User manual JEFF ROWLAND 302

[. . . ] Dual Speaker Output Terminals on each channel for bi-wiring applications. User selectable switching between balanced and unbalanced connections. Transformer coupled inputs provide universal compatibility with other components and eliminate ground loop noise and EMI. !! Ultra-high efficiency output section generates high power output with very little heat. [. . . ] The front panel of the unit should never be cleaned with anything other than a very soft cotton cloth and plain water or fine oil-based furniture polish. Because of the fine finish of the front panel, small scratches from the use of any other agent to clean the front panel will become very visible. If you have any questions about the care or cleaning of your Model 302 amplifier, please contact your dealer or the Jeff Rowland Design Group factory before attempting to clean the chassis. The use of a cleanser or abrasive to clean the chassis that has not been approved by the factory will almost certainly damage the finish and will not be covered under warranty. Protection Systems The Model 302 Stereo Power Amplifier is equipped with active circuitry and thermal circuit breakers for protection against excessive AC mains voltage. However, since no protection circuitry or system can completely protect a product from every electrical hazard, certain precautions should be observed. In the event of severe voltage hazards such as lightning or when the amplifier will not be used for extended periods of time, the amplifier should be unplugged from the AC mains to avoid potential damage to the internal circuitry. All other audio/video system components should also be disconnected from AC mains power as hazardous voltages can travel throughout an interconnected system. 11 Amplifier Installation, Use, and Care Locate the amplifier as close as possible to its final installation point. The Model 302 Stereo Power Amplifier is extremely efficient and convection cooled, eliminating the need for fans or forced-air cooling. Multiple chassis can be stacked vertically, facilitating an upward flow of warm air currents throughout the vertical heatsink areas. This upward flow must not be blocked or recirculated around the chassis if proper cooling is to be maintained. Typical installations allow the amplifier to be rigidly coupled to a support structure or floor via optional spiked coupling supports that are available separately from JRDG. In carpeted installations, these supports provide excellent anchoring from the amplifier chassis to the rigid floor or sub-floor below. If there is concern about damage to the structure or floor's finish, a coin can be placed beneath each spiked coupling support. In installations where the resonant properties of the supporting structure are poor or unknown, the amplifier chassis can be loosely coupled to the supporting structure via the supplied compliant isolation interface pads. This will help to attenuate the transfer of vibration or resonant energy from the support structure to the amplifier chassis. The output terminals or loudspeaker cables should never be shorted to each other or to ground. The Model 302 is designed to perform optimally with no adjustments or maintenance. In the event of servicing, do not attempt to open the top cover of the amplifier and refer all service issues to qualified personnel. The voltages inside the Model 302 can be hazardous. 13 Amplifier Front Panel Functions and Indicators Front Panel Power/Standby Button Front Panel Power/Standby Indicator 14 Amplifier Front Panel Functions and Indicators Before attempting any system interconnection, please familiarize yourself with the front panel control of the Model 302 Stereo Power Amplifier. The descriptions below refer to the illustration on the adjacent page. FRONT PANEL STANDBY/POWER BUTTON: Press this button to operate the amplifier. FRONT PANEL STANDBY/POWER INDICATOR: This small, blue light will illuminate when the amplifier is operational. When the light is not illuminated, all amplifier inputs are muted and internal circuitry reverts to power-saving (Standby) mode. [. . . ] Therefore, this amplifier cannot be used in certain loudspeaker switching configurations, such as those used in retail demonstrations. Failure to avoid these precautions may short the outputs to ground and can result in damage to the amplifier and will void the warranty. 19 Internal Adjustments Overall Gain The overall gain of the Model 302 Stereo Power Amplifier can be adjusted between 26 dB and 32 dB. The setting from the factory is 26 dB, which is adequate for the majority of applications, though some systems involving low efficiency loudspeakers may require the higher gain setting. Because of the potentially dangerous voltages inside of the chassis, it is recommended that you contact your dealer for information regarding the overall gain setting adjustments. Note: Do not attempt to disassemble the chassis of the amplifier and adjust the gain without explicit instructions from your dealer or Jeff Rowland Design Group. 20 Model 302 Stereo Power Amplifier Specifications Output Power: Continuous RMS watts, both channels driven @ 8 ohms @ 4 ohms Power Bandwidth: Peak Output Current: Dynamic Range: THD + Noise, 0. 1W-500W/4 ohm: CCIF Intermodulation Distortion, 19/20 kHz: Damping Factor @ 1kHz: Overall Gain: (Balanced or Unbalanced) Input Impedance: Common Mode Rejection Ratio: Absolute Phase: Inputs: 300 watts. [. . . ]