hans030390
1000+ Head-Fier
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Here’s my thread on my open-backed D2000 mod! It will apply to the D5000/7000 as well. You have no reason to not try this! It can be tested in a 100% reversible, free, easy way! All you need is a small screwdriver to pop the cups off and your hands to do the work! Read on to find out!
Two things to note first. I do not always have the best and most detailed instructions for this mod. For things like removing the cups, I am placing faith in your ability to use the search function and Google to find the countless number of times questions like these have been answered. Second, any pictures I've taken for this mod are located at the end of this post.
UPDATES AND MEASUREMENTS ARE FURTHER DOWN IN THIS POST. MAIN POST WILL BE UPDATED IN THE NEAR FUTURE. FOR NOW, PLEASE READ THROUGH THE THREAD.
The Backstory
The D2000/5000/7000 are all wonderful headphones, and I loved my D2000 when I got them. At the time, they had everything I was looking for. I thought they had fantastic bass, were very detailed, lively, and surprisingly open sounding for being closed headphones. It was quite common for me to read that they had muddy, bloated bass, recessed mids, and were occasionally too bright. At first, I never noticed this. I figured it was just personal taste, or perhaps a lack of synergy in their equipment used.
Eventually, I picked up a pair of Sennheiser HD598s. How could I not? People kept raving about how their sound stage, midrange performance, and overall natural, speaker-like sound. I had some extra cash, so I wanted to see what they hype was about.
At first, I didn’t like them. I thought they were too thin and lifeless sounding. Boring, even. I was persistent, though, and let them burn in for a long time. After coming back to them, there was an improvement in almost all areas of the sound. I tried out a wider variety of music with them and found them to indeed match the praise they had been receiving. They seemed true to the recording. If it lacked bass or was mixed and mastered poorly, you could tell. With quality music, they came to life.
I started doing some A/B comparisons with my D2000. Suddenly, I realized what people meant by them having bloated bass and recessed mids. The bass suddenly became overbearing to my ears. It lacked the tightness and texture of the HD598s. The mids on the HD598 sounded so much better, too. I used to think the D2000 sounded lively, but, man, the HD598’s mids and sound stage just killed it. The D2000 sounded boring in comparison, for the most part.
For a few months, I didn’t touch my D2000s. Sure, the HD598s weren’t better in every aspect, but they simply sounded more natural to my ears. I then found a thread here where someone had posted about their open D7000 mod. I had always wanted to do the Markl mods to my D2000, but I was intrigued by this open mod. It was just too cool! The best part, though, was that you can try the open-back mod in an easy, completely reversible way that required purchasing nothing. So, on to testing it out!
Testing the Mod – Easy, Reversible, and Free
This mod has two key parts if you want to test it out. First, remove the cups from the headphones. That’s pretty easy. Get the earpads off and take out the 4 screws holding it in.
Second, instead of locking the earpads back into place, rest them on the frame of the headphones using the plastic locking pegs as stands to offset them from the frame. Simply put, you need airflow between the pads and the frame of the headphones. Again, very easy, especially since you already had them off!
To be completely honest, the hardest part of testing this mod is keeping the earpads in place! To do this, you’ll need to use your head while you’re wearing them. Last I checked, everyone here has a head, and everyone here knows how to wear headphones. That’s how you keep the pads on.
Ok, How Does it Sound?
Here’s what you’ll notice. The bass is attenuated (meaning less emphasized) and dramatically tightened. Does that mean they are bass-light now? Well, in comparison to stock, yes. In comparison to something like the HD598, not at all. What you get is bass that extends extremely low (like stock), but it is very tight, very well defined, very textured, and very punchy. In short, you get balanced, non-bloated bass that punches hard just like it should.
The midrange is noticeably brought out now. Can you call these recessed in the mids now? Nope. They compete with the HD598 here, in my opinion. You’ll also notice that they don’t lose their sparkly treble either. This is both a good and a bad thing. The good part is that they still sound very detailed and lively in this area. The bad part is that they’re now more sibilant, bright, and aggressive than before. They have a peak at 4KHz that is particularly nasty to my ears, and other peaks that I’m best-guessing lie around 7KHz and 10KHz.
How bad is it, though? Not too bad. Things can sometimes sound unnatural, depending on the recording. They can also be fatiguing over time or at higher volumes. Overall, though, the sound is still better than stock. You trade some problems for other, smaller problems. That’s progress in my book, and I knew that I could further tweak them to my liking. I’ll be going over these peaks more later on and possible ways to "fix" them.
