JVC RM-HP700DU Intercom Interfacing

The intercom interface on the JVC RM-HP790DU camera control unit is designed to interface with balanced or unbalanced intercom systems. The unit ships set for unbalanced intercom such as Clearcom or RTS. For typical studio applications the listen level for the camera operators is sufficient, however in loud applications such as Rock & Roll, sporting events, religious events with loud singing, or other similar events, there may be difficulty hearing from the camera headset.For some cases, a resistor change in the intercom circuit of the RM-HP790DU will increase the level and also adjusting VR-304 (see figure 1) in the clockwise direction has been successful in satisfying many customers.In some cases, especially if more than three RM-HP790DU units are combined, it may be necessary to install an interface unit to convert the unbalanced 2-wire intercom to 4-wire to connect as described below, or run com-boxes directly to the cameras.For Clearcom systems, the IF4W4 will give you nearly the same level as a Clearcom belt pack. Before installing the JVC RM-HP790DU CCU’s, VR-304 (see figure 1) will need to be adjusted. In most cases the potentiometer can be turned fully clockwise. When installing the Clearcom IF4W4, it is recommended that it be kept away from the JVC RM-HP790DU CCU’s or other equipment that can introduce hum in the intercom system. The 4-wire output of the IF4W4 will need to be fed into the JVC RM-HP790DU through the 5 pin headset connection on the front of one of the CCU’s. A cable will need to be made to go from the Clearcom IF4W4 to the RM-HP790DU (see figure 2). The connector on the Clearcom IF4W4 is a 5 pole Eurostyle terminal connector and the JVC RM-HP790DU headset connector is a female 5 pin XLR so a male 5 pin XLR connector will be needed. A standard 3 pin XLR cable will be needed to connect from the Clearcom master station to the Clearcom IF4W4. On the JVC RM-HP790DU CCU’s the intercom terminal block on the back of the CCU’s will need jumper wires connecting the “G”, “C”, & “H” connections together. Once the system is installed, the Clearcom IF4W4 will need to be adjusted according to the manual provided with it. I found that the 4-wire transmit switch worked best in the -20 dB position. A headset with a four pin female connector is needed to do this. Since the JVC cameras use headsets with 5 pin male connectors, you may need to make an adapter or temporarily swap one connector. (See figure 2 for headset pin out) Once the system is nulled out, the Clearcom IF4W4 has individual in & out levels. Note: the headphone level on the JVC RM-HP790DU and the “in” level on the Clearcom IF4W4 are additive for the level going back into the Clearcom system from the cameras.RTS and Audiocom systems can be setup the same way as Clearcom systems using the Clearcom IF4W4. With Audiocom systems you will want to set it to the unbalanced mode (button on back of the power supply). Attempts with the RTS SSA-324 did not produce as good of results as the Clearcom IF4W4.