[Pibborando]

I've had these wonderful headphones for a few weeks now. From the moment I first listened to music through them, I knew they were the closest I'd ever been to audio perfection, and perhaps the closest I would ever get (at least for a long long time. poor student checking in). Despite being exceptional, I am aware that they are not perfect. Their tipped up treble (which add to the perceived sparkle of these cans, a desirable trait for many listeners) and slightly lean bass is common knowledge. I think the mids are perfect though. We need only to take a gander at HeadRoom's spiffy Frequency Response graph to see these attributes visually:

Bass starts rolling off under 200Hz and we can see a significant treble spike centered around 9KHz followed by a null at 14-16Khz and another spike after 16KHz. Of course, that last spike is near inaudible range so it's not really a concern to me.

To get this response to what I'd call perfect (for me) I'd like it too look more like this:

There's less low frequency roll off, slightly flatter lower treble and the 9KHz spike is lessened but not eliminated completely. I think if it were perfectly flat and neutral through there some of the sparkle and crispness would be lost and they wouldn't be as engaging.

So how can one achieve these results? Well, the simple and easy way is through EQ, which I've tried in both Rockbox and foobar2000. Foobar gave me more control so I will post my Equalizer setings. They are:

0, -1, -1, -2, -3, -3, -3, -3, -3, -3, -3, -4, -4, -3, -5, -6, -1, -3

-3dB is the new reference mark so I just have to turn up my amp to twice as loud as it was before to achieve the same perceived volume. I like the change a lot. I don't think anyone could call my Beyers "thin" sounding anymore. They've got some serious authority but do not sound bloated. The high end is still crisp, just not as hot, and vocals sound smoother. This is not an optimal solution however because:
1) EQing can introduce distortion into the signal chain (although I haven't really noticed it)
2) Only works when using computer as the source, so I'd be back to normal 880 response if using a CDP or a portable player
3) Does not "correct" the resonance problem, just makes it quieter

This is why I want to look into physical modding of the cans. This thread has a lot of useful info about EQing the 880s but then I found this post. The interesting part is this:

Quote:

Originally Posted by Steve999 /img/forum/go_quote.gif A filter was developed by my friend today that apparently eliminates the DT880 resonant behavior at 9 khz, and also improves treble performance above 9 khz because in addition to creating the spike at 9 khz, the resonant behavior caused some nulls above 9 khz. It will probably be a while before I get to hear it. I was sent some graphs of measurements and it seems as though it does smooth out the highs and improve treble extension. The resonant spike is reduced to nearly inaudible levels. The filter is made of a thin slice of high-grade acoustic foam with a centered hole in it and is apparently easily and non-invasively installed. I can do about the same thing with EQ, but eliminating the resonance with the filter is a more precise way of doing things, since the physical cause of the spike (the resonance) is actually being reduced or eliminated. We're playing around with the idea of having a few filters for me, to reduce the resonance to lesser or greater degrees, because the 9 khz resonance spike does result in a very live and luminescent effect -- it's part of the charm of the headphone.

I would like to pursue this mod but need more information on exactly what material was used, its thickness, the size of the hole, how to fix it into place, etc. Again, I'd rather not eliminate the spike completely, just get it more under control, and if it helps extension by reducing the null following the spike, then that's even better.

With that taken care of, there's still the matter of the bass roll off. I don't really have a clue how this could be addressed physically, so I'm looking to the more experienced modders here to provide some insight regarding that.

I'm also looking at recabling options. I know these won't "fix" the cans' issues or change its character as much as the mods, but they can help the Beyers reach their full potential. I mean recable + mods would pretty much =

right? I'd like to know what people think would be the best recabling option (dual entry please) for the 880s, under $200 preferably.

So lets please discuss how to make these fantastic cans just THAT much better.

