V700 Stem Mixing

The M769 is a stem mixing stereo input module for surround consoles. The elliptic EQ is used to reduce the base width at low frequencies and improve the mono compatibilityThe module has a balanced stereo line input with input gain control and can be used as stereo subgroup master alternatively.

The stereo to surround input module is almost identical to the M768 stereo input module; however, the panorama section of the M769 is implemented as surround balance control.

Input Section
The module has one electronically balanced stereo input that can process input levels of + 30 dBu. A stereo pair of subgroups can be used as input signal alternatively. The groups are assigned by internal jumpers. The input selection takes place by a lever switch. The selected input or group set respectively, feeds the input gain control with a standard control range of +/- 10 dB. The gain control has a precisely calibrated 0 dB center detent.

Insert
The balanced and buffered stereo insert point is located post input gain and pre fader. The insert output is always available on the connector panel and the insert input is switch into the signal chain by the INS switch. Insert input and output are electronically balanced and can process levels of + 30 dBu.

Fader, PFL, Solo, Cut, Meter
The fader is a conductive plastic stereo audio fader with 100 mm stroke that drives an ultra low noise, wide band stereo buffer amplifier that compensates the insertion loss of 10 dB. 12 dB versions are also available.

The CUT circuit that mutes the entire channel is post fader, post buffer amplifier.

The PFL system only affects the monitor system and can be used during the mix. The fader input signal is routed to the PFL mix bus.

The solo system operates independent of PFL as Solo in Place. The SAFE switch allows to prevent Solo for the channel when pressed. All channels that are not either in Solo state of in Safe mode are muted if Solo is active.

The integrated peak/present level meter reads the fader input level post mono matrix. The display with 4 LED's covers the range from - 20 dB to + 20 dB.

Sends
There are three mono aux send that can be switched pre or post fader. The two stereo cue sends, each with a level and pan control, can also be switched pre or post fader. The mono sends AUX1 to AUX3 is driven from the output of a mono matrix.

Channel Out
The channel output is electronically balanced and can process levels up to + 30 dBu. The CH-OUT switch selects the output of the group bus amp instead of the fader output when pressed.

Surround Panorama Section
The fader output feeds the surround pan pot section with a stereo signal. The panorama section uses 4 pots to distribute the stereo input signal among the 6 surround channels. The LCR pan controls the 3 front channels, L, C, and R and the surround channels SL and SR at a time. With all settings, the left stereo channels drives always the left front and surround channels while the right stereo channels always drive the right front and surround channels. The center channel and the LFE are driven from the output of mono matrix. The regulation of SL and SR is similar to the regulation of a standard stereo to stereo balance control with 0 dB center attenuation. The regulation law of the front channels depends on the position of the DIV = divergence control that allows influencing the width of the signal in the front plane. With DIV all to the left, and LCR pan at the center position, only the center channel is on. The LCR pan feeds left to front left when all to the left, mono to center only at the center position and right to front right, when all to the right. If DIV is at the center position, all front channels L, C, and R are active at a time, and with DIV all to the right, the center channel is muted and the LCR pan operates like a standard sterep to stereo balance control with 0 dB center attenuation. Independent of the DIV setting, only the left or right front channel is on in the respective end position of the LCR pan. The control law is adapted to the particular setting of the divergence control. In addition, the LCR pan provides a stereo compatible output that drives the groups, unless they are used in surround subgroup mode. This output is also used for the mix bus with MODE STEREO.

The Front - Surround pan determines the relation between all three front channels and the two surround channels. In the respective end positions, either the front channels or the surround channels are muted. The attenuation at the center position is 3 dB for all channels. The LFE pot works like a normal aux send and drive the LFE bus idenpendent of all other settings.

Mix and Group Routing
The MIX switch routs the surround output of the pan section into the mix bus rails. The 6 groups are selected by 3 switches in stereo pairs. Unless all 3 switches are pressed at a time, the groups are driven from the stereo ouput of the LCR pan. If all switches are on, the 6 groups are used as surround sub group and fed from the surround output of the panorama section.

Stereo Compatibility
The M769 Stem Mixing stereo to surround input module is fully compatible with the stereo master module M752. The routing section of the modules drives the additional stereo mix busses of the V700 stem mixing system with a stereo compatible output signal of the LCR pan. With a stereo master module or with MODE STEREO active, only the LCR pan is active and operates just like a standard stereo balance control.

Group Bus Amp
All stem mixing input modules include a mono bus amp for one of the 6 groups of the mixing system. The bus rails are assigned on the wiring pcb in the console frame. At least 6 input modules must be installed to use all groups. The output of the group bus amp drives group return busses in the console frame. All groups are available in all inputs. This principle makes possible to assign any input module to any group, independent of the frame slot where the particular module is installed. In addition, one group can be assigned to several channels in parallel.

The Module
The M769 is a 6U V700 module with 120 mm depth that can be used with standard and custom build stem mixing frames.