It's been a while, but I finally have my D2000s back! Yes, they've been out this entire time. LFF took some time to listen to them, and here's what he had to say about them (hope he doesn't mind if I share):
"I think they sound quite good to be honest. A bit bloated in the bass if I was going to nitpick but they were SOOOO much better than other Denons I have heard. You did a great job with them."
I then inquired about the large dip measured around 2.5-4KHz. I was curious if he had noticed it or any other particular oddities about the sound:
"Yes...the mids were a little recessed but not too much to make me dislike them. I think Denons in general have a very recessed middle section...probably due to the overpowering flabby bass and stringent highs. Since you reduced that flabby bass (by quite a bit to my ears at least), the mids shine through a bit more and the openness helps reduce the stringent highs as well.
As I said, your Denons are so much better than the regular stock variety. Much better.
Dips are extremely hard to hear because they can get masked by other surrounding sounds. Learning to hear dips really well is a challenge and one I haven't perfected after 12 years of practice. I can hear them well but not as well as I would like. In other words...don't expect to hear narrow dips all too well. That is one of the reasons a good mastering engineer will reduce rather than boost."
Having spent a considerable amount of time with my modded T50RP and recently having received a pair of the Paradox T50RP from LFF, I was afraid my modded D2000s wouldn't sound as good as I remembered. Not the case! They have a difference sound signature and overall "feel" to the sound, but they do sound nice!
I think the measurements don't adequately convey the amount of bass these put out. The graph makes them look a bit weak. They are not. They have lost some extension and do drop off pretty rapidly below 40Hz, but they do not sound thin at all to my ears. I was able to validate the bump around 1KHz and really heard that dip at 2.5-4KHz when running these through Sinegen. It's a pretty nasty dip, and I'm not going to lie about that.
I've been doing some tests, and I believe I've narrowed the cause of the dip down to the paper backing on the drivers. I strongly suggest that everyone leaves the paper on the back of the driver. If you are having trouble with sibilance, try placing material in front of the driver instead. I'm going to be testing various materials to see what might act as a suitable replacement for mine.
The good news is that the dip is fixable. I placed some felt over the back of the driver where the paper used to be, and it dramatically helped. There's still a small dip in that area, but it is much less pronounced and covers a much smaller frequency spectrum. Looking at the stock D2000 graph, it has a few small, sharp dips in this area to begin with.
The real trick is finding a material that will both fix this dip and not kill off the bass at the same time. I also tried stuffing the cups with some dampening material (much like cotton or polyfill), but this did not help the dip. Neither did reducing the size of the hole in my cups (which is already fairly small). It looks like it all comes down to the material on the back of the driver.
I do believe that my current mod configuration has some advantages that won't present themselves otherwise. Still, I think the overall best open mod for the D2000 is simple:
1. Drill large hole in the cups
2. Lift pads off frame and attack with velcro
3. Optional: place some earpad foam in front of the driver to help fix sibilance
4. Optional: apply dampening and acoustic foam to the cups and/or on back of the driver
Had I come across the idea of placing earpad foam material in front of the driver earlier, I'd have never taken off the paper on the back of the driver.
