K2 (60-Hz models)

The power amplifier shall be a solid-state two-channel model employing BCA^TM (Balanced Current Amplifier^TM) output circuitry.

The outputs shall be switchable as stereo or bridged-mono modes of operation. The bridged-mono mode shall bridge the outputs to provide increased output voltage.

There shall be a "Y" input on the amplifier which will combine the two amplifier input signals by paralleling them together. When the "Y" input switch is turned on, a signal fed into either input channel will be fed to both outputs and the individual level controls of each channel will continue to work independently.

The output impedance of each channel shall be less than 10 milliohms in series with less than 2 microhenries in stereo mode.

The amplifier shall contain controlled slew-rate voltage circuitry to protect it against radio frequency interference burnouts. It shall also be protected from current overload at its output stage. The slew rate of the amplifier shall be greater than 30 volts per microsecond in stereo mode.

The amplifier shall temporarily go into a stand-by mode if its power transformer becomes excessively hot and shall automatically resume normal operation once it has cooled to a safe operating temperature.

Front-panel controls shall include an enable on/off switch and a detented input level control for each channel.

Rear-mounted controls shall include an Input Sensitivity switch for each channel to select between 1.4 V or a fixed voltage gain of 26 dB for full rated output, a Bridge Output switch to select whether Bridge Mono mode is on or off, and a "Y" Input switch to select whether "Y" Input mode is on or off.

Front panel indicators shall include a green Enable indicator to show the amplifier has power, an orange Clip indicator for each channel which shall turn on when distortion of any type becomes audible in the amplifier output, a yellow IOC indicator for each channel which shall turn on before distortion is audible (approximately 1/30^th the level that would trigger one of the Clip indicators) and a green Signal indicator for each channel which shall flash dimly when a low-level signal is present in the output, or flash brightly when a louder signal (at least 1 watt) is present at the output.

The power amplifier shall meet or exceed the following performance criteria. Input sensitivity for rated output: 26 dB voltage gain (unbalanced). Rated FTC output in stereo mode with less than 0.1% THD: 475 watts per channel (1 kHz) into 8 ohms. Hum and noise: at least 100 dB (A weighted) below full rated output power. Frequency response: 20 Hz to 20 kHz, 0.25 dB at 1 watt into 8 ohms per channel in stereo mode. Damping factor: greater than 3000 from 10 to 400 Hz into 8 ohms.

The amplifier shall be safe when driving any kind of load—even highly reactive ones.

The power requirements shall be 120 VAC at 60 Hz. At idle, the amplifier shall draw 90 watts or less.

The amplifier shall have a cast-aluminum front panel coated with powder coat. Front panel labels are to be printed in color on Lexan for durability. The chassis shall be aluminum with a durable black finish.

The dimensions of the amplifier shall allow for 19 inch (48.3 cm) EIA standard (RS-310-B) rack mounting. The amplifier shall be 3.5 inches (8.9 cm) tall and 16 inches (40.6 cm) deep behind the rack-mounting surface.

The amplifier shall weigh 38 pounds (17.3 kg) and shall have a center of gravity approximately 6 inches (15.2 cm) behind the front panel.

The amplifier shall be designated the Crown K2.