Availability

The new batch is coming from the factory and should be in stock by early January. It introduces an updated and improved board layout and lays the foundation for the upcoming dual DAC version of the board. I'm working towards delivering a DSP Linux driver for the board (in 2.0, 1.1, and 0.1 modes), adding dual DAC support for the 2.1 speaker config later.

What is it?

The Louder Raspberry Pi Hat is a cost-effective version of the Louder Raspberry Pi Home Media Center. It combines the power of the Raspberry Pi SBC and the Hi-Fi audio capabilities of the TI’s TAS5805M DAC with a highly efficient D-Class output stage.

Louder Raspberry Pi Hat drops the USB-PD in favor of an external power supply up to 28V (opposed to 20V over PD) and has a step-down converter onboard to deliver 5V to the Pi, so you need only a single power source for everything. Otherwise, it delivers audio through the same highly capable DAC, capable of driving large speakers or tearing apart small ones.

Why did I build it

I did few audio projects in the past, some using ESP32, some using larger Orange Pi and Raspberry Pi devices. Each has its pros and cons, and with each iteration, I'm trying to focus on the details that were working best for me, while actually using them.

What is special about the Raspberry eco-system is of course its community support. Being a not-so-strong software developer, I often have to rely on the work that other people did and baked into the base Raspbian image. Enabling an IR reader is as simple as adding a line into the config.txt file. Adding DAC is a 5-minute job (with attached code). All the device tree definitions, kernel drivers, and dependency packages are already in place.

Sure, compared to the ESP32 platform it is not as lightweight. It requires more power, it takes some time to boot. But when it comes to rapid development, there is nothing like the Raspberry Pi.

Louder Raspberry Pi Hat

Louder Raspberry Pi is a top-of-the-range model that uses a modern highly capable TAS5805M DAC and is aimed to be paired with medium-to-large speaker systems. With up to 30W per channel stereo output, it packs a punch and can easily enliven living quarters or dorm rooms. It is highly efficient, but much more demanding for power when cranked, therefore it uses an external power adapter with up to 28V voltage reading (starting from as low as 7V).

Key features

	HiFi Raspberry Media Center	HiFi Raspberry Hat	HiFi-Amped Raspberry Pi Hat	Loud Raspberry Media Center	Loud Raspberry Hat	Louder Raspberry Media Center	Louder Raspberry Hat
Image
DAC	Single PCM5100A 32bit Stereo DAC	Dual PCM5100A 32bit Stereo DAC	Dual PCM5100A 32bit Stereo DAC working with TPA3110D2 D-Class amp	Dual I2S DAC MAX98357 with built in D-Class amp	Quadruple I2S DAC MAX98357 with built in D-Class amp	Stereo I2S DAC TAS5805M with built in D-Class amp	Stereo I2S DAC TAS5805M with built in D-Class amp
Output	2.1 VRMS Line level output -100 dB typical noise level	2x 2.1 VRMS Line level output -100 dB typical noise level	4x 25W (8Ω, 1% THD+N) at 22V; 4x 22W (4Ω, 1% THD+N) at 16V 2x 40W (4Ω, 1% THD+N) at 20V	2x 3W (8Ω); 2x 5W (4Ω)	4x 3W (8Ω); 4x 5W (4Ω)	2x 22W (8Ω, 1% THD+N); 2x 32W (4Ω, 1% THD+N) at 20V 1x 45W (4Ω, 1% THD+N) at 20V	2x 32W (8Ω, 1% THD+N) at 24V 1x 55W (4Ω, 1% THD+N) at 24V
RGB LED	yes	none	none	yes	none	yes	none
IR input	yes	header only	none	yes	none	yes	header only
External relay driver	yes	none	none	no	none	yes	none
Onboard Serial Bridge	yes	none	none	yes	none	yes	none
Ethernet	Wiznet W5500 SPI Ethernet	none	none	Wiznet W5500 SPI Ethernet	none	Wiznet W5500 SPI Ethernet	none
Powers from	5V USB-C power adapter (up to 1 A) Triple LP5907 3.3 V Ultra-Low-Noise LDO	5V from the host 5x LP5907 3.3 V Ultra-Low-Noise LDO	8..26V from external sourcepowering host (up to 3A cont.)	5V USB-C power adapter (up to 3 A)	5V from the host (up to 4A) or 5V from screw connector (powering host)	65W USB-C PD power adapter (25W/45W with limited power)	7..28V from external sourcepowering host (up to 3A cont.)
Mechanical dimensions (WxHxD)	88mm x 38mm x 100mm	65mm x 30mm x 15mm	70mm x 61mm x 20mm	88mm x 38mm x 100mm	65mm x 30mm x 20mm	88mm x 38mm x 100mm	65mm x 56mm x 20mm

Board Pinout

How to use

You can use any distribution you like. To enable the IR reader you need to add 1 line to the /boot/config.txt

dtoverlay=gpio-ir,gpio_pin=17

TAS5805M DAC is not supported by default Raspbian distribution, therefore some work needs to be done to enable it. Linked repo contains code and instructions on how to configure it. It will take you 5 minutes and one reboot.

Other software options

The project repository provides a few examples with build instructions, including Volumio setup instructions, among others.

Hardware

Please visit the hardware section of the project repo for board schematics and PCB designs. Note that PCBs are shared as multi-layer PDFs as well as Gerber archives.

PCB diagram

Image

IR reader

Please follow this guide to configure an IR reader

TAS5805M DSP Capabilities

TAS5805M DAC (and his big brother TAS5825M) has quite a sophisticated DSP inside, which is mostly undiscovered by the community at the moment. Documentation of it is scarce. The only reasonable way to use it is to obtain a TI PurePath license and Hardware Development kit ($250 if you find it). This should allow the following skills

• 2.0, 1.1, 2.1, 0.1, and pretty much any other speaker configuration
• Loudness correction (or Tone correction)
• Soft clipping
• Individual EQ (16 of them I think)
• True mono and other routing configurations
• And many more

Power considerations

Below are the power requirements for different Pi models

Consider expected audio output to be a part of the power budget and buy a reasonable power source capable of delivering the sum of Pi and audio requirements with a reasonable margin of 15%+

In the extreme scenario, using 2 channels with 4 Ohms load with Pi5 you'd need (15W [Pi] + 60W [audio]) * 1.2 = 90W, round up to 100W.