IoT Speaker Amp

Overview

The IoT Speaker Project is an attempt at creating a DIY TV speaker amplifier w/ Bluetooth and Airplay capability.

Project Goals

Input modes:

Optical Input (TOSLINK)
3.5mm Headphone In
Bluetooth
Wifi / Airplay

Output Modes:

2.1 Stereo
- Right, Left, Subwoofer

Features:

Custom Programmable EQ
Quick Adjust Pots for Treble, Bass, and Crossover
Automatic Input Mode Switching

Board Overview

Final Schematic

The hardest part of the design process was to get the schematic correct. Throughout the design process, it took many iterations and adjustments to ensure all passives were correct, whether those were listed in a data sheet, an evaluation board, or through recommendations online. Over the course of 3 weeks, ICs were added, removed, and added again in an effort to ensure a feature-complete board from the start with 0 compromises.

Schematic Details:

Microcontroller: ESP32-S3-WROOM
- Required an easily controllable chip w/ Wifi + Bluetooth built-in to reduce IC count
- Specific PSRAM and direct USB connection capabilities
Audio Processor: PCM9211PT
- Receives I2S stream for Bluetooth or Wifi from ESP32 if enabled
- Decodes SPDIF signals from optical receiver internally
- Converts analog headphone jack input into I2S
Audio Amplifier: TAS5755M
- Receives I2S stream from Audio Processor, converts into analog audio output to Left, Right, and Subwoofer
- Left and Right channels powered by a half bridge rectifier, Subwoofer powered by full bridge rectifier

Layout

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