Not only will you love your new custom headphones but after you realize that you can run a weed eater or leaf blower without having to tuck ear buds under your hearing protection and blowing your hearing in the process you'll want to build sets for all of your family and friends.
This project will require basic soldering knowledge but is simple enough it can be a great first time soldering project.
While the installation is simple the creation of the mounting bracket is not. Since it is infinitely easier to create a second bracket then start from scratch I have created kits with the necessary parts, If there is any interest in making a version that you don't need to solder together please message me or leave a note in the comments.
*Noise reduction is not rated and will be dependent on your build. I make no claims on levels of noise reduction and what is considered safe.
Step 1: Purchase a Military or Aviation Grade Headset
As you can see from the connector, this is going to take a bit of work before we can plug it into any old MP3 player.
Step 2: Dissassembly
Step 3: Building Speaker Mounts
If you compare the new speakers with the original you will notice that the new speakers are much thicker and a little bit smaller than the pieces they replace. The new speakers are rated for 3 Watts and 8 Ohms, so they have similar impedance to most headphones on the market. This basically means that they will sound about as loud as another pair of commercial headphones for a specific volume level. The difference is these can go to 11. Well, not really, but they can get much louder before failing compared to almost any other headset. For example, each speaker is rated to generate 85 decibels of sound using only 1 Watt of power from almost 20 inches away. Also keep in mind that each speaker can run at three times that power and up to four in peak situations. Clearly these are not your normal headset speakers. These are usually used in higher end computer speakers and small stereos and not made to put directly on your ear; however when you do, they sound fantastic. A quick word about the old speakers. Even though they serve the same purpose they are not built with a traditional voice coil as your typical dynamic loudspeaker. Instead, they use an electric coil to vibrate an actuator bar that pushes on a rod which vibrates a metal disk. While this is great at making a lot of noise, it is restricted to a fairly small tonal range. That is why it's great for reproducing a voice in an aircraft where quality does not matter, but it is terrible at accurately reproducing music. (An older version can be seen opened up in the last picture).
The mounting bracket holds the speaker as tightly as possible while still matching up with the same mounting screw holes and allows the wires to be easily connected. I tried to make the first one completely out of sculpting clay, however it was impossible to get the impression I wanted from the speaker and keep the shape that I needed. For the next try I used a bracket from a different David Clark headset as a base to sculpt the speaker mounts around. The black and white piece you see is actually built from 6 different plaster sculpting and casting sessions before the final shape was made. This was cast into a silicon mold and after it set was broken up and chipped out. Then the mold was sliced in half to facilitate easier extraction. Rubber bands were used to hold the halves together while the liquid plastic set. Unfortunately, it was still very difficult to get out and quite rough, requiring a lot of sanding to get into decent shape. To improve the looks, I took one of the better casts, sanded and polished it to a nice smooth finish and cast it into a new silicon mold horizontally for easier removal.
Step 4: Installing the Speakers
Step 5: Cleaning Up the Appearnce
Step 6: Wiring It Up
The trickiest part is wiring up the 3.5 mm headphone jack. The metal strain relief barely fits over the coiled wire and is difficult to slide around (which is a good thing). As for soldering, the connections are small and it would be easier with a third hand to hold everything in place. Don't forget to slide all three pieces of the cover up on the wire in the right order before you begin or you will have an opportunity to try again.