User manual ELECTRO-VOICE 729SR DATASHEET

[. . . ] All instructions concerning the handling of MOS - circuits have to be observed. Note: SAFETY COMPONENT (HAS TO BE REPLACED WITH ORIGINAL PART ONLY) 2 DESCRIPTION CONTENTS Description . 12 DESCRIPTION First of all, we would like to express our thanks and at the same time congratulate you on the decision to buy one of our Q-SERIES power amplifiers. ElectroVoice Q-SERIES amplifiers are made to meet the highest requirements of any on-the-road application. Thus they provide on-board protection against thermal and capacitive overload, short-circuit and the occurrence of HF or DC at the output. [. . . ] Thus they provide on-board protection against thermal and capacitive overload, short-circuit and the occurrence of HF or DC at the output. Additionally, special circuitry prevents the output-stage transistors from being damaged by Back-EMF. During soft start, delayed switching of the power outputs is accomplished via relays and a limiter controls the initial current inrush, preventing the mains fuse from being blown during the power-on operation. The mechanical construction as well is carried out following the highest precision standards of the industry. The robust steel chassis provides extreme rigidity and it is meant to live through any hard wearing condition of a touring application. Thermal stability is guaranteed by two 3-Mode silently running fans that offer the possibility to also use the amplifiers in a studio environment. The extensive comparator circuitry constantly monitors the input and output signals and activates the internal limiters whenever a non-linear operational state is encountered. This provides reliable protection of the connected loudspeaker systems against overload and clipping. Using comprehensive dimensioned power supply units with low-interference toroidal transformers gains a headroom that exceeds the nominal power handling capacity by far. No V/I-Foldback-Limiter circuits are employed within the power amplifiers, making it possible to operate the amps on complex loads up to ±90° phase angles without a problem. To eliminate unwanted noise and knacks in the connected speaker systems, loudspeaker output switching is performed delayed via relays. An initial current inrush limiter prevents the mains fuse from being blown during power-on. 4 REAR PANEL POWER AMPLIFIER INPUTS Parallel to the XLR-type inputs, XLR-type output connectors are provided, offering the opportunity to feed additional power amplifiers with the same signal. The inputs are electrically balanced with pin-assignment according to the IEC 268 standard. Pin-assignment of the XLR-type input connectors: PIN 1: PIN 2: PIN 3: SHIELD a, + b, - Input sensitivity is factory set to 0 dBu. LEVEL Potentiometers with a dB-scaling to adjust the overall amplification of the power am plifier. These controls should be set between 0 dB and ­6 dB, depending on the output of the connected equipment ­ e. The printed scale shows the actual amount of damping in the amplification of the power amplifier. INPUT ROUTING PARALLEL MONAURAL Setting the selector switch to the PARALLEL/MONO position puts the channel A and channel B inputs in electrically direct parallel configuration, leaving you still the possibility to control the channels' level settings separately, using the output controls A and B. DUAL STEREO When the selector switch is set to its DUAL/STEREO position both channels are amplified individually. 5 REAR PANEL Power Amplifier Outputs The power amplifier's channel A (left) and channel B (right) outputs are carried out as SPEAKON output connectors. The bridged-out connector conducting the output signal in bridged mode operation is protected by a plastic cover to avoid inadvertently plugging a speaker cable into the wrong connector. BRIDGED MODE When the bridged mode switch is engaged you will have to use the channel A input. The signal gets internally inverted and fed to the channel B power amp. The two amplifiers A+B are now used in push-pull operation providing the double output voltage at the BRIDGED-OUT connector. [. . . ] The bridged-out connector conducting the output signal in bridged mode operation is protected by a plastic cover to avoid inadvertently plugging a speaker cable into the wrong connector. BRIDGED MODE When the bridged mode switch is engaged you will have to use the channel A input. The signal gets internally inverted and fed to the channel B power amp. The two amplifiers A+B are now used in push-pull operation providing the double output voltage at the BRIDGED-OUT connector. The regular output voltages of the power amplifiers A and B are still present at the individual output connectors CHANNEL A and CHANNEL B but in respect to the inverted phase, using these signals is not recommendable. [. . . ]