How to Make an Audio Interface Out of a USB Headset

This was a project I came up with a while back as a way to record audio from microphones and guitars without spending any money whatsoever. There's a lot of ways you can alter this project or do it differently, so don't be afraid to have a little fun with it if you know what you're doing.

For context, I wrote this for an English class and just thought someone else might find it useful. (It's pretty wordy, but I tried to cover as much as I could :) )

Making music is a fun hobby for many, but taking the first step into music recording and production can be daunting. Audio setups vary widely, but one thing that all of them have in common is an audio interface. This is a device that allows the user to input a high-quality audio signal directly into their computer for recording, editing, and more. Many high-quality audio interfaces can cost upwards of $100, some several times higher than that. For someone that just wants to try out recording music as a hobby, this price can be a little steep. This project is a way that people can get access to a medium-quality audio interface on a tight budget.

This project is intended for people who have at least some experience with electronics and are willing to make some compromises and solve some problems. This can be a very fun and very useful project, but it can easily become frustrating and useless if done haphazardly or without enough preparation. That being said, almost anyone can do this if they have the willingness to learn and figure things out on their own.

Edit: I had to make a video for my English project too, so here's the video version on YouTube if you'd prefer that.

Making this interface is also going to require a handful of tools. The most necessary is a soldering iron, which will be used for making electrical connections. Soldering irons can be dangerous if used incorrectly, so always wear safety glasses when soldering and always keep a wet sponge or solder sponge near the iron. This project will also require a drill and a set of bits. A ¼” drill bit is definitely necessary, but other hole sizes may vary. A handful of small screws and nails will also come in handy. As mentioned earlier, be prepared to solve problems. Depending on the choices made during this project, it may also require a variety of other tools such as wire cutters, needle-nose pliers, screwdrivers, a hot glue gun, etc. This project is best done using only what is immediately available, since buying many specific materials for it would likely make it cheaper just to buy an audio interface rather than building one.

The goal of this is to input audio into a computer, which is why a USB headset is required. A headset is just headphones with a microphone attached, and that microphone is a way to get an audio signal inside the computer where it can be recorded. However, that little microphone is usually very poor quality, and so it’s not suitable for recording. However, if it had a nicer microphone or audio source (such as a guitar or bass) connected, it would be much higher quality. That’s what this project boils down to: replacing the microphone in a headset with a way to input higher quality audio. That input is going to be a ¼” audio jack, which is compatible with most guitars and basses, a lot of keyboards, and even some cheap microphones.

There’s two ways to get this kind of input. The straightforward way is to use a normal panel-mount ¼” audio jack, the kind that’s used as an audio input in commercial products. Most of these cost a few dollars and can be bought online or at a music store. The other, cheaper way is to make one from scratch, which requires some bendable pieces of metal. When something is plugged into the interface, this will hold it in place and connect it to the electronics inside.

Not all inputs are created equal, however. Some inputs are really quiet, for instance, the signal from a microphone. Some are much louder, like the input from an electric bass. Without a way to adjust for these kinds of inputs, the signal could get distorted or be too quiet in the best case, or actually damage the electronics in the worst case. The solution for this is a variable resistor, also known as a potentiometer, or a “pot” for short.

There are many kinds of pots, but the most common is the panel-mounting rotating kind. These are knobs that turns from side to side to adjust how much resistance the signal will get, which changes its volume. To put it simply, it’s a volume knob. This can be used to make sure that the input never gets too high and that it can be heard even if it’s really quiet.

With the headset, jack, and volume knob taken care of, the only thing left is a place to put them. This project needs a good case to keep all the components together, safe, and good-looking. Like the jack, there’s two routes: Buying/finding an case and making one.

An case could be anything from a steel cabinet to a cardboard box. Plastic electronics cases or “project boxes” – which are cheap and abundant online – work great for this, but a custom box can sometimes fill the role better. Either one will work fine. One thing to be careful of is metal cases. They can easily act as double-edged swords: Depending on how a metal case is used, it can short out connections inside the box and create problems, but it can also shield the electronics and provide much cleaner sound. People who aren’t very experienced with electronics should generally stay away from metal cases.

Whatever the case is made of, it should be relatively small, and ideally box-shaped. Somewhere around 3 to 4 inches on every side seems to be the sweet spot: enough room to work with, but small enough to stay compact. They can be much bigger and smaller, of course. This is an area that can allow for a lot of creativity without affecting the function of the project much. Make sure that, whatever it is, there is some way to access the inside very easily and a way to close it afterwards.

Panel-mount jacks and pots are convenient for cases made of thin material because it allows them to simply be screwed onto a hole in the box. Making a home-made jack will usually require a thicker material on the front (or whatever side the jack goes on) so that the metal can be easily screwed onto it from the inside. Similarly, when using a pot that isn’t panel-mount, some kind of support will need to be devised so that it can be secured inside the case, but still be turned from the outside. This could require a bit of creativity depending on the layout of the case.

Assuming all the needed parts and tools have been gathered by this point, the assembly can begin.

