MotoCross Automatic Crossfader

Purpose

MotoCross is the name of our automated crossfading mixer.  The device was developed to allow a user to trigger a timed, automatic crossfade between 2 sources.  While similar in function to the Ramped Router, it provides a mix rather than a selection of the 2 inputs during crossfade.  For the Ramped Router, the input selection is toggled at mid crossfade and for the MotoCross, the inputs are mixed at equal amplitude at mid-crossfade.

Versions Provided

Constant Power

At the midpoint of the crossfade, the input sources are summed at a gain of –3dB each.  This is referred to a constant power summation for uncorrelated sources.  This is the recommended setting.

Constant Voltage

At the midpoint of the crossfade, the input sources are summed at a gain of –6dB each.  This is referred to as constant voltage summation.  This works well for highly correlated inputs.  For uncorrelated inputs, this setting will result in a 3 dB dip in level at the 50% position.

Unity Midpoint

This crossfade option is used to bring the target source to unity gain before you begin to attenuate the current source.  The result is a summation of both sources with unity gain at the 50% position.

Controls

Current Position

Shows the relative position of the crossfade transition between Channel Input A and B, both visually (the current output display) and with a percentage (the control).  The bi-color bar across the top is simply a visual readout of where the crossfader is at the moment.  The percentage text readout can be gestured or typed over to manually move the current position.  You can copy the percentage text control out to a control panel and change the style to a h fader (horizontal fader) for manual control.  Do not use the bar for control because it is only a readout and does not accept user input.

Crossfade Time

Sets the length (in seconds) that it takes to move the current position from 0% to 100% or from 100% to 0%.  The speed of the transition is only calculated from end to end.  If the crossfader is stopped in any position other than 0% or 100%, the crossfade time will be proportionately less than the current Crossfade Time.  In this case, MotoCross is just continuing the crossfade as if it were simply interrupted.

Channel Input

Channel A represents audio from the first input node, while Channel B represents audio from the second input node.  In the above graphs, The blue color represents the first input node ("A"), while the green color represents the second input node ("B").

Current Level

Since in any crossfader, there are essentially two faders (level controls) operating in opposite directions, these text readouts show the current gain of each of the two faders.  Typically, they will have different levels, unless you have the Current Position at around 50%, which usually means that both faders are overlapping at a similar or identical level.  Current Level refers to the level of attenuation and is not a meter of the audio running through the crossfader.

Start Crossfade

Similar to the operation to the Ramp device, the button under “A” starts the crossfader moving at the predetermined rate toward the 0% point of the Current Position.  The button under “B”, likewise, starts the transition in the direction of 100%.  The buttons have an On/Off action, so it is possible to stop the crossfade in progress.  If the end goal (0% or 100%) of the button is already reached, there is no action.