Home Assistant Voice Preview Edition Enclosure Case

https://www.youtube.com/shorts/ShVcH8TVk3I

Overview

The speaker on the Home Assistant Voice Preview Edition is limited in range and clarity. This project provides a 3D-printable enclosure for a larger, higher-fidelity speaker and a dedicated amplifier, improving output quality significantly.

Printing Notes

* Printer: Prusa i3 MK3s+

* Material: PLA

* Settings: 15% infill, 3 perimeters, ironing on top surfaces.

* Support: Use user-defined supports where necessary for overhangs.

Parts List

* 1x Visaton FRS 8 M (8 Ohm, 30W, Full Range Speaker)

* 1x 12V 1A Power Supply Adapter (5.5×2.1mm barrel plug)

* 1x Panel-mounted female DC power jack (5.5mmx2.1mm)

* 1x MP1584EN Step-Down Buck Converter (12V to 5V)

* 1x DollaTek TPA3118 PBTL Mono Amp

* 1x LC Filter Module (5-50V, 3A)

* 2x NTC 5D-9 Thermistors (Inrush current limiters)

* 2x 1k resistors (for stereo-to-mono summing)

* M3 inserts (5mm) and various M3 screws

* USB-C cable (for VPE power input)

* 3.5mm audio cable (for audio input)

* Sticky pads/Double-sided tape

* Ground Loop Noise Isolator (optional). See additional notes below.

Engineering Notes

* Protection: The NTC thermistors are installed to limit inrush current at startup. This prevents power surges from damaging the MP1584EN buck converter during power-on transients.

* Noise Suppression: The LC Filter is used to scrub high-frequency switching ripple from the buck converter, ensuring the audio output remains clean.

* Wiring: I utilized "Star Grounding" rather than daisy-chaining. Both the amplifier and the buck converter are wired independently to the main DC jack to minimize ground interference.

Wiring Instructions

Use a "Star Ground" configuration: connect the ground from the DC jack directly to each component individually.

1. Wiring the Amplifier

* Power: Wire the DC jack positive (+) through one NTC thermistor to the amp positive input. Wire the DC jack ground (-) directly to the amp ground input.

* Audio: To mix stereo (L+R) to mono: Strip the 3.5mm cable. Wire the Left and Right channels through a 1k resistor each. Twist the other ends of the resistors together and solder to the amp audio input (+). Wire the audio cable ground directly to the amp audio input (-). (Use heat shrink over the resistors).

2. Wiring the 12V to 5V Buck Converter

* Power: Wire the DC jack positive (+) through the second NTC thermistor to the converter positive input. Wire the DC jack ground (-) directly to the converter ground input.

* Output: Wire the converter output (+/-) to the input of the LC Filter. Wire the output of the LC Filter to your USB-C cable (cut/stripped).

Assembly Tips

* Acoustics: I placed a very loose, teased-out layer of polyester fiberfill (from an old pillow) in the enclosure. Do not pack this tightly - it should be sparse and "whispy" to act as dampening material.

* Thermistor Safety: Ensure that the thermistors have airflow around them to disapate heat.

* Testing: Test all connections with a multimeter before finalizing the assembly.

Additional notes

Line noise I found that the MP1584EN generated a significant amount of noise. The filters didn't stop it. In the end I gave up and just stuck a cheap ground loop noise isolater to the side of the device. If anyone does find a decent 12v to 5v DC converter that doesn't generate noise please let me know!

Electronics I'm not pretending to be an expert in electroincs. So again, if anyone can see any improvements to this project, please let me know and I'll incorporate your suggestions.

Disclaimer: Proceed at your own risk. I hold no responsibility for any hardware damage resulting from the implementation of this project.