4ch_PA_DSP_Insert-7
Author: Bogen
Description: Nyquist

Setting DSP Parameters

When you select DSP (Digital Signal Processing) from the appliance’s web UI, the DSP page appears. This page presents a mixing board interface, allowing you to monitor, control, and perform various DSP operations on digital channels A, B, C, and D.

Note: Digital Signal Processing (DSP) refers to the digital operations that are performed to modify or control the digital signal.

Note: When the amplifier is being used for Sound Masking, the DSP controls should not be used to make changes. When Sound Masking is enabled, using any DSP control feature may interfere with the Sound Masking feature and have unintended results.

The signal for a channel (A, B, C, or D) can come from either of two sources:

1​An analog line input signal

2​A digital VoIP audio stream or multicast audio

The level of an analog line input signal can be adjusted via the router’s Analog Input Gain control (see "Router"), after which the analog signal is converted to a digital signal. The digital signal can then be routed to one or more of the mixer’s four output channels (A, B, C, and D) via the DSP Router, where it is processed by the mixing board interface.

Digital VoIP audio streams received over the network—whether as SIP-initiated phone calls or as multicast audio (see SIP and Multicast configuration settings in "Configuration Settings Tab Parameters")—are also controlled by the mixer’s output channels (A, B, C, and D).

Tip:​Be aware that the output levels of digital audio streams received over the network are controlled by the same sliders that control analog line input signals. You can use the DSP Router to adjust an analog signal level relative to a digital signal level on the same channel.

The digital signal, regardless of the source, is then conditioned, filtered, and enhanced via the DSP processors, and its level adjusted via the mixing board’s channel fader controls. The digital outputs of all channels are converted to analog signals and sent to the channel’s electrical output connectors. If this device is being used as an Audio Distribution source, the signals can be distributed as digital audio over the network using a Nyquist server’s Audio Distribution feature.

Note: Audio Distribution functionality is not supported in Standalone Operation mode or when the amplifier is being used for Sound Masking.

Figure 1. DSP Page

From the DSP page, you can view and control the signal levels for each channel. Selecting the DSP Features button for a channel displays a list of DSP features which can be applied to that channel (though some DSP features are channel-independent, such as Router and Status), such as compressor, noise gate, filters, equalizers, and limiters, as well as features for monitoring the signal and the amplifier status. You can even load groups of predefined DSP settings, known as DSP presets, and assign them to the channel connected to that speaker.

Note: The DSP page (including the mixing board and other DSP pages) can only be used by one browser session at a time. If another session is already connected and using this DSP page, the mixing board displayed will be disabled.

Note: If two output connectors are configured for Bridge mode (A/B or C/D), the output channel that corresponds to the second connector (B or D) will not appear on the mixing board interface.

DSP features and controls are described in the following table.

Table 11. DSP Page

Save Settings to Server | Backs up the DSP settings to the server. If this device is later replaced or reset to factory defaults, these DSP settings can be restored when the new device is “swapped” for the old on the Nyquist server. Note: This button appears on each DSP feature page.
Mute | Silences the audio for the selected channel.
DSP Features button | Presents a menu of DSP features that can be applied to the corresponding channel.
Channel Fader | Adjusts the channel volume level in 1–dB increments.
NET-IN LED | Illuminates when a signal is being received from the Network stream input. Note: When Sound Masking is enabled, NET-IN LED is illuminated.
LINE-IN LED | Illuminates when a signal is being received from the analog Line input.
Clip LED | Illuminates when a signal has exceeded the maximum threshold, indicating that the signal is “clipping.” Note: When Sound Masking is enabled, Clip LED is illuminated.
IN VU meter | Indicates the strength of the input signal.
OUT VU meter | Indicates the strength of the output signal.
Pink Noise | When set to ON, a pink noise signal will be sent to the output channel.
Phase Invert | When set to ON, the signal for this channel is inverted, usually to prevent two similar but out-of-phase signals from canceling each other out.

