Introduction: Headphone and MP3 Player Holder for Exhibiting Sound Art

By Nonpolynomial Labs
About: Engineer, specializing in fixing tools that aren't working the way the users want them to in the first place. Author of too much open source software, including drivers for many obscure pieces of hardware (in…

When deciding to do a sound art project as part of my residency at Pier 9, I had to figure out how I was going to display it at the Pier when it was done. Not to mention, it did kinda feel like I should, you know, actually make something physical.

This instructable documents the headphone and mp3 player holder I built so that Pier 9 visitors could listen to the recordings I took on different machines. Also, in order to get the most experience around the workshop, I ended up trying to make each unit on the machine it would be displayed on. This ended up being both a great and horrible idea.

The original plan consisted of making holders for the following machines around Pier 9:



• Epilog Laser Cutter
• Metabeam Laser Cutter
• Objet 3D Printer
• Mcor 3D Printer
• Omax Waterjet
• TIG Welder
• DMS Router
• Haas Mill

Step 1: Materials Required

Before I list what I used to build these, I should mention some of the considerations for this specific project. First off, this is for the AiR Art Show, meaning these holders will be hanging for a total of 3 days. Therefore, while they could last for quite a while, it's not really part of my plan. Also, due to the gallery show being in the Pier 9 Workshop, it's not exactly a quiet listening environment, so throwing project money at higher end audio equipment would be wasteful. I tried to find a good bridge between expensive, quality, and ease.

Here's the materials list, and the things I chose for it:

  • MP3 Player
    • I went with these $4 clip mp3 players on amazon. All I really needed was hardware that would play mp3s and change volume. The form factor it came in wasn't really an issue, since I planned on pulling out the electronics anyways. This actually meant that simpler was better. These MP3 players use media stored on an Micro SD Card, and it automatically loops back to the first song with you hit the last song. This means if we have a card in it with one MP3 on it, it just loops it. Not only that, it comes with a battery that lasts 6 hours, meaning if one of the units isn't mounted near power, it can just run on battery. Perfect!
  • Micro SD Cards
    • All I need it to hold is one MP3, but the cheapest card I can find is 8GB. The future is weird. I have a lot of 8GB SD cards now.
  • Headphones
    • Headphones are a little more difficult, as REALLY cheap ones are usually missing large swaths of frequency response. I tried to err on the side of caution and spend a bit more here, going with Tascam TH-02 pairs that were on sale. They're not the comfiest thing in the world, but they sound decent, and they're not going to be worn for very long since most of my recordings will be chopped down to 30-60 seconds anyways.
  • Buttons
    • Since I was providing my own volume and play/pause control, I needed my own buttons for the user. In order to make life as easy as possible on myself, I just went with SPST buttons from Jameco. Easily to wire, easy to mount.
  • Structural Materials
    • This varied depending on the holder. I used 6061 Aluminum for metal, balsa ply for the laser cut ones, and paper for the mcor because, well, it's a paper printer, not much choice there.

Step 2: Building the Electronics

Now that we've got all our materials and model, it's time to start the assembly line process on the electronics.

After removing the screws from the case and taking the circuit board out, we can see that the buttons from the player are connecting to pads on the circuit board via a metal sticker being pushed onto it. This means we can just take the sticker off, solder wires to each side of the pad, then solder those two wires to a button to do the same job. Easy! Now we've got a full mp3 player with our own controls.

In order to be able to easily reconstruct and move things, I put a detachable connector in between the wires and the buttons. This allows me to easily mount the buttons then attach them to the mp3 player. The connector I used was originally for circuit board mount, but I had a ton of them lying around and didn't feel like ordering more so they got used. Probably not ideal, but it works.

Step 3: Building the 3D Model

The holder itself has few functions. It should easily, comfortably hold the headphones, and the electronics. For the headphones, I measured the width and height of the headband when the headphones were at their smallest (earpieces fully retracted), and used that to make an ellipse for the headband to hang on.

The unit went through a couple of design iterations before I hit the final. Here I show the first and the last.

