Add Bluetooth to a Bose Series I SoundDock

This Instructible shows you how to add Bluetooth connectivity to a Bose Series I SoundDock. Adding Bluetooth to a SoundDock 10 is different, but I've covered how to do that in another instructable: Add Bluetooth to a SoundDock 10.

I have a small collection old Bose Series I SoundDocks that provide great audio quality in a small package, but that we can't use because they all require a phone or iPod with a 30-pin connector. I tried to get these working again by buying several different Bluetooth audio adapters that simply plug into the dock connector, but the ones that I've tried either sound terrible (adding annoying clicking noises) or just don't work at all. I also wanted a bit more permanent solution than a little device that could fall out, break, or be misplaced, so I set out to permanently add Bluetooth connectivity to my SoundDocks. After a little research, I found that I could buy very cheap Bluetooth audio modules (4 for $10 on Amazon) that promised to provide good sound quality and included an on-board jack that can could also serve as an auxillary input (it's actually an audio-out jack rather than an aux-in, since it doesn't cut out the Bluetooth audio when a cable is plugged in, but it works fine as an aux-in in this configuration). I had to do a bit of research to solve a few problems along the way, and ended up designing and 3D printing a nice little housing, but it turned out very well and I've now added Bluetooth to all of the previously obsolete SoundDocks that I had accumulated. The solution I came up with cost me a total of about $40 and provided enough parts to refurbish 4 SoundDocks (so about $10 per SoundDock).

How I Made this Work for a Bose Series I SoundDock
(you can skip this part if you don't care about the problem-solving details)

I had to solve a handful of problems in order to complete my project.

How to re-use as much of the existing Bose electronics as possible (to prevent e-waste)?
How to connect the audio from the Bluetooth module to the SoundDock?
How to power the Bluetooth module?
How to tell the SoundDock to turn on?
How to ensure that I don't get the noise problems I experienced with the plug-in devices?
How to mount the new components and make everything look nice and finished?

The first problem is solved by adding Bluetooth and aux-in on top of the existing Bose pre-amplifier/control board and power amplifier. This assumes that those things are working in the SoundDock, and If you have a Sounddock that does not work, you can ditch all of the electronics and mount an integrated Bluetooth receiver/amplifier in it. There are some good Instructables and videos on how to do this if you find yourself in that boat. If your Sounddock has a faulty 30-pin dock connector, my solution should still work for you, since it by-passes the dock connector and is wired directly to the docking circuit board. You should also note that there is an easy-to-resolve issue with some of these Sounddocks, where the ribbon cable that connects the main amplifier to the preamp/controller board comes loose, so you might want to check that before giving up. See the "Test Your Work" section of this Instructable for more information on this. There's also this video on Youtube.

I turned to the internet to identify the right pin connections on the SoundDock to allow audio in, to get power for the Bluetooth module, and to turn the SoundDock on. The first was easily answered from pinout specifications for the ipod dock connector, which are readily available from many sources. The Bluetooth module audio-out connects in place of the dock connector's pins 2 (audio/video ground), 3 and 4 (right and left). These pins trace to pins 12, 13, and 14 (respectively) of the ribbon connector that connects the docking board of the SoundDock to the control/preamp board, and this provides and easy place to solder wires. Problem two solved!

The Bluetooth module requires 5 volt power, so I was hoping to find a 5 volt supply being provided by one of the SoundDock pins. From the most recent iPod docking station specification, this should have been on pin 23, but voltage readings showed no such thing. Instead, it seems that the Sounddock follows the older specification, and only sends power to the 30-pin connector's "Firewire" power pins (19 and 20). My tests showed 16 volts on the pin, but this voltage is much too high and would damage the Bluetooth module, so if I wanted to power the module from the SoundDock I would need to drop the voltage to 5 volts. I knew from my other projects that there are very small and inexpensive DC-DC "buck" converters that can do that quite easily, so problem three solved.

The fourth problem was a little more vexing, since the 30-pin dock connector specs tell you about the connector from the iPod side, but they don't tell you how a device like the SoundDock is supposed to know that an iPod has been docked. Based on a solution that others have shared (putting a resistor between pins 19 and 20 on the Soundock ribbon connecor), I learned that the SoundDock turns on when it detects a positive voltage on pin 18 of the iPod docking connector (which corresponds to pin 19 on the SoundDock ribbon connector). The resistor solution emulates this behavior by sending voltage to the SoundDock's sensing pin. However, adding a single resistor doesn't change the voltage (it just limits the current), so a single resistor sends way more voltage than the SoundDock expects (~16 volts). The 30-pin docking connector spec says that the iPod provides 3.3 volts on pin 18, so a proper solution would be to use 2 resistors to create a voltage divider to bring the voltage down to an acceptable level, but since I knew that I was going to use a DC-DC converter to provide 5 volts for the Bluetooth module, I could just use the 5 volts from that to trigger the SoundDock's sensing cricuit. Since my Bluetooth/Aux-in solution would be hard-wired to the dock, I decided to include a small rocker switch to cut the power to the SoundDock and Bluetooth module so I can turn the SoundDock off when I wasn't using it). Problem four solved.

