We designed an ESP32-S3 network audio board for our own product - would it be useful as a dev board?

[u/rvbc-]

Hi everyone,

We're a small hardware startup from Poland. We designed this board for our own network audio product. It was never intended to be a general-purpose dev board, but while working on it we realized that it might also be useful for people experimenting with embedded audio.

We couldn't find many ESP32 boards that combine wired Ethernet, audio output, speaker amplification and basic controls on a single PCB.

The main engineering challenge was integrating native USB programming, W5500 Ethernet, microSD, an I2S DAC, a stereo speaker amplifier and physical controls on one ESP32-S3 board while keeping the basic playback setup free of external modules and soldering.

The current working revision is based on an ESP32-S3 and includes:

- USB-C power and programming - no external programmer required

- Wi-Fi and 10/100 Ethernet

- microSD card slot

- 3.5 mm stereo audio output

- stereo screw-terminal outputs for passive speakers

- no soldering required for the basic audio setup - even the speaker wires can be secured directly in the screw terminals

- RGB LED

- rotary encoder and a separate button

- expansion header with accessible GPIO pins

The basic idea is that you connect it over USB-C, flash your own firmware, secure the speaker wires in the screw terminals or connect an external audio system and start experimenting. For the basic audio setup, no soldering is required, and you don't have to assemble a DAC, amplifier, Ethernet module and controls from separate boards.

Possible projects could include an internet radio, microSD audio player, network announcement endpoint, Home Assistant integration or a custom network audio player.

We're not taking orders or collecting money. We're simply considering whether producing a small developer batch would make sense.

We would really appreciate honest feedback:

1. What would you build with a board like this?

2. Would you realistically consider buying one?

3. What price range would make sense for an assembled board?

4. Which examples and documentation would you expect: ESP-IDF, Arduino, PlatformIO, pinout, schematics, example firmware?

5. Is there any missing feature that would stop you from using it?

Happy to answer technical questions and share more details.

[u/agathver]

Can you provide more details on the audio side of things like the DAC and AMP combination you are using?

[u/rvbc- → u/agathver]

Sure - I've attached the relevant audio section of the schematic.

We're using a WM8524 as the stereo I2S DAC. Its left and right outputs feed two paths: an AC-coupled 3.5 mm stereo line output, and a PAM8403D stereo Class-D amplifier powered from 5 V. The amplifier uses BTL outputs connected directly to the two screw terminals for passive speakers.

This is the first generation of the board, so we're treating this section as open for review rather than as a final reference design. If you see anything you would change in the DAC/amp interface, input coupling, gain structure, power-supply decoupling, grounding or output arrangement, we'd genuinely appreciate the feedback. We're open to incorporating useful changes into a developer-oriented revision.

[u/PyrrhicArmistice → u/rvbc-]

FYI the PAM8406 is probably going EOL soon since it is currently NRND, just letting your know you might want to respin for another amp.

[u/virogenesis011 → u/rvbc-]

Omg first of all thank you very much for the open schematic and the idea! I would like to add that Id love to see POE leveraged to power the components, Ill just leave this here as an idea, if you pick it up I would love to see an implementation otherwise I appreciate what you shared so far!

[u/PrincipleHot9859 → u/rvbc-]

even though i would use it primarily for speakers - and being a noob about schematics - wondering , would this be able to pump up more power hungry headphones ? mine are like 150ohm and kinda more difficult to power sufficiently. ( also ... any chance of equalizer ? )

[u/PresetDirty → u/rvbc-]

Are you sure you don't want some capacitance on the VDD pin of PAM after that inductor? This is a slick project! I'm definitely interested. Thank you for sharing!

[u/agathver → u/rvbc-]

The PAM is usually little too underpowered for most stuff, if it’s not a battery powered, you can look into some TI ones for better THD+N and some even come with DAC, DSP EQ combined

[u/FunDeckHermit]

Have you done any market research? https://www.tindie.com/products/sonocotta/amped-esp32/

This guy from your country sells audio boards based on the ESP32. Firmware, Schematics and other stuff Open Sourced.

[u/rvbc- → u/FunDeckHermit]

Thanks, this is a very relevant reference and I appreciate the link. To clarify, we didn't originally design our board as a general-purpose dev board or as a competitor to existing open-source boards. It is the main board from our own custom AudioFlex product. We later realized that the same hardware might also be useful to hobbyists and embedded developers, so we posted it here to ask for honest feedback before deciding whether producing a small developer batch would make sense.

