The Monitor Consoles
Stage monitors are used so that the musicians can hear the things they need to hear to keep the time and to keep on pitch. When music was all acoustic this was not such a problem, but with the introduction of amplified instruments and reinforced sound the volumes on stage began to rise and mask some of the cues for timing. The simplest form of monitoring was just an additional speaker pointed back at the stage. This helped, but the musicians don't necessarily need to hear everything that is in the house speakers to keep the band tight. Eventually someone thought of using an auxiliary send to provide only those things necessary to the musicians in these stage speakers.
As music production matured the stage monitors became more specialized. Not all of the musicians need to hear the same thing at the same levels to play their best. Singers need to hear their vocals and perhaps some melody instruments to maintain pitch. The instrumentalists need to hear the timing cues to stay tight. Because of the varying needs of the various players multi-mix monitoring systems were developed.
At first the monitors were handled via aux sends on the main mixing board. Most smaller systems still use this method to provide stage monitors. There are some drawbacks to doing monitors from the same desk as is used for the FOH mix. Since the monitors need to be a separate mix they need to be sent from pre-fader sends. Modern boards either provide some aux sends that are fixed pre for their tap points or are switchable pre/post either globally or on a per channel basis. Although some boards can be configured with aux sends pre-eq most come from the factory with post eq tap points. Since they are on the same channel strip the gain trim on the channel will affect the monitors. While these limitations are minor in most situations they do limit the creativity of the FOH engineer.
Because of these limitations and because good communication regarding the monitors is needed dedicated monitor boards were developed. The monitor station has its own engineer and is located on/next to stage for good communication. A split snake is employed to send the input signals to both the FOH and monitor boards. The monitor desk still employs the aux send technology, but because the house and monitor systems are independent the FOH engineer has full creative control of the house mix. The channel strip eq on the monitor desk is applied to all of the aux buses.
The Monitor Configuration in SAC
Because SAC was designed as a virtual digital mixing system the developer had opportunities not available in the hardware world. The developer took this opportunity to innovate in the form and function of the musician's monitor system in SAC. The SAC software package comes with the FOH console and 24 identical monitor consoles. There is an internal digital split so a cumbersome split snake is not needed. Each mix is assigned to a monitor console allowing full creative control for the monitor engineer. Since the system operates in the virtual world only the high capacity computer for the host is needed. With the remote control facilities built into the software a separate monitor station can be set up using a computer of minimal capacity. While the physical gain controls on the hardware preamp/converters will affect all signals there are virtual tap points that allow complete separation of the monitor desk from the FOH system in the software.
There are definite advantages to this arrangement. A dedicated hardware monitor desk is not needed nor is an expensive split snake required. The monitor engineer is also provided full creative control of the stage sound environment. Separate dynamics and signal processing can be provided for each monitor mix. There are virtual tap points in the system that allow monitor mixer one to be used as a master section handling most eq and dynamics for the whole monitor rig but the eq and dynamics sections are still active on the remaining consoles to satisfy individual needs.
The monitor consoles can also be set up to provide separate feeds if the situation requires. A separate mix could be provided for broadcast in this way or a monitor mixer could be used as a super-matrix mixer if needed. In the hardware world yet another desk would be required to provide the flexibility of the SAC software package. The flexibility of the virtual SAC system is unexcelled in the hardware world, either analog or digital.