What is it

Louder-ESP32-Plus combines ESP32 with an external I2S DAC with powerful DSP features, capable of driving full-size speakers. This combination provides your compact and efficient ESP32 module with the necessary memory and capabilities to stream high-quality audio.

• TAS5825M DAC with integrated DSP
• Digital volume control (avoids loss of resolution compared to software volume)
• Gain digital control
• Parametric EQ (15xBQ), 128-tap FIR, 3-band DRC, AGL
• Advanced DSP: Smart Excursion, Smart Thermal, Smart Bass, SmartEQ

Use cases

Louder-ESP32-Plus is a flexible, open-source audio platform designed to fit into both smart homes and custom audio projects.

• Smart Home Audio & TTS
  Integrates with Home Assistant and Music Assistant for high-quality audio playback and text-to-speech announcements. Perfect for notifications, voice alerts, and whole-home audio driven by your smart home automations.
• Multi-Room Audio with Snapclient
  Use Louder-ESP32-Plus as a Snapclient endpoint to create perfectly synchronized multi-room audio systems. Ideal for distributed music playback without proprietary lock-in.
• Standalone Player with Squeezelite-ESP32
  Run Squeezelite-ESP32 for a self-contained network audio player supporting Spotify Connect, AirPlay, and Logitech Media Server (LMS) — no external computer required.
• Educational Projects & Teaching Platforms
  A powerful tool for schools, universities, and technical education. Louder-ESP32-Plus can be used to teach embedded systems, digital audio, networking, and open-source software — ranging from simple audio playback labs to advanced DSP, streaming, and real-time systems projects.
• Research, Prototyping & Experimentation
  Well-suited for rapid prototyping of audio devices, proofs-of-concept, and research projects involving DSP, low-latency streaming, wireless audio, or human-machine interaction.
• A Foundation for Custom Products & DIY Builds
  With all firmware and tooling fully open source, Louder-ESP32-Plus is an ideal base for custom audio devices — whether you’re building a personal DIY project, a small production run, or a community-driven product.

Features

⚠️ Louder boards will connect to passive speakers; you can't use headphones or an external amp

💡 Need to connect an external amp? Check out HiFi-ESP32 / HiFi-ESP32-Plus and Amped-ESP32 / Amped-ESP32-Plus

💡 Don't need DSP capabilities? Check out Loud-ESP32 / Loud-ESP32-Plus

💡 Looking for a more feature-packed version? Check out Louder Esparagus and Esapragus Audio Brick

Onboard PSRAM

Audio streaming requires proper buffering to work, even with the ESP32's 500K of RAM; it is a challenging task. For that reason, all Louder-ESP32-Plus board versions have an 8 MB PSRAM chip onboard, connected via a high-speed interface.

Which chip: ESP32 or ESP32-S3?

This board is available with either the 'classic' ESP32 or the newer ESP32-S3. They are not interchangeable for every use case, and picking the wrong one is the single most common support question — here's the short version:

• ESP32-S3 is the newer, more capable chip — more RAM headroom, a faster CPU, and native USB — but it has no Bluetooth Classic radio, so Bluetooth A2DP only works on the original ESP32.
• Squeezelite-ESP32 and standalone Snapclient: pick the classic ESP32. Neither firmware is fine-tuned for the S3 yet, and current S3 support is noticeably laggier.
• ESPHome / Home Assistant media player: pick ESP32-S3. The new Sendspin renderer runs much better on the S3's extra headroom.
• Voice assistant (wake word) in Home Assistant: ESP32-S3 is mandatory — the classic ESP32 doesn't have the RAM/CPU headroom to run it.
• AirPlay 1 & 2 (rbouteiller/airplay-esp32): both chips are fully supported; ESP32-S3 is preferred for its extra performance headroom.

If none of that applies to you and you just want the safe default, pick ESP32-S3 — it's the newer chip. Only choose classic ESP32 if you specifically need Bluetooth A2DP, or plan to run Squeezelite-ESP32/Snapclient today.

Board Pinout

Louder-ESP32-Plus

Ethernet

Optional peripheral

Mic header

Both versions of the Louder-ESP32-Plus boards have an unsoldered header for external I2S mic: left and riggh channels. ESP32 uses the same I2S bus with an extra DATA IN pin due to the pin limitations, while S3 uses a dedicated I2S bus. It can be used for wake word functionality in the Home Assistant or for custom firmware.

The mic model that I used for testing and validation is the INMP441 MEMS microphone; the pinout is created for this model. Other models might be available.