 

[searchenabler]

Your uber-response is easy to achieve. The treble peaks are almost entirely caused by the cavity space between the driver face and your ear structure. To remove this interaction is simple: cut a piece of premium grade acoustic absorber foam(not cushion foam, not cheap acoustic foam as sold by foambymail, etc.; get something along the grade of Auralex) into a 1/8" thick sheet. Cut out the foam in circles just big enough that will jam behind the ear pads to stay in place. Now cut a hole in the middle of this foam, about 1" in diameter, to allow treble to pass mostly unaltered from the driver. Place some black acoustic transparent fabric(a good speaker grill cloth is suitable) over the foam and tucked under the back of the ear pads. It will look stock. The peaks as seen on the Headroom graph will be almost entirely gone, though the driver itself is not perfectly linear, and has a slight inherent peak around the 4khz region.

Now that you have an incredibly linear and non-resonant headphone(if you did exactly as I described above), take a high quality equalizer such as a Behringer DEQ2496 and gently adjust your response to whatever you should desire.

Chris

 

[Pibborando]

Wow thanks. That was quick. Know any good places to order these materials?

I'm guessing you would correct the bass roll off with the equalizer. That one looks pretty nice too. Might come in handy with my speakers as well.

 

[searchenabler]

Auralex foam is easy to order. But not easy to order in small quantity. I can't suggest any place to order it in small quantity. If you don't mind buying more than you need(and selling off the rest on ebay), it's easy to find. Just type in Auralex in Google or eBay.

If you do this, try to get the biggest pieces you can, because it may not be easy to cut out flat 1/8" sheets from large stock without special equipment(a band saw with a slide jig or a deli meat slicer might work perfectly). I used an electric carving knife(like you use to cut up turkey) to cut some. After a few tries, I got enough to make and test the response.

As for the E.Q.; if you also want to use it for speakers, you might want to consider the Behringer DCX2496 instead. It also has E.Q. functions, but also has advanced loudspeaker management features that are very useful for many loudspeaker set ups if one is using components(as opposed to a receiver).

Chris

 

[Pibborando]

Oh, I see. So you can't get any of that foam already at a thickness of 1/8 inch then? I'm guessing varying the thickness slightly would have more/less affect on the resonance. What's the black fabric for? Are you replacing the foam that you see under the pads?

 

[lostbobby]

have you fully burned in, recabled, other mods (leather pads, or taping pads?). I just read about the taped pads on Grado's, have to try it when i get home.

 

[cooperpwc]

Okay, I'm not modding my DT880s but here FYI is the email I got from Dark Audio Labs http://www.headphonesguru.com/ on how to do what you discuss. This guy is in Poland and his website is quite interesting.

Quote:

Hi Thanks for your interest. The highest models of Beyerdynamics DT 770-05 and DT880-05 are impressive in terms of sound quality and comfort indeed. However (for reasons probably connected to general preferences of pop-music listening ), they provide a strenghtened reproduction of low and high end (depending of the model). Beside of this, the characteristic of the midrange is very flat, natural. To correct this uneveness, the following dhould be done: DT770 - damping of the treble. You need to remove the earpad and the ring of foam, then cut a new ring of fabric (of the same diameter) and put it directly on the transducer's grid. Next put the original foam ring again and mount the earpad. DT880 - dampling the treble, enhancing the bass. Do the same as above, but you should aditionally remove (unstick) the dense-foam ring, that is stuck on the transducer's grid. This ring is responsible of bass attenuation. ABOUT THE MATERIAL. We experimented with a lot of fabrics/materials, and the right one that has suitable parameters is a synthetic, 1-2 mm thick, material, something like "artificial wool" or thin felt/plush. The idea is that it has to dampen frequencies above ca. 8kHz. You can experiment with diffrents fabrics. Too dense materials will kill highs, while the stiff ones will attenuate the bass. For best, verified results you can order our material (15 euros). The modifications are not intrusive and fully reversible (if you are careful). Concerning your observations related to different earpads, I agree that leather earpads strongly change the tonal balance (harmfuly enhance the lower midrange - higher bass). Headphones are a whole system and one can not change earpads - because they are a part of this system and it will not function right anymore. I don't know why manufacturers offer different earpads, but probably they don't care so much about the tonal balance (as a lot of headphones have a wrong balance from the beginning)... As far as I know Sennheiser, AKG usually do not offer different earpads for each model because each model is designed with specific ones. Hope it helped. If you have a site or you write on head-fi please -if you could - put www.headphonesguru.com in the text because I need links, you can quote my textes if you find interesting. Thanks a lot. Bests, Alex

