Surround Control Room Module for 4-Channel LCRS Surround
The W761 is a control room unit for 4 channel surround audio systems and contains all the necessary controls and switch functions. Several controls make possible the cut of all the speaker systems, the selection of an alternate speaker system, phase and left - right reversal. A downmix matrix produces a stereo signal and an additional mono signal. A remoteable, adjustable dim control, a stereo headphone amplifier with separate volume control and a PFL switchover unit with separate level control complete the euqipment.
The Inputs of the device are balanced. The maximum level is + 30 dBu. The integration of an external surround decoder is possible. The selection of the control room format takes place by a set of 2 switches. If no switch is pressed the stereo mode is selected. The DECODER switch inserts the external surround decoder into the control room path. The input of the external decoder is fed from the L and R inputs of the device. In this way the output of the decoder can be easily compared to the 4 channel signal.
The center channel is mixed to the left and right front channel to form the stereo signal. The mixing level is determined by internal jumper setting. Both the surround channels are added to their corresponding front channels. The surround channel is mixed to stereo left and stereo right with a default level of - 6 dB. This level can also be changed by internal jumpers. Mono is produced by adding the stereo output of the downmix matrix with a jumper selectable level of -3 or -6 dB.
The L-R switch reverses left and right. The phase reversal affects the right channel and is only active if Stereo mode is selected.
A balance control give the choice to modify the center of the control room stereo base and to cut off the left or right channel if the control is set all to the right or vise versa.
The volume control is implemented by acalibrated rotary control. The overall gain of the device in 5.1 mode without using any matrix function is 0 dB for a volume of 92 dB. A cut switch mutes all the speakers. ALT switches to an alternate speaker system that is always a stereo system. If Alt is activated stereo mode is automatically selected.
The integrated headphone amplifier operates always in stereo mode is well suited for any existing headphone. A separate level control for the headphone is implemented. The headphone is connected by a standard phone jack on the top plate.
The selection of the PFL signal, (which has a separate input), is done either via the PFL switch or via a control signal, which is controlled by an opto coupler. A potentiometer controls the volume of the PFL signal. In the case of using the module as a source select, automatic controller, any other audio signal can be applied in place of a PFL signal. The DIM circuit is adjustable by a potentiometer between 10 and 30dB. Also here the release can take place either the DIM key or by a control signal. An opto coupler also electrically isolates this signal; both control signals operate within the range of between 9 volts to approx. 30 volts.
The unit is a standard V700 cassette that fits into standard frames. To use all inputs and outputs a special addional wiring is needed.