User manual ELECTRO-VOICE 624 DATASHEET

[. . . ] these protections include Dynamic Audio Limiters , Inrush Current Limiter , Short Circuit Protection and Thermal Overload Protection. All PA-Series power amps feature different hi-pass filters with switch selectable cut-off frequency to attenuate unwanted low-frequency signals. Infinitely variable low-noise high performance fans guarantee absolute thermal stability while keeping fan noise to a minimum. Direct ow-thru chassis design allows for a smooth ow of air from front-to-rear, which allows trouble-free operation even in smaller amp-racks. [. . . ] If this is not possible, please use mounting-rails instead. The power amplifier has to be protected against: moisture (dripping or splashing water), direct sunlight, high temperatures or the direct in uence of heat sources, high humidity, extensive dust and vibrations. Condensation on internal parts may occur after transporting the power amplifier from a cold into a warmer environment. In that case operation is only permissible after the appliance has gained the new temperature (after approximately one hour). If ob ects or liquids have intruded the power amp s enclosure, disconnectthe appliance from the mains immediately and contact an authorised service center for inspection before continuing to operate the unit. Do not use any sprays or solvents for cleaning the appliance, because they might severely damage the surface of the enclosure or lead to dangerous fire ha ard. Mains Switch Use the mains switch to switch the unit s power on. A soft-start function prevents inrush current peaks on the mains, additionally preventing the mains line protection switch from activating during the amp s power-on operation. Loudspeaker outputs are activated via relay switching with a delay of approx. 2 seconds, which effectively eliminates eventual power-on noise. During this delay period, the Protect LED lights to confirm correct operation of the protection circuitry. BDGD: Audio signals need to be fed to channel A (or C) when in Bridged Mode. Power amps A and B (or C and D) now work in push-pull operation delivering doubled output voltage. You can choose from three cut-off frequency settings: Power Amps with low impedance outputs Power Amps with output transformer 00H 50H , 12dB , 12dB Oct. As a basic principle, all models with output transformer have a 50H Hi-Pass filter in the audio signal path to protect the transformer from being driven into saturation by high level low-frequency signals. Loudspeaker Outputs The speaker output acks are suitable for connecting speaker cables with a maximum diameter of 2. The provided screwlock connectors can be screwed to the power amp to prevent inadvertent disconnection. Power amps offer low impedance outputs and or oating outputs (ISOLATED OUTPUTS) with nominal voltages of 50V, 0V and 100V, depending on the amp model. Caution: The symbol of a FLASH at the loudspeaker connectors indicates that these outputs may carry high voltages which, when getting in contact with, can cause serious harm. Establishing connections at these outputs is only permissible for persons who have been instructed on how to do so. For bridged operation, the load has to be connected according to the BRIDGEDlabel and the Mode switch needs to be set to Bridged . Please, make sure to keep in mind that in Bridged Mode the minimal impedance is ohms and that the input audio signal has to be fed to channel A (or C). [. . . ] Although connecting unbalanced cables to the power amplifier inputs is possible as well, using balanced cables is always preferable. A great number of today s audio appliances provide balanced outputs carried out via XLR-type connectors. With balanced cabling, the shield interconnects all metal enclosure parts and therefore efficiently eliminates the introduction of external interference mostly noise and hum. Mains Operation The following tables provide a useful aid in determining power supply and cabling requirements. [. . . ]