MUSIC ALL DSP-480 Network DSP FIR Processor

Chapter 1: Introduction

The DSP-480 is a 4-input, 8-output FIR DSP audio processor featuring a high-performance DSP processor, Dynamic EQ, FIR filter, and other advanced functionalities. It connects via RJ45 (Ethernet), USB, and RS232. The PC software, MusicAllDSP, allows for easy control of multiple devices, with RS232 supporting integration with third-party control systems.

Applications:

• Meeting room
• Broadcast
• Multi-function hall

Features:

• 4 analog inputs and 8 analog outputs.
• High-performance DSP processor with a 96kHz, 24-bit sampling rate.
• Input processing includes 15 bands of PEQ; output processing includes 10 bands of PEQ.
• Supports High-Pass Filter (HPF) and Low-Pass Filter (LPF) with Butterworth, Bessel, and Linkwitz-Riley alignments. Also supports LSLV and HSLV, and ALL-PASS filters.
• Input processing includes 3 bands of Dynamic EQ.
• Input processing includes 4 x 1024 Taps 48kHz FIR linear phase setting.
• Output processing includes 4 x 512 Taps 48kHz FIR linear phase setting.
• Supports preset archiving and locking, with options to hide setting parameters.
• Control connections: USB or TCP/IP. Configured with RS232 central control connection.
• User-friendly GUI for Windows 7/8/10/11 software.

Chapter 2: Technical Parameters

Chapter 3: Functions Structure and Panel Operation

The front panel of the DSP-480 features an LCD display, function select and setting buttons, and various input/output connectors. The display shows device status and parameters. Buttons allow navigation through menus, parameter adjustment, and quick actions like muting or bypassing channels.

Front Panel Layout Description:

• LCD Display: Shows current status, menus, and parameters.
• Function Select and Setting Buttons: Used for navigating menus and adjusting parameters.
• BACK, NEXT, MENU, ENTER, BYPASS, QUIT Buttons: Standard navigation and control buttons.
• FREQ, Q, GAIN, PARAMETERS Knobs/Buttons: For adjusting specific audio parameters.
• USB-B Connection: For connecting to a PC.
• Balanced XLR Input and Output: 4 inputs and 8 outputs.
• RS232 Connection: For serial communication and integration.
• RJ45 Connection: For network (TCP/IP) control.
• Power Plug and Switch: For power supply.
• Indicator Lights: For Clip, Level, Edit, and Mute status on input/output channels.

Panel Operation:

Pressing the MENU button displays the menu list. Use NEXT or BACK to select functions like GLOBAL MEMORY, INPUT SECTION, MATRIX, or SYSTEM. Press QUIT to exit.

Pressing the BYPASS button quickly accesses the RECALL a Memory function. Use NEXT or BACK to select presets, then press ENTER to enable a preset.

Input & Output Channel Operations:

• Quick Mute: Short press the button under the channel's LED. The light turns red.
• Set Parameter: Long press the button under the channel's LED. The light turns blue. The LCD will display the input/output channel name and parameter.

Functions - Input Channels:

Functions - Output Channels:

Remark: 'X' denotes the selected channel number. If a setting has no effect, check if BYPASS is selected.

Channel Linking: Long press the button under the LED of each channel to link them. The LCD will display 'IPX+' or 'OPX+', indicating that subsequent channels will adopt the settings of the first channel. Short pressing a button in link setting mutes all linked channels, turning their LEDs pink.

Chapter 4: Operation of Control Software - MusicAllDSP

MusicAllDSP software facilitates interaction with one or more devices via TCP/IP, USB, or RS232. It allows for easy configuration of DSP functions, checking of central control codes, and storage of parameters in presets for various applications.

4.1 Operating Condition

MusicAlIDSP is compatible with Windows 7/8/10/11 (x86/x64) systems with Microsoft .NET Framework 4.0 installed. Launch the software by double-clicking the MusicAlIDSP executable file.

The main interface will display options for File, Device, Camera, Connection, Preset, and System.

4.2 Connect to PC

Connection can be established via network cable (TCP), USB A-B cable (USB), or serial cable (COM). To connect:

• TCP/IP: In the 'Device List', click 'Setting', then choose 'TCP' in the 'Connection' window.
• USB: In the 'Device List', click 'Setting', then choose 'USB' in the 'Connection' window.
• RS232 (COM): In the 'Device List', click 'Setting', then choose 'COM' in the 'Connection' window. Ensure the correct port and baud rate are selected.

The software scans for devices using the last selected method. Connected devices appear in the 'Device List'. From this window, users can mute, refresh, or delete devices. Single-clicking a device loads its function interface.

Network Connection Note: If using TCP control and only one device point is displayed after scanning but connection fails, the device's IP address may need to be changed to match the PC's network segment. Right-click the device in the list, open 'Net Setting', and adjust the IP address accordingly.