I assumed that the noise problem would be solved by using a bluetooth module with plenty of good marks for audio quality. And when I first tried the module using USB power (before I received the DC-DC converters), the sound came through with no discernible noise. Problem five solved, or so I thought. After I received the DC-DC converters and connected them. I started to hear clicking noises and thought my efforts had been in vain. However another Youtube video put me onto an easy solution to the problem. The 30-pin dock connector specification calls out a separate ground for audio, but I had taken the shortcut of connecting the audio ground from the Bluetooth module to the main ground on the docking station circuit board. It turns out that doing so creates a ground loop that introduces noise from the power supply. By changing this to the dedicated audio ground, I eliminated the noise. Problem five solved.

For the sixth problem, I planned from the start to use my 3D printer to print a housing that leaves the SoundDock completely intact and covers the 30-pin docking port. I used Tinkercad to design a housing for the Bluetooth module, DC-DC converter and switch that would fit perfectly in place of the 30 pin docking insert. After printing my first model, I decided that I wanted to make some more complicated adjustments, so I ported the design to Fusion 360 so I could make them more easily. Problem six solved. After printing a couple of these, I also decided to provide a solution for people who don't have access to a 3D printer, which I detailed in the final step of this Instructable.

Supplies

Here's a list of things you need to build this solution for yourself. Note that the purchasing links I provided are for multiple quantities of each item. This worked out for me because I have a small collection of SoundDocks, but it's also not that much cheaper to buy single quantities (e.g., a single MH-M28 module goes for $5 on Amazon), so if you're going to build this project, I encourage you to buy the multiple quantities then find friends and family who can benefit from your efforts.

Bose SoundDock Series 1 (in good working order)
MH-M28 Bluetooth module Amazon link for qty of 4 modules for $10
5 Volt regulator module Amazon link for qty of 5 modules for $8
Round Rocker Switch for 14mm hole Amazon link for quantity of 10 switches for $5
(note that the description of these say "15mm hole" but they are in fact 14mm )
30 AWG Silicone Electrical Wire Amazon link for package of 5 spools for $12
optional: 3 very small screws (I used ones salvaged from dead electronics devices) to install the cap on the Bluetooth module housing. You can also just use hotmelt glue to fasten it.

A note about the wire specified for this. If you're tempted to use different wire, bear in mind that the advantage of the silicone-insulated wire is that it's harder to accidentally burn through the insulation, and the wire is less likely to break from repeated bending. Do not use solid wire, as it will be harder to solder and will surely break as you are trying to assemble everything.

You'll also need access to a 3D printer or service to print the model. Here's a link to the model on Thingverse: Bose Series 1 SoundDock Bluetooth Aux-In Housing. I used PLA for the print.

For tools, you'll need the following:

A soldering gun with a very fine tip (along with solder and flux)
Wire strippers capable of stripping 30 AWG wire
A magnifying glass to help with small parts soldering
Something to hold small circuit boards while soldering
A T-9 torx srewdriver
A hot melt gun
Sandpaper for finishing the print.
optional: A tiny drill bit set if you want to use screws to fasten the cap on the Bluetooth module housing.

Step 1: Print and Prepare the Bluetooth Housing

You can complete this project without a 3D printed housing and instead install the Bluetooth module, DC-DC converter, and switch in one of the spaces under the body of the SoundDock (see the last section on options for doing that). If you want to leave your SoundDock mostly intact and want a nice, finished look that covers the 30 pin dock, you can use the housing I designed. It took 5-6 hours to print the housing and cap on my little Monoprice Select Mini. For print settings, I set the bed temp to 65 C and printed with a brim and some gluestick on the bed for less warping on the edge of the print. I printed my first one at the default 60 C bed temp and no brim or raft and had pretty bad warping along the edge of the main housing.

Once you have the prints, check the fit between the body and the docking recess in the SoundDock, and between the switch and the cap, and sand, file or grind as needed to achieve a good fit. I'd also recommend that you remove any sharp eges with some fine grit sandpaper.

