Sound cards and amplifiers

The Raspberry Pi has a headphone jack of its own (not on the Zero models). For better sound, or a speaker without a power supply of its own, add a sound card or an amplifier board that sits on the pin header. This page is about those. A USB speaker or a Bluetooth speaker needs none of it: see Sound and Bluetooth.

All sound cards are set up the same way:

1. Choose the card in the question Which sound card sits on the header? of lauschctl setup, or later with lauschctl setup hardware. HiFiBerry boards that name themselves (via the HAT EEPROM) are recognised and preselected.
2. lauschctl setup raspi writes the matching line (dtoverlay=...) into /boot/firmware/config.txt, switches the Pi’s own audio off and keeps a backup (config.txt.backup).
3. Restart the box (sudo reboot).

The web page (Settings → Hardware) shows the device, which pins are used, and while a change is still waiting for the restart. If a card is attached but not set up, the player shows a note.

HiFiBerry

The DAC+ was recognised and set up on a Pi 3. The other boards are not tested on real hardware yet.

HiFiBerry DAC+, DAC2 HD, DAC+ ADC, Digi+ and the like, and cheap boards with a PCM5102A. The boards with an EEPROM are recognised; the Amp and Amp+ (and boards without an EEPROM) you choose yourself from the list.

The boards sit on the 40-pin header. If you need the other pins for buttons or a reader, you can wire the board separately; it needs these pins:

Board pin name	Board pin	Raspberry Pi pin	Name
3.3V	1	1, 17	3V3
5V	2	2, 4	5V
GND	6	6, 9, 20, 25	ground
PCM_CLK	12	12	GPIO18
PCM_FS	36	36	GPIO19
PCM_DIN	38	38	GPIO20
PCM_DOUT	40	40	GPIO21

Raspberry Pi pin overview. Setup after the instructions of HiFiBerry.

MAX98357A (I²S amplifier)

A small amplifier for one speaker that needs no driver beyond the overlay. Choose max98357a as the sound card.

MAX98357A	Raspberry Pi	Pin
VIN	5V	2 or 4
GND	ground	6
BCLK	GPIO18 (PCM_CLK)	12
LRC	GPIO19 (PCM_FS)	35
DIN	GPIO21 (PCM_DOUT)	40

GAIN and SD can stay open (normal gain, amplifier always on).

The board has no volume control of its own. The box sets the volume in software. If it is too loud or too quiet at the same setting, change volume.mixer and the output’s volume_limit in the settings.

Known problem: the amplifier can click when it starts. The box plays a short silence first and fades in, which makes the click smaller but does not remove it. A fix is being worked on: the box would switch the amplifier on only after the sound has started, using a pin connected to SD.

Pimoroni pHAT BEAT (Pirate Radio)

The pHAT BEAT, for example in the Pirate Radio kit, has a DAC with amplifier, six buttons and two rows of eight RGB LEDs. It is in daily use in a Pirate Radio.

1. Answer yes to “Is a Pimoroni pHAT BEAT attached?” in lauschctl setup (or switch on the plugin Pimoroni pHAT BEAT under Settings → Plugins and restart).
2. lauschctl setup raspi, then restart. This switches the DAC on and the on-board audio off.

Button	Pin	Does
Play/pause	GPIO6	player.toggle
Next	GPIO5	player.next
Previous	GPIO13	player.prev
Volume up	GPIO16	+5, repeats while held
Volume down	GPIO26	-5, repeats while held
On/off	GPIO12	shuts down when held for 2 seconds

Each button can run any other action instead. The LEDs show the volume after a change and light green for a known card and red for an unknown one. With leds: vu they also show the level of the music while it plays. leds: off leaves them dark and frees their pins; animations: false switches off the animation at start and shutdown; colors picks classic, rainbow, ocean, sunset, unicorn, forest or fire; reverse: true turns the bars round if the HAT sits the other way. The on/off button only shuts the system down; the Pirate Radio has no circuit that cuts the power.