[Cassianoaran]

   
Frequency response gragh @ Headroom does show a very slightly raised lower midrange. To my ears, voices and instruments do have a warmer,more rounded sound than some other headphones. As you know,some people quite like the sound of the 558's; others prefer a sharper, less rounded sound.
When and if you do try the hd 558's; it would be interesting to know your impressions.

 
First of all, I'm learning to speak english, so sorry for grammar errors here.
 
I'll give my impressions on the HD558.
 
Initially, I quite liked the sound of the HD558. Actually, it was what I expected in terms of sound signature, according to all that I researched here in the forum. Slightly recessed bass, slightly forward, warm mids and slightly recessed higs. A good, relaxing sound signature to my tastes.
 
However, when I compared the sound of the HD558 with my HD600, i noticed that the HD558 had some kind of "muffled" aspect, specially on the mids (this was more evident on distorted guitars). I'm not talking about a sound with "body". I'm talking about some kind of reverberations in the sound. This muffled aspect was very clear and pronounced to my ears. I could easily make a blind test between the sound of these two headphones and I would know every time wich headphone is playing.  The HD600 doesn't have this muffled issue (nor my old HD201). So I suposed that this muffled mids were caused by the famous piece of foam inside the cups. So I decided to do the foam mod, by curiosity, and to compare them again with the HD600, but this time with the HD558 moded.
 
Then it happened. Without the piece of foam, the muffled aspect are now gone. The mids are now VERY similar to the HD600's mids. Actually, I noticed that all the sonic range is now very similar to the HD600's, bass and higs included. Really, it was the foam piece that was causing this muffled aspect to the sound, due to reverberations inside de cup, I think. The distorted guitars and voices that I love are now very defined, sharp and more proeminent, the bass is now a bit stronger (but yet recessed in comparison to the mids, and I like that) and the higs are now slightly more airy and shiny (but yet far from grueling).
 
I've heard some people saing that with the foam mod, the bass becomes a bit uncontrolled, but that is definitelly not the case, to my ears. Bass is so controlled as it was before the mod. Now it has a little more punch, only. If I only removed a "wall of foam" and let the sound move out the open designed cups freely, why would this make the bass uncontrolled? That doesn't make sense to me.
 
Now, with the foam mod on the HD558, I can't be sure on saying what headphone is playing in case of a blind test (between the HD558 and the HD600), because now their sound signature is very similar to my ears. Honestly, I was suspecting that the people who recommended the foam mod to the HD558 were just mistaken or suffering of placebo, but the comparison that I've make with the HD600 removed my doubts. I think that, if Sennheiser wanted to create a more smooth sound signature in the HD558, they should make the driver differently, and not only put that piece of foam inside the cups. Maybe this could give body to the sound, avoiding the muffled aspect. But I'm not a sound engineer, hehe.  
 
I love my HD558's with the foam mod! Hope my impressions can help some people.

 

[Cyrix]

   
First of all, I'm learning to speak english, so sorry for grammar errors here.
 
I'll give my impressions on the HD558.
 
Initially, I quite liked the sound of the HD558. Actually, it was what I expected in terms of sound signature, according to all that I researched here in the forum. Slightly recessed bass, slightly forward, warm mids and slightly recessed higs. A good, relaxing sound signature to my tastes.
 
However, when I compared the sound of the HD558 with my HD600, i noticed that the HD558 had some kind of "muffled" aspect, specially on the mids (this was more evident on distorted guitars). I'm not talking about a sound with "body". I'm talking about some kind of reverberations in the sound. This muffled aspect was very clear and pronounced to my ears. I could easily make a blind test between the sound of these two headphones and I would know every time wich headphone is playing.  The HD600 doesn't have this muffled issue (nor my old HD201). So I suposed that this muffled mids were caused by the famous piece of foam inside the cups. So I decided to do the foam mod, by curiosity, and to compare them again with the HD600, but this time with the HD558 moded.
 
Then it happened. Without the piece of foam, the muffled aspect are now gone. The mids are now VERY similar to the HD600's mids. Actually, I noticed that all the sonic range is now very similar to the HD600's, bass and higs included. Really, it was the foam piece that was causing this muffled aspect to the sound, due to reverberations inside de cup, I think. The distorted guitars and voices that I love are now very defined, sharp and more proeminent, the bass is now a bit stronger (but yet recessed in comparison to the mids, and I like that) and the higs are now slightly more airy and shiny (but yet far from grueling).
 