One thing I noticed when comparing them to my HD598s is that the open-back D2000s sounded more transparent and clear. The HD598s, in comparison, sounded slightly veiled and wooly. The open Denons sounded much more clear and natural in this regard. This was strange, as I never considered the HD598s to be veiled (and most don’t). Again, though, the open Denons did sound more fatiguing in the upper mids and treble. I do miss the smooth treble of the HD598s.
What really got me, though, was the sound stage. Holy cow! To my ears, it is at least as good as the HD598 in that regard, if not better. They are not only very wide sounding now, but have also gained extra depth and height in the sound stage.
To add icing to the (delicious) cake, they don’t simply have a big sound stage. It sounds accurate. The open Denons easily replicate distance and intensity in this regard. If someone is whispering in your ear, the open Denons will replicate that intimacy and not place them artificially farther away. If someone is yelling in the distance, it sounds like they’re yelling in the distance. It combines these effortlessly as well. On Opeth’s album, Heritage, there is a part in the song “Haxprocess” that briefly has an acoustic guitar playing right up next to you on the right. It sounds like it’s there next to you. On top of that, though, you can also clearly hear the sound reverberating off the walls of the recording studio from the opposite walls with fantastic depth. It easily replicates the feeling of intimacy and a wide open space at the same time.
Going off of that, imaging is great as well. All I can say is that you can clearly place anything you hear. What more is there to say? The sound stage and imaging send shivers down my spine.
Despite some problems as mentioned, I did NOT expect the open Denons to sound this good. It’s eerily good, really. In fact, I was so impressed that I permanently modded them right away and soon after sold my HD598s.
Why do I Need to do Both Parts of This Mod?
Because I said so. Ok, really, here is what happens if you only do one of the two parts of this mod.
With just the cups off, you’ll notice the sound is definitely much more open. Wide sound stage and all that. You’ll also notice that they sound kind of slow and muddy now. It’s like everything in the sound has been wrapped in wool and sludge. The treble isn’t well defined, the mids are still recessed, and the bass gets even sloppier. Nothing sounds detailed or agile. But, you do get hints of a more open sound.
With just the earpads being raised off the frame of the headphones, you might as well be sticking knives in your ears. The bass disappears, the treble gets super bright, aggressive, and fatiguing, and it's just generally hard to listen to.
You might be able to see why you need both parts now. The raised earpads fix the slow, bloated sound that you’ll get from the cups being off. It tightens and attenuates the bass considerably. Well, in general, it tightens the sound. It makes them sound very agile. It also adds the treble and mids back that you lose from the cups being off. The cups being off, in turn, adds the bass, warmth, and lushness you’ll lose from raising the earpads and generally makes them much, much more natural and pleasing to listen to.
You can experiment with this to see how it works together. In fact, I encourage you too! For all I know, you might like the sound of them having the cups off with the earpads being locked in like normal (or vice versa). This also leaves room for, say, experimenting with different earpads with the cups being off or open-backed. Since this mod requires airflow under the earpads, perhaps earpads designed to allow airflow through would work well in combination with this. Perhaps someone will look into this, but I'm not about to start spending a bunch of money on a variety of earpads. I'd much rather work with the earpads I have, because I really do like them.
Anyway, on to how to make this permanent!
How To Do The Mod Itself
The easy part of the permanent mod is getting the earpads to stay in place while still having them raised. I used adhesive Velcro strips that I got for around $3 a pack at Wal-Mart (it’s way more than I’ll ever need). Cut the Velcro up into small strips and place them on the bottom of the earpad and the frame of the headphones. You’ll need to make sure you line up the pegs and everything first before doing this. Your earpads will now stay on thanks to the Velcro, but you’ll still get the airflow under them that they need.
The hard part of this mod is making the cups open-backed. I won’t be able to provide great instructions for this part, as I’m no expert with tools. In all honesty, my work was a bit sloppy, and I definitely didn’t do it in the safest way possible.
First, you need to find the center of the cups. I did this by drawing straight lines connecting the screw pegs/holes on the inside of the cups. The center of the cups is where these lines converge, if that isn’t obvious.
