#0025: Modifying a pair of Game Boy Advance SP earphones into an auxiliary audio dongle

Preamble

This article will consist of a basic tutorial on how to create a Nintendo Game Boy Advance SP (GBA-SP) audio dongle using a broken third party pair of GBA-SP earphones. Additionally I will also provide some related commentary (ramblings) on the similarities between Apple and Nintendo; particularly the way they design their products, and the way that their fanbases receive them. So if you have any old earphones you got as a child and broke yet kept, or maybe even recently purchased as spares and repair? Or if you are inclined to hear me bemoan tribal consumers and corporate avarice. Well here you are.

Creating an audio dongle

The actual conversion is rather simple. You just need to first cut the earphones off; then connect the wires as shown in the pinout and wiring diagram below.

Pinout

Audio jack
1: left speaker positive
2: right speaker positive
3: common ground

GBA-SP port
1: right speaker positive (red wire)
2: closed loop switch
3: (pin absent)
4: left speaker positive (blue wire)
5: common ground
6: closed loop switch

Now that we have the broad methodology of what to do to create an audio dongle, I’d like to talk about a few specifics.

Closed loop switch

In the pinout diagram I labelled pins 2 and 6 as “closed loop switch”. What I mean by this is that there is continuity between these two pins. This means that they are electrically connected to each other. I believe they are configured in this way in order to act as a switch when the plug is inserted into the device.

The electrical connection between the two pins effectively closes an open loop within the device. One that terminates with these pins’ respective sockets. This loop is probably used so that the device can know when an audio peripheral has been connected. This is so that it can act accordingly, by for example switching off it’s built in speaker.

Where to cut the donor earphones cord?

This might seem like a rather simple question at first. However in order to answer it, I needed to answer a few other questions before knowing where exactly I wanted to make the cut. The most important question that needed answering is does the pair of earphones actually work properly, or are they broken somewhere.

Assuming that they have at least one fault somewhere within them, where is the fault? If you can not easily identify it, yet the earphones are still not outputting sound. Then perhaps the fault is hidden. In this case, it will mostly likely be either at the earphones themselves due to snag damage; or if you are unfortunate, it’ll be located near the plug due to something akin to repeated flex damage. Please note that I am just speculating from my experience with repairing headphones.

Once the fault is found, then you must make a decision. Repair the fault, or cut if off (if applicable). In my case the fault was at the left earphone itself. I didn’t probe further than identifying roughly where it was, since I had no intention of repairing something that far down stream. I did however consider whether or not I wanted to retain the inline volume dial. After some consideration I decided to remove it. The reason for this is that I feared that the relatively low quality of the componentry involved; such as the potentiometer, or the PCB and it’s solder joints may actually negatively affect sound quality. So I just snipped it off. Didn’t like it much anyway. It didn’t feel nice to use.

What type of plug or socket to terminate the cord with?

This question was primarily answered by the materials I had available at the time. I did not have an appropriate female 3.5mm audio socket available. However I did have plenty of male 3.5mm jacks on hand; including ones that were corded. In the end I went with a jack that was colour matched (black) and that had the smallest profile.

This male jack enabled me to plug the GBA-SP into an auxiliary port on a sound system should I wish to do so. Additionally when coupled with a female-to-female 3.5mm audio adapter, it enabled me to use headphones or speakers with the dongle. This setup basically gave me the same functionality as having an adapter that terminated in a female 3.5mm socket, paired with a typical male-to-male auxiliary cord.

Soldering the jack

When it comes to soldering audio jacks like these: the first actual thing I did was prepare the heat-shrink tubing for it. Selecting the right sizes and cutting them to length. I prepared two pieces, which I thought was sufficient at the time; however in hindsight I should have prepared three distinct pieces. One to isolate each line.

As it is, it has one to insulate the central shaft from the surrounding ground pad, and one to act as an outer cover; protecting all three wires and acting as a general guard against flex damage for the entire cord. It’s good enough, but it would be better in my opinion if the inner two wires were separated by more than just the enamel coating of the wire strands themselves, as I have left them. A smaller gauge piece of heat-shrink tubing on the inner terminal to cover it’s solder joint would’ve been better.

As for the soldering itself: audio jack terminals like the one pictured can be rather tricky to wire up and solder properly. The reason for this is due to a range of factors. Factors such as: the general fiddliness and fragility of the enamel wires themselves. Although more-so the close proximity of the jack’s terminals to each other, coupled with the convex curve and orientation of their soldering pads, is what adds difficulty; as the awkward angles involved can diminish dexterity.

