Live Sound Systems
PA diffusion involves the installation of an audio system capable of covering the audience area with sufficient sound quality and pressure. The complexity of the audience area naturally requires an equally complex diffusion system, often consisting of multiple speakers positioned in various zones at different heights.
Mixers suitable for managing this type of system are primarily characterized by the presence of a section called the “Matrix,” available in both digital and analog models of medium to high quality. The Matrix section is used to manage complex PA diffusion systems; located in the Master area of the mixer, it is equipped with physical outputs and corresponding master controls, mute functions, AFL (After Fader Listen), and assignment capabilities.
The matrix functions as a Group of Groups, where source assignments (Groups and Masters) are made via rotary faders. This allows for the control of multiple PA destinations from one or more sources.
For instance, in a complex setup comprising PA L&R, a mono Front-Fill, and a mono delay tower (4 different physical outputs), the Master (which is always a group) will be assigned to Matrix 1, 2, 3, and 4 in various modes and levels.
In other scenarios, matrices are indispensable when wanting to allocate groups of channels to different destinations. For example, if working with a stereo PA system for musical performances and a mono PA for spoken parts, matrices facilitate this allocation seamlessly.
The matrix is essentially a Group of Groups, where source assignments (Groups and Masters) are made via rotary faders. This allows for the control of multiple PA destinations from one or more sources. For example, in the case of a complex diffusion setup consisting of PA L&R, mono Front-Fill, and a mono delay tower (4 different physical outputs), the Master (which is always a group) will be assigned to Matrix 1, 2, 3, and 4 in various modes and levels.
In other cases, matrices are essential when wanting to allocate groups of channels to different destinations. For example, when working with a stereo PA system for musical performances and a mono PA for spoken parts, matrices facilitate this allocation seamlessly.
In the latest generation of digital consoles, it is possible to assign channels to matrices, making them suitable for specific sub-mixing purposes or simply as an addition to pre or post-fader “Aux” channels.
VCA
VCAs (Voltage Controlled Amplifiers) are dedicated sections for voltage control of the levels of the channels assigned to them. This assignment is done through assignment buttons located in the channel fader area, similar to those used for group assignment.
The master controls of the VCAs are faders located in the Master Area and, unlike groups, they do not have corresponding physical outputs. This allows VCAs to be used as groups of channels without the disadvantages of groups, such as the ability to adjust the level of a section (e.g., brass) without losing the balance of effects in Aux Post.
VCA/DCA Management
The master control allows for varying the level of the channels assigned to it without physically adjusting the corresponding faders, but rather directly adjusting the voltage on the individual channel VCAs. This operation occurs without altering the signal path, as is the case with groups.
Another significant advantage of VCAs is the absence of audio signal in level management; everything is controlled by voltage, which helps avoid annoying crackles and pops due to wear or poor maintenance of channel faders. VCAs can also undergo multiple channel assignments, all valid and applicable from the individual VCA master controls.
In the latest generation of digital consoles, assignment to VCAs/DCAs is permitted not only for channels but also for output mixes (Aux, Groups, Matrix), making them particularly convenient in monitoring management.
