Ultimate Google Nest Mini Audio Mod – Custom Hi-Fi Enclosure With Full Smart Features

This project upcycles a Google Nest Mini Smart Home Speaker. The idea is that the software and level of integration of the Google Nest Mini are great! It integrates with your smart-home and provides access to e.g. playback Spotify music. The problem is that the speaker is simply not good enough to really listen to music..

It came to my attention when I was watching a video from Scott Yu-Jan, but how he used a secondhand speaker to upcycle the Google Nest Mini. (Link: https://www.youtube.com/watch?v=P3XCPywlXBI). The sound seemed massively improved and he had a very convenient approach to get results fast. I liked the idea of upcycling the speaker, but I wanted more...

This project really disassembles the components of the speaker, maintains all the functionality of the Google Nest Mini, and provides a custom enclosure with a more or less "best-practices" approach to audio fidelity. The video below shows the enclosure in action.

Please note that this project challenges how much we can get out of the Google Nest Mini. It's probably overengineered and over-designed. The total cost to DIY this, would be 50 to 80 euros.

Parts

1. 1x Google Nest Mini, you can buy them second-hand for as little 10 euros.
2. 1x Speaker: Dayton Audio DMA45-8 1-1/2" Aluminum Cone Full-Range Driver
3. We use an 8 ohm driver to make sure that we can't underload the amp, potentially blowing it up.
4. 2x Passive Radiators: Dayton Audio DMA45-PR 1-1/2" Aluminum Cone Passive Radiator
5. 3D Printer and Printing Filament ~0.5 Kg, I used Bambulab PETG
6. Some stuffing: if you want to do it like the pro's you can get polypropylene fibres. Other fibres or even cardboard-shreds work fine too, but the amount and performance will vary slightly. We only need about 4 grams of fibres! Glass fibres work too, but be careful as you would rather not touch or inhale these fibres!
7. Screws and Threaded inserts. I use the threaded inserts from CNC Kitchen, as they come with perfect dimensions for designing the holes. The screws and threads that I used are:
8. 1x M3x10 for the Lower Lid, including M3 threaded insert
9. 15x M3x16 for mounting the speakers and for the buttons on top, including M3 threaded insert
10. 1x M3x20 for mounting the bracket that holds the power connector, including M3 threaded insert
11. 3x M2x20 with nuts and threaded inserts for mounting the Main PCB to the top lid.
12. 2x M2x10 with nuts and threaded inserts for mounting the Power PCB to the bracket.
13. Flexible Flat Cable 10 Pins 0.5mm Pitch 150mm FPC FFC Flexible Ribbon Cable
14. Wire to extend the speaker connector. Extra point for a multicore copper wire with a large gauge. Props if you use proper speaker cables. The max output of the Google Nest is only 5 Watts.
15. Optional
16. Cork to give the bottom a nice surface that vibration resistant. I got some self-adhesive cork
17. Speaker Connectors and Crimp Pliers, for if you want fancy connectors. Soldering is fine too!

Tools

1. Pliers, screwdrivers and/or allen keys if you are using Hex to tighten the screws
2. Note that M2 screws and nuts are really small, so precision pliers help here!
3. Note that you need very small Torx bits for dissasembly (size 6)!
4. Soldering Iron and solder, and if you have it, a kit to set the threaded insert properly. CNC kitchen has beautiful kits for it (just a fan, not affiliated)
5. M3 Washer for improved closure of lower lid
6. Patience! I would argue that this is somewhat of an intermediate project.

Where to get what?

(Not affiliated with any of these companies)

1. I got my supplies for the speakers and passive radiators from SoundImports:
2. https://www.soundimports.eu/en/dayton-audio-dma45-8.html
3. https://www.soundimports.eu/en/dayton-audio-dma45-pr.html
4. The Flat Cable I got from Amazon: https://www.amazon.de/-/en/dp/B07SWJ1RJQ
5. For the screws, I would recommend getting a simple kit of M2 and M3 screws from Amazon. I preferred Hex heads.

So the first step is to of course get the parts, but after that, it's time to 3D Print. I am using the Bambulab X1 Carbon.

The print files you can find on: https://www.printables.com/model/1587329-google-nest-mini-audio-mod

My setup is:

1. Wall thickness of 4 Layers
2. I used Brims and Supports here
3. Infill is Cubic, with 55%
4. I used a 0.4 mm Nozzle, this is important!

Things to know:

1. The body is printed upside down, and we barely have any supports connecting to the outside surfaces, presenting a smooth finish.
2. The lower-lid has a pillar going up, and therefore is best printed separately.
3. The other parts are the upper lid, the bracket for the Power PCB and the 3 Conductive Connector Rings.
4. The Conductive Connector rings need to be printed very precisely! They are very small, and isolate the “buttons” from ground. If this is not perfect, your controls won't work! So consider that you might need to reprint these if they don't come out perfect. It's a non-issue, as it only takes 10 mins to print 3. If they don't come out well, consider printing 1 at a time so that the nozzle doesn't have to travel between rings.

