Speakeasy Firmware

Ready-made ESP32-S3 multi-room audio hardware and firmware.

Low Cost (off-the-shelf only)

A ~$30 per-room speaker using off-the-shelf modules and no soldering beyond wire terminals.

Parts

Part	Qty	Price	Link
ESP32-S3 Supermini	1	~$4.25	Amazon B0GS283V6F
MAX98357A I2S amplifier breakout	1	~$2.00	Amazon B0B4GK5R1R
Saiyin 3" wall-mount passive speaker	1	~$18.00	Amazon B0DGLMY9SB
Dupont jumper wires F-F (recommend 10 cm)	5	<$1.00	Amazon B07GD312VG
USB-C power supply + cable	1	~$4.50	Amazon B08G4GRQYV
Total		~$29.75

Wiring

MAX98357A pin	ESP32-S3 Supermini pin
BCLK	GPIO 11
LRC	GPIO 10
DIN	GPIO 12
VIN	5V
GND	GND
Speaker+/−	Speaker terminals

Setup

Wire the MAX98357A to the ESP32-S3 Supermini as above.
Connect the speaker to the MAX98357A output terminals.
Plug the ESP32-S3 into USB and flash firmware from the Flash tab.
Provision WiFi credentials via Improv Serial (USB, all builds) or Improv BLE (requires a Bluetooth-enabled build).
Add the device to Music Assistant or your Snapcast server.

⚠ These are experimental development builds. Expect bugs.

Plug in via USB and flash below. Requires Chrome or Edge, or Firefox with the WebSerial extension.

Hardware pin mappings

Hardware	Signal	GPIO	Component
OTS	LRCLK	4	MAX98357A
	BCLK	5	MAX98357A
	DOUT	6	MAX98357A
PCB	LRCLK	6	MAX98357A
	BCLK	5	MAX98357A
	DOUT	4	MAX98357A

Hardware

Off-the-shelf is the generic ESP32-S3 Supermini — hand-wired or on the Speakeasy Lowcost PCB — with LRCLK/BCLK/DOUT on GPIO 4/5/6. PCB is the custom Speakeasy board (ESP32-S3-MINI-1U-N4R2), which uses the same three pins but swaps LRCLK and DOUT: DOUT/BCLK/LRCLK on GPIO 4/5/6.

OTSESP32-S3 Supermini

PCBCustom Speakeasy board

Protocol

The audio streaming protocol. Sendspin integrates natively with Music Assistant for synchronized multi-room audio. Snapcast (ESPHome) wraps CarlosDerSeher/snapclient with Home Assistant integration. Snapcast (standalone) runs CarlosDerSeher/snapclient bare on ESP-IDF with no ESPHome or HA integration.

SendspinMusic Assistant

SnapcastESPHome + HA

Snapcast (standalone)bare ESP-IDF

Bluetooth

BLE is used for WiFi provisioning via Improv — configure WiFi credentials from a phone without USB. Disabling it frees ~100 KB of RAM and is recommended once the device is set up.

Disabledmore free RAM

EnabledWiFi setup via BLE

Pull OTA

Pull OTA lets the device fetch and flash firmware from a URL via its web UI.

Enabledupdate from web UI

Disabled

Use Chrome, Edge, or Firefox + WebSerial Requires HTTPS

Memory usage (idf.py size)

Changes vs upstream snapclient

Based on CarlosDerSeher/snapclient with the following additions:

Exponential volume curve — maps the volume slider to perceived loudness using a dB-range exponential curve; range (0-90 dB, default 40 dB) is adjustable in the DSP settings page and persisted to NVS.
Channel routing — runtime Stereo / Left Only / Right Only / Mono mode in the general settings page, persisted to NVS. Enables two speakers to act as a stereo pair; Mono mixes L+R to both outputs.
WiFi TX power — slider in the general settings page (dBm), applied at boot and live on change, persisted to NVS. Useful for compact PCB antennas that self-interfere at high power.
Web OTA (push) — firmware updates over WiFi via a browser UI at /ota-update.html or POST /api/ota/upload. Displays current and pending firmware details (version, build date, SHA256) side-by-side before flashing. The OTA binary is also available for download above.
Web OTA (pull) — device fetches a manifest URL (POST /api/ota/pull), version-checks against running firmware, then downloads and flashes the listed binary with SHA-256 integrity verification. Pre-configured to pull from this page.

Source on GitHub.