User manual ELECTRO-VOICE 729SR DATASHEET

[. . . ] Use of a mains separator transformer is mandatory during maintenance while the appliance is opened, needs to be operated and is connected to the mains 3. Switch off the power before retrofitting any extensions, changing the mains voltage or th e output voltage. The minimum distance between parts carrying mains voltage and any accessible metal piece (metal enclosure), respectively between the mains poles has to be 3 mm and needs to be minded at all times. The minimum distance between parts carrying mains voltage and any switches or breakers that are not connected to the mains (secondary parts) has to be 6 mm and needs to be minded at all times. [. . . ] 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. 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. The sound quality of the Q-SERIES power amplifiers is superb. POWER ON INDICATOR This LED lights when the appliance's power switch has been engaged. If the indicator does not light after you have engaged the power switch, either the amplifier is not connected to the mains or the internal mains fuse is blown and has to be replaced. 5. POWER SWITCH Using the POWER switch you turn the amplifiers power on. 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. [. . . ] Bridged mode operation on loads of 2 ohms is not admissible. GROUND-LIFT SWITCH The ground-lift switch is meant to help you in avoiding ground noise loops. Whenever the power amplifier is installed in a 19" rack system being operated together with other equipment, the recom mended setting of the switch is the GROUNDED position. In case the power amplifier is used together with appliances that are connected to different ground potentials, the recommended setting is UNGROUNDED. 6 SPECIFICATIONS Technical Specifications: Q44, Q66 Amplifier at rated conditions, both channels driven with 8 ohms loads, unless otherwise specified. Q44 Load Impedance M aximum Midband Output Power THD=1%, 1kHz Rated Output Power THD< 0. 2%, 20Hz . . . [. . . ]