Control Room Unit with Downmix Matrix for 5.1 Surround
While the surround controller system Director covers every aspects and includes all the functions that are needed for the handling von 5.1 surround signals, the W762 is a device that contains the most important functions for a 5.1 control room section. Several controls make possible the cut of all the speaker systems, the selection of an alternate speaker system and phase and left - right reversal. A downmix matrix which can be switched to the common parameters by two stepper switches produces a stereo signal, a 4-channel surround signal and an additional mono signal. Independend cut switches for each of the 6 channels allow the controlling of any combination of channels. A remoteable, adjustable dim control and a PFL switchover unit with a separate level control complete the equipment.
The inputs of the device are balanced. The maximum level is + 30 dBu. The downmix matrix produces besides the stereo and mono signal an additional 4 channel surround signal for encoder/decoder technique. The integration of an external surround decoder is possible. The selection of the control room format takes place by a set of 4 switches. If no switch is pressed the 5.1 format is active. The 4CH switch selects the 4 channel downmix matrix output while the SRD-DEC 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 matrix output and the original 5.1 signal. The 4 channel matrix combines both the surround channel to a mono surround channel and adds the LFE after passing a 80 Hz low pass filter to all the front channels L, C and R. The level can be internally adjusted.
The center channel is mixed to the left and right front channel to form the stereo signal. The mixing level is determined by the setting of the C-LR stepper switch and can be 0, -3, -4.5 or -6 dB. Both the surround channels are added to their corresponding front channels. The stepper switch S-F determines the level, which can be set to 0, -3 or -6 dB. The 4th position of the switch disables the surround channels. The Stereo switch selects the output of this matrix and automatically cuts all the other channels. Mono is produced by adding the stereo output of the downmix matrix with a jumper selectable level of -3 or -6 dB.
All channels can be separately muted by independent switches. This makes it possible to listen to single channels as well to any group of channels. The L-R switch reverses front left and right and surround left and right as well. The phase reversal affects the right channel and is only active if Stereo mode is selected.
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 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.