Software Options

• Home Assistant smart home audio and notifications. Start from the web-installer, as soon as you configure WiFi, the boards will be discovered by the ESPHome add-in automatically. Dedicated configs can be found in the documentation for simple and stable media-player, experimental sendspin protocol, and experimental snapclient component
• Squeezelite-ESP32 Spotify Connect, AirPlay, Bluetooth or Logitech Media Server. Flash directly from your browser using the web-installer. Configure WiFi using Hotspot (default password: squeezelite). Don't forget to exit Recovery mode when done.
• Snapclient multi-room audio streaming with snapserver. Flash directly from your browser using the web-installer, as soon as you configure the WiFi board will discover the snapserver automatically
• Snapclient (edge) - developer version. Developer's version of the snapclient, less stable and more feature-rich for those who cannot wait for new features to be released. Installed via web-installer, similar to standard snapclient
• AirPlay 1 & 2 with Sendspin, Bluetooth, and full DSP control. Native, actively developed AirPlay 1 & 2 firmware (rbouteiller/airplay-esp32) with PTP multi-room sync, an experimental Sendspin renderer, Bluetooth A2DP on the ESP32 revision, and full 15-band DSP control over the TAS5825M from the board's web UI. Flash straight from your browser with the web-installer — no toolchain needed. See AirPlay 2 support below for details.
• Your own software. Use Arduino IDE or Platformio IDE and the provided software samples

AirPlay 2 support

Louder-ESP32-Plus runs rbouteiller/airplay-esp32, an open-source AirPlay 1 & 2 receiver you can flash straight from your browser via the web-installer — no PlatformIO or toolchain required. It's a separate firmware image from Squeezelite-ESP32 and Snapclient above, so flash whichever matches how you want to use the board.

• AirPlay 1 & 2 — shows up natively in Control Center and any AirPlay app, with PTP-based multi-room sync
• Sendspin (experimental) — an open multi-room protocol renderer sharing the same output path, DSP, and volume control as AirPlay
• Bluetooth A2DP on the ESP32 revision — phones and laptops can stream directly whenever AirPlay is idle (the ESP32-S3 revision has no Bluetooth Classic radio)
• OLED status display — track metadata and progress for AirPlay, Bluetooth, and Sendspin alike
• USB audio (UAC) — the ESP32-S3 revision can be built as a USB sound card for a connected computer, sharing the same DAC path and DSP
• Full DSP control — the TAS5825M's on-chip EQ is fully exposed: 15 cascaded biquad sections per channel, each an arbitrary peaking filter, shelf, high/low pass, band pass, notch, phase shift, or raw coefficients, plus a crossover builder and full PurePath Console 3 tuning replay for tone, loudness, and DRC beyond the EQ page — all from the board's web UI

TAS58xx DSP: full parametric EQ and crossover control

AirPlay 2 support above isn't just playback — it exposes the TAS5825M's on-chip DSP in full from the board's web UI:

• 15 biquad (BQ) filters per channel, usable as a full 15-band parametric equalizer
• Bi-amp filter configuration for 2-way speaker systems — split the signal between tweeter and woofer with independent filter chains per amplifier
• Low-pass filtering for subwoofer tuning and bass enhancement
• Generic filters for speaker and room equalization — peaking filters, shelf filters, and EQ sections with a configurable Q-factor, applied per channel individually or to both at once

A	B

Work in progress: REW (Room EQ Wizard) integration, to drive automatic room-correction algorithms directly from a measured response.

Using with Home Assistant

Both Louder-ESP32 Plus versions were created specifically to be used with Home Assistant via ESPHome integration. For both boards, rich configs were pre-created with hardware configuration for common use cases. These include

• media_player component for simple and robust media playback and TTS announcements (with ducking effect)
• Sendspin media player – new experimental protocol for multi-room sync with media controls and more
• An experimental snapclient component that allows near-perfect multi-room sync and seamless integration with Music Assistant
• Another snapclient fork with an implemented 15-band software equalizer and a rich set of EQ presets
• Voice assist config for S3-based boards, allowing local voice-controlled assist and automation

Configurations are being actively maintained and upgraded, new experimental components added for you to test and enjoy

Flashing ESP32-S3

ESP32-S3 boards have two ways of firmware update: (1) similarly to classic ESP32, they can be flashed over built-in UART, or (2) uniquely for S3, over built-in USB host controller. Since it is firmware-controlled, it may be disabled if not used (or, more commonly, not available with factory default empty firmware). When come unflashed ESP32-S3 device comes into a boot loop, with a USB-CDC device appearing and disappearing every second, and requires a special flashing initialisation sequence to get flashed:

• Press the IO0 (FLASH) button and keep it pressed
• Press and release the RESET button. Release the FLASH button.
• ESP32-S3 will enter download mode, and the USB-CDC device will appear and stay available
• Run flashing routine as usual, either through web-serial or esp_tool
• This time, it is not possible to reboot the device over USB, so press RESET once more
• Device will boot normally into firmware, and if USB-CDC is enabled in the firmware, you will be able to flash it normally, download mode and reset sequence will work over USB.
• If you manage to flash firmware without USB-CDC support, you need to go through the above sequence once more

Hardware

Please visit the hardware section for board schematics and PCB designs. Note that PCBs are shared as multi-layer PDFs.