Next, you’ll need to drill a preliminary hole at that spot with an electrical drill. I did this from the inside of the cups again (because that’s where they’re marked). I don’t remember what size drill bit piece I used…I just used one. I tried using a clamper to hold the cups in place, but that wasn’t working out for me. I ended up finding something I could lay the cups down on with open room below them for me to drill without hitting anything. I used my hands to hold them in place. Probably not the smartest idea, but I didn’t hurt myself! I had some scares, though, when my hold would loosen and the cups would start spinning around wildly with the drill bit.
With our center hole in place, I used a drill bit piece specifically designed to bore holes. I have no idea what these are called. It looks like a regular drill bit, but it also has a circular saw part surrounding the drill bit itself. I believe the size I used was between 1.75-2 inches. I did not check or measure it, so that is my best estimation.
You’ll want to drill this hole from the outside of the cups, as it’s much easier to do it this way. I had a wooden workbench to use for this, so I wasn’t worried about accidentally drilling that at all. The key here is to do things slowly and carefully. Again, I used my hands to hold the cups in place.
Once you have the holes drilled, I used fine-grit sandpaper to smooth out the rough edges. If you’re not careful, you’ll end up scratching the outside of the cups a bit like I did.
Next, you’ll need some material to cover the holes. I had some extra window screen mesh that I used. I cut out two circles and have them held in place inside the cups by duct tape (on both sides of the mesh). Probably not the most elegant solution, but it works. I’d go with a type of strong glue for best results. Also, the mesh I used isn’t very strong. Fine wire mesh would probably be best.
Lastly, put it back together! You’re done! These are the two key parts of the mod. I was not content just stopping there, though! I encourage you to look into further tweaks and do your own experiments, and I’d love it if you could share your results! I’ll bring up some of the experiments and tweaks I’ve done myself to fine-tune everything to my tastes.
Further Tweaking and Experiments - Dampening
As I mentioned previously, this mod does bring some aggressiveness and sibilance to the upper midrange and treble that was previously not an issue with them being stock. Some people might like this, but I just couldn’t stand the peak at 4KHz. It made things sound unnatural and sibilant. “Wonky” is the term I use for it.
Having recently purchased some sound dampening/acoustic foam material for the Fostex T50RP mods, I decided to start with dampening the headphones much like that seen in the Markl mod. For this, I used the Silverstone Sound Dampening Acoustic Foam (adhesive back), which I got pretty cheap off Amazon ($13 for two large sheets!). It’s normally used for computer cases. I doubt this has the dampening capabilities of Dynamat Extreme, but I figured it’s better than nothing! I’d like to eventually see what differences Dynamat makes.
One thing I noticed is that there is a very, very slight difference in sound between the open-backed cups being on and off. Things sound ever so slightly less natural and more sibilant with them on. It's slight enough that it could just be placebo. Either way, I went ahead and put the acoustic foam all over the inside of the cups (just one layer). It was pretty easy to work with, but cutting out the proper shapes was a bit tricky and time consuming. Now, I really can’t tell a difference between the cups being on or off. I believe this mostly helped reduce sound wave reflections that have have been contributing to the aggressiveness and sibilance.
I also put the material on the back of the drivers like in the Markl mod. Together, I think this dampening makes them sound slightly more refined and easier on the ears. It made a slight difference in those peaks I’ve mentioned and, overall, made the headphones easier to listen to.
I have not yet put the material on the front side of the drive baffle. I intend to do this once I have a proper hole punch!
Further Tweaking and Experiments – More Dramatic Measures (aka Paper Removal)
This tweak is not something I expect people to jump on right away, but, for me, it made a remarkable difference. If you look at the very back center of the driver, you’ll notice there is a single large hole covered in paper. I’m not talking about the “outer rim” of the driver (which has two open holes and the rest covered). This is the very center hole. Just for the sake of seeing what would happen, I plugged that hole up with my fingers while listening (being careful to not break the paper). Well, it made them sound nasty.
However, after further experimentation with that hole, I found that the more material that was in front of the hole (not even covering or touching it!), the more certain frequencies would spike up. You’d also start losing bass. I started bringing my fingers up to the hole and kept in mind how the sound changed. To my ears, it sounded like it was making the peak at 4KHz larger. I then went to my EQ and boosted the 4KHz band. Sure enough, that’s what was happening!
