Mix Matrix Operation

Primary Mix Matrix

The DSP architecture contains a primary mix matrix that connects the mic/line inputs and virtual bus returns to the line outputs. The DSP Configurator GUI provides control of the primary mix matrix, used to set mix levels from the inputs and virtual returns, post-input processing, to each of the mono Line Output busses. Each of the 6-mic/line inputs and 4-virtual bus returns is connected to a mix-point for each of the 4-line outputs. In general, mix levels are set relative to each other, achieving a desired blend of input signals at an optimal output level, i.e., close to but not exceeding 0dBFS at the Line Output Volume block level meter (while accounting for processing that occurs at the line output signal chain).

Clicking a mix-point brings focus. Double-clicking a mix-point opens a configuration dialog window with the following components:

• Mono Faders – sets mix level to the output bus. Gain range is -35dB to 25dB. Fader behavior is identical to input channel Gain block, described in the Mic/Line Input section, Gain, with the exception that course adjustment (Page Up/Down) increases/decreases level from the previous setting in 5dB increments.

• Channel Mute – mutes the signal to the output bus.

• OK/Cancel buttons – click OK to accept changes and close the window, and Cancel to exit and cancel all changes.

Mix-point behavior is as follows:

• No mix information – a faint gray ball behind the mix-point indicates that the mix-point exists, yet contains no mix information (i.e., the mix-point is muted).

• Mix information – a solid teal-colored “bubble” indicates that the mix-point contains mix information (i.e., the mix-point is unmuted).

• Mouse-over – the cursor changes to a “Hand” when a mouse-over occurs at a mix-point.

• Single-click – a single click brings focus, indicated by a dark green circle around either the ball or bubble, depending on mix status.

• Double-click – double-click to open the mix-point dialog box. The focus circle turns light green in color for an open dialog box.

• Multiple open dialog boxes – when multiple mix-point dialog boxes are open, the mix-point for the most recently opened dialog box receives the light green focus circle, while previously opened dialog boxes relinquish their focus.  

Shown below is a drawing of the DMP 64 represented in the DSP Configurator, with a circle to indicate the area that is the Primary Matrix.

Secondary Mix Matrix

The DSP architecture contains a secondary mix matrix that connects the Line Input, Mic Input, and Virtual Bus Return signals to the Virtual Bus Sends. The DSP Configurator GUI provides control of the secondary mix matrix, used to set levels from the post-processing input and virtual bus return signals to the Virtual Bus Send busses. Each of the 6-mic/line and 4-virtual return inputs is connected to a mix-point for each of the virtual busses. Each mix-point is muted and set to 0.0dB (unity gain) by default. In general, mix levels are set relative to each other, achieving a desired blend of input signals at an optimal level, i.e., close to but not exceeding 0dBFS at the Virtual Bus Gain block level meter.

The secondary mix matrix contains a section (see below, Virtual Bus Rtn to Virtual Bus Send) that allows virtual bus returns to be routed back to the secondary matrix. To prevent feedback loops, a virtual channel is prevented from being routed back to itself by eliminating the mix-point that routes a bus to itself.