If you plan to use screws to fasten the cap to the body, now's the time to drill the holes for them. I marked the location of the screws (see the pictures for where I placed them), then taped the cap to the body and drilled very small pilot holes through the cap and into the body. I then removed the cap, changed to a 1/16" drill bit, and drilled the through holes just in the cap. These should be big enough to let the screw go through the cap without engaging the threads. Since I was using flat head screws, I also countersunk the holes in the cap so the screws would sit flush with the surface of the cap. I used a 3/16 bit to drill the countersinks.

Step 2: Remove the Docking Circuit Board From Your SoundDock

To get started with the electrical work, you need to remove the docking port on your SoundDock so you can get to the circuit board. To do so, use the T-9 torx screwdriver to remove the three screws on the bottom of the docking port (the semi-circular part that sticks out from the front of your dock). Make sure that your dock is not plugged in while you do this.

The docking circuit board is attached to the controller/pre-amp board inside the SoundDock with a 1" ribbon cable. Gently pull the cable free from the connector on the docking circuit board. You're now ready to start soldering!

Step 3: Set the DC-DC Converter for 5 Volts

Before you start to wire the components together, you have to prepare the DC-DC converter so it delivers 5 volts. By default this is configured to be adjustable via a very small potentiometer on the board. However there are also resistors on the board that set the voltage to a number of different common voltages. Rather than fuss with setting the potentiometer, I followed the board's directions to use one of the onboard settings, by cutting the connection between the 2 pads for the "ADJ" option (repeated scraping cuts with an exacto or similar sharp knife does the trick), and soldering a bridge over the to pads for the 5V option. The pictures above show the two modifications you need to make to the board.

Step 4: Solder the Bluetooth Module, DC-DC Converter and Switch

Next cut 9 pieces of 30 AWG silicone wire. I was using a 5 color spool set, so I used the following wire color scheme.

3" green (audio ground from Bluetooth module to SoundDock)
3" red (audio right from Bluetooth module to SoundDock)
3" yellow (audio left from Bluetooth module to SoundDock)
3" blue ("docked" sensing voltage from VO+ to SoundDock)
4" red (12 volt positive from SoundDock to switch)
3" black (power/main ground from DC-DC converter GND to SoundDock)
2-1/2" red (5 volt positive from switch to DC-DC converter IN+)
1-1/2" red (5 volt positive from DC-DC converter VO+ to Bluetooth module 5V)
1-1/2" black (power ground from DC-DC converter GND to Bluetooth module GND)

Strip the ends of each wire (you need about 1/16" bare for the docking circuit board ends, and about 1/8" bare for the other connections). Then follow the wiring diagram to connect the Bluetooth module and DC-DC converter together and connect the docking sensing wire to the switch and to the VO+ of the DC-DC converter board. Check your wiring before proceeding, to make sure it's all good.

Step 5: Solder Wires to the Docking Circuit Board

After you've got the wires properly soldered to the Bluetooth module, DC-DC converter, and rocker switch, position the components in the housing and thread the wires through the bottom of the housing. My components fit well enough that they snapped into place without any adhesive, but if yours are loose you can hold them in place with a little dab of hot melt adhesive (but I'd wait to do that until you've tested your work after the next step). Now position the Bluetooth module housing near the docking circuit board as shown in the photos, and follow the diagram and pictures to solder each of the wires to the proper location on the docking circuit board.

Step 6: Test Your Work

I'd recommend that you check your work before re-assembling everything. To do so, reconnect the docking circuit board by carefully inserting the ribbon into the connector on the circuit board. You can pull a little of the ribbon out from inside the docking station (you might need to loosen the 2 front screws holding the bottom panel on to do so). Then plug your docking station into its power supply and turn the rocker switch on, and see if the blue LED starts blinking on the Bluetooth module. If it doesn't check your wiring and soldering job.

Now pair your Bluetooth module with a phone, tablet or PC. There's no pairing button on the module, you'll just see it in the list of available devices under your Bluetooth settings as "MH-M28", and you just have to connect to it. Once it's paired, play some audio from your connected device. If you don't hear any sound, make sure the volume is turned up on the SoundDock (using the little volume up button) and on your connected device. If you still don't hear anything, unplug and plug in your SoundDock again (I don't know why but sometimes the SoundDock needs this jump start). If that doesn't work, there a chance you accidentally unplugged the ribbon cable from the main amplifier to the preamp/controller board on your SoundDock. You can easily check this by looking through the gap between the docking board holder and the bottom of the grill on your SoundDock. If the ribbon cable that comes out from behind the grill looks like the one in the photo above, then it's come unseated from the connector and you have to re-seat it. To do so, you'll have to remove the grill (just gently pry it off starting from the bottom) then remove the 4 screws that hold the power amplifier in. Gently pry the amplifier module up and lift it out of the housing enough to pull the ribbon cable out. You can then reseat the cable and re-attach everything you just removed. There are Youtube videos that go into more detail on this, so you might want to check those out.