When you are printing, you can already start the next step!

Validate functionality

Before you start disassembling the Google Nest Mini, make sure that everything works. The features that we want to test is:

1. Does it boot up?
2. Does it make sound?
3. Do the center, left and right buttons work (do they respond)

This is important if we want to validate the assembly later down the line.

Disassembly

To begin disassembly, you can start unscrewing the bottom screws and work through the layers. This is also where you will need your Torx 6 bit!

There is a great video available from 416 DIY here: https://www.youtube.com/watch?v=AyeGW0otFs8 and from IS IT SO YAAR that shows the prying https://www.youtube.com/watch?v=QOsVLwSBKZs

If you are at the stage in the video where it says: "From here the piece is non-serviceable" at 4:34, we continue the teardown. Note that this is the point of no-return. The steps are:

1. Pry off the PCB: Be gentle here, and know that there is an adhesive that was used to keep the PCB connected to the shell. When prying try to use minimal force and when applying minor pressure, make sure to wait a little as well, as it simply takes some time for the adhesive to release. The plastic rivets will eventually pop-off. You will have a foil that goes towards the chips By the end you should have:
2. The main PCB
3. The power PCB
4. The heat sink (keep the thermal paste on the heat sink)
5. On the sides, we have some 0.2 mm thick foil that are our contact pads for the buttons. In the centre we also have a contact pad that is more circular. Harvest all three. You will need to release them from tape and adhesive. So at this stage you will have harvested:
6. 2x Side contact pads
7. 1x Circular contact pad
8. Keep the Speaker enclosure for now, it will enable us to test and we will harvest the connector later down the line.
9. The last steps is to clean off the contact pads. Isopropyl alcohol and a razor blade help to scrape off the glue residue. I straightened the pads in my vice by squeezing them.

Tip: Pay special attention to the enclosure and how it mounted these contact pads! If you look closely, you will find that the pads did not make contact with the screws. They have an inner liner to prevent this from happening. This is very important for assuring that the contact pads work later down the line. The contact pads work based on conduction, meaning that minimal current will flow when touching these pads. The screws are mounted through a shielded heat sink, meaning that the heat sink itself is connected to GND.

If the screw touches the pads, then the current will always leak to GND, therefore no capacitance can build up on the pads, making them unresponsive to touch.

So this is fiddly. I mentioned that you needed to bring patience, well, it's exactly for this part! The goal is to:

1. Fit the capacitive plates to the Main PCB
2. Fit the assembly to the upper-lid

To make it slightly easier, we are first going to bolt down the plates with an extra nut, test the connection and only then connect it to the lid.

Fitting the capacitive plates

1. You have harvested and cleaned the plates in prior step
2. You are going to cut them to size, like in the 3rd picture, or similar, so they will fit in under the lid later. This is an as long as it fits kind of problem/solution. Make sure that you are not shortening anything under the PCB. Especially the Circular Contact pad will require some tape between the PCB and the pad, as we are rotating it 180 degrees from it original position.
3. I used my vice to fixate and wiggle the plates to fatigue the material and create a breaking line.
4. If we like the sizing, we can start moving the contact pad lugs over the 3 Conductive Connector Rings that we 3D printed.
5. Make sure that you are precise and delicate.
6. The golden side of the pads should be facing the PCB for the best connection.
7. You can use a vice and a large ring to press the lug over the 3D-printed part. Make sure that you don't squeeze 3D-printed part, though. The walls are 0.4-0.6 mm thick here and extremely fragile.
8. Now we have 3 assemblies of contact pads with Conductive Connector Rings. These we want to fit on the PCB. Again, we need to make sure that we do this delicately. A vice can help to apply very linear force, but be careful to not use too much force. The circular pad goes in the middle. ;)
9. If the assemblies are in, we now should have the Main PCB, with 3 Pads and 3 Conductive Connector Rings. Let's add the heat sink and fixate the assembly with screws and nuts. We use the M2x20 and M2 Nuts for this. Make sure that you have a tight fit (we need pressure to make good contact) but that the screw itself can still rotate. This rotation will be the mechanism for bolting it to the upper lid later down the line.

Testing Assembly

This assembly is the most prone to issues, which is why we want to test it. We can test it by:

1. Connecting the assembly to the power
2. We use the flat cable, power PCB and the power adapter to power it on
3. Connect the assembly to a speaker
4. We saved the speaker from the disassembly process.

Make sure that you use a non-conductive surface for the electronic parts when laying them out. A wooden table or silicon mat are excellent for that. Expected behaviour should be:

1. System boots up and makes noise
2. All the buttons work.
3. Left and right respond by changing volume
4. Center button doesn't do much, but activates the lights.

