[Hellome7]

- The cotton is to damp the excessive bass that is generated when you create too many (or more than necessary for your taste) holes. 
 
- The easiest and safest way to drill the holes is by using a welder.
 
- No. Just drill 1 hole on each earcup, re-assemble everything and test it. If you like what you hear leave it as it is, if not disassemble it again and drill 1 more hole on each earcup and once again  re-assemble everything and test it. If you test it and you hear that the bass is overpowered, then disassemble the headset and add some cotton on the inside of the earcup (as shown on the many images). 
 
I've put a link above your comment. Its a video I made on how to mod it. It will simplify your life a lot .
 
Greetings
 
 

 

[MyvTeddy]

Quote:

- The cotton is to damp the excessive bass that is generated when you create too many (or more than necessary for your taste) holes. 
 
- The easiest and safest way to drill the holes is by using a welder.
 
- No. Just drill 1 hole on each earcup, re-assemble everything and test it. If you like what you hear leave it as it is, if not disassemble it again and drill 1 more hole on each earcup and once again  re-assemble everything and test it. If you test it and you hear that the bass is overpowered, then disassemble the headset and add some cotton on the inside of the earcup (as shown on the many images). 
 
I've put a link above your comment. Its a video I made on how to mod it. It will simplify your life a lot .
 
Greetings
 
 

Thanks bud! I'm still unsure where to place the cottons (I tried looking for images, I think I keep overlooking them) and some of the wording in your vid did confuse me a bit but nonetheless, it helped alot!

I did the mod with 2 holes on each side, absolutely ******* fantastic. I was using a sennheiser PC 151 and it sounded amazing. Switched to the Pc 350 and I felt the quality was off. Until I came across this mod and bam, the PC 350 became a new favourite.
 
Best headset and mod ever. Though I do have some ideas for a mod...
 

 

[Jaawa]

Quote:

 I'm still unsure where to place the cottons
 

Here's a pic of my PC 350's. You can experiment with the amount of cotton, but you should always try to fill the cup evenly. I don't think there's much to gain from trying different placements for inner dampening material, as the point of it is to ease the reverberation of the lows, hence it needs to be everywhere IMHO
 

 

[badbod]

MyvTeddy nice pics, I would like to have posted pics on my mod but didn't get a digi cam til recent. Please all, post pics of your mods to help new modders, and show seasoned modders how you did it. 
 
We all have slightly different expectations and tastes. When you mod you are tailoring to your taste. You can take the stock sound and suggest it is perfect, but if you cannot tailor it to your own ears, then maybe they are not the phones you thought they were.
 
The beauty of the PC350 is the fact you can play with it. Just like we all have our own equalizer settings, then if you can ailor your can's then it is as close to perfection as you will get.
 
I did do some more experimenting with cotton wool and more / larger holes. Here are my results -:
 

1. holes too large, compensate with cotton wool. 
2. too many holes, compensate with cotton wool.
3. baffle holes, not easy, and unreliable. This is the killer. Proper baffles make these cans sound amazing but -- you can't get consistently sized baffles without proper equipment. Stopping them from falling out without commiting is a problem. You can't super glue them in unless your sure they are right. The reason all Hi-Fi speakers use baffles is because they work. 
4. Multiple baffled holes - see above, beyond casual modding, indeed even pro manufacturers don't do this. The precision required is just not trivial to replicate on a large scale manufacturing process.
5. For my ears, a single ~2mm hole, using a heated T-bar driver to make the hole, gave me the best sound without needing cotton wool.
6. Over porting an then damping is preferable to many ears.

 
So you see, it is not so simple. I stand by my original recommendation of starting off small, then if you don't think it sounds 'enough' try a little more. you can then use cotton wool to dampen (some ears prefer this) or reduce your holes and hole size (some ears prefer this).
 
If you really want the best then make a single hole and baffle it. You will need to experiment with the length of the baffle and the diameter. but if you think you have a winning formula, then please let us know so we can try it out too. Just remember that you have a closed speaker right next to your ear. As such you can use any method employed by normal closed speakers, which almost universally  have baffles in the bass port
 
In case you are not sure what I mean by baffles, it is a length of tube which is inserted in the 'Bass' port (the round empty hole in the front of most speakers) which is designed to limit airflow variably with the amount of airflow. Some speakers will 'Flap' badly if this tube is removed, but they are very well designed, high quality speakers which do rely on the baffles to prevent flapping. Cheap speaker will not normally be so well built and will not miss the baffles, as they are merely cosmetic to emulate the look of high quality speakers.
 