 

[Pibborando]

At this point, I definitely want to pursue some kind of dampening mod, as it should be a really good value. I will probably get a re-cable somewhere down the line, but I can't afford to spend that kind of money at the moment. I also want to try painting the enclosure (the dark turquoise plastic parts) to straight black and get black velor pads. Then I'll be in business.

Thanks for sharing that cooperpwc. I'm having a little trouble following the instructions there though...

 

[cooperpwc]

Well he doesn't give too much detail but perhaps send him an email at the address on his site: dark-audio@go2.pl. (That's what I did.) Alex seems to be a good guy.

 

[Pibborando]

Ok, so I decided to open up of the cups to get familiar with the inner workings. I got the cup of the metal forks no prob, got the pads off and the little screen, but now I'm stuck. I don't know how to get the driver out. Then again I don't know if I will need to but anyway.

Here's some picks:

There's a circle of what looks like thick felt over the driver. Would this dampening stuff go over that, or behind the driver? Also on the back of the pads, there's some rubber looking stuff with holes in it. I was wondering, what would happen if I put some electrical tape over those holes? Would it boost the bass?

 

[searchenabler]

Quote:

Originally Posted by Pibborando /img/forum/go_quote.gif Would this dampening stuff go over that, or behind the driver? Also on the back of the pads, there's some rubber looking stuff with holes in it. I was wondering, what would happen if I put some electrical tape over those holes? Would it boost the bass?

I don't know anything about the supposed bass modification. I always thought that the DT880 had just about perfect/neutral bass for my preferences.

For my modification, you do not have to disassemble (not even removal of the pads).

I verified the acoustic reaction of my modification with careful measurement.

Chris

 

[cfcubed]

Not related to a physical mod, but it would seem possible to make mods to a headamp (or a box bet. phones & headamp) e.g. a passive EQ for the 9khz notch. I don't know the particulars, but I *think* I remember there being a headamp design that featured DIP switch for various 3db notches (or was that DIP for input impedances?).
I wouldn't be the guy to design this tho I think it would not be hard for more hardcore elect guys.

 

[ManAtWork]

Pibborando, glad you have a DT880 and want to drive its best. However, it doesn't make sense to refer the frequency response diagram because human ears don't require flat response which doesn't mean it sounds balanced. I suggest to modify or find other options to fine tune the sound with your ears directly and your favorite. Remember, a can with flatter frequency response doesn't mean it sounds better.

 

[cooperpwc]

Quote:

Originally Posted by Pibborando /img/forum/go_quote.gif There's a circle of what looks like thick felt over the driver. Would this dampening stuff go over that, or behind the driver?

My reading of Alex's description is that you would put the new material in front of that circle of white felt. In other words, no further disassembly required from where you are in the pictures. Then replace that Black disc.

However.... he also suggests increasing bass by first unsticking that black foam piece that you have exposed which is attached to the white felt. I wouldn't do it - but I'm not modding my DT880s. That is however what he suggests.

He seems like a very bright and technical guy. You should check his site.

 

[Capt. Z]

I have re-cabled my 20 year old DT990 with Canare Star quad. That will also roll off some high frequencies, while 'boosting' the mids and bass a bit.

Canare is not too expensive. About $ 0.60/ft

Example: http://procablesnsound.com/items/mic...010-detail.htm