Debug

What if something is wrong? We assume that you started the Google Nest Mini beforehand and validated the core functionalities beforehand.

1. Board doesn't boot up?
2. Are you sure you have power? Get Power.
3. The flat cable might be broken? Do you see any harsh bends in it? Replace cable.
4. The PCB might be broken, you would need a new Google Nest Mini if you want to continue.
5. The Board powers up, but there is no sound:
6. Cable and/or speaker might be broken. Validate this with a different speaker.
7. The PCB might be broken, you would need a new Google Nest Mini if you want to continue. (unlikely)
8. The board powers up, there is sound, but 1 or more buttons don't work.
9. The buttons might not connect properly.
10. You can test the buttons by touching the ring-pad on the PCB directly. This should always work. If not, the PCB might be broken, you would need a new Google Nest Mini if you want to continue. (unlikely)
11. You can add some solder on the lugs of the contact pads to make them slightly thicker. A few 10ths of mms can be meaningful when it comes to these connections. I added some solder to the centre contact pad to make it work.
12. Did you tighten the screws/nuts properly? We require a fair amount of force here.
13. The buttons might be touching the screw. This means that the Conductive Connector Rings are broken. Please check for damages.
14. The buttons might be touching something else on the PCB. Make sure that the Main PCB and the pads are isolated from one another. Simple electrical tape will do the job.

Fitting the Upper Lid

You are over the hardest part. The next step is to prep the upper lid and screw the assembly to it. The steps are:

1. Melt the M2 and M3 threaded inserts into the Upper lid. The outer 3 holes are M3, the more inward holes are M2. Make sure that you have great alignment, as this will determine whether the assembly will want to fit to the lid or not.
2. Bolt on the assembly. The assembly already has 3 protruding M2 screw that should fit right into place.
3. When the assembly is connected to the Upper lid, we can screw in the M3x20 screws in the 3 outer holes. We screw them in from the outside in, and they should touch and bend the capacitive plates to make contact.
4. Make sure that the make contact. A little forceful bending and alignment can help to assure contact.
5. At this stage, you want to test again whether the lid is assembled correctly. We need power and a speaker to do so, and expect that we can use the outer screws on the other side of the top lid to change the volume and activate the speaker. If certain things are not working, you can review the debug section above.

This is the most rewarding part: we are getting some real results here! When the print is done, you can do the following steps:

1. Added the threaded inserts into the holes
2. We have 4 Threaded inserts of M3 per speaker/passive radiator, a total of 12 threaded inserts.
3. At the back, we have another M3 threaded insert that we use to bolt down the bracket for the power cable.
4. Connect the wires to the speaker. You have 2 options here.
5. Solder the wires directly to the speaker
6. Create connectors with a crimping set and pliers. The last option is fancier, but really doesn't impact sound too much.
7. After that, we can mount the speaker and the passive radiators, we use M3x16 for that
8. I removed 2 out of 3 of the rings on the passive radiator later down the line to tune them properly. If you want a good starting point, I would start there.
9. Splice the connector; in order to have the original connector of the speaker, you must:
10. Push the wires from the lower compartment to the upper compartment through the round hole
11. Strip the wires back
12. Clip off the original wire from the speaker and strip those back too. Tip: if you crack open the speaker enclosure, you can get some more length from the wire. I used a vice to crack open this box.
13. Solder the wires together. You can use some electric tape of some heatschrink tubes to isolate the bare connections.
14. After that, we can add about 3-4 grams of fibres. I used Polypropylene fibres for this.

Make sure that everything works. To do so, you should:

1. Connect the Main PCB to the speaker cable
2. Connect the flat cable to the Main PCB. The other end is connected to the Power PCB.

Checks

1. When it starts up it should make a sound, if you can hear this, the speaker is connected properly.
2. When you touch the screws, it should increase or decrease the volume on the sides. The middle one will not do much for now, but the board should light up.

1. Prep the Power PCB:
2. Melt in the M2 threaded inserts into the bracket. Make sure that you are accurate, as the tolerances are not very forgiving.
3. Connect the flat cable first to the PCB, you won’t direct access after that
4. Bolt down the PCB to the bracket. Note how there is 3 mm clearance for the connector and flat cable in the bracket.
5. Bolt down the Bracket with the Power PCB with an M3x20 screw
6. Get the lower lid ready:
7. Melt in the M3 threaded insert
8. optionally, you can add some cork to the bottom
9. Put in the lower lid and make sure that stuffing is not sticking out and that you are not mashing up any cables
10. On top, you can lock down the lower lid by screwing it down. Optionally, you can add a washer.
11. Connect your top-lid and Main PCB to everything
12. Press fit the top lid onto the main enclosure, make sure you are not squishing any cables! The flat cable can be broken easily!
13. Connect to power
14. Make sure that everything is still working

and you are done! Congrats!