The first unit was quite large, because the plan was to have iconography with the unit, since all units would be made of laser cut wood. The large holes in the front were for wooden pegs to secure the unit together. I also wasn't really sure where I'd be storing the circuitry at that time, and was initially thinking of just letting the MP3 Player be its own audio interface.

There were multiple problems with this.

  • The MP3 player buttons weren't real easy to use.
  • The holder was going to be attached to the machine that's recordings it was playing. Iconography seemed redundant.
  • The show was going to involve MANY artists, and I wanted the audio to be front and center for my piece, not the holder. The holder should be the minimal functional piece.

The redesign took this into account. Instead of iconography, I decided the material of the holder itself should reflect the recording, so I ended up making each holder on the machine it was playing recordings of. Hollowing out the center means I can store the electronics inside the player, and have the minimal number of buttons available for the user interface. I moved the securing holes outward, instead going with 1/4" holes which could be tapped for 1/4"-20 screws. While not reflected in the model, I also made simple iconography to go above the buttons for signifying which did what.

The final model consists of 3 pieces:

  • The front plate, which holds the buttons and icons, with a slight lip at the top to keep the headphones secured.
  • The middle piece, which is a hollowed out sort-of ellipse. It has a notch near the backplate for running power and headphone wires out.
  • The back plate, which will be secured to a surface of the machine in the show.. I put countersinks on the back of the model to account for nuts holding screws on, though these were not always as large as they needed to be.

This meant that I could also easily rebuild pieces if there were issues, without having to rebuild the whole thing.

Attachments

Step 4: Fabrication: Laser Cutters

Fabricating the models on the laser cutters was basically the same between the Epilog and the Metabeam.

  1. Cut pieces on laser cutter
  2. Align wood on bolt holes and glue up
  3. Sand outside, finish with polyurethane.

The only differences came in the thickness of wood I used. I ended up using 1/8" for everything on the Epilog, and 1/2" to 1/8" on the Metabeam. I also set the Metabeam settings slightly too high, so it ended up getting a rather charred look, but that also serves to set it apart from the Epilog.

Step 5: Fabrication: 3D Printers

There's not a whole lot to say about the 3D printer fabrication, because, well, it kinda just prints it. I put STLs for the 3 pieces of the holder in, and out they came. I ended up not polishing the 3D print due to lack of time, but the Mcor paper print got a few coats of polyurethane to reenforce the structure.

Step 6: Fabrication: Waterjet

The waterjet ended up being the most difficult and experimental of all the holders. I decided to try and make the middle piece in one go, using a 2.5" piece of aluminum stock, the thickest piece of stock to have been cut at Pier 9 thus far. I faced the stock on the Bridgeport mill, then set it up in the OMAX using double sided tape and a plywood spoiler board for mounting. The cut itself took a little over 90 minutes, but came out looking amazing. The cuts were super clean and lined up fine.

In order to hold everything together, I tapped the holes in the back plate. This meant I didn't need to use nuts, as everything just held together using those threads.

Step 7: Fabrication: the Ones That Never Got Made

You may notice that this instructable only lists 5 machines so far. Due to running out of residency time, only 5 holders got made. Here's what the plans were for the other ones:

  • TIG Welding - Exact same idea as the waterjet, except the middle piece would be cut into smaller pieces and welded together. Was also thinking about bandsawing the front piece and rewelding it for that Texas Chainsaw Massacre look. I just ran out of time to get the stock cut, waterjetted, and welded.
  • DMS Router and Haas Mill - The idea on both of these was to make the front plate and middle piece a single unit. Unfortunately I never even touched these machines during the whole of my residency because I was so busy with everything else and they seemed like the ones I was least likely to encounter after the residency.

Ah well. Still happy I got 5 done.

Step 8: Conclusion

I'm quite happy with how the holders that got finished came out. They work well, but aren't overly large or showy. It was also interesting to have to focus on what was going to present the sounds I recorded, versus just working with the sound itself.