I put two and two together…the more material that is in front of this hole, the more certain frequencies change (boost at 4KHz in particular, which was my main problem from the start). That said, I figured that paper being there was only boosting it further. I took a big risk and removed it!
How did that change the sound? Well, for one, it really, really helped reduce those peaks I’d been hearing, especially at 4KHz. The headphones are much easier to listen to now. They are still quite detailed but have lost most of their aggressive, fatiguing edge. They still retain their fantastic sound stage and imaging, though, if anything, it is slightly better now.
However, this also brought back some of the bass that had been lost in this mod. While still not as elevated and boomy as it is stock, it is definitely looser and boomier sounding than before removing this paper. Personally, I still find them to be very well balanced, fairly tight, and definitely punchy. It also seems to be highly dependent on the music you’re listening to as well. Even if it returned the bass back to stock levels, you’re still left with more elevated mids and the wonderful sound stage that the open mod brings. I have no issues with that!
Personally, I would much rather have this than the tighter bass and nasty midrange and treble peaks. I’m no basshead, but I don’t mind a tiny bit of extra bass. This offers that. It gives heft to recordings with heft but doesn’t seem to step out of bounds in recordings with relatively little bass. Again, to my ears, it still sounds very natural, and having those peaks mostly ironed out is a relief to my ears.
Other Tweaks, Experiments, and Future Trials to Come
Before any dampening or paper removal mods, I had tried experimenting with placing felt and other materials in between the drivers and the ear pads. I could never really find anything that helped. I tried cutting a small circle of felt to go directly over the driver (in the open spot of the foam donut surrounding the driver), but all that did was roll off the bass and treble. I also tried using a larger circle of foam that went over the foam donut, but all that did was boost the bass. I believe it restricted that necessary airflow under the earpads. I did try different felt thickness as well for both of these. I also tried a thin layer of tissue paper, which seemed to help somewhat, but wasn’t what I was looking for.
Long story short, placing material in between the drivers and the earpads only seemed to make things worse. I’m sure there are many other materials that would work well, but I only tried a few things. Even if they did help somewhat, they detracted from other areas of the sound in unacceptable ways.
UPDATE (10-3-2011): I tried stuffing the earpads like seen in the Markl mod. I personally did not like what this did to the sound. A lot of intensity and intimacy was lost. The sound stage didn't get any bigger, though everything sounded farther away than before (in a bad way). Seems like some treble and mids were lost while some parts of the bass were brought out. I think that raising the earpads off the frame of the headphones already gives them the air, soundstage, imaging, and other effects on the sound signature that the cans require. Not only does it seem like padding them is unnecessary, but it really just seems to detract from the sound.
For future tweaks, I plan on dampening the front side of the driver baffle to see what that gets me. I may also eventually try swapping out my current dampening acoustic foam with something like Dynamat. That might help tighten the bass up a bit more that had been loosened from the driver paper removal mod.
I will also eventually get these recabled, likely with Mogami 2534 cable. I imagine that will help further refine the sound, as I’ve heard there is a difference to be had with nicer cables on the Denons (or, at least with the D2000).
As I’ve said before, I encourage everyone to try this mod out and further experimentations with it! I’d love to hear your findings!
My personal notes on the measurements can be found on page 13 of this thread (well, page 13 for me, at least).
If you have not been keeping up with this thread, this original post it outdated! I plan on updating it in the near future, but there have been a LOT of changes I've made to my headphones. It's been a long process and will take me a while to update this post, so please read through this thread past the 3rd of October to see everything I've done with them.
Last Words and Thanks
I hope that people will be willing to give this mod a try. I think you’ll be pleasantly surprised (if not jaw-droppingly surprised) by what these open Denons can do! They are truly wonderful sounding open headphones. You should not pass this up! As I’ve said, you can try this in a 100% easy, free, reversible way. If you don’t like it, don’t sweat it! Just put it back together and be on your way! I do think you will be impressed, though.
Lastly, I’d like to thank lmswjm for originally posting about this mod with his D7000s. I can’t take the credit for originally coming up with this mod! Here's the link to his original thread on the mod.
General picture of the open-backed D2000 before any further modding or dampening:
This picture show the raised cups being held in place by velcro. You can kind of make out the plastic locking peg that now helps offset the earpads from the frame of the headphones:
This is a picture of the dampened cups (using Silverstone sound dampening acoustic foam):
This shows the back of the drivers being dampened (Silverstone material again). You will notice that the paper has been removed from the center back of the driver as detailed in my tweaks and experimentation section of the post:
Two things to note first. I do not always have the best and most detailed instructions for this mod. For things like removing the cups, I am placing faith in your ability to use the search function and Google to find the countless number of times questions like these have been answered. Second, any pictures I've taken for this mod are located at the end of this post.