Optional Ethernet

Every board has a header that allows soldering in the W5500 SPI Ethernet module, which is very easy to find. The only downside is that with the module installed, the board will not fit the case unless it is cut to accommodate extra height.

Case

Louder-ESP32 and Louder-ESP32-Plus boards are mechanically compatible with Raspberry Pi 4 cases, and they are very easy to source

Louder-ESP32-Plus

BTL and PBTL mode (TAS5825M DAC)

TAS5825M DAC Allows 2 modes of operation - BTL (stereo) and PBTL (parallel, or mono). In Mono amp will use a completely different modulation scheme and basically will fully synchronize output drivers. Jumpers on the board allow both output drivers to connect to the same speaker. The most important step is to inform the Amp to change modulation in the first place via I2C command. In the case of sqeezelite DAC controls, the set value is the following:

dac_controlset: {"init":[{"reg":3,"val":2},{"reg":3,"val":3},{"reg":2,"val":4}],"poweron":[{"reg":3,"val":3}],"poweroff":[{"reg":3,"val":0}]}

compared to default: dac_controlset: {"init":[{"reg":3,"val":2},{"reg":3,"val":3}],"poweron":[{"reg":3,"val":3}],"poweroff":[{"reg":3,"val":0}]}

One can test audio with a single speaker connected between L and R terminals (plus on one side and minus on the other). Optionally, jumpers on the board will effectively connect the second driver in parallel, doubling the current capability.

Important point, this will send only one channel to the output, that’s just how the DAC works. True mono as (L+R)/2 is possible via more in-depth configuration (very poorly documented), but I haven’t managed to configure that on the stand. I’m still working on that. (Along with a few more really cool DSP features that this DAC has, like EQ, subwoofer mode and tone compensation settings)

	BTL	PBTL
Descriotion	Bridge Tied Load, Stereo	Parallel Bridge Tied Load, Mono
Rated Power	2×23W (8-Ω, 21 V, THD+N=1%)	45W (4-Ω, 21 V, THD+N=1%)
Speaker Connection

TAS5825M DSP capabilities

The TAS5825M DAC has a very powerful DSP, which allows doing lots of data processing on the silicon, that otherwise would take a considerable part of your CPU time. As of the moment of writing it is mostly an undiscovered part of the DAC, since unfortunately, TI is not making it very easy for developers. (A minute of complaint) To be more specific, you need to be (A) a proven hardware manufacturer to get access to the configuration software, namely PurePath. (B) you need to apply for a personal license and go through an approval process, and after a few weeks of waiting you get access to one DAC configuration you asked for. (C) You find out that it will work with TI's own evaluation board that will set you back $250 if you'd be able to find one. Otherwise, all you have is a list of I2C commands that you need to transfer to the device on your own cost. No wonder no one knows how to use it.

But moanings aside, what do you get after:

• Flexible input mixer with gain corrections
• 15 EQ with numerous filter configurations
• 3-band Dynamic Range Compression with flexible curve configuration
• 128-tap FIR filter
• Automatic Gain Limiter with flexible configuration
• Soft clipper
• Smart Excursion, Smart Thermal, Smart Bass, SmartEQ - not really sure what they do though

At this moment, I'm adding the most useful features one by one, focusing on EQ and Bi-amp filtering capabilities. All of the above are available right now for experimentation. I'm keen to hear your feedback while I'm moving forward with porting this to other software options

• [ ] - espragus-snapclient software with self-hosted UI
• [x] - ESPHome component with on-the-fly configuration changes
• [ ] - squeezelite-esp32

Sponsorship & Community Support

If you’re working on an open-source project, an educational initiative, or any pro-bono/volunteer effort, feel free to reach out for sponsorship details. I’ll do my best to provide discounts or even free boards.

Custom Design & Consultation

If you’re interested in a custom design based on or inspired by my boards, I also offer contract design work and consultation when needed.

Video review

Nice video review of the Louder-ESP32-based project performed by tmuWolverine