Holy Cow!!
So I've done the Bass mod on several 428's before, nothing really new there.  I've also modded my 439's before, no biggie right?   Well every time I've done the Mod I have only opened one hole on the tape.
So I scored another 439 off ebay for 38 bucks.  Not a bad deal, they looked basically brand new.
So I said eff it why not mess around with them???
 
I opened them up and pulled off the whole tape strip.  Put them back together and cued up some Marley.
OMG!!!   These suckers have more Bass then the DT770.  It is truely earth shaking.  It hits so tight and deep the cans are shaking on my head.  It is insane.  What's even more crazy is nothing else is smeared up.  The mids and highs are right where they should be.  And the soundstage even has more depth!!!   I think it might be too much for me really, One hole has always sounded pretty dang good to me.   I haven't done a straight up ipod test, I'm running these amped thru my M-Stage so that could help out quite a bit, but my god!!!  I don't see how so many of you Bass Heads can take this:  This is crazy Bass levels!!!   

Well, I am glad I am not alone in this!
 
Just recently, I also opened up all 3 holes in my HD-439 and found out that this is A HELL OF A HEADPHONE! Apart from the breathtaking BASS (perhaps the stronger there is for a headphone) the highs and mids did not subside, they are actually better now (!) than any other hole combination! What I mean is they sound better in all respects with all holes open, even if the bass should make the highs seem lower (which they kind of do with the one hole mod)!
 
Also they are not annoying at all, the known warmth of 439 is kept, even after the highs are more distinct now. In fact, they have improved so much that I fell asleep without them bothering me as they did with harsh songs... Don't get me wrong, the sound is NOT muffled now, it is actually CLEARER! I didn't like classical music with them, (preferred my 449), but now they are (more than) just fine for that too!
 
I too confirm that the soundstage is improved; they are very close to my (slightly) modded HD-449. I have put a thin layer over all 3 holes in them, thinner than the default tape, haven't tried the "all 3-holes open" mod yet... but I don't think I can resist much. I fear the bass would be too much for them, perhaps due to their pleather pads. But I can always be wrong and they could prove to be yet another monster!
 
I 've always been having the feeling that my HD-439 where holding back, especially in clarity of sound, and they did sound like a cheaper set with that tape on...
This 3 hole mod unlocked their full potentiall. And, as Magicman74 have stated in another post, they seem to breath MUCH better with all holes open. Now, they are close to my HD-497 as far as breathing is concern. But the 497 is an open headset!
 
Oh, and I don't use an amp! Just my pc and laptop, whith their default soundcards (set at 24/192) with asio and mad plugins for winamp. My collection is mailny mp3s, I also tried a few flacs, they too sound much better now. Naturally...
 
Perhaps Magicman74 you can compare the two HD-439 you have, one with all 3 holes open and the other with the normal mod, and tell us of your preference, or have you already stripped that other tape too? 

I have a pair of 439s and I'm interested in this mod.  However, this is my first pair of "nice" headphones, my first step into the audiophile world.  I listen to a lot of dubstep, techno, house, edm, etc.  Lots of bassy music.  I want to do this, but I don't want to screw up.  When I was trying to remove the earcups it felt like they were gonna rip.  I don't feel comfortable doing this because I can't find any pictures or a good tutorial.  Could one of you link me or explain how to do the mod please? 
 
Thanks.

To remove the pads it takes extra caution not to rip them. You have to grap from the inside the plastic underneath, not just the pads. You reach inside and grap the plastic surface with your pointer finger, holding the pad from the outside with your thumb, and pull outwards. That thin plastic base (inside, not outside the pads) goes out too, it is the base of the pads, so that is what you pull.
 
For the bass mod there are plenty of tutorials arround with pictures, but I bet you will just uncover all 3 holes, so, that makes things simpler. Finding the screws is easy, unscrew, then to open up you have to try shortening the headphones (the distance of the rim) and the point them inwards, so they will open. Then, be VERY carefull not to drop anything, the cables holding the drum are REALLY tiny, they can be broken easily... You have to find a position in the table were each drum will not be far apart from the main body, but you also have the space to do the mod. For the left pad (the one with the cable) the distance should be even shorter, so it takes extra caution! I use something underneath to shorten the distance, otherwise it hangs from the flimsy cable, wich is REALLY dangerous!
 
Then, you strip the tape, assuming you found where it is (there are pictures arround pointing to it), reassemble, put back the screws and pads, and preapare to be THRILED!

Interesting. I didn't think there would be people able to tolerate (much less enjoy) such heavy bass from these. I tried it with the tape strip completely off and did not like how they sounded. They vibrated the drivers too much but then again I didn't have the blue tack mod at the time.
 
+1 on someone posting their findings between the mainstream bass mod and completely having the tape removed.

Would it be possible to just take the tape off of all three holes, cut it into pieces, and then cover two of the holes?  I know it's possible, but would it be practical?  Also, what do you mean by "Blue Tack"?

Quote:

imps said:

Would it be possible to just take the tape off of all three holes, cut it into pieces, and then cover two of the holes?  I know it's possible, but would it be practical?  Also, what do you mean by "Blue Tack"?

Click to expand...