Step 7: Final Assembly

Once you know that everything is working, you can assemble your SoundDock.

Working from the bottom of the SoundDock, slide the Bluetooth module housing up through the opening in the docking base and let it hang from the wires while you fasten the bottom cover with the three torx screws.

Now flip the SoundDock over (rightside up) so you can fasten the cap on the new Bluetooth module housing using either the screws or, if you didn't opt for those, a few dabs of hot melt adhesive. Don't get carried away in case you need to remove the cap for some reason. Now fasten the Bluetooth module to the mating recess in the Sounddock with a small line of adhesive at either end of the recess.

Your new Bluetooth enabled SoundDock is ready to go. The volume controls on your Sounddock still work with this setup, and you can also control the volume on your device. Things will get very loud with both set at maximum, so I just set my device volume at a little over 1/2 and then use my SoundDock volume from there.

If you want to use the Aux-in, just connect a cable from your device to the Bluetooth module, but remember that this jack merely connects in parallel to the audio output of the Bluetooth module, which means that your SoundDock will still receive the Bluetooth audio out along with whatever signal is being sent from the cable. So if you're still streaming audio via a Bluetooth connection, you'll hear that on your SoundDock along with the signal from your plugged-in cable.

If you ever need to pair it with a different device, you have to first disconnect it from whatever device it's paired with, or if the originally-paired device is turned off or is out of range, you can simply select it and pair it with a new device.

Step 8: Bonus! Skip the 3D Printed Bluetooth Housing

After I shared this Instructable on social media, a friend commented that they had an old SoundDock that they would like to fix but lacked a 3D printer. I thought about that scenario and decided to add one more problem to solve.

7. Can I do this without a 3D printed housing?

It turns out that you can. There is plenty of room on the bottom of the SoundDock for housing the Bluetooth module and the DC-DC converter, and the rocker switch fits nicely on the front of the SoundDock along the bottom edge. You can reasily run slightly longer lengths of wire from the docking circuit board to either of the cavities on the bottom of the SoundDock. So problem seven is solved!. But then I also thought, well what if you wanted to get rid of the docking shelf altogether? Since it's no longer needed to hold the Bluetooth housing, why keep it around? This gives rise to 2 more problems.

8. Can I wire directly to the preamp/controller board?

9. Will the SoundDock work without the docking board connected?

To answer the first question above, I inspected the preamp/controller board to see if there were any obvious solder points near the mating ribbon connector on the preamp board. No such luck. You could simply connect your six wires to the pins on the controller board, but I'm a pretty good solderer and I was easily frustrated in my efforts to do. There are a lot of larger pads on the preamp board that would be easy to solder to, so I used an ohm meter to check the resistance between pads on the preamp board and the desired points on the docking circuit board, and was able to find the right pads to connect to on the preamp board. I did a quick test by wiring my components to those points on the preamp board and it worked perfectly, and the correct preamp connection pads are indicated in the first photo above.

To answer the second question above, I unplugged my SoundDock and disconnected the docking circuit board and powered up the SoundDock again. It worked perfectly. With the docking circuit board removed, I had no volume control on the SoundDock, but this isn't a problem since I can control the volume from my phone (or whatever's connected to the SoundDock), and can also use the SoundDock remote. The SoundDock seems to remember the last volume you set when there's no docking circuit board connected, but you can use the SoundDock remote to change it. If you don't have the remote, you may need to wire two pushbutton volume switches and install those on the front of your dockless SoundDock. I've identified the connection points that you can use to connect volume pushbuttons, and these are also pointed out in this first picture above. Each switch simply connects to the corresponding switch input and ground.

As long as I had it this far, I decided to finish mounting the components in one of my SoundDocks to see how things could fit, and it turns out they fit pretty well. I just had to locate and drill holes for the jack and the LED for the Bluetooth module, and drill a hole for the switch (hole locations and sizes are included in the drawing above). You need a 9/16 inch (~14mm) hole for the switch, which I didn't have, so I drilled a 1/2" hole and then used a rotary tool equipped with a small sanding drum to enlarge it to fit. I also had to file a small notch that determines the orientation of the switch and I used the rotary tool with a small burr grinder to grind slots between the center bottom cavity and the cavity where my components were to be mounted so I could run the wires without pinching them. With all of this done I secured the Bluetooth module and the DC-DC converter with hotmelt adhesive, and snapped the switch into place. The results are shown in the photos above.

So there you go. It is possible to skip the 3D printed housing and either keep the docking platform or remove it. If you keep it on, you're pretty much done. If you remove it, you'll probably want to do something to cover the opening left in the front of the SoundDock. Maybe you could 3D print something...