UPDATES AND MEASUREMENTS ARE FURTHER DOWN IN THIS POST. MAIN POST WILL BE UPDATED IN THE NEAR FUTURE. FOR NOW, PLEASE READ THROUGH THE THREAD.
The Backstory
The D2000/5000/7000 are all wonderful headphones, and I loved my D2000 when I got them. At the time, they had everything I was looking for. I thought they had fantastic bass, were very detailed, lively, and surprisingly open sounding for being closed headphones. It was quite common for me to read that they had muddy, bloated bass, recessed mids, and were occasionally too bright. At first, I never noticed this. I figured it was just personal taste, or perhaps a lack of synergy in their equipment used.
Eventually, I picked up a pair of Sennheiser HD598s. How could I not? People kept raving about how their sound stage, midrange performance, and overall natural, speaker-like sound. I had some extra cash, so I wanted to see what they hype was about.
At first, I didn’t like them. I thought they were too thin and lifeless sounding. Boring, even. I was persistent, though, and let them burn in for a long time. After coming back to them, there was an improvement in almost all areas of the sound. I tried out a wider variety of music with them and found them to indeed match the praise they had been receiving. They seemed true to the recording. If it lacked bass or was mixed and mastered poorly, you could tell. With quality music, they came to life.
I started doing some A/B comparisons with my D2000. Suddenly, I realized what people meant by them having bloated bass and recessed mids. The bass suddenly became overbearing to my ears. It lacked the tightness and texture of the HD598s. The mids on the HD598 sounded so much better, too. I used to think the D2000 sounded lively, but, man, the HD598’s mids and sound stage just killed it. The D2000 sounded boring in comparison, for the most part.
For a few months, I didn’t touch my D2000s. Sure, the HD598s weren’t better in every aspect, but they simply sounded more natural to my ears. I then found a thread here where someone had posted about their open D7000 mod. I had always wanted to do the Markl mods to my D2000, but I was intrigued by this open mod. It was just too cool! The best part, though, was that you can try the open-back mod in an easy, completely reversible way that required purchasing nothing. So, on to testing it out!
Testing the Mod – Easy, Reversible, and Free
This mod has two key parts if you want to test it out. First, remove the cups from the headphones. That’s pretty easy. Get the earpads off and take out the 4 screws holding it in.
Second, instead of locking the earpads back into place, rest them on the frame of the headphones using the plastic locking pegs as stands to offset them from the frame. Simply put, you need airflow between the pads and the frame of the headphones. Again, very easy, especially since you already had them off!
To be completely honest, the hardest part of testing this mod is keeping the earpads in place! To do this, you’ll need to use your head while you’re wearing them. Last I checked, everyone here has a head, and everyone here knows how to wear headphones. That’s how you keep the pads on.
Ok, How Does it Sound?
Here’s what you’ll notice. The bass is attenuated (meaning less emphasized) and dramatically tightened. Does that mean they are bass-light now? Well, in comparison to stock, yes. In comparison to something like the HD598, not at all. What you get is bass that extends extremely low (like stock), but it is very tight, very well defined, very textured, and very punchy. In short, you get balanced, non-bloated bass that punches hard just like it should.
The midrange is noticeably brought out now. Can you call these recessed in the mids now? Nope. They compete with the HD598 here, in my opinion. You’ll also notice that they don’t lose their sparkly treble either. This is both a good and a bad thing. The good part is that they still sound very detailed and lively in this area. The bad part is that they’re now more sibilant, bright, and aggressive than before. They have a peak at 4KHz that is particularly nasty to my ears, and other peaks that I’m best-guessing lie around 7KHz and 10KHz.
How bad is it, though? Not too bad. Things can sometimes sound unnatural, depending on the recording. They can also be fatiguing over time or at higher volumes. Overall, though, the sound is still better than stock. You trade some problems for other, smaller problems. That’s progress in my book, and I knew that I could further tweak them to my liking. I’ll be going over these peaks more later on and possible ways to "fix" them.