 
Here's the guide with my own impression in here: http://www.head-fi.org/t/646251/sennheiser-hd-428-hd-428s-modding-guide-january-2013

I have tried several mods, mainly on my HD-449. However, perhaps due to the pleather pads, the bass is too much in them, even with only one hole open. Luckily, I found a material to cover all 3 holes that is thinner than the original tape. And that mod is just perfect for the 449. They do vibrate though, haven't tried any anti-vibration mode yet, not to fond of plastecine...
Now, my HD-439 are a different story: Using the thin material to cover all 3 holes made them gain in the upper bass and mids. However, the mids where too much now! And they felt lacking in lower bass and depth (soundstage). I then tried completely removing the tape in front of the holes, just for fun: The result was amazing! The bass was as deep as it can be, really powerfull but not annoying or muffling at all. The mids remained just as they should be, and the highs ...gained some clarity!!
 
Perhaps the velour pads help with the deep bass mode, that is why my 449 (pleather pads) can't take it. I don't know...All I know is that the sound for my 439 is not so much pleasing and full when covering only one hole, as it gets when all holes are left open.
 
Also, not so many vibrations there, contrary to my 449 which suffers a bit... (also strange). 

Well, after reading all the good results people have with this mod i tried it myself. I opened all three holes. Holy molly all I can say. Bass became very very powerful. Didn't expected it will change so much. The best part, nothing else has change. Nothing is muffled or disorted, everything else left in it's place. As a thread name says, it really is a budget bass king. If you are a basshead, hd 439 would be perfect for you with this mod.

..edited

..edited

Is this mod worth it for a bass head, to the extent of abandoning the 2 year warranty that Sennheiser provides with their HD 439s. As I listen to a fair bit of electronic and dubstep music and I find myself EQed to the Bass Booster setting on iTunes.

Anyone who has tried this mod have any experience with Q40s or CALs? If so how do they compare?

magicman74 said:

Holy Cow!!
So I've done the Bass mod on several 428's before, nothing really new there.  I've also modded my 439's before, no biggie right?   Well every time I've done the Mod I have only opened one hole on the tape.
So I scored another 439 off ebay for 38 bucks.  Not a bad deal, they looked basically brand new.
So I said eff it why not mess around with them???

I opened them up and pulled off the whole tape strip.  Put them back together and cued up some Marley.
OMG!!!   These suckers have more Bass then the DT770.  It is truely earth shaking.  It hits so tight and deep the cans are shaking on my head.  It is insane.  What's even more crazy is nothing else is smeared up.  The mids and highs are right where they should be.  And the soundstage even has more depth!!!   I think it might be too much for me really, One hole has always sounded pretty dang good to me.   I haven't done a straight up ipod test, I'm running these amped thru my M-Stage so that could help out quite a bit, but my god!!!  I don't see how so many of you Bass Heads can take this:  This is crazy Bass levels!!!   

Click to expand...

pouskidis said:

Well, I am glad I am not alone in this!

Just recently, I also opened up all 3 holes in my HD-439 and found out that this is A HELL OF A HEADPHONE! Apart from the breathtaking BASS (perhaps the stronger there is for a headphone) the highs and mids did not subside, they are actually better now (!) than any other hole combination! What I mean is they sound better in all respects with all holes open, even if the bass should make the highs seem lower (which they kind of do with the one hole mod)!

Also they are not annoying at all, the known warmth of 439 is kept, even after the highs are more distinct now. In fact, they have improved so much that I fell asleep without them bothering me as they did with harsh songs... Don't get me wrong, the sound is NOT muffled now, it is actually CLEARER! I didn't like classical music with them, (preferred my 449), but now they are (more than) just fine for that too!

I too confirm that the soundstage is improved; they are very close to my (slightly) modded HD-449. I have put a thin layer over all 3 holes in them, thinner than the default tape, haven't tried the "all 3-holes open" mod yet... but I don't think I can resist much. I fear the bass would be too much for them, perhaps due to their pleather pads. But I can always be wrong and they could prove to be yet another monster!

I 've always been having the feeling that my HD-439 where holding back, especially in clarity of sound, and they did sound like a cheaper set with that tape on...
This 3 hole mod unlocked their full potentiall. And, as Magicman74 have stated in another post, they seem to breath MUCH better with all holes open. Now, they are close to my HD-497 as far as breathing is concern. But the 497 is an open headset!

Oh, and I don't use an amp! Just my pc and laptop, whith their default soundcards (set at 24/192) with asio and mad plugins for winamp. My collection is mailny mp3s, I also tried a few flacs, they too sound much better now. Naturally...

Perhaps Magicman74 you can compare the two HD-439 you have, one with all 3 holes open and the other with the normal mod, and tell us of your preference, or have you already stripped that other tape too? 

Click to expand...

Magicman74pouskidis

Is this mod worth it for a bass head, to the extent of abandoning the 2 year warranty that Sennheiser provides with their HD 439s. As I listen to a fair bit of electronic and dubstep music and I find myself EQed to the Bass Booster setting on iTunes.

Warning, once you mod the 439, the headphone us done for, there's no turning back or reversing it. Yes it's true, once the three holes have been opened up by removing the tape cover, it will turn the 439 into a mega super basshead with full high details that after you listen for awhile your ears will hurt. I would say this mod will turn the 439 into a headphone for critial listening (like for shortwave listening), but for short term only, your ears will thank you at a later age. I did this mod on my 439, I wish that I didn't.