4.3 DSP Functions Setting

Double-click the HOME icon to open all functional interfaces, or double-click individual function icons to open specific interfaces. Multiple function windows can be opened and dragged to switch between settings.

4.3.1 DSP Functions Setting - INPUT

This interface allows for:

• Setting the input signal's phase.
• Setting the input signal's mute status.
• In Pro versions, selecting Analog, AES, or Dante input signals.
• Choosing test signals (Sine, Pink Noise, White Noise) for each input channel.

4.3.2 DSP Functions Setting - NOISE GATE

The Noise Gate function provides control over audio signal gating. Key parameters include:

• Attack: 1 to 2895ms.
• Release: 1 to 2895ms.
• Threshold: -120 to -60dBu.

Click the Noise Gate ON button to enable this function.

4.3.3 DSP Functions Setting - PEQ-X (Input and Output)

This section configures the Parametric Equalizer (PEQ) for both input and output channels.

High Pass Filter (HPF):

Enter the desired frequency and select the filter type (Butterworth, Bessel, Linkwitz-Riley with various slopes like 6, 12, 18, 24, 36, 48 dB/octave). Press ON to enable.

Low Pass Filter (LPF):

Similar to HPF, set frequency and select filter type (Butterworth, Bessel, Linkwitz-Riley). Press ON to enable.

Input Channel PEQ: Offers 15 bands. Filter types include PEQ, LSLV, HSLV, and ALLPASS-1/2. Frequency, Q, and Gain can be set by inputting values or using the mouse pulley. The frequency dot on the curve can also be dragged for adjustment.

Output Channel PEQ: Offers 10 bands with similar filter types and adjustment methods as input PEQ.

The interface displays phase curves, allows viewing/hiding balance points, bypassing EQ, and saving/recalling presets. Parameters can be copied and pasted between channels.

4.3.4 DSP Functions Setting - DYNAMIC EQ

Dynamic EQ adjusts EQ bands based on signal level. Parameters include:

• Mode: Boost Above, Boost Below, Cut Above, Cut Below.
• Threshold: -90 to 24.0dBu.
• Q: 0.27 to 15.
• Ratio: 1.0 to 100.0.
• Max Gain: 0.0 to 12.0.
• Attack: 1 to 2895ms.
• Frequency: 20 to 22000Hz.
• Release: 1 to 2895ms.
• Type: BYPASS or PEQ.

Use the Bypass button to switch modes.

4.3.5 DSP Functions Setting - DELAY (Input and Output)

This function allows setting audio delay for input and output channels.

• Maximum delay for input channels: 1000ms.
• Maximum delay for output channels: 1000ms.
• Click the enable icon (represented by a green play button symbol) to enable the function.
• Click the reset icon (represented by a circular arrow symbol) to reset each channel's delay.
• Users can switch measurement units for delay: feet (ft), centimeters (cm), or milliseconds (ms).

4.3.6 DSP Functions Setting - MATRIX MIX

The Matrix Mix allows flexible routing and mixing of input signals to output channels. Input channels are listed at the top, corresponding to output channels. The value boxes represent mixing keys; when green (double-clicked), they indicate an active mix. The right side of the interface controls gain, reset, and clear functions for the matrix mix.

4.3.7 DSP Functions Setting - COMPRESSOR

The Compressor reduces the dynamic range of an audio signal. Key parameters include:

• Soft knee: 0 to 30.
• Threshold: -90.0 to 24.0 dB.
• Attack: 1 to 2895 ms.
• Ratio: 1.0 to 100.0.
• Release: 1 to 2895 ms.

Click the Compressor ON button to enable this function.

4.3.8 DSP Functions Setting - LIMITER

The Limiter prevents audio signals from exceeding a set threshold. Key parameters include:

• Threshold: -90.0 to 24.0dBu.
• Release: 1 to 2895 ms.

Click the Limiter ON button to enable this function.

4.3.9 DSP Functions Setting - OUTPUT

This section allows configuration of output channels:

• Set phase of signal.
• Set mute status of output channel.
• Set gain of output channel.

4.4 Monitoring and Setting of Channels

The channel monitoring interface displays input and output levels via faders. Users can monitor gains and adjust levels using faders or mouse pulley.

Input Signal Types: The device supports ANALOG and testing signals, indicated by labels.

4.4.2 Quick Buttons of DSP in Channels

Quick access buttons are available for common DSP functions on input and output channels, including Mute (M), Phase (+), Noise Gate (N), PEQ (E), and Delay (D). Output channels also have controls for Compressor (C) and Limiter (L).

4.4.3 Group and Channels Link

Channels can be grouped for simultaneous control of mute, phase, noise gate, PEQ, and delay functions. The 'Channels Link' window allows users to select corresponding channels to form groups for parameter setting.

4.5 Menu - File

The 'File' menu provides options for project management:

• New Project: Resets the project to its initial state.
• Demo Device: Allows viewing all device functions without a connected device.
• Open: Loads an existing device management project from the computer.
• Save: Saves the current project to the computer.
• Save As: Saves the current project to a new file on the computer.