One thing I noticed when comparing them to my HD598s is that the open-back D2000s sounded more transparent and clear. The HD598s, in comparison, sounded slightly veiled and wooly. The open Denons sounded much more clear and natural in this regard. This was strange, as I never considered the HD598s to be veiled (and most don’t). Again, though, the open Denons did sound more fatiguing in the upper mids and treble. I do miss the smooth treble of the HD598s.
What really got me, though, was the sound stage. Holy cow! To my ears, it is at least as good as the HD598 in that regard, if not better. They are not only very wide sounding now, but have also gained extra depth and height in the sound stage.
To add icing to the (delicious) cake, they don’t simply have a big sound stage. It sounds accurate. The open Denons easily replicate distance and intensity in this regard. If someone is whispering in your ear, the open Denons will replicate that intimacy and not place them artificially farther away. If someone is yelling in the distance, it sounds like they’re yelling in the distance. It combines these effortlessly as well. On Opeth’s album, Heritage, there is a part in the song “Haxprocess” that briefly has an acoustic guitar playing right up next to you on the right. It sounds like it’s there next to you. On top of that, though, you can also clearly hear the sound reverberating off the walls of the recording studio from the opposite walls with fantastic depth. It easily replicates the feeling of intimacy and a wide open space at the same time.
Going off of that, imaging is great as well. All I can say is that you can clearly place anything you hear. What more is there to say? The sound stage and imaging send shivers down my spine.
Despite some problems as mentioned, I did NOT expect the open Denons to sound this good. It’s eerily good, really. In fact, I was so impressed that I permanently modded them right away and soon after sold my HD598s.
Why do I Need to do Both Parts of This Mod?
Because I said so. Ok, really, here is what happens if you only do one of the two parts of this mod.
With just the cups off, you’ll notice the sound is definitely much more open. Wide sound stage and all that. You’ll also notice that they sound kind of slow and muddy now. It’s like everything in the sound has been wrapped in wool and sludge. The treble isn’t well defined, the mids are still recessed, and the bass gets even sloppier. Nothing sounds detailed or agile. But, you do get hints of a more open sound.
With just the earpads being raised off the frame of the headphones, you might as well be sticking knives in your ears. The bass disappears, the treble gets super bright, aggressive, and fatiguing, and it's just generally hard to listen to.
You might be able to see why you need both parts now. The raised earpads fix the slow, bloated sound that you’ll get from the cups being off. It tightens and attenuates the bass considerably. Well, in general, it tightens the sound. It makes them sound very agile. It also adds the treble and mids back that you lose from the cups being off. The cups being off, in turn, adds the bass, warmth, and lushness you’ll lose from raising the earpads and generally makes them much, much more natural and pleasing to listen to.
You can experiment with this to see how it works together. In fact, I encourage you too! For all I know, you might like the sound of them having the cups off with the earpads being locked in like normal (or vice versa). This also leaves room for, say, experimenting with different earpads with the cups being off or open-backed. Since this mod requires airflow under the earpads, perhaps earpads designed to allow airflow through would work well in combination with this. Perhaps someone will look into this, but I'm not about to start spending a bunch of money on a variety of earpads. I'd much rather work with the earpads I have, because I really do like them.
Anyway, on to how to make this permanent!
How To Do The Mod Itself
The easy part of the permanent mod is getting the earpads to stay in place while still having them raised. I used adhesive Velcro strips that I got for around $3 a pack at Wal-Mart (it’s way more than I’ll ever need). Cut the Velcro up into small strips and place them on the bottom of the earpad and the frame of the headphones. You’ll need to make sure you line up the pegs and everything first before doing this. Your earpads will now stay on thanks to the Velcro, but you’ll still get the airflow under them that they need.
The hard part of this mod is making the cups open-backed. I won’t be able to provide great instructions for this part, as I’m no expert with tools. In all honesty, my work was a bit sloppy, and I definitely didn’t do it in the safest way possible.
First, you need to find the center of the cups. I did this by drawing straight lines connecting the screw pegs/holes on the inside of the cups. The center of the cups is where these lines converge, if that isn’t obvious.
Next, you’ll need to drill a preliminary hole at that spot with an electrical drill. I did this from the inside of the cups again (because that’s where they’re marked). I don’t remember what size drill bit piece I used…I just used one. I tried using a clamper to hold the cups in place, but that wasn’t working out for me. I ended up finding something I could lay the cups down on with open room below them for me to drill without hitting anything. I used my hands to hold them in place. Probably not the smartest idea, but I didn’t hurt myself! I had some scares, though, when my hold would loosen and the cups would start spinning around wildly with the drill bit.
