So I have been playing around with modding my d600 now that I got a measurement setup to better quantify what is being affected. I am trying to tighten up the bass without losing the nice impact these have from the factory. The bass hangs around too long and can feel bloated. This makes the d600 really fun with some genres/tracks like edm and hip-hop but with some rock and country the bass takes over. This is where I am at right now...
First I tested a LOT of different tweaks to find out what variables have a noticeable affect on the sound.
Areas I messed with to get my current result:
-three holes in the cup, directly behind the driver
Stock the d600 has 3 holes that vent into a small chamber behind the cup. 2 of these are covered with filter paper and the third is left open from the factory. I tested many different combinations of # of holes open and filter material. Opening up the holes causes bass to become more bloated and increases the dip around 200-400Hz
In the version measured above I left the top 2 holes covered and used bluetack to secure a small piece of black foam(soft porous not creatology) over the bottom hole.
-dampening material inside the cup
There is a dark colored foam material on the back of the cup from the factory. The dampening material inside the cup did not change the FR measurements much, I used it to reduce reveb inside the cup. Polyfil had positive effects on reducing this further but I left it out because it is a pain in the ... to get placed properly. The polyfil has no effect unless you put a lot in the cup. In the d600 the cup is a sealed chamber(for the most part), the polyfil will cause leaks if it is not pushed in the cup as you shut it. Once I finish all other mods to these I will probably go back and put some in the cups.
In the version measured above I used bluetack to secure small strips of orange felt along the outer edge of the cup.
-placing material under pad
I used poly-foam backer rod wrapped in a soft cotton material to stiffen the pads. Once the pads are on the d600 I tucked the material all the way in the bottom of the pads in the groove under the bulk of the pad. This pushed the pads up and added enough tension to tighten the leather. This helps reduce the bass bloat, but it also causes the treble to become somewhat sharp.
I am still playing with the mods to get the sound right where I want it. I am going to be trying to even out the treble peaks and lower it by a few db now.
Edited by JBal4 - 8/26/16 at 10:34am