1. Overview

DDX320 board is an all-digital amplifier with only S/PDIF digital audio inputs and outputs directly to speakers. The volume/channel and other configuration parameters can be easy controlled by a rotary encoder or an IR remote controller, and value/state of the parameter will be displayed on the LED display panel. All functions are handled by an on-board microcontroller. Comprehensive user control requires an infrared remote controller adopted by the DDX320 in “learning-mode” after which you have remotely control all the amplifier’s functions.


2. Electrical specifications


Table1. Specifications list




3. Function Description

3.1 Inputs

3.1.1 Up to 192kHz/24bit S/PDIF signal can be accepted in four stereo channels


Optical inputs (Channels 1, 2)

Coaxial inputs (Channels 3, 4)


3.1.2 The board can select a further 4 inputs – see Table2 DIP4_s1 for details.

Inputs 5 and 6 are S/PDIF mode

Inputs 7 and 8 are CMOS mode


3.2 Outputs

The output can be set for 2.0 or 2.1 channels - see Table2 DIP4_s3 for details.

Note the subwoofer output is not active when 2.0 mode is selected.


3.3 Hardware setup

A minimum 300 watt power supply is recommended. This can be either a dual rail AC transformer input or a single rail linear, or switched mode, DC power supply.  If you use a DC power supply the negative lead is connected to the central terminal of the power block and positive lead connects to the inner terminal of the connector block. We recommend the SMPS300RS.


Several functions can be configured on/off by switch – see Table2 DIP4 below for details.


Table2. DIP4 switch settings


3.4.1 Display.3.4 Display and Control

The DDX320 uses a 4 digits, 7-segment LED display. The LED will display function values including: volume, channel, EQ, bass volume, crossover frequency, (note the display can be auto-off when DIP4_s2 is set to OFF).


3.4.2 Control by rotary encoder (we call it RE in short below)

Volume adjustment: turn the RE to left or right to control volume down or up.

Channel switching: press the RE button to increment the channel (cyclic from CH1 to CH4/8 )

Standby/Wake-up: press the RE button ~3 sec to enter standby mode or to wake up to active state.


3.4.3 How to adopt an IR remote controller

After remote learning advanced functions like EQ and display brightness can be used by remote. The full set of remote controlled configuration parameters is given in Table3 below.  The DDX320 responds to most domestic Infra-Red Audio-Visual remotes.  However, some remotes issue multiple commands and these are unsuited.  Experiment with several until the DDC320 follows your button pushes one-step-at-a-time.


Follow the steps as given below to enter remote learning mode and configuration of the remote. Once you are in learning mode (000 showing on the display) the DDX320 will learn each button press and increment its display ready for the next button push (000 à 111) (111 à 222) etc through to displaying “EEE”

1. Power off the DDX320.

2. Push-in and hold the rotary button (RE) during power on.

3. Release the rotary button (RE) when the display shows “000”

4. Press the key you want to use as “POWER” and the display should increment to “111”

5. Press the key you want to use as “MUTE” and the display should increment to “222”

6. Continue to press keys one-at-a-time until you have entered all 14 buttons and the display is showing “EEE”

7. Push-in the rotary button (RE) to exit leaning-mode

8. Power off the DDX320.

9. Power on the DDX320 and it should now respond to the remote buttons it has learned as in Table3.


Note.1: You can exit the learning sequence at any time by a “push-in” of the rotary encoder (RE).

Note.2: The learning sequence is stored and remembered in the DDX320 at the first “power-off” after learning.

Note.3: If you make a mistake, just continue to push buttons to cycle through the sequence and back to “000”).

Note.4:    Saving of remote learning only works consistently if the power is cut instantly. This means that if you use a switched-mode power supply (SMPS) which has large value capacitors then the power will “fade away” and the setting will not be saved. If this occurs then temporarily install an “on/off switch” in the power lead to the DDX320.  Once learning is completed this “fix” is not needed anymore unless you want to learn a new remote. )


The remote control functions are listed in table3 below.


Table3. Remote key functions

4. Save settings and current state

All settings and the current channel and volume level will be saved on power down.


5. Installation

PCB size: 135 x 105mm