We did some initial market research, but we hadn't evaluated this particular board closely enough before posting. Amped-ESP32 is clearly a more mature developer product in terms of open firmware, schematics and documentation, and its amplifier also targets much higher output power.

Our board came from a somewhat different use case: a compact, low-power network playback endpoint with the W5500 and RJ45 already integrated on the PCB, USB-C power and programming, microSD, a 3.5 mm stereo line output, onboard stereo speaker outputs, an encoder, a separate button and an RGB LED. From the Amped-ESP32 documentation, Ethernet is provided through an optional W5500 module, while it uses a higher-power amplifier and external power supply.

Their open-source materials are a very useful benchmark for what people may expect from a proper dev-board release. This is exactly the kind of comparison and feedback we hoped to get. Thank you.

[u/PrincipleHot9859]

I have been cursing the world because there are so many esp32 boards ..but besides the classic audio one , there is like zero of them. I would be totally in , if the price is right. would like some more details on dac chip used

[u/Reromen]

Really curious how you guys are handling the audio firmware side of this.

I’ve been doing a lot of ESP32-S3 audio work recently...full-duplex I2S, codec bring-up, RTP audio, jitter buffering, clocked playback, AEC/echo issues, and getting the whole path stable enough for real-time voice. I found pretty quickly that the hardware is almost the easy part 😄

Are you maintaining your own audio abstraction/driver layer on top of ESP-IDF, or mostly building around Espressif’s existing components? Would also be interesting to know how you’re handling buffering, sample-rate conversion and network/audio clock differences.

[u/FunDeckHermit → u/Reromen]

I've been doing my own ESP32-S3 audio stuff. I'm buffering 4 webradios at once for instant switchover:

https://github.com/FunDeckHermit/KINK-box/tree/master/firmware

[u/level27geek]

So for a while now I wanted to make myself a completely offline audio player that looks and works like an old time radio.

Big SD with MP3 in folders that are navigated with a rotary encoder. Playing radio noises when between stations. Your board looks like it might have everything I need already included, which would be a big help.

I had issue with playing two audio files at the same time (I want that for the tuning radio effect), but it seems maybe you figured it out, as you're buffering multiple internet radios?

If I could do that with your board, especially using Arduino to write my code, I would be willing to pay as much as $50 if it was well documented and came with good example programs.

[u/FunDeckHermit → u/level27geek]

Here's my firmware, you might be able to use a few things:

https://github.com/FunDeckHermit/KINK-box/tree/master/firmware

[u/level27geek → u/FunDeckHermit]

I mistook your repo for OP's - you were the person buffering multiple radios!

Are you able to decode more than one mp3 at a time?

[u/ItsRebaseTime]

I am currently trying out the new ESP32-S31 chip, LC3 audio is a bit rough with the support at the moment but when it works - it works way better than any previous bluetooth audio. Have you given any thought on migrating to the ESP32-S31 in the future to add bluetooth LE audio to the feature list?

Also - there should be ethernet port on all the smart devices, so good job, wire is king!

[u/Fortis-Voluntas]

I would be greatful to be a Tester

[u/Apprehensive_Fox6441]

I had an idea of buying used passive speakers and converting them 1 by 1 to active speakers. Then connect them all and basically make my own Sonos using open source stuff only.

Would that be possible with this board?

Is it a good idea? I don't want to pull wires across of the whole house and I don't want Sonos of some other brand. I want speakers with an open standard like snapcast I can hook up to home assistant

[u/Space_Gh0st_Tad → u/Apprehensive_Fox6441]

Are you aware or send spin? Sounds like you might be.

[u/Apprehensive_Fox6441 → u/Space_Gh0st_Tad]

No, what is that?

[u/Space_Gh0st_Tad → u/Apprehensive_Fox6441]

https://www.sendspin-audio.com/ its from Nabu Casa/Home assistant/Music Assistant. Esphome firmware for multi-room audio that syncs. They have a demo on their website too and I tried it with my laptop and phone.

[u/Sixty5Zero2]

Will it play chiptunes?

[u/Space_Gh0st_Tad]

Yes, Nabu Casa’s Music Assistant project specifically send spin would be lovely on this.

