Re-housing the PortaPro

[ballincolin]

I'm pretty much broke all the time, so that means that the PortaPro's are the best headphones I've been able to own. Don't get me wrong, I love them, but they're definitely not top-of-the-line. Even though I consider them the best headphones I've owned, I rarely used them because they're open headphones, meaning they have zero isolation. I decided that that could be fixed, and here's how I did it.

I bought some low-profile, folding Peltor hearing protection, drilled some holes, sanded and painted, soldered some stuff, and came up with this:




I drilled a hole on the top for ventilation, since open headphones require airflow. I also put metal mesh over it for looks, and glued the PortaPro badge on.



I drilled 3 holes in the bottom for more air flow, and I decided to make the cord come out of the front face rather than the bottom, purely for cosmetics originally, but it turned out to be nice since it keeps the cords off of my neck.



The drivers sit under the foam that came with the hearing protection



I had to splice the wires to get the cords through the holes I drilled. I fed them through, soldiered them up, and then put heat shrink tubing around them.

There is an effect on the sound quality. Putting the PortaPros in a closed environment made them sound less clear, and just generally more like closed headphones do. It's a worthy sacrifice, and if I did it again I think I could make them sound better by drilling the holes in more ideal locations.

[CrowdAds]

[ballincolin]

Oh and let me know if the pictures don't work; I have the worst luck with that nonsense.

[The DarkSide]

There are no pics, and I really want to see this.

[skip252]

Your pictures are stored in your Album here. As long as that Album is Private the pictures won't show in the forum. Once you change that status they should show.

[WalkGood]

I see them just fine, nice mod and hope you enjoy the new sound

[ballincolin]

Originally Posted by skip252

Your pictures are stored in your Album here. As long as that Album is Private the pictures won't show in the forum. Once you change that status they should show.

Gotcha. I did that; they should work for everyone else now

[JK98]

Get rid of the foam over the drivers if you want clearer sound.

[The DarkSide]

Nice job bro!

[WalkGood]

Originally Posted by JK98

Get rid of the foam over the drivers if you want clearer sound.

That sounds like a good idea; another would be to look for more porous foam and various foam consistencies to test which would produce the most pleasing sound. I think that thickness would also affect it, so I’d look for paper thin options.

[ballincolin]

Originally Posted by WalkGood

That sounds like a good idea; another would be to look for more porous foam and various foam consistencies to test which would produce the most pleasing sound. I think that thickness would also affect it, so I’d look for paper thin options.

Yeah the foam over the drivers is about half an inch thick. The weird thing is that without the foam, the drivers have this echo that presumably comes from the sound bouncing around the plastic enclosure. I guess I could put the foam behind the drivers, and then put a thin layer over them

[JK98]

The foam that came with the hearing protector is designed to block sound. There are other foams that are designed to let sound pass through as unaffected as possible.

[ballincolin]

Yeah for now I just put the drivers above the foam and am using the stuff that came with them to cover them for comfort.

[The DarkSide]

Why don't you cut out a circle over the drivers, as you'll get the padding + the sound directed towards your ears that way. The speakers stay stable, your don't get the echo effect, and the sq rocks.

[WalkGood]

Originally Posted by ballincolin

... The weird thing is that without the foam, the drivers have this echo that presumably comes from the sound bouncing around the plastic enclosure. ...

This sound echo effect you mention is definitely caused by sound waves bouncing around inside the housing. This can be due to a lack of/or poor insulation used between the housing wall and the drivers or even cheap plastic lacking a damping effect/material. You should test different types of sound absorbing insulation (cotton, fiberglass, etc.) in that area as I’d guess the Peltor hearing protection housing may lack the ability to damping the sound waves.

[TexasRockbox]

Those phones use the Koss 60ohm Titanium drivers. I think the Koss Pro3AA uses the same driver.

[ballincolin]

Originally Posted by WalkGood

...I’d guess the Peltor hearing protection housing may lack the ability to damping the sound waves.

I think the foam the hearing protection came with is designed to dampen sound though, since originally it was made to block sound. With the drivers in front of it, the echo is gone, so I may do what The DarkSide suggested. But yeah I'll definitely play around with different materials and see what sounds best

[The DarkSide]

I usually either use foam for wall socket insulation, or cotton balls or cotton batting. The foam will block outside sounds, and the cotton just fills space and helps prevent the echo effect. Try different things, but try to keep the drivers clear so the sound is unobstructed on it's way to your ears. The less it's blocked the more it should sound the way you like it.

[WalkGood]

Here's an example of the insulation within the housing behind the driver that I was talking about, looks like cotton. I've seen better examples but I only did a quick search to show a picture and I think you know what I'm talking about.

[ballincolin]

Thanks guys, I'm gonna try different things using your advice, and I'll let you know what happens!