The first step is going to be figuring out what exactly is being replaced and where it is. The microphone on most headsets is at the end of an arm on the side of one earphone. Open up the plastic around it to find the little microphone inside. There should be two wires connected to it. Take a close look at those wires and write down what color they are and what they look like. Often, the microphone will be connected to a shielded cable, which looks like one wire that splits into two, one of which is bare (usually a brownish copper color or a grayish zinc color) and has lots of strands. These are the wires that will be connected to later to replace the microphone. All that’s needed right now is to remember what this looks like so it can be identified later.

Somewhere along the cable, there should be a small box-like thing, maybe with some labels on it. Start at the USB end of the headset cable and move upward until the first part that looks like that. Some will have two, but the one that’s important is the one closest to the USB port. This is the part where all the different parts of the headset connect together, which in this case, is called an “ADC”. Open up the plastic shell and look inside.

Once inside the ADC, there should be a circuit board with two ends, one for the USB plug and one for the headset itself. The USB side should have 4 wires: Black, red, green, and white. That side should be left as-is. Look at the headset side of the board and try to find the same cable that was connected to the microphone. Some boards may even say “MICROPHONE” or “MIC” on it to show what’s what. One the cable has been found, cut the headset wire about 6 inches from the ADC. Separate out the mic wires from the rest of the cables on that end. The plastic shell can be completely taken off and thrown out, as well as the rest of the headset itself. The microphone cable is the only part that’s needed on that side. Again, be sure to keep the USB side completely intact. Now that the only thing left is the mic cable, strip the end of the cable or otherwise expose both wires. Solder two wires to it, about 4 to 5 inches long. Set this aside to be used later.

The next step is to mount the ¼” jack to the front of the case.

The process is fairly straightforward for panel-mount jacks. Drill a 3/8” hole in a thin part of the case where the jack will go and screw the jack onto that hole, tightening the nut on the front to keep it secure. For homemade jacks, the process is a little more complex.

If the case is pre-made, open it up and attach a thick piece of material to the side where the jack will go. This needs to be thicker than the shortest screws available. Drill a ¼” hole in the front where the jack will be and make sure a ¼” plug fits in without much resistance.

For custom cases, get the material for the front side – remember, it has to be thicker than the smallest screws available. Make sure it’s cut to the right size already because it will be very hard to change it after the jack is attached. Drill a ¼” hole where the jack will go and check that a plug goes in easily without being too loose.

After the hole is prepared, the contacts are needed to connect to the plug and hold it in place. Get the thin pieces of metal ready by cutting them into strips about ¾” wide. Make sure they are bare metal, otherwise, they won’t conduct electricity and the jack won’t work. Bend one into a shape that will press against the side of the plug and one into a shape that will press against the notch at the end of the plug when fully inserted. This second contact will provide the tactile “snap” that keeps the plug in place and ensures good contact. One at a time and with the plug removed, place these contacts next to the hole on the inside of the case. From the inside, drill holes through the metal and into the thick front plate for screws. It’s best to use 2 screws for each contact to keep them firmly secured. Use short sheet metal screws for the best results, although lots of screws can be made to work by putting a washer around them.

With either kind of jack installed, the next step is to install the pot. Panel-mount pots also screw onto a thin part of the case, so mount them exactly like a panel-mount jack. If the pot doesn’t screw into a panel, drill a hole in the case for the knob and make a support to hold the body of the pot in place inside the case. Be sure to leave the pins (the 3 metal prongs in a row) open so they can be soldered to.

Now that both the jack and pot are mounted, the case can be (mostly) put together. If the case requires assembling, put it all together, but leave the back open for now.

Connect 2 wires to the jack contacts by unscrewing one of the screws on each just a little and putting the ends of the stripped wires underneath and re-tightening the screws. Solder these wires to opposite ends of the pot’s pins, leaving one in the middle unconnected. Next, solder the two mic wires from the ADC onto two adjacent pins of the pot. One wire should share a contact with a jack wire and the other should be connected to the middle pin on the pot. Now the wiring is complete!

Put a hole in the back of the case for the USB cable coming from the ADC so it can be plugged into a computer. Make sure the ADC ends up inside the case and not outside. Put a zip tie around the end of the USB cable on the inside of the case to make sure the cable can’t be pulled out. Now the case can be entirely closed up.

Plug the interface into a computer and open up a recording program such as Audacity. Find the input selector and choose the one that corresponds to the headset you used. Now, the input from a microphone or instrument plugged into the interface should show up under that name! Record some audio to make sure it works. Turn the knob all the way to one side, record some audio, repeat for the other side. This will make it clear which direction is + or – on the volume knob. Labeling this with a marker can be very helpful.

As long as it works correctly, it can be used for recording or calls or anything else that could use an input. Be careful, though: Because the headset had an output with it (the headphone part), the computer might sometimes still want to output sounds through speakers that aren’t connected anymore. Some software might switch to this output automatically and this can cause a lot of frustration if overlooked. Other than that, using this interface should be pretty straightforward.

Using this interface will likely require a bit more
post-processing than others since they tend to be very noisy – a noise-reduction plugin seems to be the best way to mitigate this in recordings. It’s typically not loud enough to be a problem in calls, but it’s something to be aware of. Generally, these are very temperamental and fragile but get the job done.

It’s complete! Enjoy your medium-quality audio interface.

I'm by no means experienced or an expert (or a musician, for that matter), but I've done a bit of recording using this interface before I bought a real mixer. Here's some music I recorded with this and mixed with Audacity.