User manual ELECTRO-VOICE 655C DATASHEET

[. . . ] Do not block any of the ventilation openings. Install in accordance with the manufactures instructions. Do not install near any heat sources such as radiators, heat registers, stoves, or other apparatus that produce heat. Only use attachments/accessories specified by the manufacturer. [. . . ] Since, during operation, the temperature inside the rack system could easily rise up to 40° C, the maximum allowable ambient temperatures of the rest of the incorporated modules and appliances within a specific rack-shelf system have to be taken into careful consideration. When mounting the power amplifier inside of a closed rack system, it is recommended to use special rack-rails or optionally available rack-mount ears NRS 90235 (112733) to prevent bending of the appliance's front panel. Note For maintained trouble-free operation of the appliance, the maximum admissible ambient temperature of +40°C is not to be exceeded. The amplifier has to be protected from: - water drops or splashes - direct sunlight - high ambient temperatures and the direct radiation of heat sources - high humidity and moisture - heavy dust - massive vibrations Moving the amplifier from a cold into a warm environment can result in the occurrence of condensation on inner parts. Operating the appliance is only permissible after it has accommodated to the altered temperature (approximately after one hour). Should any foreign solid parts or liquids inadvertently intrude the enclosure, immediately unplug the device from the power source and have it checked at a DYNACORD service center, before further use. Cleaning the appliance should not be performed using chemical solvents or sprays, as this might damage the finish and could even cause hazard fire. Before The First Operation Before switching the amplifier's power on, the included mains cord has to be connected to a 230 V - 50/60 Hz wall outlet. On the appliance itself, the cord has to be connected to the 3-pole mains socket. To remotely start the amplifier, it is necessary to connect an external 24 V power source to the terminal strip POWER REMOTE. Providing correct connection and with an external power supply being present, the POWER ON indicator will light and the power amplifier is ready for operation. The mains switch POWER on the rear of the appliance is meant for service and maintenance purposes only. Through bridging the mains switching relay this option provides the possibility to operate the amplifier without an external 24 V power supply connected. Caution The mains switch POWER on the rear of the appliance is only meant for maintenance. Remotely switching off the device is not possible when the POWER switch is engaged. The total impedance of the loudspeaker line has not to decline 20 ohms*2 = 40 ohms. figure: example configuration ­ DPA 4260 channel A in mixed mode 22 Bridged Mode Doubling the power amplifier's output power is accomplished by engaging bridged mode operation, where the two power amplifier output stages are linked for push-pull operation. In other words, a monaural power amplifier is "created" offering double the output voltage and double the output power capacity of a single channel. As a result you are provided with floating 50 V, 140 V, and 200 V as well as with a direct output with doubled nominal output voltage. If the BRIDGED-MODE switch is engaged, the audio input signal has to be fed via the CHANNEL A input while the CHANNEL B input is without function. The signal is internally inverted and the power amplifier stage B is driven by that inverted signal. The power amplifier stage A is still driven by the unaltered incoming audio signal. Bridged mode operation is possible with using the isolated and/or the direct outputs. When using the isolated outputs, bridging the (­) binding posts of channels A and B is mandatory, using short cables with suitable diameter (1. 5 mm2 . . . Careful consideration of the loudspeaker systems' correct connection is important in preventing phase correlation problems. Channel A carries the signal "in phase" and therefore has to be connected to the (+)-pole of the correspondent loudspeaker system while the loudspeakers (­)-pole has to be connected to the (+)-output connector of channel B. The output voltage of each power amplifier stage A&B is present at the binding post strip, but utilization is not recommended because of the negative correlation. figure: output connection in 50 V bridged mode operation *Caution! [. . . ] In PROTECT mode all loudspeaker lines and output transformers are disconnected via relays and the power amplifier's audio inputs are short-circuited to prevent the connected loudspeaker systems from being damaged. When the power amplifier enters the PROTECT mode please examine first whether the appliance is overheated. If this is the case, the front and rear ventilation louvres are possibly covered, the nominal load impedance has fallen below the specified minimum value, or a short-circuit occurred at the power output. When switching the power amplifier on, the PROTECT-LED lights for approximately 2 seconds. [. . . ]