Delay: Distance

Functionality

The Distance Delay block delays the audio from input to output by a time calculated from distance and temperature parameters (entered in either metric or imperial units). The acoustic propagation delay of sound waves through air is a function of the distance from the source and temperature (humidity also affects propagation delay, but that effect is negligible). The Distance Delay block takes Distance and Temperature parameters, calculates the delay required to simulate the propagation delay of sound through air of that temperature over that distance, and then applies that delay to all channels in the Distance Delay block. The delay time is adjustable from 0 seconds to the maximum delay setting, in 21 microsecond increments. The maximum delay available to the block is 250 milliseconds to 1 second, adjustable in 21 microsecond increments. Adjusting the maximum delay recompiles the HAL DSP code, which forces the software to disconnect if connected to a HAL device.

How to Use

The Distance Delay block is most useful for loudspeaker driver alignment.

Adding the Block to Your System

Click the Processing tab to open the Processing Workspace.
In the palette area, click the DSP tab.
Expand the Misc: level, delay, meter... category of blocks.
Click and drag the Delay: Distance block into your Processing Map.
Wire it into your system in the appropriate location. If you need additional inputs and outputs, simply wire to the <Add> node or click the <Add> text. Each input channel is routed to the opposing output channel through a delay.
(Optional) Customize the names of the block and/or the input and output channels by clicking their current name and then typing the custom name in the text box that appears. Click the X to save the name.

Configuring the Block

Open the Level block's properties by double-clicking the block or hovering and clicking the properties icon that appears in the upper right of the block's title bar. The properties dialog box contains Distance and Temperature controls. Designers typically use the Distance Delay block to align the audio from loudspeakers separated by some distance. From this dialog box, you can do the following:

Set the Distance value, which should represent the distance between the two loudspeakers.
Set the Temperature value. It should represent the average temperature expected in the space between the loudspeakers.

note: Halogen automatically calculates the required delay to align the audio from the loudspeakers and applies it to all the block’s channels.

Adjust the Max Delay setting. To do so, expand the Max Delay area and adjust its value using the slider or by entering a value in the Max Delay edit box. You can increase the value from its default of 250 milliseconds to a maximum of 1 second (approximately 1000 feet or 300 meters).
warning! The system allocates the maximum delay for each channel in the Delay block. If you set the Max Delay to a high value (for example, 20 seconds), you can quickly use up the amount of delay allowed by the system. Total system delay for HAL1 is 80 seconds, HAL2 is 40 seconds, and HAL3, HAL3s, and HAL4 is 20 seconds.

note: Adjusting the Max Delay value reallocates DSP memory, which requires a recompile of the HAL DSP code. If Halogen is connected to a HAL device, Halogen disables the Max Delay control to prevent DSP recompile.
tip: When you store the Distance Delay block in a preset, Halogen does not store the Max Delay parameter (to prevent the preset from changing the Max Delay value, resulting in a recompile of the HAL DSP code). Set the Max Delay value so that all required block delay settings are available using the Distance and Temperature controls. You can then use the Distance and Temperature controls to achieve different delays by storing the Distance Delay block in presets that recall different Distance and Temperature settings.

User Interface Elements

Delay: Distance Block

UI Element	Purpose
Input nodes	Connection point for wiring input to the Distance Delay block. Each input channel is routed to the opposing output channel through a level control.
Output nodes	Connection point for wiring the Distance Delay input channel to a specific output
<Add> nodes	Click to add another Input/Output pair of nodes, or wire to the <Add> node to automatically create a new channel.

Delay: Distance Block Properties

(Hover over the thumbnail below to view the properties dialog box.)

When not connected to HAL: (Offline)

When connected to HAL: (Online)


UI Element	Purpose
Distance	Represents the distance between two loudspeakers. The Distance Delay block uses this value in addition to the Temperature value to calculate the required delay to align the audio from the loudspeakers, and then applies this delay to all the block’s channels. The maximum distance allowed is 1000 feet or 300 meters (translates to a delay of approximately 1 second). Default = 0 feet
Temperature	Represents the average temperature expected in the space between the loudspeakers. The Distance Delay block uses this value in addition to the Distance value to calculate the required delay to align the audio from the loudspeakers, and then applies this delay to all the block’s channels. The allowable temperature range is -22° to 140° F or -30° to 60° C. Default = 72° F
Max Delay	Specifies the maximum allowable delay. Changing this value causes the DSP code to recompile. If Halogen is connected to a HAL device, the Max Delay control is disabled and displays a warning icon and note indicating that the control is for offline use only. Because of this recompile requirement, Halogen does not save this parameter to presets (when you add this block to a preset). Ranges from 250 milliseconds to 1 second, adjustable in 21 microsecond increments. warning! See warnings above—in the How To Use section—about the use of Max Delay. Default = 250 milliseconds
Metric Units	Check this box to display Distance and Temperature in metric units.