I've heard some people saing that with the foam mod, the bass becomes a bit uncontrolled, but that is definitelly not the case, to my ears. Bass is so controlled as it was before the mod. Now it has a little more punch, only. If I only removed a "wall of foam" and let the sound move out the open designed cups freely, why would this make the bass uncontrolled? That doesn't make sense to me.
 
Now, with the foam mod on the HD558, I can't be sure on saying what headphone is playing in case of a blind test (between the HD558 and the HD600), because now their sound signature is very similar to my ears. Honestly, I was suspecting that the people who recommended the foam mod to the HD558 were just mistaken or suffering of placebo, but the comparison that I've make with the HD600 removed my doubts. I think that, if Sennheiser wanted to create a more smooth sound signature in the HD558, they should make the driver differently, and not only put that piece of foam inside the cups. Maybe this could give body to the sound, avoiding the muffled aspect. But I'm not a sound engineer, hehe.  
 
I love my HD558's with the foam mod! Hope my impressions can help some people.

I'm somewhat new to the audiophile community, but have recently ended up with quite a few decent over-ear headphones, one of which is the HD558. I've had it for a few months, and am considering this foam mod. I've seen that there are videos on how to do this, but I thought I'd ask someone who has done it before: What process did you use, and Is it really as easy and risk-free as they make it out to be, or do i really need to be incredibly careful? Like i said, modding is something I've never done before, so I'd like to verify the method from multiple sources prior to attempting it.

 

[gargani]

  I'm somewhat new to the audiophile community, but have recently ended up with quite a few decent over-ear headphones, one of which is the HD558. I've had it for a few months, and am considering this foam mod. I've seen that there are videos on how to do this, but I thought I'd ask someone who has done it before: What process did you use, and Is it really as easy and risk-free as they make it out to be, or do i really need to be incredibly careful? Like i said, modding is something I've never done before, so I'd like to verify the method from multiple sources prior to attempting it.

 

   
First of all, I'm learning to speak english, so sorry for grammar errors here.
 
I'll give my impressions on the HD558.
 
Initially, I quite liked the sound of the HD558. Actually, it was what I expected in terms of sound signature, according to all that I researched here in the forum. Slightly recessed bass, slightly forward, warm mids and slightly recessed higs. A good, relaxing sound signature to my tastes.
 
However, when I compared the sound of the HD558 with my HD600, i noticed that the HD558 had some kind of "muffled" aspect, specially on the mids (this was more evident on distorted guitars). I'm not talking about a sound with "body". I'm talking about some kind of reverberations in the sound. This muffled aspect was very clear and pronounced to my ears. I could easily make a blind test between the sound of these two headphones and I would know every time wich headphone is playing.  The HD600 doesn't have this muffled issue (nor my old HD201). So I suposed that this muffled mids were caused by the famous piece of foam inside the cups. So I decided to do the foam mod, by curiosity, and to compare them again with the HD600, but this time with the HD558 moded.
 
Then it happened. Without the piece of foam, the muffled aspect are now gone. The mids are now VERY similar to the HD600's mids. Actually, I noticed that all the sonic range is now very similar to the HD600's, bass and higs included. Really, it was the foam piece that was causing this muffled aspect to the sound, due to reverberations inside de cup, I think. The distorted guitars and voices that I love are now very defined, sharp and more proeminent, the bass is now a bit stronger (but yet recessed in comparison to the mids, and I like that) and the higs are now slightly more airy and shiny (but yet far from grueling).
 
I've heard some people saing that with the foam mod, the bass becomes a bit uncontrolled, but that is definitelly not the case, to my ears. Bass is so controlled as it was before the mod. Now it has a little more punch, only. If I only removed a "wall of foam" and let the sound move out the open designed cups freely, why would this make the bass uncontrolled? That doesn't make sense to me.
 
Now, with the foam mod on the HD558, I can't be sure on saying what headphone is playing in case of a blind test (between the HD558 and the HD600), because now their sound signature is very similar to my ears. Honestly, I was suspecting that the people who recommended the foam mod to the HD558 were just mistaken or suffering of placebo, but the comparison that I've make with the HD600 removed my doubts. I think that, if Sennheiser wanted to create a more smooth sound signature in the HD558, they should make the driver differently, and not only put that piece of foam inside the cups. Maybe this could give body to the sound, avoiding the muffled aspect. But I'm not a sound engineer, hehe.  
 
I love my HD558's with the foam mod! Hope mvy impressions can help some people.

