Comm-Tec MMA220 User manual

Mini Digital Amplifier, with MIC Mixer and EQ
1
MMA220
Mini Digital Amplifier, with EQ/Mixer
Index:
1. General Instruction ................................................................2
2. Product Picture.......................................................................2
3. Features..................................................................................3
4. Specification..........................................................................4
5. Audio Connection..................................................................5
6. Buttons Controlling ...............................................................6
7. RS232 Communication Protocol...........................................8
8. System Diagram...................................................................10
9. Panel Drawing .....................................................................11
USER MANUAL

Mini Digital Amplifier, with MIC Mixer and EQ
2
1. General Instruction
MMA220 is a small digital amplifier (Class-D), with EQ control and MIC mixer function.
It is compact-size but powerful functions, including the bridge connection, dual-mono,
EQ control, microphone mixer etc.
It has a good application in different places, including classroom, small meeting room,
lecture hall, bar, pub etc.
2. Product Picture
Front Panel
Rear Panel
Top Panel

Mini Digital Amplifier, with MIC Mixer and EQ
3
3. Features
2x20Watt@4Ohm as the default amplifier output.
Bridge connection function. The user can switch the MMA220 to be
1x40Watt@8Ohm by bridge connection.
Dual-mono function. The user can sum up the stereo audio to two times mono
audio.
Microphone mixer function. The microphone will be mixed to the line
audio output, and separately controllable.
Ducking power technology. It keeps detecting the audio and MIC input,
and reducing the power consumption when there is no inputs coming.
Two stereo audio inputs, switchable by button, remote or RS232.
Volume/Bass/Treble controllable by buttons or RS232
Line audio output, with volume controllable.
Optional control solution, by IR remote or volume panel.
RS232 controlling function, with smart feedback.
Antistatic case design: providing good protection for long-term and stable
performance
Internal international power supply (100Volt~240Volt AC, 50/60Hz) For
worldwide compatibility.
Fast switching speed. It is the high speed for the good performance.
LED indicator, for power and working status.

Mini Digital Amplifier, with MIC Mixer and EQ
4
4. Specification
Audio Input
Audio Output
Input
2 stereo audio,
1 MIC
Output
1 amplifier,
1 stereo audio
Input Connector
2 RCA
1 3.5mm jack
1 6.5mm jack
Output Connector
1 3.5mm jack
1 captive screw connector, 4
pole
Input Impedance
>10KΩ
Output Impedance
50Ω/stereo, 4~8Ω/Amplifier
Audio General
Frequency
Response
20Hz ~ 20KHz
CMRR
>70dB@20Hz~20KHz
SNR
80dB at maximum output
Bandwidth
20Hz ~ 25KHz
Stereo Channel
Separation
>75dB@20Hz to 20KHz
THD + Noise
1%@1KHz, 0.3%@20KHz at
nominal level
Voltage Gain
32dB
Power Output
20 Watts X 2 (4 Ohms)
Control Parts
Serial Control Port
RS-232, 9-pin female D
connector
Pin Configurations
2 = TX, 3 = RX, 5 = GND
NOTE: All nominal levels are at ±10%.

Mini Digital Amplifier, with MIC Mixer and EQ
5
5. Audio Connection
5.1 Default output: 2x20Watt@4Ohm
The default output of amplifier is 2x20Watt@4Ohm. So, the user can connect the
amplifier output in the regular way.As the picture below:
5.2 Bridge connection: 1x40Watt@8Ohm
The MMA220 has the bridge connection, to double the output power at
1x40Watt@8Ohm. It will sum up the input left channel and input right channel to be
mono output, and the power is up to 40Watt.
The bridge connection is:
1x40Watt@8Ohm
2x20Watt@4Ohm
Switching to the
“STEREO”
Switching to the
“BRIDGE”
Connecting the two pins, like this
Connecting the four pins, like this

Mini Digital Amplifier, with MIC Mixer and EQ
6
5.3 Dual-mono output:
The MMA220 also has the function of double-mono output. It can sum up the left and
right channel, to be the mono audio output. In this way, the both of the outputs are
showing the same mono audio.
The connection is:
6. Buttons Controlling
The buttons provides the control of volume/EQ control and switching.
6.1 Audio switching:
There are two switchable stereo audio inputs, one 2xRCAinput, one 3.5mm jack input.
It can be switched through the buttons as below:
6.2 Volume/EQ controlling:
Source
Selection
Switching to the
“MONO”
Connecting the four pins, like this

Mini Digital Amplifier, with MIC Mixer and EQ
7
The line volume and Microphone volume can be controlled by the buttons.
The Mic Volume/Line volume/Line bass/Line treble will be selected by the buttons,
and controlled up/down/mute by the function buttons. Please check the picture below:
For example, to turn up the line volume, you should select the “LINE” first, and then
press the button “ ”.
Select the function from this
menu in advance
Turn up/down the level.
Or mute the line volume

Mini Digital Amplifier, with MIC Mixer and EQ
8
7. RS232 Communication Protocol:
Baud rate: 9600 Data bit: 8 Stop bit: 1 Parity bit: none
Command
Function Desctription
Feedback Code
1A1.
Switching the audio to input 1
A: 1 -> 1
2A1.
Switching the audio to input 2
A: 2 -> 1
0A0.
Mute Audio of MIC and Line out
Mute Audio
1A0.
Mute audio of MIC
Mute MIC
2A0.
Mute audio of line out
Mute LIN
0A1.
UnMute Audio
UnMute Audio
600%
Checking the working status
A: 1 -> 1
Volume :30
Bass 00
Treble 00
601%
MIC volume up
Volume of MIC : 51
602%
MIC volume down
Volume of MIC : 51
603%
Line volume up
Volume of LINE : 51
604%
Line volume down
Volume of LINE : 51
605%
Bass level up
Bass of LINE ：04
606%
Bass level down
Bass of LINE ：04
607%
Treble level up
Treble of LINE : 04
608%
Treble level down
Treble of LINE : 04
609%
Initialization, back to the default setting
A: 1 -> 1
Volume :50
Bass 07
Treble 07

Mini Digital Amplifier, with MIC Mixer and EQ
9
Command
Function Desctription
Feedback Code
5[x][x]%
Preset MIC volume, [xx] is aranging from [00]
to [60].
61 degrees in total.
Volume of MIC :50
7[x][x]%
Preset line volume, [xx] is aranging from [00]
to [60].
61 degrees in total.
Volume of LINE :50
8[x][x]%
Preset the bass level, [xx] is aranging from [00]
to [08].
9 degrees in total.
Bass of LINE : 04
9[x][x]%
Preset the treble level, [xx] is aranging from
[00] to [08].
9 degrees in total.
Treble of LINE : 04
Notice:
1: The letter inside bracket [ ] is the variable code, which is the changeable.
2: The bracket [ ] is not included to the RS232 commands.
3: Any dot “.”after the letters is part of the commands.
4: At the end of each command sent to the amplifier put a <CR> <LF>
5: The feedback is always without <CR><LF>
Example 1
Switching the input 2 to the line out. We should send the RS232 command: [2A1.]
Example 2
Turning up the volume of line audio. We should send the RS232 command: [603%]
Example 3
Preset the MIC volume to be “21” degree. We should send the RS232 command:
[521%]
Example 4
Checking the working status of MMA220. We should send the RS232 command:
[600%]

Mini Digital Amplifier, with MIC Mixer and EQ
10
8. System Diagram
2x20Watt@4Ohm
Looping connection
1x40Watt@8Ohm

Mini Digital Amplifier, with MIC Mixer and EQ
11
9. Panel Drawing
Unit: mm