User manual ALTEC LANSING 6125A POWER AMPLIFIER

[. . . ] 6125A 4200A Multi-channel power amplifiers Professional Altec Lansing Professional 1000 W. Suite 362 Oklahoma City, OK 73116 USA A division of Altec Lansing Technologies Inc, Milford PA 18337-0277 Made In USA Operating Manual 6125A and 4200A Multi-Channel Power Amplifier Table Of Contents 1 2 3 INTRODUCTION . 5 5 5 5 5 6 7 FRONT PANEL FEATURES . 7. 7 Dual Channel Mode/Bridge Mode Switches . [. . . ] The speaker is then connected across the (+) output connections of each channel, resulting in twice the power to the speaker that either channel could deliver by itself. Since in Bridge Mode both connections have voltage present, never connect or touch either speaker wire to ground. The 6125A is capable of three channels of bridged output (two channels on the 4200A). To use bridged mode, first press MONO from the Stereo/Mono switch on the channel pair to be bridged. This sends the same audio signal to both channels. Then press BRIDGE from the Dual/Bridge switch on the channel pair to be bridged. This inverts the phase of the input signal to the second channel. These two channels are now operating together in Bridged Mono mode, and the output must be taken from the two (+) terminals of the corresponding bridged channel pair 7. 8 Loudspeaker Output Connectors Three terminal blocks (two on the 4200A) provide connections for the speaker outputs. In BRIDGE mode, the channel 1, 3, or 5 (+) connection is the Bridged (+) speaker output terminal, and the channel 2, 4, or 6 (+) connection is the Bridged (-) speaker output. NEVER CONNECT THE TWO BRIDGED OUTPUTS TOGETHER OR CONNECT EITHER BRIDGED OUTPUT TO GROUND. 7. 6 Stereo/Mono Switch The 6125A is comprised of three stereo amplifiers (two on the 4200A), each operating independently of the others, with Stereo/Mono switching available for each channel pair. If this switch is set to Stereo mode, the channel pair operates as two discrete amplifiers, each with its own input connection and level control. Switching to Mono mode allows one input (channel 1, 3, or 5) to drive both channels of a stereo channel pair. Pressing the Mono switch disables the channel pair's 8 Operating Manual 6125A and 4200A Multi-Channel Power Amplifier Model 6125A shown. Model 4200A has only four channels. Outputs 7. 9 AC Inlet The 6125A and 4200A amplifiers can be configured by the customer for operation at either 115VAC or 230VAC mains. Switching from one to the other simply requires the following steps: 1. ) Unplug the amplifier from the wall and remove the power cord from the rear of the amplifier. 2. ) Using a small screwdriver as a lever, unlatch the fuse holder in the AC inlet and remove it. 3. ) Remove the voltage selection insert and rotate until the new nominal mains voltage level indication (115 or 230) is on top and properly oriented for reading. 4. ) Replace the voltage selection insert in the AC inlet, making sure that it is plugged in all the way. 5. ) Replace the fuse with the appropriate size (see #6 below), and press the fuseholder back into the AC inlet until it latches. 6. ) Using a power cord of the appropriate size and with the appropriate terminations, plug the cord into the rear of the amplifier and then into the wall. The amplifier is now ready for use at the new mains voltage. If the mains voltage is 110-125VAC, the required fuse is MDA 12, 250V, and the required power cord is 3wire grounded, 13 Amp (16AWG) minimum. If the mains voltage is 220-250VAC, the required fuse is MDA 10, 250V, and the required power cord is 3wire grounded, 10 Amp (18AWG) minimum. [. . . ] Turn down the input level control, or reduce the output level from the signal source. 2. ) Clip LED is not flashing at all Amplifier input signal may be exceeding input headroom, which is greater than +12dBu, or 3. 4V rms (measured using continuous 1kHz sine wave). Incoming signal level higher than +12. 8 dBu will cause distortion in the amplifier. Turning down the input level controls will not eliminate distortion if the input headroom is exceeded. [. . . ]