 
Hi Cassianoaran Thanks for giving your impressions of the 558's and the comparison to the HD600's. Your impressions of the 558's mentions a muffled sound; after the mod you heard sharper more detailed instruments; more like the HD 600's. If I compare the558's to my momentum over ears(m1) or my audio technica m40x; the 558's do sound less sharp. I don't hear resonances specifically; but I would say some instruments do sound slightly muffled in comparison. However, when I'm listening to The 558's I don't notice it very much. If I switch back and forth with the other headphones, I do notice it. Very interesting that with the foam mod, the 558's sound closer to the 600's. Here in Canada the 600's cost at least 2x as much as the 558's. Like Cyrix, I've never modded a headphone. I tried, gently, to pull the earpads off, but they felt like they were attached to the plastic frame underneath. Did you pull the frame and the pads off in one piece or did you pull the pads off of the plastic frame.Just curious. Anyway thanks again for your impressions. By the way, your English and grammar are excellent.

 

[Cassianoaran]

   
 
Hi Cassianoaran Thanks for giving your impressions of the 558's and the comparison to the HD600's.Your impressions of the 558's mentions a muffled sound; after the mod you heard sharper more detailed instruments; more like the HD 600's. If I compare the558's to my momentum over ears(m1) or my audio technica m40x; the558's do sound less sharp. I don't hear resonances specifically; but I would say some instruments do sound slightly muffled in comparison. However, when I'm listening toThe 558's I don't notice it very much. If I switch back and forth with the other headphones, I do notice it.Very interesting that with the foam mod, the 558's sound closer to the 600's. Here in Canada the 600's cost at least 2x as much as the 558's. Like Cyrix, I've never modded a headphone. I tried, gently, to pull the earpads off, but they felt like they were attached to the plastic frame underneath. Did you pull the frame and the pads off in one piece ordid you pull the pads off of the plastic frame.Just curious. Anyway thanks again for your impressions.By the way, your English and grammar are excellent.

 

  I'm somewhat new to the audiophile community, but have recently ended up with quite a few decent over-ear headphones, one of which is the HD558. I've had it for a few months, and am considering this foam mod. I've seen that there are videos on how to do this, but I thought I'd ask someone who has done it before: What process did you use, and Is it really as easy and risk-free as they make it out to be, or do i really need to be incredibly careful? Like i said, modding is something I've never done before, so I'd like to verify the method from multiple sources prior to attempting it.

 
Gargani and Cyrix, this was the first mod I did on a headphone. I was a bit nervous on doing it. The mod is very easy and reversible, but it requires some care on doing it. This video-tutorial helped me a lot: 
 
https://www.youtube.com/watch?v=k-kJ7sN16qw
 
But careful: please DON'T remove the foam piece in front of the driver (between the driver and your ears), like the guy in this video did. There's no need to do that. Just unscrew the screws and driver will come out. Additionally, when you are holding the driver that came out, be careful to not break the thin strings.
 
Gargani, I don't now if I understood correctly your question, but I pulled the pads off of the plastic frame, exactly like the video linked above. It requires some firmness on doing it. It's a bit scary. I would like to say that the muffled mids only become clear to me when I did the comparison with the HD600, exactly like you said in your comparisons with other headphones. If you want to do this mod, please listen to a music with sharp distorted guitars, like this one: https://www.youtube.com/watch?v=xsTOOZsZWm4 , before and after the mod. This will make the difference in sound more evident. Ah, and thanx a lot for your compliment.

 

[gargani]

 Cassianoaran, Thanks for the information. I will check out the You Tube tutorial on the mod and the song with the distorted guitars.
 
Also, I have another pair of 558's on the way. I got a good price on a factory refurbished pair; when they arrive I will attempt the mod. If all goes well, I'll have a modded pair and an unmodded pair to compare back to back.
 It will probably be a couple of weeks, though.
 
Thanks again.

 

[Butter123]

Not trying to ride the Philips SHP9500 hype train, but I sold my HD558 as soon as I got the shp9500. 
The HD558 just sounded slow and congested for modern music even when amped. 

 

[Mad Max]

Revisitng HD558 here, even with the foam tape removed, there's still noticeable reverb versus my other headphones.  Despite the cups being perforated to vent cup resonances, the grill structure itself is probably not thin enough to avoid contributing to resonances, I speculate.  Some fiberfill, like what studio monitors use inside of their cabinets to kill resonances, might be the solution.  I'll mess with it later.