With our center hole in place, I used a drill bit piece specifically designed to bore holes. I have no idea what these are called. It looks like a regular drill bit, but it also has a circular saw part surrounding the drill bit itself. I believe the size I used was between 1.75-2 inches. I did not check or measure it, so that is my best estimation.
You’ll want to drill this hole from the outside of the cups, as it’s much easier to do it this way. I had a wooden workbench to use for this, so I wasn’t worried about accidentally drilling that at all. The key here is to do things slowly and carefully. Again, I used my hands to hold the cups in place.
Once you have the holes drilled, I used fine-grit sandpaper to smooth out the rough edges. If you’re not careful, you’ll end up scratching the outside of the cups a bit like I did.
Next, you’ll need some material to cover the holes. I had some extra window screen mesh that I used. I cut out two circles and have them held in place inside the cups by duct tape (on both sides of the mesh). Probably not the most elegant solution, but it works. I’d go with a type of strong glue for best results. Also, the mesh I used isn’t very strong. Fine wire mesh would probably be best.
Lastly, put it back together! You’re done! These are the two key parts of the mod. I was not content just stopping there, though! I encourage you to look into further tweaks and do your own experiments, and I’d love it if you could share your results! I’ll bring up some of the experiments and tweaks I’ve done myself to fine-tune everything to my tastes.
Further Tweaking and Experiments - Dampening
As I mentioned previously, this mod does bring some aggressiveness and sibilance to the upper midrange and treble that was previously not an issue with them being stock. Some people might like this, but I just couldn’t stand the peak at 4KHz. It made things sound unnatural and sibilant. “Wonky” is the term I use for it.
Having recently purchased some sound dampening/acoustic foam material for the Fostex T50RP mods, I decided to start with dampening the headphones much like that seen in the Markl mod. For this, I used the Silverstone Sound Dampening Acoustic Foam (adhesive back), which I got pretty cheap off Amazon ($13 for two large sheets!). It’s normally used for computer cases. I doubt this has the dampening capabilities of Dynamat Extreme, but I figured it’s better than nothing! I’d like to eventually see what differences Dynamat makes.
One thing I noticed is that there is a very, very slight difference in sound between the open-backed cups being on and off. Things sound ever so slightly less natural and more sibilant with them on. It's slight enough that it could just be placebo. Either way, I went ahead and put the acoustic foam all over the inside of the cups (just one layer). It was pretty easy to work with, but cutting out the proper shapes was a bit tricky and time consuming. Now, I really can’t tell a difference between the cups being on or off. I believe this mostly helped reduce sound wave reflections that have have been contributing to the aggressiveness and sibilance.
I also put the material on the back of the drivers like in the Markl mod. Together, I think this dampening makes them sound slightly more refined and easier on the ears. It made a slight difference in those peaks I’ve mentioned and, overall, made the headphones easier to listen to.
I have not yet put the material on the front side of the drive baffle. I intend to do this once I have a proper hole punch!
Further Tweaking and Experiments – More Dramatic Measures (aka Paper Removal)
This tweak is not something I expect people to jump on right away, but, for me, it made a remarkable difference. If you look at the very back center of the driver, you’ll notice there is a single large hole covered in paper. I’m not talking about the “outer rim” of the driver (which has two open holes and the rest covered). This is the very center hole. Just for the sake of seeing what would happen, I plugged that hole up with my fingers while listening (being careful to not break the paper). Well, it made them sound nasty.
However, after further experimentation with that hole, I found that the more material that was in front of the hole (not even covering or touching it!), the more certain frequencies would spike up. You’d also start losing bass. I started bringing my fingers up to the hole and kept in mind how the sound changed. To my ears, it sounded like it was making the peak at 4KHz larger. I then went to my EQ and boosted the 4KHz band. Sure enough, that’s what was happening!
I put two and two together…the more material that is in front of this hole, the more certain frequencies change (boost at 4KHz in particular, which was my main problem from the start). That said, I figured that paper being there was only boosting it further. I took a big risk and removed it!
