Simple DT990 mod.
Jul 29, 2007 at 3:23 PM Thread Starter Post #1 of 40

Kees

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A couple of weeks ago I traded my PROline 750s for a pair of DT990s.
I had been very curious about them for quite a while, but never got to listening to a pair.

Not being a fan of long winded stories I will keep it short: I found they sound(-ed!) terrible. By far the worst headphones I ever had.
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Boomy, sloppy, echoing, overpowering bass, that completely pushed the midrange to the back, leaving only the highs to penetrate everything.
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I love bass, I am a fan of the JVC DX1000 and love my Darths (with plugged-up holes in the rim of the cups), but this bass was just of very poor quality and ruining the rest of the sound.

My old (and as I read here also the new 2005) DT880 had no such issues with bass. It was a bit lean, but of good quality.
Since I thought I remembered that the DT880 and the DT990 use the same drivers I figured that the difference beween the two must be in different acoustics of the housing (semi-open / semi-closed).

Time for some experimenting and tinkering!
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In order to remove too much bass acoustically you have to make the housing (more) closed. Place your hands over your open phones (without pushing!) and you will know what I mean.
So I took the DT990 apart and started experimenting with different ways of closing them and with different materials.
I'll spare you all the trials and get right down to the winning mod: Close the best part of the housing (from the inside) with a disc made of thick (2mm) stiff cardboard. The cardboard has enough mass and density to stop sound going out and is inert enough to not produce sound by itself.

The result:
Much more detail and attack in the bass.
Much better balance in the whole spectrum.
No more (seemingly) weak mids.
No piercing highs (they don't stick out any more because the rest is better balanced now).
A very enjoyable set of headphones!!!! (that still have bass that can be compared to Darths
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).
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The mod is very easy and fully reversible.

Here is how you can do it:

First remove the little screws on the front of the hinges so you can remove the fork/headband from the housing.

Just gently pull it out. The hinges come loose, they are held in the housing by the fork, but it is very easy to put them back in again.
Also remove the earpad of course.
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Then very gently with a small screwdriver pry the ring loose that holds the driver in place. Don't worry, it comes off (and goes back on again) very easily, with a little click.
The ring goes in and out in only one position! look carefully around the rim and you will see a small part sticking out a bit and a small recess in the housing to indicate the right position. You can't miss it in the pic, right next to the screwdriver.
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Next you see the driver lying in the housing. It is loose, you can just take it out carefully (in the pic it is taken out and you are looking at he back of the driver).
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Underneath in the housing is a thick ring of felt.
I filled up the hole in the middle with some more felt (you can also use cotton wool). Over that I put a piece of cardboard.
7cm diameter, 2mm thick stiff cardboard. (the green disc in the pic).
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After that just put everything back in again:
First the driver on top of the cardboard (there is enough space, don't worry).
Then the ring back on (watch the position!), just click it in.
Put the earpads back on (MUCH easier when the housing is not yet attached to the fork).
Put the hinges in and slide the fork back in the slits in the hinges.
Search the little screws until you finaly find them again somwhere under your desk and screw them back in.
Have a drink.
Happy listening.
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Jul 29, 2007 at 3:30 PM Post #2 of 40

warrior05

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Very interesting indeed! I think I'll try this after I get a new driver from Beyerdynamic. My right one went belly up. I pulled the driver out of the housing and saw one of the finer than hair wires that go to the driver itself was broken in a place that I just can't fix. Grrr!
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Jul 29, 2007 at 3:32 PM Post #3 of 40

BushGuy

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or, simply switch out those Leather earpads and install Velours. They DO sound better with dt990. Getting the Gen. Leather with dt990 is, IMO, a mistake.
 
Jul 29, 2007 at 3:39 PM Post #5 of 40

apnk

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Quote:

Originally Posted by BushGuy /img/forum/go_quote.gif
or, simply switch out those Leather earpads and install Velours. They DO sound better with dt990. Getting the Gen. Leather with dt990 is, IMO, a mistake.



First thing I thought of as well.
 
Jul 29, 2007 at 3:46 PM Post #6 of 40

warrior05

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Though I do agree about the velour pads - which is what I use - it would be interesting to try this out since on several tracks the 990s can still be harsh in the highs. It would be fun to collect those tracks and then do an A/B. I love futzing with stuff so this is right up my alley.
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Jul 29, 2007 at 3:48 PM Post #7 of 40

Kees

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Quote:

Originally Posted by holland /img/forum/go_quote.gif
Interesting. In essence, it sounds like a closed DT880?


No.
But it seems the DT990 is essentially a more open DT880.
Now it sounds like a mostly closed DT990.
 
Jul 29, 2007 at 3:51 PM Post #8 of 40

AudioCats

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Quote:

Boomy, sloppy, echoing, overpowering bass


likely all due to the leather pads.

adding a cardboard disc will reflect more mids/highs back and might make it more echoy. It can also kill the extra-low bass extensions, so all you hear is mid-bass........

Just theory though, will be interesting to see a real life report.
 
Jul 29, 2007 at 3:53 PM Post #9 of 40

Kees

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Quote:

Originally Posted by BushGuy /img/forum/go_quote.gif
or, simply switch out those Leather earpads and install Velours. They DO sound better with dt990. Getting the Gen. Leather with dt990 is, IMO, a mistake.


I know what you mean (I also have the velours pads), it lessens the bass a bit.
This mod sounds a bit different: it gives the bass some more detail and attack.
 
Jul 29, 2007 at 3:59 PM Post #10 of 40

swt61

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Quote:

Originally Posted by warrior05 /img/forum/go_quote.gif
it would be interesting to try this out since on several tracks the 990s can still be harsh in the highs.



I haven't experienced this phenominon. Oh wait you have the lowly 250Ω version.
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This isn't really a dig at the 250Ω 990's, it's just a little fun with Scott since he wants some 600Ω's.
 
Jul 29, 2007 at 4:08 PM Post #13 of 40

BushGuy

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There is also a recent thread (Snacks) here where the cardboard mod. was done with x-deep Darthbeyers. It makes him happier even with them.
 
Jul 29, 2007 at 4:58 PM Post #15 of 40

MaZa

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NOOOO!!! What have you done Kees!? You destroyed my DT990!
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Interesting mod though, why I havent thought doing it when I still had them.

Side question, how much it affected isolation?
 

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