User manual HAFLER SERIES 9303

[. . . ] 9303 / 9505 Installation & Operation ® ® an tr va no s USA IN T E HE MAD PROFESSIONAL POWER AMPLIFIER AMPL NOTICE - IMPORTANT SAFETY INFORMATION CAUTION RISK OF ELECTRIC SHOCK DO NOT OPEN !! 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 product's 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. Furthermore, extension cords or power strips must provide the same three wire grounded connection. [. . . ] Make sure the BALANCED/UNBALANCED switch is set for UNBALANCED operation. Unbalanced Source with Balanced Input Better noise rejection for long cable runs can be achieved by using a twisted pair balanced cable from the unbalanced source. At the source end of the cable, connect an RCA plug with the return (­) wire and shield connected to the ground shell of the plug. Wire the plug at the amplifier end of the cable the same as for the regular balanced input connection. OUTPUT CONNECTIONS The speaker output connectors are dual binding posts. These binding posts will directly accept 12 AWG wire or banana plugs and are spaced on 3/4" centers to accept dual banana plugs. MONOPHONIC USE For systems with high power requirements, the amplifiers can be configured for single channel bridged mono operation. To bridge the amplifier, set the rear panel STEREO/MONO switch to the Mono position; use only the left channel input, and connect the speaker to the red output binding posts. Any speaker which requires a common ground from the amplifier output cannot be used in this application. Since a bridged amplifier shares the load between the two channels, the amplifier will effectively drive half of the load. Therefore, for bridged mono operation we recommend using an eight ohm load as the minimum impedance. ­2­ OPERATION POWER SWITCH The POWER switch is located on the front panel of the amplifier. Standard practice is to turn the amplifier on last and off first when switching components individually to prevent sending damaging transients, generated in the source components, to the speakers. It is possible to leave the power switch in the on position and switch the amplifier remotely through a power distribution block or preamp switched outlet. When doing so make sure the switch is rated for the current required by the amplifier. BALANCED/UNBALANCED INPUT SWITCH The BALANCED/UNBALANCED switch configures the input grounding when using the RCA phono input jacks. In the UNBALANCED position the balanced differential input return (­) port is grounded inside the amplifier. This prevents noise pickup or unstable amplifier operation caused by the open input. In the BALANCED position the differential amplifier inputs are connected to the hot (+) and (­) incoming signal connectors. GROUND SWITCH Ground loops are characterized by a hum or buzz in the system and are caused by a voltage potential difference between two points in a ground circuit. Ground loops are aggravated when multiple paths exist for a given circuit. Mounting components in a rack with metal rails may introduce ground loops between associated equipment, because the rails can establish an additional ground path. The CHASSIS/FLOAT switch allows you to select the amplifier grounding scheme for best system compatibility. [. . . ] The transformer has a separate secondary for each channel high voltage power supply, each feeding a conventional split full wave bridge rectifier. High voltage power supply capacitance is 20, 000µF per rail for each channel for the 9505 and 5, 000 for the 9303. The third transformer secondary feeds a regulated supply for the input stage and driver circuitry. Low voltage power supply capacitance is 1, 000µF per rail, with additional decoupling for each channel. [. . . ]