How did that change the sound? Well, for one, it really, really helped reduce those peaks I’d been hearing, especially at 4KHz. The headphones are much easier to listen to now. They are still quite detailed but have lost most of their aggressive, fatiguing edge. They still retain their fantastic sound stage and imaging, though, if anything, it is slightly better now.
However, this also brought back some of the bass that had been lost in this mod. While still not as elevated and boomy as it is stock, it is definitely looser and boomier sounding than before removing this paper. Personally, I still find them to be very well balanced, fairly tight, and definitely punchy. It also seems to be highly dependent on the music you’re listening to as well. Even if it returned the bass back to stock levels, you’re still left with more elevated mids and the wonderful sound stage that the open mod brings. I have no issues with that!
Personally, I would much rather have this than the tighter bass and nasty midrange and treble peaks. I’m no basshead, but I don’t mind a tiny bit of extra bass. This offers that. It gives heft to recordings with heft but doesn’t seem to step out of bounds in recordings with relatively little bass. Again, to my ears, it still sounds very natural, and having those peaks mostly ironed out is a relief to my ears.
Other Tweaks, Experiments, and Future Trials to Come
Before any dampening or paper removal mods, I had tried experimenting with placing felt and other materials in between the drivers and the ear pads. I could never really find anything that helped. I tried cutting a small circle of felt to go directly over the driver (in the open spot of the foam donut surrounding the driver), but all that did was roll off the bass and treble. I also tried using a larger circle of foam that went over the foam donut, but all that did was boost the bass. I believe it restricted that necessary airflow under the earpads. I did try different felt thickness as well for both of these. I also tried a thin layer of tissue paper, which seemed to help somewhat, but wasn’t what I was looking for.
Long story short, placing material in between the drivers and the earpads only seemed to make things worse. I’m sure there are many other materials that would work well, but I only tried a few things. Even if they did help somewhat, they detracted from other areas of the sound in unacceptable ways.
UPDATE (10-3-2011): I tried stuffing the earpads like seen in the Markl mod. I personally did not like what this did to the sound. A lot of intensity and intimacy was lost. The sound stage didn't get any bigger, though everything sounded farther away than before (in a bad way). Seems like some treble and mids were lost while some parts of the bass were brought out. I think that raising the earpads off the frame of the headphones already gives them the air, soundstage, imaging, and other effects on the sound signature that the cans require. Not only does it seem like padding them is unnecessary, but it really just seems to detract from the sound.
For future tweaks, I plan on dampening the front side of the driver baffle to see what that gets me. I may also eventually try swapping out my current dampening acoustic foam with something like Dynamat. That might help tighten the bass up a bit more that had been loosened from the driver paper removal mod.
I will also eventually get these recabled, likely with Mogami 2534 cable. I imagine that will help further refine the sound, as I’ve heard there is a difference to be had with nicer cables on the Denons (or, at least with the D2000).
As I’ve said before, I encourage everyone to try this mod out and further experimentations with it! I’d love to hear your findings!
Measurements and 11-1-2011 Update
Finally got the headphones measure. Thanks, Tyll! Check them out!My personal notes on the measurements can be found on page 13 of this thread (well, page 13 for me, at least).
If you have not been keeping up with this thread, this original post it outdated! I plan on updating it in the near future, but there have been a LOT of changes I've made to my headphones. It's been a long process and will take me a while to update this post, so please read through this thread past the 3rd of October to see everything I've done with them.
Last Words and Thanks
I hope that people will be willing to give this mod a try. I think you’ll be pleasantly surprised (if not jaw-droppingly surprised) by what these open Denons can do! They are truly wonderful sounding open headphones. You should not pass this up! As I’ve said, you can try this in a 100% easy, free, reversible way. If you don’t like it, don’t sweat it! Just put it back together and be on your way! I do think you will be impressed, though.
Lastly, I’d like to thank lmswjm for originally posting about this mod with his D7000s. I can’t take the credit for originally coming up with this mod! Here's the link to his original thread on the mod.
Pictures
General picture of the open-backed D2000 before any further modding or dampening:
This picture show the raised cups being held in place by velcro. You can kind of make out the plastic locking peg that now helps offset the earpads from the frame of the headphones:
This is a picture of the dampened cups (using Silverstone sound dampening acoustic foam):
This shows the back of the drivers being dampened (Silverstone material again). You will notice that the paper has been removed from the center back of the driver as detailed in my tweaks and experimentation section of the post:
