The Master Module MST-S includes the main stereo master, the stereo cue send master and another stereo effect return. The mix chain offers a range of processing stages that allow the control of the stereo base width and direction, an elliptic EQ to maintain mono compatibility and a master compressor.

The master module of the master section S includes a stereo return section, the master and output amplifiers of the cue send and the main stereo master mix. The mix master chain contains some outstanding processing stages.

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Stereo Mix Master Section

Certainly, the mix master chain is the most important piece of equipment in a mixing console. Every signal passes these amplifiers and processor at least during the final mix. The quality of this section determines directly the quality of the final mix. Besides the quality level, we have included some very special features. Many users were involved in the development and the optimization of these circuits.

The bus amps of the mix master section are optimized for very low noise, because the mix bus adds two signals of each inline module. In total, more than 100 sources are summed into mix in a 48 channel console. Therefore, the noise performance of the mix bus amps is of crucial importance for the dynamic range of the entire console. Carefully pre selected, special operational amplifiers are used for these bus amps. The output of the bus amp feeds the mix insert output thru an additional output buffer. The mix insert input is also buffered. While the output is always available on the patch bay, the insert input is switched into the signal chain when the INS button is pressed.

The M/S based stereo direction mixer is a very important processing device that is installed in the master chain. This section allows the control of the stereo base width and direction. The left and right input signal is converted into the M/S format with a matrix. The controls are part of the M/S signal chain and make it possible to control the stereo base width and the stereo direction. Unlike a normal pan pot or balance control that cuts off the right channel if the control is set all to the left, the direction control in the M/S chain moves the center position to one of the channels. If this control is all to left there is a mono signal on the left channel that is an addition of both the stereo channels. This offers the choice to readjust the stereo direction without loosing signal parts. The base width control has a range from 0 % via 100 % to 200 %. The 100 % position is internally calibrated and leaves the base width unchanged. Values below 100 % decrease the base width from stereo normal to mono at 0 %. The values above 100 % increase the base width, which offers many very interesting sound effects. However, the mono compatibility is decreased as soon as the base width is more than 100 %. How critical a particular setting is, depends on the program material. If you use the base width control above 100 % to enhance your mix, it is crucial that you check the mono performance every time you change the setting of the base width control. The output matrix of the direction mixer reconverts the signal into the Left-Right format. The DIR switch inserts the entire section.

The Elliptic Equalizer can reduce the side effect of a base width setting above 100 %. The EEQ switch activates it. The unit decreases the base width frequency dependent. The lower the frequency is, the smaller is the base width. Since the human ear is not able to locate any sound source with a frequency below 300 Hz, the base width of these low frequencies can be reduced without any negative effect. Every subwoofer system uses this principle. The elliptic equalizer has a frequency control pot with a center detent that is calibrated to a crosstalk of 15 dB between the two stereo channels at 300 Hz. If the level difference between the stereo channel is at least 15 dB, every signal is located only from the side that has the higher level. As far as the location is concerned, there is no difference if the level difference is 15 dB or more. This crosstalk excludes that there is any additional audible effect when the elliptic equalizer is used. Setting the frequency control to left reduces the '15 dB crosstalk frequency' while a setting to the right increases this frequency. Depending on the program material this may result in audible effects. If you use this setting to find a compromise between a high setting of the base width control and an appropriate mono compatibility you must carefully check every setting. The combination of the elliptic equalizer and the base width control offers the opportunity of large improvements of the spatial impression of the entire mix that cannot be produced with another system.