I will try to keep how-to thread as brief as possible, nothing is worse than wrestling through 10 paragaphs to find the relevant information.
This is a modification where I coated the velour surface of the hifiman velour earpads with leather. I decided to do this because I wanted a hybrid of the jerg pads and the velours in sound.
The velour pads lack on thing in my opinion, that is neutrality, there is a gap in the high mids, and the treble has a pretty obvious spike somewhere around 8-9Khz. They do have superior bass extension, bass punch, soundstage, imaging, seperation and clarity compared to the pleathers (in every configuration).
I figured that leather could solve the balance issues in the velours, it should reduce the treble spike and increase the high mids due to the reduced damping (thanks Jerg).
The inner cirkle needs about triangular cuts to remove the redundant fabric. If this circle was a straight piece of leather this wouldn't have been necessary. But I think stitching a straight piece of fabric to another circle would be harder.
Stitch elastic to the outer rim of the large circle, this will crop the circle in the right shape.
Just fold the entire piece around the velour pads, and attach the leather to the velour with double sided tape.
Note that the double sided tape is attached to the plastic underside of the velour pads.
I also added some holes in this underside of the velour pads to give it some damping. I added about 4 holes per pad, but they are about twice as big as the original holes.
EDIT: After using another headphone I noticed that the highs of the HE-400 were still a bit tizzy. So I decided to increase the damping, and cut some extra holes. Now there is a hole about every 4mm.
I noticed that these pads could sound a bit boomy with bass heavy songs, and figured this might have something to do with the lack of damping. I also noticed that the plastic ring that folds around the attachment ring covers those ventilation holes almost entirely!
So I just folded the inner rim of the circle inwards, and used double sided tape to hold it together.
There is much more air, and clarity is much better with bass heavy songs. If you want boomy bass everywhere, anywhere you can skip this step. However I recommend using an EQ to boost the bass frequencies. This maintains the overal clarity of the sound.
I think this step is the biggest contributer to the jergpad mod. Without removing the blockage of these holes in some way there simply is barely any damping.
The theory was that they should sound more balanced (because of the reduced damping) and less reflection of the treble.
And this is basically what I am observing, they sound much like the velours but more neutral, with a bit more warmth.
They still have the big soundstage, excellent imaging and seperation that the velours offer. But there is no treble spike and the mids are all there, and the mids sound a bit warmer. Bass extends noticeable better than with the pleathers, but it's still very tight and punchy.
The jergpad is an easier mod, no stitching, and it is free (if you don't count the pleather pads). However the pleather pads have some inherent flaws imo, they are a bit soft and not really deep enough. This translates to slower bass and soundstage-imaging-seperation that isn't on the same level as the velours.
Total costs were about 10-15 euros, You're going to need about 1.5 A4 of leather.
Make sure that the leather is supple, smooth and not too thick.
This modification is fairly reversible, you're only going to lose the leather if you mess up the patterns, and you'll have holes in the bottom of your velours.
Edited by Marleybob217 - 2/20/13 at 11:07am