Block Diagram (Of the core Amplifier Module)
In below illustration a simplified block diagram of the SMA-1 hardware is displayed. The heart of the system is the
DSP which not only does the processing of the audio signals according to the needs of the user but also controls the
internal household of the whole module to ensure worry free reliable operation anywhere, any time in any conditions.
In the top-left side there are two balanced analog line inputs, one digital SPDIF/AES and one I2S input which all can
be processed by the DSP simultaneously.
Below, some lines intended to externally control the module are provided. There are some general purpose I/O lines
which can be used to connect external switches or indicating LED’s, some ADC inputs to connect for instance to an
external pot meter to implement volume control and last but not least a user selectable SPI/I2C serial interface to
enable external communication with more advanced user applications which may require this.
The SMA-1 also accommodates Auxiliary standby power for powering optional user applications (+ and – 15V) for
enabling low-standby power applications.
On the right side of the diagram you can see the two Digital to Analog converters which drive their corresponding
Class D amplifier which power the connected loudspeaker loads. The HF driver is powered by a single ended Class D
amplifier while the LF driver is powered by a Bridged Class D amplifier configuration. In the drawing it can also be
seen that the output current for both channels is sensed and fed back into the DSP which internally uses this for
protection purposes adding up to best reliability possible.
| General | ||
| Operating temperature range | 0 to +50°C | Full load over entire voltage range |
| Isolation | 3000VAC | Class I construction |
| Max. Operational Altitude | < 2000m | |
| Max. Standby Power | < 500mW | Module in Standby mode; User application < 10mW |
| Max. Active Idle Power | < 12W | Amplifier active; Channels not driven |
| Mains inputs | ||
| Input Voltage range | 100 – 240VAC | |
| Input Frequency | 50 – 60Hz | |
| Input Current | < 5A @ 230VAC | |
| Inrush Current | < 80A | Over entire voltage range |
| Input Protection | Internal T6.3AH/250VAC fuse | |
| Analog Audio Input | ||
| Input Impedance | 47k | |
| Max Full Scale Input Voltage | 21dBu | |
| Digital Audio Input | ||
| Digital I/O voltage levels | 3.3V | |
| Max Sample Rate | 192kHz | |
| Audio output channel 1 | ||
| Max. RMS Output Power | 750 W | @8Ohm, 1kHz, 1% THD |
| Max. THD+N | 0.01% | 20Hz – 20kHz; Pout < Pr/2 |
| Typ. CMRR | 70dB | |
| Max. Output Noise | 50uV | 20Hz – 20kHz |
| Min. SN Ratio | 100dB | |
| Frequency Response | 20Hz – 20kHz | |
| Audio output channel 2 | ||
| Max. RMS Output Power | 300W | @4Ohm, 1kHz, 1% THD |
| Max. THD+N | 0.01% | 20Hz – 20kHz; Pout < Pr/2 |
| Typ. CMRR | 70dB | |
| Max. Output Noise | 50uV | 20Hz – 20kHz |
| Min. SN Ratio | 100dB | |
| Frequency Response | 20Hz – 20kHz | |
| Auxiliary output voltage | ||
| Typ. Auxiliary Output Voltage 1 | 15V +/- 1V | Available in standby |
| Typ. Auxiliary Output Voltage 2 | 15V +/- 1V | Available in standby |
| Max. Auxiliary Output Current | 250mA | |
SMA-1
This self-powered Class D amplifier module is set out to be an easily customizable full turnkey solution targeting the active 2-way PA speaker market. The heart of this solution is a purposely designed amplifier module which basically has all the bells and whistles on board to easily adapt it to the customer’s wishes without the need for a long and expensive custom development trajectory. It combines the switch mode power supply, two class D power amplifiers, a powerful Analog Devices ADAU1462 DSP supported by high-performance AKM Analog to Digital (AK5552VN) and Digital to Analog (AK4452VN) conversion stages and all the necessary analog circuitry optimized for best sonic performance possible on a single very compact PCBA. The customizing is basically done by means of the small input connector PCB together with the mechanics which still allows you to determine the layout of the connectors and controls, possibly additional input sources like microphone inputs, BT and even network audio, the control over the advancedness of the user interface (i.e. graphic display or simple LED indicators). This will enable you to keep control over the general look of your brand.
The very basic customer implementation like the one pictured above would be a single Line Input, a Link Output, a volume knob and some status LEDs for signaling Power, Signal and Limit requires no advanced electronics knowledge at all it is basically just connecting wires and you are all set to go. Because of the very versatile input section of the core module, even the most advanced functionality can be designed with the absolute minimum of effort.
The integrated high-performance DSP enables the user to easily implement custom filter algorithms and thus creating their sound signature without having to worry about the hardware or any interconnections. Just connect an input signal, be it analog, digital or even wireless, connect the loudspeakers and plug it into any mains in any country and PLAY! Simple as that!