Wharfedale Studio 20 speakers are a case in point. They will flap badly at only 3-4 Watt RMS input without the baffles. With the baffles a full 20 Watt will still not see them flapping despite the well beyond orchestra crescendo volume output.
 
Happy modding.
 
 
 
 

 

[tmacmich]

Hey just wanted to reply to this thread, tried the mod, turned out to be excellent.

My friend experimented with two then three holes however I found it best to stick to one hole in each enclosure. I found the bass was nice and punchy, it isn't muddy or overwhelming very, in fact it's very clean sounding. I didn't add any dampening material whatsoever in my results vs. my friends results, I came to the conclusion it shrinks the sound stage too much and the bass wasn't as clear either due to the structure of the cotton (thinner as it spreads and more dense in other places makes for unevenness).

Hope this helps for anyone investigating this thread. I've also had about 70 hours of burn in on pink noise alone, closer to 100 hours of total burn in time with music played. Using a X-Fi Forte, (I know it isn't for music but I game a lot).

Again, these phones weren't really worth it until I came across this mod and now I consider it a very good investment. Now I just need to pick up some new ear pads.

 

[Dar3k]

Hi
 
I just registered here to post in this thread and tel you my experience. I have had mine PC350's for several years. I really liked them for gaming, but music.. not so much, so when i saw this mod, i thought.. why not.
 
I drilled one hole like this:

 
But i felt the bass was way too much.
So I tried to cover up the hole with black tape and make two small holes in the tape with a needle, it worked quite well but i wanted to try some cotton padding also.
So i ended up with this:

 
I put a small piece of cotton so it would cover the hole when the headphones are assembled and fastened it with some black tape (I don't have any tape covering the hole now).
I didn't want to clutter the whole thing in cotton. I thought if it only covers the hole it should be enough.
The result.. I think it sounds really nice now, it feels like the sound is a little more open and the bass is stronger. Although it's allot less then without the little piece off cotton, the damping makes a lot of difference. Without the cotton the bass was way to strong, sounded somehow muddy and made the mids sound really bad.
 

 

[AlteredCarbon]

I registered here just to say thanks, and WOW! I didn't expect this mod to work as well as it did. I'm a big skeptic when it comes to audio mods, so I started off with one hole and a thin layer of  (real) cotton. I don't have to swap these headphones going from chatting on Skype to music anymore.
 

 

[Ninefingers]

I've ordered the PXC450 earpads for my PC350. As soon as they get in, I'll be doing this mod.
 
Thanks for all the work you've done with this mod. Thanks Hero. =) I'll see if I can steal my wife's camera to take a few pictures.
 
Ninefingers

 

[theimapwnu]

Thanks guys just registered to say thanks for this mod  
 
Did this on mine and a friend's PC350s yesterday and love it. I started with 2 smaller holes (3/32") and expanded them to a bit bigger (around 5/32")
 
If I want to seal off a hole is a few layers of electrical tape good enough? Or is it better to add some cotton?
 
Also just wondering where you guys got the PXC450 pads (I could only find some aftermarket pads on ebay/amazon for $25 - http://www.amazon.com/NEW-pads-Sennheiser%C2%AE-PXC450-Headphones/dp/B005JU5R9A)

 

[xMarcWithaCx]

Just got these on sale from Newegg for $109.  Was pretty disappointed until I did the mod.  WOW. Thanks again for everyone's hard work on this.
 
I did 2 holes with a hot tack nail on the side of the longer part of the chamber matching this post in the thread
http://www.head-fi.org/t/406187/modding-the-sennheiser-pc350-headset/255#post_6887919
 
Sounds great. I'll have to play with dampening but right now it's night and day from pre-mod.  Was pretty straight forward too. Thanks for the great pics and video. 
 
Now to get some velour pads and break these in.  These are my first higher end pair.  Excited to get back into my music. Now I'll have to get better source material though

 

[Saxi]

I just did this with the pair I got from with my Asus XSense Extreme Edition.

