[streetdragon]

  I think the main purpose of the foam was to cushion the driver in cases of the headphone being dropped. The byproducts of the foam are a slightly better frequency response and slightly worse imaging. 

No the foam has very clear distance between the driver, so its no way used as a shock cushion, the foam does make the bass a bit more impactful however.

 

[Rampy]

i did this mod a few days ago and thought id share my opinion.
 
 
mod first impressions(one ear cup modded): quieter. (side effect of sound stage)
bass is much more present and gives nice long heavy bass notes and deep powerful kicks
the mids feel like they are being swept out of the gap left by removing the foam. quieter, but more detailed and alive.
the highs are barly effectected. however they are a little overpowed by the bass.
with this mod the response rate is far from flat(not that they were in the first place) but increases detail and sound stage enough to validate the losses (fequency response rates can allways be altered with an EQ).
 
 
after doing it on both earcups:
treble seems to be quite loud and prominant, although the sound isnt bright. the mids are gorgeous, and extremely detailed. what i metioned earlier about loss of accurate frequencies seems to be less obvious now. sounds much better, 
a good improvment. i noticed that sound leaks more and more sound comes in.
 
 
id recoment this mod for: people who like trap future bass hip hop ect, however the quality improvments can be appreciated through all genre's as it cleans up the sound a fair bit.
 
 
verdict: if you own HD 558's chances are you like high detail, large sound space and very open sounding headphones. to improve on these allready good features, i strongly recomend this mod for everybody.
 
 
pro tip: if your on the fence about doing the mod try covering the open backs of the headphones with your hands while listening to some music, the effect is basically an exagerated version of what the foam tape does.
if you prefere the sound without your hands covering it you will probably like this mod.
 
 
note: i am using a fiio ek10 amp/dac and i will deffinatly be keeping this mod.

 
songs genre's i used: future bass, glitch hop, electro, electro swing, funk, nu-funk, future funk, trap, pop, medolic dubstep, rock, nightcore, and chill. (watched anime and played games on them aswell).

 

[Sennheiser84]

It is completly worth it, if HD 518 doesn't have the useless foam why should HD 558 have it? think about it lmao

 

[ibob4tacoz]

Well, I finally decided to do the foam mod, mostly waiting on it because I didn't want to risk ruining the sound... I regret that... Oh man it sounds so good now. A bit more airy and spacious. There's some layers in a few songs I just relistened to that I never noticed. Bass is not necessarily boomy, but is louder and less tight though. The toms in Best of You (Foo Fighters) hits home. I don't hear too much on the mids, but it's seems a touch more forward and lush. Treble sits away from everything else and is more clear, maybe almost sparkly.
EDIT: Take back what I said about the almost sparkly... XD Not used to hearing the higher end like this.

 

[ionengine]

The mod really makes a big difference in sound quality and all for the good. For me this headphone handles everything I throw at it with flying colors. Am really satisfied with this headphone.

 

[Mark Up]

Could someone clarify the three different parts to the mod? I want to be sure I have this right. Taking out layer of foam over the driver for more highs (changes nothing else, may expose them to dirt). Taking a strip of tape off the driver (ie. the side of it that faces your ear) that increases highs (again - no effect on any other frequencies). Finally, a rectangle of foam on the inside of the ear cup, across from the back of the driver. Taking it out increases bass? I am only interested in more bass. Not any more treble.

 

[cr0wnest]

Dont mean to resurrect an old thread, but I've owned a pair of HD 558s for awhile now and have thought of doing this mod. HOWEVER.. there are times where I feel the treble/upper mids can have a bit of siblance. I've read some people saying removing the foam makes the treble more detailed, or more sparkly. But yet at the same time the bass quantity has improved. For those who have performed the mod, is there any noticable increase in siblance in the high end but at the same time increases the bass?

I find it contradicting because by having the foam there it should keep the headphone more "closed" rather than "open" by removing them. And more closed should equate to more bass at the cost of some sound stage.

I've tried Rampy's method of covering the headphones with my hands and without, and I prefer the sound of my music without my hands covering it as they sound too sharp with my hands covered. And he mentioned if you prefer the sound WITHOUT your hands covering, chances are you'll like the mod. But my logic about having a more open headphone tells me otherwise.

What do you guys think?

 

[Ambiance]

After reading this thread and in other pages around the Internet I decided to go ahead with the modification of the HD 558 which I purchased the other day. The differences are subtle to me, but they are indeed noticeable. My impression is slightly wider Soundstage, slightly increased detail and if I'm not imagining, the bass sounds a bit tighter. To me the sound was a bit darker before and more closed in with less detail and less tighter bass. This is the first post I make in this forum and I registered mainly because I wanted to confirm what others are saying about the mod. I have seen only one or two people who didn't like the sound after this modification after looking scanning around the Web moderately thoroughly. Some guy on the YouTube did it and didn't like it, he thought the bass was no good after, I don't agree, my cans sounds really good now, it was worth the small effort, undoubtedly. I Would like to thank everyone that has supplied information in this thread! Kudos!

English is not my first language so I apologize for spelling errors and grammar etc.

