This Instructable outlines my project of retrofitting earmuffs/hearing protection with Bluetooth headphones. This project was undertaken with several objectives in mind.
Integrate a stereo, Bluetooth headset into hearing protection
Keep hearing protection as original as possible
Make headset more comfortable
Allow multi-function button to be discreetly placed on exterior for easy access to Play/Pause, Pair, and Power.
This wasn't the easiest or cheapest build I've ever done and certainly could have been done any number of ways. This isn't a permanent install and will eventually need new parts due to wear and tear. Nevertheless, I'm extremely satisfied with my finished product and its functionality, and I truly welcome your comments, criticisms, and suggestions.
Step 1: Items I Used
3m Optime 98 Peltor Hearing Protection
Normally around $10-$15
Creative Soundblaster Jam Bluetooth Headphones
Found on Amazon for around $50
Rosin Core Solder
Rosin Flux (Optional)
I found a small container for around $6 at Radio Shack
Cut some off a pair of old earbuds
Memory Foam (Optional)
Managed to find two small sample pieces at a mattress store
Small Heat Shrink Tubing
Any hardware store
A momentary Switch/Button
Found a 30 pack on ebay that matched the color of the headset perfectly for around $3
New Headphone Ear Pads
The folks at headphone.com were really helpful and led me to the ear pads for the Shure SRH-840. These fit the hearing protection perfectly and are way more comfortable than the original pads. These were around $20.
Step 2: Swapping the Ear Pads
The hearing protection originally comes with earpads that are okay, but can cause you to sweat and itch easily if worn for longer periods. In order to fix this issue, I looked to different online retailers for headphone pads. The ones I settled on (see parts list) not only fit the dimension perfectly, but are way more comfortable and prevent excess heat buildup. I can definitely handle these for long periods on hot days.
I needed a way to mount these to the shell of the headset, so I cut the backing off the old earpads. There are frames to the old pads that snap into the shell and it just so happens that there is a lip on the frame where you can slide the new earpads snugly around. I used a dremel to slice into the old pads, but I would advise just poking a hole and carefully cutting off the frame with some scissors.
Once I cut into the old pads, I realized there was a thin membrane inside that was filled with some sort of oil. I'm not sure if this is for added comfort or to take away heat, but it definitely made a mess. I opted to drain the oil from the second frame as well and made sure to clean up the oil as best as I could.
Step 3: Modifying the Shell
At this point I could have stopped and settled on some comfortable hearing protection, but I didn't want to... Yeah. I had to figure out a way to discreetly run wires for the stereo phones. This step involved some planning and a bit of drilling.
For the holes on the muffs, I used a dremel with a 1/8" shank burr ball bit. The bit came with the Dremel. This allowed me to drill tiny holes more precisely into the shell for my headphone wires. I drilled from the inside and poked out through the mount for the head frame.
The metal head frame also has plastic couplings that snap to the shells and hold the unit together. I needed to drill into these plastic pieces as well in order to run my wires up the metal frame and back down the other side to keep wires from being exposed. I had to drill two holes on two of these plastic pieces: One for the wires going into the shell and one for the wires coming out and up. The reason for this is because the metal frame has to push down into these plastic couplings so in order to avoid shorting out my wires from being jammed by the metal frame, I measured how far down the frame would need to sit and drilled out the side of these pieces under that point. The portions of wire that were exposed were later covered by shrink tubing.
Step 4: Running Some Wires
This step required some patience, a hanger, and some headphone wires that I snagged from an old set of earbuds. I began running the wires in sections by measuring out the headphone wire and stripping off what I may need. The wires have an enamel coating so once they're stripped you don't have to worry about them touching and cutting out your signal, but in order to chain them to the other wires, you'll need to remove this coating. I just removed enough coating off the ends in order to tie and solder my wires together. To remove the coating, you can use a lighter, but don't let the wire burn too long or else you'll burn off too much of the enamel. I also cleaned up the ends with some sandpaper before soldering.
For this step, I could have used one large strand of wires and left it there, but I found it was easier to do this in sections so that I could properly shrink tube my wires to the frame.
For the wire that ran along the frame and up through the head pad, I used a wire hanger with a notch cut in the side to hook the wire. I had to fish the hanger through the pad very carefully so that I didn't poke through it, but with enough force in order to make my way to the other end. After some struggling and bending of the hanger, I finally got the hanger through the rubber pad. I ended up tying the headphone wire to the hanger by the hook I had cut out and used a thin piece of tape to hold it in place. Fishing it back through was easier than the first time, but still somewhat of a pain. Eventually, I succeeded without doing any damage.
Step 5: The Headphones.
The headphones I used (Creative Soundblaster Jam) have held up great so far, but you can use any pair. I chose this pair for the multifunction button. I needed to have a discreet play/pause/pair button on the bottom of the yellow shell that sat flush to the outside. This button operates by holding it for different periods of time. Initially, one long press and hold powers the unit up, a shorter hold enables pairing. Once paired, the unit will start to play with a quick push and pause with another push. To power down the unit you just need to hold the button for another 5 seconds.
In order to have another multifunction button for the outer shell, I needed to solder up a new button. For this I had to disassemble the headphones and locate the multifunction button. I used a yellow momentary switch and soldered it directly to the leads on the existing button so that both buttons technically work, though I only use my new button.
I'm not the greatest at soldering, but I found that a little flux can go a long way and make your solder joints look a whole lot nicer. I picked some of this up at Radioshack, but it's totally optional.If you go this route, just make sure you're using rosin electrical flux and not the plumbing stuff. For real!
Once I had my button wired up, I drilled a small hole in the shell for the new button. I wanted the button to sit flush with the outer wall of the shell and I placed it on the under side so I could quickly grab my headset and pause within one motion while taking them off. I had to countersink a square hole for the button from the inside so that it could sit flush. I used some super glue between the button and the inside of the shell and then hot glued over the top of the button.
Step 6: Final Touches
I found some memory foam pads to use for some dampening and to hold the components in the shell snugly. You can find these at a mattress store or online. These fit much nicer in the unit than the original dampening foam and even do a better job at attenuating outside noise. If you want to be able to hear more of the outside for any reason, you could either slice these in half the long way, or just don't use them. The new headphone pads have a black cloth membrane stretched across the ear hole not only offering a nice aesthetic, but potential support for the headphone components. I also purchased a micro usb extender that sits at a right angle. I found these on Amazon for a few bucks. This allows me to easily charge the headset without having to completely remove the right headphone in order to access the usb port. Unfortunately I still have to pop off the headphone pad every time to charge, but luckily the charge lasts me for around 7-8 hours of continuous use.You could choose to drill a port to allow for charging without removing the earpad. I didn't for looks.
To wrap things up, I just wanted to say I had a really great time building this unit and found it suits my needs better than any build I could find. If you plan on using these, make sure you pay attention to your surroundings and don't use these where guidelines may prohibit headphones. Feel free to ask any questions. Enjoy!