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Manafacture: Altec Lansing File size: 1.73 mb File name: Language of manual:

This makes it easy to properly adjust the gain for each input module while efficiently using the rest of the system in terms of performance and headroom. Figure 7. Block Diagram of 1707C/1715C Mixer/Power Amplifiers The mixer/power amplifier then sums the signal at the wiper of each input channel level control into a true virtual ground summing node or bus. The summing amplifier has eight input channels — input channels one through six on the front panel, tone generator output, and the link input or LINK IN on the rear panel. The summing amplifier’s output signal drives the link output, or LINK OUT, located on the rear panel of the mainframe. The E.Q. and compressor/limiter sections are in series with each other, as shown in Figure 7. The compressor/limiter s output signal drives the preamplifier output, or PREAMP OUT, located on the rear panel which then provides the input signal to the main amplifier section. The BASS and TREBLE E.Q. controls are ideally suited to make adjustments to the overall response of the mix. The low and high frequency shelving equalizers provide *12 dB of boost and cut with the maximum boost occurring at 100 Hz and 10kHz, respectively. The compressor/limiter section features variable release time, compression ratio, and threshold. The circuit uses a feed-forward topology that will minimize level differences for a more nearly constant output level. The compression ratio can approach o=:1, and the attack time is fixed at approximately 10 ms. The main amplifier section protects itself and the load against radio frequency interference, spurious oscillatory waveforms, excessive temperatures, direct current, turn-on/turn-off transients, and excess voltage/current phase shift due to reactive loading. A signal overload circuit monitors the level at the output stage of the amplifier section. The front-panel CLIP LED indicator illuminates 7 when signal levels are high enough to cause significant output clipping. A dual slope V-l limiter protects the output devices. It keeps the output devices operating within their SOA (safe operating area) as defined by the device manufacturer. A special integrated circuit function block monitors the heatsink temperature, power-supply voltage, and the amplifier’s output When it detects a problem, it immediately disengages the output relay. Output Connections Make output connections to the seven-ter-minal barrier strip connector located on the lower-left side of the mainframe’s rear panel. The 1707C main output connections include an 8 Q direct output (24.5 vrms) and three transformer balanced outputs; 4 O (17.4 vrms), 25 vrms (8.3 Q), and 70.7 vrms (66.6 Q). The 1715C main output connections include a 4 £2 direct output (24.5 vrms) and a 25 vrms (4.2 Q), an 8 Q (34.6 vrms), and a 70.7 vrms (33.3 Q ) balanced transformer output. Refer to Figure 8 for a display of the direct output connections and Figure 9 to see the transformer output connections. ОТ an 70V 2SV 4Л COM IN + - t yy Figure 8. Direct Output Connections ОТ 8Л 70V 25V 4П COM IN 4- — T [ • 1 l._j Insert shorting С yy the unit. If the fuse continues to blow, check the load to see if it shorted or is exceeding the rated power consumption. If the problem continues, have a qualified service technician service the unit. Mute/Tone Generator Connections The seven-lug screw terminal connector located on the mid-left rear of the mainframe provides access to the system mute and tone generator. For connection details, refer to Figure 10. Table III. Maximum Allowable Cable Resistances MUTE S/T BUZZER COM COM R/T YELP О о о о о о о ******* Function Resistance О S/T Chime 13 кО R/T Chime 15.8 кО Buzzer 8 кО Yelp 8 кО Mute 8 кО External SPST switches (not included with mainframe) Figure 10. Mute/Tone Generator Switch Connections A switch closure between the mute and common (COM) terminals will mute any input modules configured in the slave mode. You can use the remaining switches to select one of the following sounds: A single-tone chime (S/T), A repeating-tone chime (R/T), A buzzer, or A yelp (siren). For the duration of a tone, the tone generator automatically mutes any input modules configured in the slave mode. Output-Level Control: The tone generator's output-level control is conveniently located on the rear panel of the mainframe. To increase the tone generator’s output level, rotate the screwdriver-slotted control shaft clockwise. LINK IN/LINK OUT Connections The LINK IN/LINK OUT phono connectors on the mid-rear panel of the mainframe permit you to dynamically link two or more systems together. If you require more channels, the 1707C/1715C mixer/power amplifiers are fully compatible with 1700C mixer/preamplifier. For more information on the 1700C mixer/ preamplifier, you may order the operating instruction manual (P/N 42-02-029241) or the specification sheet (P/N 42-07-029242) from our Order Entry Department. The signal appearing at the LINK OUT c...

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