front panel indicator LED will blink rapidly, remaining<br />
unlit most of the time. Once the fault condition is removed, the<br />
amplifier can be taken out of sleep mode.<br />
In addition, the AC input to each transformer is fused to protect<br />
against excessive current conditions such as driving shorted<br />
outputs. Inrush limiting prevents premature aging of power<br />
supply components during power-up, and switches off-line once<br />
the power supply has been charged.<br />
Finally, your amplifier incorporates a controlled clipping circuit<br />
that prevents the output devices from saturating. The harsh highfrequency<br />
harmonics generated by hard-clipped output devices are<br />
avoided by the wave-shaping action of this controlled clip circuitry.