Additionally, the presence of structural plastic insulation between the terminals, meant that a lower heat and a shorter soldering dwell time was needed. This in order not to damage the jack’s plastics with radiant heat from the work area. Otherwise the plastic will melt and warp the plug’s general shape and structure. All these various factors can make it difficult to solder in a reliable and repeatable manner. However practice and work flow optimisations will mitigate these type of annoyances as one gains experience in this task.

An example in which I optimised the process: was by preparing the wires for soldering by removing their enamel insulation. This is because prior to this: during soldering, the enamel coating on the wires sometimes wouldn’t burn off within the liquid solder blob itself; especially with the necessary (relatively) low heat and short dwell time. When this happened, it resulted in the wire not forming a good electrical connection and/or not bonding physically with it’s solder pad.

I chose to prep the wires by burning off a segment of their enamel coating using a lighter. This had to be done in very quick manner in order to not oxidise the underlying copper strands too much. Burning off the insulation in this manner allows me to quickly solder the wires into place without worrying about any complications from the insulation.

After removing a segment of insulation in this manner, I chose to attach the wires in a way that limited any exposed segments of wire present outside of the solder joint. This is to limit any exposed conductors. Consequently, the solder joints were close to their respective wires’ insulated ends, and only used the exposed segments to get a good electrical connection within the solder joint itself. After-which I’d snip off any excess exposed wire that preceded the joint.

Testing the cable

The attentive readers amongst you probably have noticed that my repair notes contain several resistance tests of the various lines. Most I ran while working on the device, those are the numbers closer to the hand-drawn diagram. Some of which have been struck out. Discount those. The ones of interest are at the bottom of the notes. Those are the results from the post repair test.

The reason for the final test was because I was dubious of the quality of the cables that I was working with. As well as generally dubious of audio cables of this calibre. Specifically, cables that consist of a small collection of loose strands dipped in (I believe) enamel for insulation; then interwoven with additional plastic or nylon strands for strength. They all look and feel fragile and cheap. Having said that however, I should say that a post repair test is a good general practice. Even when confidence in the repair is high.

As you can see the left speaker line has a end-to-end resistance of 10 ohms. Five times that of the right speaker line, and ten times that of the common return (or ground) line. The right and return lines have acceptable resistances in general, and accurate relative resistances to each other. I expected the return common line to have half the resistance due to the doubling of the lines. However, what was unexpected was that the left line was clearly an outlier in line resistance. This in my opinion is due to either the low quality of the cable in general, or a hidden defect I did not find.

It’s not ideal, but upon testing with actual sound, the loss of volume on the left line speaker due to it’s higher line resistance was not noticeable at all. So I just left it be. The effort necessary to track the fault that is adding the 8 ohms to the line, is not worth the reward of having perfectly balanced lines for a GBA-SP’s audio. I used to call it laziness not ploughing down these types of rabbit holes. However as I have aged, I have come to understand the diminishing returns on investments that this type of perfectionism offers.

Completed mod demonstration

Related thoughts on Nintendo and their Game Boy Advance SP console

Now that we have created our own DIY audio dongle, let’s talk about why we needed to do this in the first place. In other words, why the Game Boy Advance SP doesn’t have a built-in 3.5mm audio port to begin with. In order to get at this answer, let’s first discuss a completely different technology company and it’s products. As to why, I’ll let you join the dots.

Many people today (2021) credit Apple as one of the most anti-consumer consumer technology companies, specifically with regards to their product design. Although there are numerous examples I could pick out, the one relevant instance here: is the removal of the generic 3.5mm audio jack from their 2016 iPhone 7 models. Anyone who pays any critical attention to this company probably came to a similar conclusion to my own. (Proceeds to pat self on back.) This naturally being that they did so in a bid to to sell first party audio peripherals at a premium. This being to their captive audience of fruity cultists. Cultists that would happily eat that up.

Why am I mentioning this in a Nintendo article? Well it’s because peoples’ memory is generally fickle and often mired with nostalgia; and the residual emotional attachments that it incurs. This leads them to holding double-standards when it comes specifically to childhood brands like Nintendo, often holding them to a lower standard of conduct than brands like Apple. These same people forget that their friend Nintendo did the same thing 13 years prior in 2003 with the incremental release of the Nintendo Game Boy Advance Special (GBA-SP) portable games console.

