The active line array requires a separate speaker and amplifier for the woofer or subwoofer section, as well as an analog-to-digital (ADC) and a digital to analog (DAC) module for the woofer. There is also a small OLED display to monitor status and help with debugging.
Woofer/Sub amplifier
Woofer/Subwoofer amplifier module needs to be sized for the woofer and enclosure used with the line array. For the original line array built over 10 years ago, I used a commercial 300W plate amp for each tower. This was an appropriately sized amplifier for the 12″ Peerless XLS woofers in a sealed enclosure. For the newer line array described in this project, I used a “Ripole” configuration that uses 2 12″ woofers for each side. This enclosure uses an open-back design with less back pressure than a sealed enclosure, so the amplifiers don’t need to provide as much power to achieve large excursions. For the project with the Ripole woofer, I used a stereo TPA3255 amplifier for each side and used both channels for the two 12″ drivers. These modules are available for around $25-$40 and they require a 24V to 48V power supply. I used a relatively small 36V 100W Meanwell power supply for the woofer amplifiers, but obviously, you can use something larger if you need it.
Line array power supply
The power supply for the midrange and tweeter array doesn’t need to be much more than 80 to 100watts. The large number of motors in the array makes the speaker very sensitive, and it doesn’t require huge amounts of power to get reasonable room-filling output. I’m happy with a low-cost 15V 100W Meanwell power supply, but if you are trying for massive output, you could increase the power supply for the midrange/tweeter array to 150 or 200 watts.
ADC/DAC
The ADC module is the popular PCM1808 board that sells for $4 to $7 on Amazon, eBay or the overseas vendor bazaars. This board is only for bringing in TV or other medium-fidelity analog signals, and the 24-bit 105dB SNR specification is fine for those inputs.
The DAC module is the PCM5102 board that is sometimes called “GY-PCM5102”. It is a commonly used board for the Raspberry Pi CPU, and you can buy it for $7 to $9 on Amazon. Both the ADC and DAC boards are often available in 5-packs or 10-packs that get the unit cost in the $3 to $4 range.
OLED Display
The OLED display is the 4-pin I2C board that uses the SSD1306 controller with a 128×64 pixel panel. The board doesn’t take up much space on the motherboard, but it can display 8 rows of information with 20 characters in each row. That’s enough text to provide a continuous update on all 5 amplifier boards. It can also be used for debugging or status without having to hook up an external computer to the CPU serial monitor. Thes boards are available from Amazon in 5-packs for around $15.