Pi 400 Desktop Speakers with Soberton 3D Printed Speaker Enclosure

2021-12-17 | By Nate_Larson

License: See Original Project

Recently, while browsing the internet using my Raspberry Pi 400, I happened upon an interesting video. I clicked on the video and, as it began playing, I noticed my setup was missing an important interface peripheral. As the video played, I sat in silence due to the lack of speakers on my desk.

A simple remedy, or so I thought, as I grabbed a pair of nearby headphones. Looking to the back of the Pi 400, I soon realized my folly, as I found the keyboard was designed with no 3.5mm headphone jack to which I could connect the speakers that were happily hugging this maker’s melon.

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Okay, I can deal with this. After all, the Pi 400 has built-in Bluetooth, and while I have a classical mindset in keeping wired headphones handy as my initial go-to audio source, I’m not old-school, so I have Bluetooth earbuds around. However, upon pulling the wireless earbuds from the case and powering them on, I was presented with an auditory announcement that charging was required, followed immediately by powering down due to the low battery level.

At this point, I concluded that what I really needed, and wanted, was a set of desktop speakers that could take up permanent residence alongside my Pi 400 setup. And while there are off-the-shelf solutions, I wanted a custom solution that would compliment the Raspberry Pi in both performance and appearance.

This is where Soberton stepped up to the plate to help my vision come to fruition! Soberton, in addition to producing a wide variety of speakers and other audio products, understands the importance of a properly designed speaker enclosure.

Anyone who has ever designed a speaker enclosure knows that every little detail plays a part in the performance of the completed assembly, whether it be the air volume, ports, surface finish, or even the general shape of the enclosure. Soberton has eliminated this workload and guesswork by offering 3D models of printable speaker enclosures, along with printing instructions, for many of their speakers.

I selected part number 433-1157-ND as my speaker of choice for this project. The frequency response of this speaker covers the majority of the typical audio spectrum, making it a great choice for general audio such as this. Additionally, Soberton offers the aforementioned 3D printable enclosures for this speaker, which can be downloaded right from the product page.

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Following the provided printing instructions, I printed both the single and dual piece enclosure designs to compare the sound from each and determine which was best for my application. I printed two of each style enclosure to put together a complete stereo solution for comparison. Below is the time-lapse video of the enclosures printing on a Lulzbot TAZ Pro S using white PLA filament from MG Chemicals. Keep in mind, if you don’t have a 3D printer of your own, Digi-Key offers 3D Printing Services.

Once the printing was complete, I soldered wires to the speakers and followed the assembly instructions, using a bit of super glue to hold the speakers in the enclosure once they were properly positioned.

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The speakers were then connected to Soberton’s 433-XPCB-12BT-ND development board. This board not only functions as a stereo Class D audio amplifier but also has onboard Bluetooth, which allows an easy wireless connection to the Raspberry Pi 400.

With the wiring and mechanical assembly complete, I powered up the Soberton amplifier board and connected the board to the Pi 400 via Bluetooth. Then set about testing and comparing the audio from each enclosure design and that of bare speakers with no enclosure, which you can see and hear in the following video.

In the above video, you can clearly hear the difference between the three tested variations. The bare speakers are quiet, and very tinny sounding, though to be fair, the speakers were unanchored so, some of the harshness could be attributed to rattling on the desktop. Regardless, the sound they produced was unarguably not as clear or pleasant as those of the speakers housed in proper enclosures.

The small enclosures had stronger highs and mids, but the smaller air volume resulted in stifled low-frequency sounds. Still, this would be a good option for scenarios where space is limited and/or where only alarms and voice prompts would be expected, such as equipment controls.

The final, large two-piece enclosure design is adjustable, and in the test, was adjusted to provide maximum air volume behind the diaphragm of the speaker. This resulted in a more pleasant tone with even sound reproduction across the frequency response spectrum of the speaker and was the obvious choice for this application.

With the enclosure design now determined, I designed speaker grills using the Raspberry Pi logo and added a stand, so they would sit properly on the desk. These consist of a front frame, large insert, and leaf inserts.

Once printed, red fabric was sandwiched between the front frame and the large insert, which is held in place by friction. From there, the fabric was trimmed around the edges and a few dabs of super glue were added to hold the frame and insert together, as well as to hold the leaf inserts in place.

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