User manual DOD FX747

[. . . ] For units equipped with externally accessible fuse receptacle: Replace fuse with same type and rating only. U. K. Mains Plug Warning A molded mains plug that has been cut off from the cord is unsafe. Discard the mains plug at a suitable facility. Never under any circumstances should you insert a damaged or cut mains plug into a 13 amp power socket. [. . . ] Severe injury or death can then result if the chassis and earth ground are touched simultaneously. SR Crossover SR823 / SR834 INTRODUCTION The DOD SR834 is a stereo 3-way, mono 4-way crossover, and the SR823 is a stereo 2-way, mono 3-way crossover. These high-quality crossover networks are designed to extract maximum sound quality from your multiamped sound system at a price working musicians can afford. Accurate 24dB/octave Linkwitz-Riley state-variable filters prevent peaks or dips in the output at crossover points, ensuring good driver protection by rolling off crossover frequencies rapidly. A 4-pole, 24dB/Octave Butterworth filter may be electronically inserted at 40 Hz using a switch on the front panel (834 only), and a variable low frequency summed output is available for mono subwoofer applications. The rear panel of the SR834/SR823 is clearly labeled for stereo and mono operation, and all outputs on the SR834 except the mono Low Frequency Sum output include phase switches. ADVANTAGES OF A MULTIPLE AMPLIFIER SYSTEM Multi-amped systems use separate amplifiers for each frequency band, allowing each amplifier to deliver maximum efficiency within a specified range. This method of amplification yields a cleaner overall sound and a significant decrease in the amount of power needed to drive the system to the same levels as a full-range amplified system with more power. The greatest power demands in a sound system are made by the low frequencies of the program material. This is because music and voice signals contain mostly low frequency information, and low frequency drivers are generally less efficient than high frequency transducers. In a multi-amped system, the power amplifier(s) for the low frequencies can be large enough to handle greater power demands, allowing high frequency power amplifiers to be much smaller, yet adequate to handle the demands of the high frequency content of the program material. Since each element of the system is driven by its own amplifier, any distortion that occurs is limited to the frequencies of the overdriving power amplifier. SR834: Set the LOW/MID crossover frequency for each channel according to the front panel markings. If below 180Hz is desired, press the ÷10 switch** on the rear panel. If the desired frequency is below 180 Hz, the ÷10 switch must be engaged (LED indicator lit). If the desired frequency is above 180 Hz, the Range switch must be disengaged (LED indicator off). When the ÷10 switch is engaged, the frequencies marked around the LOW/MID (LOW/HIGH for SR823) frequency control are divided by 10. In other words, if the LOW/MID (LOW/HIGH for SR823) frequency is set at 250Hz and the range switch is engaged, the actual crossover frequency is 25Hz. SR834: Set the MID/HIGH crossover frequency. The Channel 2 MID/HIGH frequency control has two sets of markings. When using the crossover in stereo mode, use the lower frequency markings to set the MID/HIGH crossover point. This frequency control has no range switch. WARNING: BEFORE PRESSING THE ÷10, LF SUM OR STEREO/MONO SWITCHES, LOWER THE OUTPUTS OF YOUR POWER AMPLIFIERS TO AVOID DAMAGE TO DRIVERS AND LOUDSPEAKERS. 4 SR Crossover · Connect the outputs of the crossover to the appropriate amplifiers. [. . . ] These transients can damage power amplifiers, speakers, and drivers. STEREO OPERATION USING A MONO SUBWOOFER This mode of operation provides: SR834: Channel 1 and Channel 2 high frequency outputs, Channel 1 and Channel 2 mid frequency outputs, and one summed low frequency output. SR823: Channels 1 and 2 high frequency outputs and one summed low frequency output. The setup procedure is the same as for the stereo mode, except that, instead of connecting both low frequency outputs, connect only the Low Frequency Sum output to the low frequency amplifier. [. . . ]