Monday, March 16, 2015

Soundproof Headphones

My neighbor makes a lot of noise, which is pretty annoying. I have tried speaking with them, but they don't care to reduce noise levels. I can drown out most of the annoying sound with multimedia speakers (turned up real high), but it doesn't do much against washer/dryer and routine stomping (which pretty much goes on all day... every day).

I found these Peltor 3M X5A hearing protectors on amazon for $26, which have a high NNR value of 31. They are also really comfortable, since the cups have a nice amount of padding, and go over the entire ear. They have really good build quality too (and can take a beating), since they are designed to be used for construction. Also, the ear pads are replaceable and easy to come by.

The only thing that sucks, is that it is pretty boring wearing them for long periods of time and hearing nothing. I figured that it would be easy enough to turn them into headphones, as the cups are quite roomy on this model. So I decided to pick up some decent enough quality headphones and cut out the drivers to put them in. There are probably better options out there where you can buy just the speakers, or some higher quality wiring or whatever. I did this kind of quickly, buying some over the counter at Walgreens. There are different versions of these (2XL) phones, varying from 15 to 25$. They all have the same drivers, so getting the cheapest ones is probably smart. The ones that I got were 22$ and had two cables. It looks like there is a similar model for $14 here in an unpopular color (which doesn't matter for this). These models have 30mm drivers, and the casing was just about the right fit to be held in place by the padding in the 3M muffs. There is a 40mm version of this product, but it may be too large. I had to trim the edge of the casing into an oval shape all the way down to the driver to make a 40x30 sized plastic insert. The driver is glued into the insert (I think) and probably not easily removable. Every speaker/brand will vary. Anyways, these work quite well, have good volume, and a lot of bass. I have to turn the bass down most of the time // use equalizer.

All of the components to make this should come in under 40$

I was a bit surprised, because I have owned dozens of headphones over the years, and most don't sound good, and cost way too much. Most large headphones do not actually go over the ears and seal with the head to block out sounds like these do, they have a cushion that compresses the ear, which can be annoying and uncomfortable. Quiet listening with these is quite good, and other people won't be able to hear what you're listening to (even at high volumes).

A simple conversion requires no extra materials aside from glue, a drill, a razor blade, a soldiering iron, and some sandpaper.

First take apart the headphones, they are screwed together, so they come apart fast. Be careful to preserve the foam covering, and the wires, as they will be used later. Clip the wires at the soldier points to free the cables and unknot them. The wires are kind of cheap, they have some kind of paint/non-conductive coating to prevent contact with ground, so you can sand that off or whatever before soldiering it. This is probably what causes most headphones to fail over time. If this is the case, just toss them later if they do and soldier in new wiring.

I decided to add rca adapters to make them detachable at first, and able to plug into my cable box and other stuff. This required me to use some extra cables that I already had around the house. Seemed like a good idea at the time, but rca adapters are a bit bulky and get in the way when angled downward :3

Modifying the 3Ms is very easy. The cups detach from the headband when turned 90 degrees. Pulling on the white flange of the cups will release the housing. The pad can also snap off of the white flange (it is replaceable).

The foam insert is also replaceable, and can just be pulled out.

Find a spot to feed in the wire. Probably angled forward/downward from the front would be best, at a 45 degree angle. This model does not have a padded headband, so it's not possible to wrap/conceal a cable over the band easily for a one-ear wired setup.

The muffs are coated in a durable thick rubber, so it is not possible to drill directly into the housing without tearing it up. Cut away a circular section from the rubber in the size of the hole to be made. If using an adapter (like a 3.5mm phones jack, or other adapter) with a flange, it could be placed between the rubber and the plastic and glued in place.

Once the rubber piece has been removed, drill the hole. The housing is fairly thick, so it won't move around much...

If using the wire from the headset, the flanged spacer can be fed in, and then the wire knotted from inside the cup. When I did this it fet pretty snug with a standard drill bit. I didn't have to use any glue or anything.

The 3M foam insert does not need to be cut, and can just be rotated to fit around the wire/hole opening. If you put in a jack, you'll want to rotate the pad, else you can just feed the wiring in through the gap somewhere.

See if the speaker housing will fit into the cup, the foam should hold it in place without compressing the foam too much. If it is too tight, cut the sides of the plastic housing around the driver and sand them down so that it does. The foam is pretty durable, but the cloth cover is not, and might snag on the plastic if you don't smooth it over after cutting.

Tin the wires, and soldier them to the speakers. Test them, should work fine.

Take the padding from the headphones. In my case, there was no way that they would be able to fit over the entire speaker due to the foam padding. However, I was able to reverse the pad and use that after cutting away some fabric and padding from the front.

If you have the same model, or similar style, it should work. Cut along the outer part of the cushion, along the stitching. The foam ring will come out when done. Clip the circle of fabric in the middle. Now, invert the fabric, so that it creates a large, flat surface, and place that over the speaker. Fit the speaker in place, the thick foam of the 3M muffs will hold it in place with no movement. The speaker should sit back far enough so that it does not contact your ear without the padding/flange on. It may if you have larger drivers, but once the set is reassembled, there may be enough of a gap from the 3M padding that it won't make contact.

The cup is air tight, so when you place the phones on/off your head it will compress/expand the speakers, and also dampen them a bit (you may hear them crackle/pop, probably isn't good). This can be fixed by drilling some small holes in the white plastic flange (or somewhere else) to let some air exchange. I detached the vinyl ear protector and drilled four holes in each white flange. I then crammed some cotton in the holes to dampen the air flowing in/out of them. This would probably be a bad idea if using these for actual hearing protection in a construction environment.

Snap the housing back on, and reassemble.

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