 

[undeadninja125]

Hello all from 2016! I just bought these headphones about a month ago, and I just learned today that there was a foam piece inside (it's still there in 2016). I took this out, and wow! The bass is more pronounced, but not muddy, and the mids and treble are even clearer than they were before. The sound stage is fantastic, especially on my 96/24 songs plugged into my DAC. 
 
I'm not a bassy person, and much rather prefer clear sound. This piece of foam seems to be for the people that want more "concentrated" sound, but if you want the deeper sound stage, definitely remove this.

 

[Ambiance]

Seems we got ours approximately at the same time, cheers! 

 Very good investment and the value is amazing, especially after removing the black rubber tape. Excellent sounding headphone!

 

[Roxo]

I just bought a pair of 558's after a pair of HD530's that I had (a true friend) gave up the ghost after about 20 years of wonderful service.  I knew I wanted to stick with Sennheiser because I loved how accurate my 530's were and I also knew what my budget was.   I picked the 558's up at Best Buy's online website for $75.00, no tax and free shipping.  That was well under my budget.  (If you are in the market I strongly suggest you try to wait until they go on sale.  They WILL go on sale somewhere).  I was slightly disappointed after some critical listening to lossless songs that I know very well.  I say slightly disappointed.  The 558's just didn't seem to match up to the 530's.  Something was missing.  (After all of my experience with cans, IEM's and the research I have done, I do not believe in "burn in", so in my opinon, that wasn't it)".  I had heard about the Sennheiser "veil" but never really understood what that meant because my 530's were so revealing.  Then it hit me.......THAT'S was what my slight disappointment was.  The 558's sounded somewhat veiled.  Not that I lost detail in songs, but the detail wasn't quite as evident.  I performed the mod which is quite easy to do and removed the black foam.  BINGO!  Disappointment gone.  I am now totally happy with the 558's.  As far as other people saying that the mod affects bass, mids, highs, instrument separation or soundstage, I personally don't think that the mod does that.  (Maybe somebody can provide measurements to prove or disprove).  I believe that the mod just opens up the cans to be more revealing.  Is the mod worth it?  In my opinion, yes. 
Here are some wonderfully recorded songs for critical listening if you are interested:
 
Slippery People, by the Talking Heads, from the album "Speaking in Tongues".
Temptation, by Dianna Krall, from the album "The Girl in the Other Room".  (Masterfully recorded!  Most of her stuff is).
Rhythm is Gonna Get You, By Gloria Estefan, from the album "Greatest Hits".  (There is so much going on in this song you can't keep track of it.  It will give your cans a workout.  And the Miami Sound Machine is one of the tightest bands ever).
Solar Sex Panel, by Little Village (John Hyatt), from the album "Little Village"
Misguided Angel by the Cowboy Junkies from the album "Trinity Sessions"  (Recorded with ONE microphone on DAT.  And nobody plays slower than the Cowboy Junkies).
Get Here by Oleta Adams, from the album "Circle of One"  Oleta has one of the purest voices on the planet.  (If your headphones are any good you will pick up the studio echo of her voice at about 3:38 into the song).
Right Next Door (Because of Me) by Robert Cray from the album, "Strong Persuader".
 
There you have it.  Some of my favorite songs to test headphones with.
 
If you are on the fence about buying the Sennheiser 558's or performing the modification.....DO BOTH!
 
Happy listening.

 

[Cephan]

I've been researching headphones for the past month and decided to jump on the HD558 for $80 deal at Best Buy. I figured they would be a good first headphone that didn't break the bank.

Warm overall signature, good mids and midbass, but the treble rolled off. I figured I'd give the black foam mod a try and it only took a few minutes to remove it from each cup. That opened up the treble but gave also gave it a slightly rough edge, most noticeably in vocals.

Well, instead of complete removal, why not reduce the amount of foam? I considered cutting the black foam but decided against in case I wanted to reverse the mod.

While at a craft store, I found a single sheet of adhesive-backed foam in the kid's section for the grand cost of 99 cents. Black was all gone so I picked white (the red foam sheets were covered in glitter). Not like anyone was going to see it anyway. The foam was the same thickness as the Sennheiser foam but a little stiffer and firmer.

Now the question is how much foam should I use? There's only a bit of harshness in the treble so I decided to go small. I cut two 1/4 inch wide strips of foam, checked if they were centered correctly, and pressed them into the cups.

That seemed to do the trick, it smoothed out the rough edge I was hearing in the treble. Clarity, detail remained.

I re-opened the cups and removed the 1/4" foam strips so I could A-B a few songs to make sure it wasn't my imagination. It's really a slight difference and some may not notice at all. But if anyone does hear that bit of harshness, I recommend trying a 1/4" foam strip.

Edit: Added image.

 

[serman005]

Sounds like a very clever solution to the problem. Good on ya.

 

[tworule]

60 usd at now best.buy. Is it worth it?

 

[Cephan]

60 usd at now best.buy. Is it worth it?

I think they're very good $80, even better for $60. But I would mod them with a 1/4" foam strip, otherwise they sounded muffled.