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. [. . . ] At turn-off, this same system rapidly deactivates the amplifier's circuitry before the power supply begins to collapse, again eliminating any spurious noises. THERMAL PROTECTION SYSTEM The 9130 Amplifier is equipped with a Thermal Protection System that constantly monitors the temperature of the heatsinks. When the heatsink temperature reaches a pre-determined level, the amplifier's circuitry is electronically shut down through the same system that provides the Soft TurnOn function. When the heatsinks cool to a safe operating temperature, normal operation of the amplifier resumes. -8- CIRCUIT HIGHLIGHTS The 9130 employs a single ended, current source driven, differential input stage. This stage is connected to the rest of the circuitry through a balanced push-pull current mirror system. A combination current mirror and bias multiplier drive the final output stage driver emitter followers. 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. [. . . ] Therefore, this method of ground isolation should be employed only when absolutely necessary, rather than as a general practice. When using a ground adaptor for isolation, make sure that the power cord plug is inserted into the receptacle in the same orientation as if no adaptor were present, to maintain the same hot/neutral polarity. -ll- SPECIAL NOTE ON VIDEO CABLE "GROUNDS": As mentioned above, the ground conductor of cable service and antenna feeds should be connected to earth ground. Often, however, due to long feed lengths, especially in apartment distribution systems, this ground will be of poor quality and could be a source of noise. This interference is usually characterized by a high frequency noise, rather than a hum or a buzz. [. . . ]