A games console that had no tangible advantages over it’s Game Boy Advance (GBA) predecessor other than a few quality of life (QoL) improvements. Both consoles played exactly the same games, however the SP boasted: an internal rechargeable lithium-ion battery, and an LCD backlight. For consumers tired of repeatedly buying new AA batteries for their GBA, or always awkwardly angling the unlit LCD towards a light-source whilst avoiding glare; these were improvements worth investment. Those of you who can read between the lines, might’ve guessed that this internal battery naturally required a specific Nintendo battery charger. A theme that they continued in later products such as with the Nintendo Dual Screen portable console (NDS).

However, a more apt feature of criticism in the iteration from the GBA to the GBA-SP, is the removal of the 3.5mm audio jack. Why did they do this you may ask? Well, now I could be wrong, but the cynic in me says that it was to facilitate Nintendo selling official audio peripherals at a premium, to their captive audience of pedantic neck-beards in waiting. That’s us mate.

Laughably, Nintendo’s official response against their audience’s pushback in 2003 was basically the same as Apple’s in 2016. They both said something to the tune of: that the new device simply didn’t have the space for a 3.5mm audio jack. Apple added some device waterproofing claims to this as well. But the core reason was the same: that there’s simply no space for it. Now shut up and buy our official peripherals. Peripherals that use the same port for both audio output and power delivery. So good luck using wired headphones and charging the device at the same time. Enjoy.

To cut it short. My point is that Nintendo has proven themselves to be as anti-consumer as Apple when the mood takes them. However it saddens me that their customers are prone to look at this company through rose tinted spectacles. Often even shouting down valid criticism, yet many within the community still consider themselves distinctly different from the stock of Apple enthusiasts.

That’s what happens when one thinks with their feelings. It’s tribal fanboy-ism at it’s finest. People for whatever reason forget that an individual’s relationship with a company or business like Apple or Nintendo, is strictly transactional. Nothing more. They are not your friends. A corporation does not have the capacity for camaraderie, or loyalty. Only the capacity to take advantage of such feelings in order to sell more to the same people.

Obviously, I am not talking about the entire consumer base here, just the vocal fanatics that seem to dominate public discourse. If anything a logical or reasonable person who likes the products of a particular brand to the point of becoming brand loyal; should ideally, be even more critical (than the average Joe) of their chosen company when it strays into anti-consumer practices. Due to their investment within the brand and it’s products. They likely would wish for them to stay good, more than a person who isn’t all that invested. But that’s not the world we live in. Instead the more invested a person is in a brand, it seems the more likely they are to tribally defend them regardless of circumstance. It’s sad really.

Closing thoughts

I know what you might be thinking, this article is nice and all, but it’s also almost twenty years too late. I mean in previous years getting a hold of an audio dongle for the GBA-SP might have been troublesome or expensive. Back when (the famously litigious) Nintendo were still protective of the console. However in 2021, one could easily purchase a NEW Game Boy Advance SP audio dongle from Ebay for less than a fiver. Since Nintendo doesn’t care much about protecting the rights to peripherals for a console that old (read unprofitable). Sure, the item that you buy won’t be an official Nintendo product, or even a notable third party contemporary brand peripheral, like Competition Pro. But it’ll work. Probably.

To answer that question: Yes, yes you could. You could purchase an unbranded china special peripheral for your almost twenty year old console. Alternatively you could also make use of any old and/or broken first and third party peripherals that you may already have lying around, or even purchased in a mixed joblot or bundle. Essentially converting (basically) e-waste like that into a useful cable. One made to your exact use case and specification no less. Chances are your convert will also be better quality than a bought cable depending on what materials you use to make it.

Mine isn’t, I made mine from a pair of Competition Pro earphones. But still you get my point; I bet if you made yours from a pair of official Nintendo earphones (should you happen to have them), they might be better quality. As for making something for a specific use case: I totally use mine to blast Castlevania: Aria of Sorrow’s soundtrack, via my home sound system. I do it for maximum “immersion” during my midnight gaming sessions. I also want my neighbours to know that I am cool. The banging on the wall seems to indicate that they do.

Thank you for reading.

Links, references, and further reading

https://docpop.org/2016/09/apple-learn-nintendos-headphone-mistake/
https://arstechnica.com/gaming/2016/09/no-headphone-jack-nintendo-did-it-first/
https://en.wikipedia.org/wiki/IPhone_7#Headphone_plug_removal
https://en.wikipedia.org/wiki/Game_Boy_Advance_SP#Headphone_jack