User manual HAFLER SERIES 9130

[. . . ] HOME AUDIO COMPONENTS Series 9130 Power Amplifier 0 M W A N N E U R A S L Series 09130 P 0 W E R A M P L I F I E R NOTICE - IMPORTANT SAFETY INFORMATION Ap!!!J!A WARNING: TO PREVENT FIRE OR SHOCK HAZARD, DO NOT EXPOSE THIS EQUIPMENT TO RAIN OR MOISTURE. 1. The lightning flash with arrowhead symbol within an equilateral triangle is intended to alert the user to the presence of uninsulated "dangerous voltage" within the products enclosure, that may be of sufficient magnitude to constitute a risk of electric shock to persons. The exclamation point within an equilateral triangle is intended to alert the user of the presence of important operating and maintenance (servicing) instructions in the literature accompanying the appliance. READ INSTRUCTIONS All the safety and operating instructions of your Hafler equipment should be read before power is applied to the equipment. RETAIN OWNERS MANUAL These safety and operating instructions should be retained for future reference. HEED WARNINGS All warnings on the equipment and in the operating instructions are important and should be followed. FOLLOW INSTRUCTIONS All operating and use instructions are important and should be followed. [. . . ] Special linearizing techniques are used that dramatically reduce harmonic distortion. The final output stage uses two multiple lateral MOSFET's (Metal Oxide Semiconductor Field Effect Transistors) per channel. These devices, unlike conventional bipolar transistors, have a negative temperature coefficient, which means that they do not exhibit "thermal runaway". Thermal runaway is a phenomenon whereby a transistor heats up as it conducts more current, which causes it to get hotter, and conduct more current, and so on, until the device self destructs. Since MOSFET's are inherently self-protecting, no sonically degrading, complex circuitry is required to monitor and protect the output devices. Furthermore, these lateral MOSFET's exhibit a very linear input to output transfer function. Their connection in circuits and operating characteristics are very similar to vacuum tubes, which is perhaps responsible for their widely recognized sonic trait of being very "musical" and non-fatiguing. Conversion to Mono Mode is accomplished by driving the negative input (feedback point) of the right channel with the output of the left channel. This causes the right channel to mirror exactly the output of the left channel, but 180 degrees out of phase. This creates twice the voltage swing to be available across the two red output binding posts. This simple method of bridging the amplifier (involving only one resistor) eliminates the costly and sonically degrading inverter circuitry used in other amplifiers. The Thermal Protection System consists of thermistors (temperature sensitive resistors) mounted to the heatsinks, connected to a comparator system that activates when the heatsinks reach an unsafe operating temperature. The output of the comparator system is connected to a small transistor switch that turns off the input stage of the amplifier, which effectively shuts down the entire amplifier. When the heatsinks cool to a safe temperature, the amplifier is turned on again. The Soft Turn On/Off System cooperates with the Thermal Protection System by sensing the output of the high voltage power supply. At power up, when both the comparator and power supply have stabilized to normal operating levels, the Soft Turn On System activates the amplifier circuitry through the same transistor switch in the input stage. At power down, the system deactivates the amplifier rapidly before the power supply begins to collapse. This system eliminates spurious noises during the turn on/off cycle. The power supply utilizes a large El type transformer with dual multi-tapped primaries to allow alternate connections for world-wide voltage operation. Selection of the various voltage options is made via a simple multi-position plug inside the unit. The transformer feeds a conventional split full-wave bridge rectifier system. Power supply capacitance is 6800 UF per rail. [. . . ] This may be accomplished by sandwiching a thin sheet of insulating material (i. e. , plastic washers or several layers of electrical tape, etc. ) between the rack and the preamplifier, and securing the unit with non-metallic (i. e. , nylon, etc. ) hardware. It may be necessary to insulate other components so that only one component is directly connected to the rack rails. CLEANING/ MAINTENANCE If the faceplate should become soiled, it may be cleaned with a slightly damp, soft cloth and, if necessary, a mild detergent. Do not use any abrasive cleaners or solvents. Unplug the power cord before attempting any cleaning operations. [. . . ]