For a while now I’ve been meaning to try to modify my Sennheiser HD555, after reading in a few forum topics this modification would drastically improve the audio quality of the headphones.

I bought these headphones about 5 years ago now at some local electronics store in Holland. With music playing in the background, I spent all of one minute listening to some god-awful poppy song before I decided to purchase them. I had little knowledge regarding what to look for in headphones, and mostly let the brand and the price-tag of the headphones tell me how good they really were.

I ended up with the open-can HD555 headphones. They’re not bad, but they spit out awfully murky sounds, almost as if you’re listening to your music through a wall. Definitely not all that pleasant.

It became increasingly apparent I disliked the sound they produced way too much, especially after I started wearing several other portable headphones for at work or during my daily commutes. It’s a bit of a problem when your $50 portable headphone produces sounds far better than your $160 “at home” headphones.

As time went by, the HD555s ended up tucked away in the corner of my closet, unused. I brought them with me when I moved to Korea, but still did not use them. I later ended up with the Sennheiser HD 380 Pros, closed-can headphones that I use every day in the office.

Today I finally started and completed the “open stage” modification, which involves cutting out the plastic mid-section of the headphones, which in turn gives the headphones more breathing space. I first did one ear, just to try it out. I put everything back together and put them on, not remembering which ear I did the modification on. I turned on Lester Bowie’s Great Pretender, and from the very first second of the track the difference was more than apparent. Whereas before the murky sounds would cover up most details, I felt like the sponge that used to be between me and the music was no more.

So, I immediately took the headphones apart again and modified the other side as-well.

I used a box cutter to cut through the plastic, then used a file to smoothen the surface. There was a thin layer of cloth glued tightly to the plastic I removed, so I used a cigarette lighter to smoothen the left-over edges and avoid tiny pieces from sticking out.

I also took my time to make sure all little cracks and fallen apart pieces of the headphones would be fixed. Because of it’s age the plastic shell had a few cracks here and there, and the glued-together soft padding separated from the shell. I used some simple glue I picked up at a local store to fix all these. In the case of the plastic cracks, I used the glue as a layer on top of the crack to hopefully avoid it getting any worse.

The end-result is worth all the trouble (it actually wasn’t even all that much work). From The Shins’ New Slang to Talk Talk’s Spirit / Eden / Desire to Lester Bowie’s Great Pretender, each and every sound sounds much better than before. While I do enjoy my HD 380 Pro more in general still, mid-way through The Great Pretender I started to question that very feeling, with the modified 555s sounding so open and comfortable, it felt like the music was all around me in the room.

It looks bloody gorgeous as-well, if I do say so myself: