[markimus]

I did the mod and wanted to say "THANK YOU!!!".  This is what I always knew these headphones should sound like.  I did not need to add any clay to my headphones though as the design is slightly different when compared to the images that you used, and instead of using the permeable membrane tape that you suggested using to cover the two outer bass ports I used a needle to puncture the two outer membranes three times in the shape of a triangle calculating that the needle hole and remaining material would replicate the tape and it seems to work.  Thank you again for sharing, now I am listening to my copy of, "AC/DC Live: Collector's Edition" as it should be heard!!! \m/ \m/  

 

[lostmage]

A while back I actually took a dremel to the internal driver cup (the one with the ports on it) and cut it off completely. With the bare cups and no internal driver cup, the resonance is insane, unbearably bad, and the bass is so much louder than the rest of the frequencies that it completely drowns everything else out.
 
I ended up adding some modeling clay to the back, which cut resonances and the bass down by a bit, then, since the back of the driver itself is OPEN (like it's a skeleton frame driver, you can poke the back of the membrane from the back of the driver, not sure what the actual term for this is) I put a layer of micropore tape over the driver itself. This cut the bass down by a fair bit, so it's now at the level of a somewhat bass heavy set of cans.
 
I'm pretty sure I threw them out, so if anyone has the rough dimensions of the internal cups, that would possibly be helpful in moving forward with this. Tuning the volume of the whole cup may have an effect on the bass. There's still, unfortunately, not a very good soundstage with these. No matter what I tried, they simply will not open up.

 

[totheark]

Ive been looking for a good mod for these headphones for a very long time and wow thank you so much!

 

[pilez]

They are now $25 on Ebay, I just got 2 in the mail, they look brand new, as does the packaging, but it says the condition are factory refurbished... 
 
I already had a set, that just sat there because they were less than all that, after just the tape a thin layer of clay they are now my go to pair, even though I own a pair of MS2's, ATH-AD700, and a very much modded Fostex T50RP. I personally blame wje for making me spend money to play with these really cheap headphones, because they DO sound so good, these are going to be xmas gifts after I am done rewiring, recabeling, and them taping and laying down some clay on them that is.
 
Now to go back to my Fostex modding to try and get it sounding this good. 

 

[pilez]

Has anyone thought about Sugru to make the seal for re-cable after removing the stress relief piece? Or does someone think it is possible to use the existing one and just drilling it out and then sealing it back up with silicon?
 
Thanks!

 

[dirkpitt]

This is really cool..
 
I got the 429s today because my 558's (open cans) dont block out enough office noise. As soon as I plugged them in I was disappointed. The bass was pretty poor, even compared to the 558s.
 
I didn't hold much hope in the mod, but was pleasantly surprised when I opened the middle hole. For interests sake, I opened all 3, but my ears hurt straight away.. it was way too much, but clearly demonstrated the bass unleashed. I covered up the two outer holes again which tamed it a little. I also added the blue tack to test.. the difference is probably less pronounced with the blue tack but they feel quite comfortable to listen to now, so I will leave them like this for a while.
 
With such a huge difference I have to wonder why the manufacturer has covered the holes in the first place, flattening the response so much? They are certainly punchier now... does anyone think this could just be a safety thing to prevent hearing damage?

 

[MaztotheUla]

So for the best sound should I just uncover the middle hole? Don't have any putty

 

[Peter West]

I bought a set of HD-439s out of the bargain bin at a New Year's Eve midnight sale for $40. I've always liked them especially for the price. They work very well as my office headphones where I don't want as much music or weight as my LCD-X. They're much like my much maligned HD-590s without the same amount of brightness. And, after reading the posts here, I've always wanted to mod them. It took three attempts but once I got them open and gently popped the driver casing using forceps to get a grip it was easy to cut the tape over one bass hole and reassemble them. I'm listening to Diana Krall and the difference in bass is very much evident. I'm coming to the conclusion that different headphones work better out of different DACs and for different purposes. Now my HD-439s sound really musically full coming out of a Fiio Olympus II (E-10K) streaming from Tidal without throwing so much music into my ears that I can't think after an hour or so. Very nice mod on a decent set of headphones. Thanks. Thinking about getting a set of Fostex T50RPs now.
 
Update: Needed to turn the bass boost off the E-10K so obviously the mod works just fine. Always had the bass boost on before with the HD-439sand the gain switch on high (where it remains).
 
Update 2: Do not under any circumstances listen to Discover deadmau5 with bass boost on the E-10K after modding the HD-439s. You've been warned. Gets more than a little thud in the bass. Same for some Dusty Springfield songs which happen more in the right side than the left (almost painfully so) which I'm guessing is due more to the poor recording than the mod to the headphones as I'm not hearing the same effect yet elsewhere. The mod is revealing moments of real listening pleasure (Shawn Colvin for example). Very nice. Thanks again.

 

[Shaakasu808]

I ended up getting some HD-428s from new egg for about $34. And after doing the mod they have really come through as a great pair of cans. I ended up using dynatak and some Plasticine clay to dampen the actual bass mod because I opened the center and 1/2 the top holes. They sound like dreams and have completely made me wish i never got my Sony MDR-7510s (unmodded) .

 

[gcb0]

man, i bought those ages ago at best buy no less for $30!
 
i never used them much because after one year the earpads just crumbled.
 
what are good leather replacements i can use? can i use ear pads from any HD series? the redish velour from the 598 looks good. would it fit?
 
 
I may try to mod the headband with a steel or other material after i get the nicer earpad. I'm looking for any earpad with a nice touch and lots of padding so that i may hold it by pressure on the ear as my more expesive ones does. Holding on top of the head gets tiring after a while.

 

[hardwiredcnd]

Thanks for the write-up, I moded my HD-428s, I did get them in none working state so replaced the cord as well. I used plumbers putty only opened the center hole. They sound great!

 

[Rocko1]

I pulled these out of the closet after about 2 years. Compared to my AT M50's these sound really bad. Bloated bass, veiled sound, just not great.

 

[ThePirate]

Thanks for the info!!
 
I have a pair Senn 428S and modding them. How thick do want on putty?  And approximently how putty total did you use?