The DSP features that can be applied to a channel, accessible through the DSP Features menu, are described in the following table.

Table 12. DSP Features

Amplifier Mute | Eliminates low-level analog noise, such as the “pops” that can occur when the device is turned on or off.
Compressor | Lessens the dynamic range between the loudest and quietest parts of an audio signal.
Delay | Delays the signal by a specified number of milliseconds.
Graphic EQ | Uses fixed frequencies to tailor the frequency content of an audio signal.
High/Low Pass | Filters out frequencies in the input signal that are above and below specified high and low cutoff frequencies.
Limiter | Prevents a signal from exceeding an adjustable maximum level.
Noise Gate | Eliminates low-level hiss, noise, or leakage, particularly when there is a high level of ambient noise.
Parametric EQ | Uses a center/primary frequency to allow tailoring of the frequency content of an audio signal.
Peak Limiter | Limits the signal to a specified threshold based on the signal’s instantaneous levels.
Presets | Provides predefined configurations of DSP features, tailored for specific speakers models.
RMS Limiter | Limits the signal to a specified threshold based on the signal’s average levels over time.
Router | Routes the audio signals from each input channel to zero or more output channels, as well as adjusting the level of each input signal per selected output channel.
Settings | Allows you to provide names and colors for the input and output channels.
Signal Present | Allows you to specify the signal level at which the signal LED will be lit, as well as how long it will remain lit.
Standby | Allows the amplifier to automatically put itself in a low power standby mode when there is little or no signal.
Status | Provides real-time status for the amplifier, including for which mode (2-channel or single-channel bridge mode) the outputs are configured, channel output limits, and more.
Reset button | Present on almost all DSP screens other than the main mixer, this button will reset the DSP settings to the displayed feature’s default setting.

Setting the Channel Level

The channel level control is a channel fader, which is adjusted in 1-dB increments and controls the output level for the channel. The channel levels can range from −60 to +12 dB. If you place the mouse over the fader, the numerical value of the level appears.

Adjusting Volume Levels

The channel fader control can be used to adjust the channel’s output level in 1-dB increments between −60 and +12 dB. The overall adjusted output level of the channel signal can be viewed on the OUT VU meter, marked in 2-dB increments between −60 and 0 dB.

Tip:​For best results, adjust input signal levels until you have a strong signal (i.e., within the green and yellow areas on the meter), then adjust the final output levels using the DSP Outputs controls.

To adjust the channel volume level:

1​On the appliance Web UI’s main page, select DSP.

2​Use the channel’s fader to adjust the volume level.

Knob Adjustments

Many DSP controls use knobs to adjust one or more settings. The value of a knob can be adjusted in one of two ways:

1​Click the knob control, hold the mouse button down, and drag the mouse up or down to increase or decrease the value.

2​Double-click the knob, type a value into the resulting popup, and click the Save button.

Signal Indicators

Each input channel has signal indicators and two vertical volume unit (VU) meters, labeled “IN” and “OUT”.

The green input signal LED(s) automatically illuminates when a signal is being received.

The red Clip LED automatically illuminates when the signal is clipping (i.e., exceeding a predefined threshold). Clipping can result in distortion and, for output signals, can even damage speakers. Note that the specific level and duration that a signal must reach in order to trigger the input signal LED can be configured via the Signal Present settings.

The “IN” VU meter indicates the strength of the channel’s input signal (after gain adjustments), while the “OUT” VU meter indicates the strength of the channel’s output signal. The VU meter not only illuminates green, yellow, or red (depending on the signal level), but also has a scale ranging from −60 to 0 dB to indicate the actual signal level.

Muting a Channel

You can mute a channel to cut off an audio signal and stop the input signal from being sent to the output channel. Note the input signal will still be visible on the IN meter, but the OUT meter will show that nothing is being forwarded to the output channel.

To mute a channel:

1​On the appliance Web UI’s main page, select DSP.

2​Click the Mute button for the channel that you want to silence.
The Mute button will illuminate red. You can click the Mute button again to unmute the channel.