Purrin, care to measure these without the fuzz front? I suspect the fuzz is unnecessary and might actually hurt the sound.

Hmm, mine have less of a vent too, 50% less thick. I'll mod them to 100% w/ extra tape to prevent leaks elsewhere.

The velour is sewn onto the pads, no way to remove them without wrecking the modded pads.

Oh, I used the two-sided tape instead.

Hmm. There is one other mod, but it's not related to the pads - check if removing the grille and/or cloth (front, back) does something interesting to the sound - to my ears, it does.

It all does.

The dust screen fabric coupled to the pleather earpads helps attenuate the treble (relative to the thinner fabric in velour pads, or having no fabric at all).

The grill fabric seems to attenuate upper treble extension or something of that sort, because removing it definitely improves the clarity of upper treble / plankton extraction (whatever that means  ).

The metal grills themselves add some minor resonance in the upper mids ~ treble region, it's evident in pink noise tests with / without the grills.

The grill cloth / grills change the sound at such a small scale that they are fairly irrelevant when you put them beside mods to the earpads.

Quote from: Thujone on September 17, 2013, 07:17:55 PM

Wow, the hump completely disappears. I gotta say, I'm a little surprised about that! I guess this is a great explanation as to why these pads sounded much bassier than the jergs I made for myself (my vent was much smaller than the vent on these). That said, the sub-bass adhesion mod isn't actually increasing sub-bass after all (unlike the HE-500).

In a way it does increase sub-bass with HE400 still, well...maybe not sub-bass, more like low-bass and the upper end of the sub-bass.

With HE500 the low-bass hump linked to the open backvents may actually carry onto sub-bass. Like I mentioned in a post earlier, to my ears the hump at sub~low bass just flat out sounds better subjectively than without. Our hearing naturally rolls off at very low frequencies, and this boost (again, HE500) is like a slight EQ to counteract that.

What I meant to say is that the adhesion mod by itself is not actually doing much. The vent is what is causing the bass boost. It seems possible that the chamber between the driver and your ear is leaking sub bass frequencies when vented, and this makes some sense. However, the boost at 50Hz may be because the back pressure caused by closed chamber between the driver and ear (when not vented) is no longer there and the driver is allowed to push more air without resistance. I can't think of any other way to describe why the bass is nearly 5dB louder at 50Hz.

When I look at the FR, the HE-500 has a slight decline from  50Hz up to 1kHz. I think that this would make the transition into the vent mod much more gradual to the ear. Don't get me wrong, I was enjoying the hell out of the bass hump on my HE-400, I just think that I can make a better compromise (i.e. a smaller vent for a more gradual bass boost and more gradual roll off). As I've said, I would like to find why they sound somewhat hollow with modulor's revision of the pads. All of this trouble shooting seems to point to the vent mod because this particular vent does not provide for a very smooth curve. Bottom line though, I can't stress enough that his pads are far superior to mine overall. The build quality and the velour top mod are awesome. Also, I think his extra line of holes might be contributing to the smoother treble (treble was still on the tizzy side with my jergs).

What it comes down to is that these pads are a wonderful asset to these two headphones. Especially now that we can pin point several steps within the mod so that others can choose to do use them or not. 

I just wanted to note that I have since removed the vents completely and the hollowness that was heard is now gone. The 50Hz boost provides for a fun listen, no doubt, but I wanted my mids back.

Mmmm...pianos...

It (the back vents) does seem quite detrimental to HE400s, unlike the more mild measurable changes on the HE500s. If I had designed the mod around HE400s in the first place, I would not have done the back vents anyhow, because HE400s do not have a metal bar welded across the middle of the drivers that like to irritate ears; also, HE400s are open-sounding enough, the backvents would not offer nearly as much soundstaging improvement as they do on the HE500s.