 

[gargani]

   
 
Gargani and Cyrix, this was the first mod I did on a headphone. I was a bit nervous on doing it. The mod is very easy and reversible, but it requires some care on doing it. This video-tutorial helped me a lot: 
 
https://www.youtube.com/watch?v=k-kJ7sN16qw
 
But careful: please DON'T remove the foam piece in front of the driver (between the driver and your ears), like the guy in this video did. There's no need to do that. Just unscrew the screws and driver will come out. Additionally, when you are holding the driver that came out, be careful to not break the thin strings.
 
Gargani, I don't now if I understood correctly your question, but I pulled the pads off of the plastic frame, exactly like the video linked above. It requires some firmness on doing it. It's a bit scary. I would like to say that the muffled mids only become clear to me when I did the comparison with the HD600, exactly like you said in your comparisons with other headphones. If you want to do this mod, please listen to a music with sharp distorted guitars, like this one: https://www.youtube.com/watch?v=xsTOOZsZWm4 , before and after the mod. This will make the difference in sound more evident. Ah, and thanx a lot for your compliment.

 It's been a couple of months, but I now own 2 pairs of 558's. One is stock ( unmodded) and the other has the foam piece removed. The link to the you tube foam mod tutorial, provided by Cassianoaran, showed quite clearly how to do the mod. So I have been able to compare the stock 558's to the modded 558's.
 I listened to" Doesn't Matter' by Tremonti, as suggested by Cassianoaran. At first I couldn't really hear a difference; but after switching back and forth a couple of times, I did notice a small difference. On the stock 558's the bass sounded a touch thicker, and the overall sound was a bit muffled.The modded 558's did sound slightly less muffled and the bass sounded just a hair leaner, to my ears.
 I also listened to some other various songs,and again, after a number of back and forth switches,my impressions were the same.
 The differences were subtle to my ears, but to others with more acute hearing, The differences might be more noticeable.
 
 Anyways, I enjoyed doing the mod and making comparisons. Once again, thanks to Cassianoaran.

 

[Mad Max]

Got it.
Less coloration, less cup reverb.  With less reverb, little bit more precise imaging.
 

 
I also added some Dynamat, it cleans up and tightens up the sound, but the result has been less than I expected.  Definitely recommend the fiberfill, it will be a process of trial and error to get the right amount.  It is not that much in any event.  If you  get a muffled sound to an extent, you put in too much.
 
Edit: Fiberfill is cheap and easy to find, at least in the Americas.
 
Edit2: Many more fine details come through now.  Soundstage is bigger, too.

 

[zslipknot]

 
  Try my TP mod! Remove the pads, trim and add desired amounts until they sound as silky as you like. I've owned both the 558 and 555, both could use it. Though 558 was a bit more congested no matter what I tried. It's ghetto, but try it haha. You'll be amazed.

 

[brf100]

Waiting for my fiio e10k to listen their full potenitial!!

 

[Matrixnobu]

Just got me a pair. I love the laid back sound of these headphones. You can listen all day : )

 

[Hypespazm]

SO I got a pair of 558's BARELY used for 55$ USD im talking about worn twice..... at first I wasnt a fan on the sound.... NOW after the mod I can definitely like these alot more..... this did work for me NOW I do have a pair fo HD600's coming soon.. and im hoping to god these wont even touch those by the ankles lol... I also have a pair of G4me Zero's that are supposedly the same drivers as the 598's but after opening them up i dont think so... they sitll sound a bit better on the highs than the 558's I can see myself using my 558's for more urban types of music

 

[teb1013]

SO I got a pair of 558's BARELY used for 55$ USD im talking about worn twice..... at first I wasnt a fan on the sound.... NOW after the mod I can definitely like these alot more..... this did work for me NOW I do have a pair fo HD600's coming soon.. and im hoping to god these wont even touch those by the ankles lol... I also have a pair of G4me Zero's that are supposedly the same drivers as the 598's but after opening them up i dont think so... they sitll sound a bit better on the highs than the 558's I can see myself using my 558's for more urban types of music

You probably already have your 600s by now. I find that the 600s have much more presence and detail than the 558s. I still like the 558s if I am listening to something on my ipad and want to use it without an amp. The 558s do a good job that way, I could never use the 600s without an amp.

 

[NeenerPhones]

 I also added some Dynamat, it cleans up and tightens up the sound, but the result has been less than I expected.  Definitely recommend the fiberfill, it will be a process of trial and error to get the right amount.  It is not that much in any event.  If you  get a muffled sound to an extent, you put in too much.

I stuffed my 558s with polyfil before doing any prior research. Took a guestimated shot in the dark and apparently found gold.