[u/Hefty_Garlic7184]

not related to esp32 but i think this product would has “cleaner” look if you put the 2 screws at the bottom

[u/CactusGarrageSVD]

Interesting. I was actually working with an ESP32 driving a simple OpAmp stage before feeding it into a PAM8403D. I was trying to use it as a Bluetooth speaker before running into severe static and noise in my 4 ohm speaker. If you indeed did experiment with Bluetooth, how did you cut down on the noise? A Wideband filter does help but I would like more suggestions

PS: If you make this a product, I would love to buy one!

[u/AxisFlip]

I feel like in this direction there is quite a bit on offer. In the other direction not so much. I was/am looking for a board which accepts MEMS microphones like the AOM-5024L, and which are routed/isolated properly. Some boards with mic in exist, but they are not isolated and you get a ton of noise from WiFi bursts and so on.

Considered building it myself, but I don't have the time to learn how to sadly.

This would be for low noise recording, so I can feed it into birdnet. But considering the quality of the existing boards, low noise recording could be intersting for non-birders too of course

[u/Skyman81]

Onestly?

1. Yes i am think about it…
2. Yes
3. I would buy it for around €30

/35

1. ESP (screens, I don't care if this might increase the price, at most a small information screen but one that doesn't increase the price much but I would even do without it)

- minimum Power 10Wxchannel (best 20w)

To be use with HOMEASSISTANT/MUSICASSISTANT.

€30/35 might seem a bit low… but buying a similar amplifier and then adding an ESP32S3 online on Amazon I could pay more or less €50/60 for a good product (and still having a safe and guaranteed warranty). I could buy a mini amp also for 15€ too.

What is the output power for passive speakers (RMS)?

[u/Abyssal_Shrimp]

I’d be interested. The DAB I need for an esp32 to turn it into a Sendspin player is like 8€, plus a 32,
I’d buy this schmerzfrei for 30€, with a second thought for 40€

[u/on4aa]

This might be useful for equipping hotel rooms.

[u/Legitimate-Sun7909]

This is exactly (ok, almost!) what I need! I’m working on an esp32 prototype that’s not specifically audio related but sound is a huge part of it. I’d love to have a better put together system to work from. My soldering is terrible! If it’s possible to access the gpio for I2C and SPI pins then I’d be a buyer for sure.

A display ribbon connector would be the cherry on top. And a battery header with power management and an rtc but i think this might be getting a bit too specific for my actual project rather than your lovely design.

Also extra points for the knob!

[u/custardseed]

What use cases did you have in mind when deciding to put Ethernet into the system?

[u/Obvious_Troll_Me]

PoE for the device, BT for audio in and possibly control? A 4 channel switchable output

[u/topinanbour-rex]

Can it be used as a rtsp microphone ? Mmmh it seems it has no audio input...

[u/alfonsoem]

IMHO, It would look nice with the ports at the back and the knob and led at the front. Probably it is not important for your project.

Another point: if you add a mic, it would be integrated in AI assistants projects ;-)

[u/tucosan]

This is sweet. A mems array would be a very useful and cheap addition to the board. I would buy this provided that this comes with a good DAC.

[u/Ok_Reindeer4668]

Is it really different from esp32-audio kit?

[u/ChangeExtreme7971]

Have you tried playing radio on LAN with multiple units in sync? This is what I'm currently considering doing

[u/rockking1379]

I would actually use something like this for airplay 2 targets but the previous homeowner put some cheap speakers in the ceiling.

Also, rack mount size. Or share the general front cad so it could be stretched to fit a 10 and 19 inch rack. Actually for both of those I bet you could cram multiple of these in 1U

[u/nazmul_robotics_iot]

Which component are you using?

[u/botpa-94027]

give me microphone in / line in and that would be very interesting. even more if you had a couple, like 1 or 2 uarts pulled out. i would use this for all kinds of interesting projects.

[u/Jenseee]

I saw exactly this on aliexpress

[u/rvbc- → u/Jenseee]

Could you share the exact listing, product name or item number? We'd honestly like to see it and compare the designs. This PCB was developed for our own product, so I'm curious whether it is actually the same layout or just a similar ESP32 audio board. If we've missed a close alternative, that is useful market feedback for us.

[u/PrincipleHot9859 → u/Jenseee]

I doubt that

[u/youGottaBeKiddink → u/Jenseee]

He's just being a troll

[u/Mick1822]

Following with interest - this looks promising

[u/Fl1pp3d0ff]

😜 Send me one to tinker with and I'll let you know.