3/10/13 Swan Song Update:
I’ve since changed the mod by closing off the pad slots with tape and sealing the gap between the pad and frame with black caulk. The result is stronger bass at the cost of a little bit of soundstage. I prefer these to the technically superior TH900 because of the openness.
Purrin and Tyll both agreed to listen and measure these with the new mod.
Purrin created a thread at Changstar on these:
lmswjm is my hero. You've got to have guts to do this: http://www.head-fi.org/t/464640/denon-ah-d7000-open-back-modification
Long story short: He sent them to me for measurement via Fedex who lost it, but the box somehow made it to my house a few weeks later. Go figure. And I thought some illegal aliens swiped it too.
Couple of points / subjective impressions (going through 14 test tracks very quickly):
- I can't stand most D7000s. That ringing razor of death at 9k surrounded by 6.5k/13k double-penetrator action hurts my ears. Can't stand to listen for more than 8 seconds.
- Oddly enough, this modded pair does not exhibit this nasty treble behavior. It possible that Anetode just happens to get the T1 and D7000 rejects. I'm not sure if this is the result of the open mod or product variation. Tyll has measured two D7000s, and their frequency responses were slightly different.
- The modded D7000 does sound like there is a tizz near 10kHz at higher volumes. But it doesn't sound too bad and very tolerable for me. At 10k, the ringing, if any, seems moderate and not out of control.
- There's still a mid-suckout, but it seems less prevalent. Hard to describe. Don't get me wrong. This open-backed mod still has the U shaped curve.
- It's still just as bassy. And the bass quality isn't that much better than stock. I guess the TH900 drivers are indeed something special.
- Indeed more open sounding.
Tyll's comment and measurements:
This is an open-back / open-front modification for the Denon AH-D7000 inspired by the HiFiMan HE-5 orthodynamic headphones.
First, a little history behind the motivation that inspired this project: I’ve been into this scene for a good 4 years now with an evolution of my listening actively taking place. It has been a process of undoing years of accustomed colored listening. The infamous graphic equalizer is definitely a great enabler! It’s kind of analogous to getting used to foods that are not over seasoned / salted. It may seem bland at first, but after a while you wonder how you ever tolerated those excesses, and finally appreciate the true essence of the food.
My phones chronology / preferences : Ultrasone HFI-700 < HFI-780 < AKG K701 < Sennheiser HD-650 < Ultrasone Edition 9 < D2000 < Markl D5000 < D7000.
Also, I have auditioned the Sennheiser HD-800 on my system using the Audio-GD Phoenix, single ended, stock cable, no burn-in. Many will justifiably think that these are not the proper conditions to pass judgment on these phones, and as such, I will not. I will however mention that I believe in the notion that there are basically two kinds of listeners: “Analytical” versus those who “feel” the music. Detail versus palpability. As you probably have guessed, I subscribe to the latter. But, as time goes on, I have moved closer to the analytical side, comprehending that a lot of the palpability (i.e.: bass) is coloration of the music.
My latest revelation in my listening can be attributed solely to the HiFiMan HE-5 orthodynamic headphones. Combining them with the EF5 amp may represent the best value on the market today. Before I heard them, my balanced re-cabled D7000’s with JMoney pads had been the most natural, sonically balanced phones that I have experienced. My musical taste is primarily from the baroque era, which is inherently bass light. At live performances, I prefer to sit closer to the basso continuo.
I will say that as soon as I plugged the HE-5’s in, I immediately realized that the 7000’s mids sounded like they had been sucked out comparatively, and the highs seemed rolled off due in large part to bloated bass. The comparison reminded me of the reasons why I sold the Ed. 9’s. I relished in the never before heard frequencies for several days. Then I started to miss something. The bass / counterpoint wasn’t felt like I needed it to be. I instinctively wanted to take the wooden cups off of the D7000’s to get that open sound I was loving, but retain the low end that I was missing.
Bang, I removed the eight screws to get the cups off, and I knew I was on to something. What else could I do to further open the sound? How about rotating the ear pads off, and then place them back on passively? The pad’s anchors normally fit into keyhole type slots. Incidentally, the eight cup screws are accessed though these same openings. I allowed the pad’s anchors to sit freely on the frame. In effect, this gives you an open space between the pad and frame. This also yields four open ports on each frame that is usually sealed with the anchors. These two reversible steps instantly balanced all of the frequencies. I was amazed. These drivers absolutely require free movement of air on both sides. They were simply stifled.
Further comparison with the HE-5’s told me that the 7000’s highs weren’t quite as sharp and quick. Okay, I could live with that. Wait, I could try the stock Denon earpads in place of the JMoney’s for a hoot. My luck was still running hot. The stock pads put the treble response into the same league as the HE-5’s. No joke. The stock pads being thinner, get your ears closer to the drivers. I believe that some would say the HE-5 treble response still would have a slightly sharper edge, but others might prefer the Denon’s this way, possibly thinking that it sounded more natural.
The modified Denon’s bass extension and dynamics simply outclass the HE-5’s. No contest. The impact and dynamics give you a 3D presentation. My acid test is the reproduction of percussion. My current favorite tracks are from the Jazz album Jacques Loussier Plays Bach featuring Andre Arpino on drums / percussion. Gavotte in D Major and the Allegro movement from the Concerto in D Minor are my references. The latter track doesn’t really get surreal until you get past the first 6 minutes. Excellent audio quality and miking immerse you in his kit. The dynamic attack and crack of him hitting the drums are addictive. The Denon’s sound is more akin to a real drum kit as the HE-5’s sound like headphones.
Jacques Loussier Plays Bach CD
The next step was to make this a more permanent modification. I lucked out and got an extra set of D7000 cups to experiment on. The first thing to do was to blast a good sized hole through each cup. My 54mm self-feed drill bit did the trick. I then used my Dremel to further open things up and finish them with assorted bits. Then I scored the insides of the cups on the vertical surfaces of the screw mounts to act as retentive grooves to secure the grilles(pic#6). I’ve got some metal mesh grilles on order from AllParts, but I couldn’t wait. I went to the hardware store and bought a $5 window screen to experiment with. I used 2 layers of screen per side. I cut 3 ¼” squares and converted them to octagons. The 2nd layers were done the same except a little smaller at 3 1/8”. Luckily the retentive grooves secured the screens without the need for adhesive. The screens are on the flimsy side, but definitely get the job done.
I used Velcro to attach the pads back to the frames, placed in between each of the anchor slots. I figured I wouldn’t need the plastic discs with the anchors to provide spacing because of the thickness of the Velcro. Wrong! I gave another comparative listen with the HE-5’s and thought I had dreamed up all of my previous findings. Mids were okay, but bass bloat and treble roll-off were back. I put the discs with anchors back in place. The discs were placed such that the anchors were close the slots, but not occluding them, to provide the necessary support. Apparently the pads had been covering up the slots. The bass control and extended highs were back. I wasn’t dreaming after all.
Proper venting of the pads are definitely the most important aspect to this mod. The open-back mods to the cups are not as dramatic, but definitely make a significant difference. If you cover up the openings on the cups with your hands while listening, you can hear the mids get squashed and the soundstage compress.
Hey, all of this is my subjective, humble findings. As always, YMMV! Give it a whirl if you can, and post your impressions. Peace
Edited by lmswjm - 5/16/13 at 7:46pm