Huge difference, I put two holes by corners like mentioned about halfway through the thread.  Took me a while to figure out how to get the case off, once I found out there are actually two screws under the tape.  I also super glued the bumpers in place, no way I wanted to mess with making sure they stay in while I put it together.
 
I like the new sound from them.

 

[k1DBLITZ]

Can you elaborate on this rubber grommet? Mine fell out when I was doing the mod and I didn't bother to put them back in.
 
Can you show me where they go from any of the pictures that have been posted?
 
 

Wow, just tried this on my PC350.  Amazing what an effect a small hole has... Using some HD650s as reference so it's not just in my mind.  The PC350 started out sounding very anemic and bass light, but crisp and clear.  Now they are more bass heavy than the HD650s.  A touch too much actually as there is a bit of a hall effect now.  I got a bit carried away and put 4 small holes in each side.  I've covered two up and added some cotton wool, but it's still a touch too much comparing back and forth.
 
One thing I noticed in comparison to the open back HD650 is that the sound changes quite markedly as you move the speaker towards and away from your ear.  Without the mod, I could press the cans into my head quite hard and get an acceptable level of bass.  This was at the point of my earlobe hitting the grill though.  Pull them away slightly and they immediately sound tinny.  The HD650 don't change in sound signature nearly as much, mostly it is just the volume that changes as you move them away or towards the ear.  This implies that tuning a sealed can is much more tricky and will change based on head and ear shape as well as the condition of the pads.
 
Some tips:
 
1. There are 2 screws hidden under the foam sticker on the left side.  Took me a while to find the second one.
2. Be careful with the wire that exits the left speaker at the bottom. I put some stress on this trying to find the above screw and once I did open it found that the wires had separated from the sleeve inside.
3. There's a tiny rubber pad at the top of each driver that softens the impact against the headband frame.  This is held in place by the driver assembly and so is free to fall out as soon as you pull the driver away.  Find this and put it to one side before you lose it.  If your driver assembly does not go back in easily, you might find it has fallen out and is in the way of the driver assembly
 
One final thing - there is what looks like a filter on the PCB for each driver (some resistors and capacitors).  You can see a separate circuit for the mic and then sections for each of the left and right drivers.  I'm sure this has some effect on the sound vs what is in the other headphones that use the same driver.  This is also something to consider when re-cabling.
 
Still listening and I do have too much bass now...
 
4. make one small hole at a time and then listen for a bit, it's easier to not make the hole than to try and seal it up again
 
After another couple of days...
 
5. Too much pressure on the inside of the outer cup will make the middle part (the piece with Sennheiser written on it) separate over time.  It is glued on with a type of glue that remains sticky and can be pulled apart.  So, don't use too much wadding back there, or allow that piece of rubber I mentioned in 3. to fall into the back of the cup and put pressure on it.  Unless you want to go for an open headphone design

 

[Hezer]

http://www.head-fi.org/t/406187/modding-the-sennheiser-pc350-headset/45#post_5865224
 
Check out this post by Jaawa and ask again if you're still having difficulties.

 

[theimapwnu]

The finished mod; single 3mm (1/8") bass port on each side, no filler, with HeadphoneMate PXC 450 pads they sound mind blowing
 
 

 

 

[zachimal]

Count me amongst the multitude of hero-modders.  Thank you hero!  I joined, like many others, just to say thanks to hero and all the other helpful modders who have posted here.  I've had my PC350s for about a year now but haven't had the balls, for lack of a better word, to mod them... I'm so glad I did.  It took about 10 minutes being very careful and they are AMAZING now with a single whole at the top center of each cup (probably about 1/8th of an inch in diameter) with no cotton or other additions.
 
I used a very small screwdriver attachment on my Leatherman multitool heated over a candle to poke the whole... very simple and clean.  When I first saw the mod I was worried I'd need something special, but I guess I'm just a noob to modding and didn't realize how easy this one was.  I can hardly believe the difference.  This allows the PC350s to completely replace my HD280s as my primary listening headphones—they are more comfortable than the 280s, after all, and now they sound even better!  This is all just hooked up to my MacBook, even.  I've got an ASUS Xonar Essence STX that's being RMA'd right now, so that'll be even more impressive once (hopefully) it's fixed.