4.6 Menu - Device (including Device lock)

The 'Device' menu offers management and configuration options:

• Devices: View or modify software version, device name, and IP address. Set device password.
• Channel Name: Rename input and output channels.
• Channel Copy: Copy input/output channel parameters between devices of the same type.
• Central Control: Inquire codes for central control system integration. Refer to the 'Center Control Code User Manual' for details.

Device Locking: Users can set a 4-digit password to protect audio projects. The password can be entered via the software or the front panel. A lock icon indicates a locked device. Incorrect password attempts are limited (5 times); exceeding this limit requires returning the device to the dealer or factory for reset.

4.7 Menu - Connection

The 'Connection' menu configures communication settings:

• Port: Set connection mode, port number, and baud rate.
• Connect: Establish connection and download device parameters.
• Disconnect: Terminate connection with a device.
• Connect All: Connect to all devices in the list.
• Disconnect All: Disconnect from all connected devices.

4.8 Menu - Preset

The 'Preset' menu manages saved configurations:

• Save: Save current settings to a device preset (slots 2-30).
• Recall: Load a saved preset to the current configuration.
• Delete: Remove an existing preset (default presets cannot be deleted).
• Clear: Delete all presets.
• Boot: Set a preset to load automatically upon device power-on.
• Import Preset: Load a single preset file from a computer.
• Export Preset: Save the current state as a single preset file to a computer.
• Import Preset Package: Load multiple presets from a package file.
• Export Preset Package: Pack multiple presets into a package file for export.

4.9 Menu - System

The 'System' menu provides system-level options:

• Language: Switch between simplified Chinese, traditional Chinese, and ENGLISH.
• About: View current control software and device firmware versions.
• Upgrade: Update firmware using a .bin file provided by the manufacturer. This is typically only needed for bug fixes or new features.
• Help File: Access help documentation.

4.10 FIR Filter and Function

4.10.1 FIR Filter and Applications

While IIR filters can alter signal phase, FIR (Finite Impulse Response) filters in DSP products allow for linear phase adjustments to audio signals. This is crucial for maintaining phase coherence, especially in speaker systems.

FIR Calculations:

• Frequency resolution = Sampling Rate / Taps.
• Minimum usable frequency ≈ Frequency resolution * 3.

For example, with a 48kHz sampling rate and 1024 taps, FIR filters are effective above 141Hz. Higher tap counts result in steeper filter curves.

FIR Delay:

FIR filter processing introduces a delay calculated as: Delay = (1 / Sampling Rate) * Taps / 2.

Applications of FIR Filters:

• Achieving a linear phase response for speakers.
• Matching phase and magnitude across different speaker models in a system for easier debugging of groups and arrays.
• Optimizing linear array systems for audience coverage.
• Improving frequency response consistency across multi-division speakers for better coverage.

Devices Required for FIR Setup:

• Measurement Microphone (x1)
• Audio Interface (x1)
• Windows PC (with software like Smaart, rePhase, FIR Designer, MusicAllDSP) (x1)
• FIR audio processor or DSP network power amplifier (x1)
• Speaker (x1)

A connection schematic diagram illustrates the setup involving a laptop, audio interface, measurement microphone, DSP processor, and speakers.

4.10.2 Using Third-Party Software to Set FIR Magnitude and Phase

This section details the process of using external software (Smaart, rePhase) to create and import FIR filters:

1. Step 1: Measure Phase Curve in Smaart V7. Use Smaart V7 to measure the speaker's transfer function, including magnitude and phase response.
2. Step 2: Copy Curve to ASCII in Smaart V7. Select the desired measurement data and use the 'Copy To ASCII' function (Ctrl+C) within Smaart.
3. Step 3: Copy Curve to rePhase Software. In rePhase, use the 'Import Measurement From Clipboard' option to paste the copied data.
4. Step 4: Adjust Phase EQ in rePhase. Modify parameters within rePhase (e.g., phase EQ, linearization) to achieve a linear phase response for the speaker. The software displays magnitude and phase curves, allowing for adjustments.
5. Step 5: Export .txt File. After setting parameters in rePhase, configure settings like taps (e.g., 512) and sample rate (e.g., 48000Hz). Specify an export directory and click 'generate' to create a FIR .txt file.
6. Step 6: Import FIR .txt File into DSP-480. Open MusicAllDSP software. Select an input or output channel and navigate to the FIR function window. Use the 'IMPORT' button to load the generated .txt file, then press 'STORE' to apply the FIR filter. Ensure 'BYPASS' is cancelled for the FIR function.
7. Step 8: Measure Speaker Curve Again. After importing the FIR filter, re-measure the speaker's response in Smaart to confirm the improved linearity.

Marks: Remember to set taps (e.g., 512), sample rate (e.g., 48000Hz), and save the final configuration as a preset.