[Armaegis]

mass loading - making the structure heavier and more stable relative to the diaphgram in the driver; heavier the better usually, but since we still need comfort there has to be a compromise somewhere
(mechanical) vibration damping - certain materials absorb mechanical vibrations in the structure better than others; oftentimes these add a bit of mass loading as well
acoustic damping - certain materials absorb/reflect sound waves better than others
 
The first two primarily contribute to making the driver more stable, thus leading to a cleaner response. The last one affects how sound eventually reaches your ear.
 
The simplest/cheapest way to mass load is to use some putty (poster/plumber's putty, plasticine, etc). Fancier stuff would be vibration absorbers like dynamat, but those are generally more difficult to work with and often cost prohibitive to obtain in small quantities.

 

[Pingupenguins]

Basically, try to create enough inertia to stop harmful vibrations but allow some to accompany the driver? 
 
I'm kind of looking for a easy way out right now as I am learning. Is the goal to create more inertia by adding mass thus stopping ALL vibrations other than that of the driver. Or is it to just play around till it sounds good. In a ideal driver. What am I looking at?
 
Tested mods today.
1. Plasticine around the vents opposite to ear side. 
-Seals the horrible noise leakage prone in Aviators
-Possibly narrows sound stage, but to me sounds better
 
2. Plasticine around the driver leaving on the vents open. Mass load behind the driver
-Horribly trebly. Needles in my ear.
-Accentuated mids. Very nice mids.
 
3. Mod #2 with gauge lightly packed in the cup.
-More needles. Clunky bass.
 
End of the day:
Mod 1 prevails.

 

[Armaegis]

Basically when the diaphragm moves to produce sound, you have an equal and opposite reaction in the driver assembly/baffle. Since the baffle is heavy compared to the diaphragm, the relative movement here is small, but it still affects the quality of sound coming out. The heavier, the better. The plasticine will also absorb those vibrations after they've been produced since they don't just go away but will resonate across the baffle.
 
An ideal baffle is one that is infinitely heavy compared to the driver.

 

[Pingupenguins]

So idealy, no vibrations. Also the drivers have a hard metal mesh protecting them. Probably steel because its magnetic. Should I replace this or drill holes in it similar to a kramer mod?

 

[Armaegis]

Hard to say without seeing pictures... but in general, no drilling holes unless you're really sure of what you're doing  

 

[Pingupenguins]

My Aviators

 
Hella thin without the cup

 
Mod

 
Earside pads removed

 
 
 
Now I'm thinking. Should I remove the foam earside and put some dynamat? but then the vents would be open bare. Should I just put some cotton cup side when I remove the foam? Should I surround the driver earside with plasticine?

 

[Armaegis]

Don't drill holes in the grill. That close to the driver you have no guarantee on whether fragments will tear the diaphragm or not.
 
You could replace the foam with dynamat; just don't cover the vents. I wouldn't bother with plasticing on the ear side. Diminishing returns with all the weight, but comfort will just keep decreasing. After this I would just experiment with acoustic damping in the cup.

 

[Pingupenguins]

Oh no. The mesh pops out easily. It's only held by magnetic force.
 
I wanted to test with plasticine before i put dynamat on. I heard the dynamat is a one try operation.
 
I've tried filling the cup with cotton and got horrible results. Imo. I'm thinking that stablizing the baffle is the only work that I can do. Someone said something about not having a hard spot behind the driver. What works for that?
 
PS. Would felt be better than cotton balls because it's denser?

 

[TMM]

Mass loading also lowers the resonant frequency of whatever you are adding mass to. For ideal damping, you'd want it lower then the driver's resonant frequency but that may not be practical without taking up too much space inside the headphones. Having the enclosures resonant frequency around that of the drivers will extend the bass response, at a small cost of the bass becoming 'laggy'. For what it's worth, in my experience even adding a small amount of blutack provided enough damping to completely eliminate any audible resonance. After all, headphone drivers aren't exactly creating an earthquake like a subwoofer.
Blutack/plasticine is just as effective as dynamat at mass loading, and as a bonus it is easy to remove and doesn't have the foil layer which reflects high frequencies. The amount in the above pics is more then enough IMO. Adding any more would just be adding unnecessary weight.
 
Cotton filling the cups needs to be done sparingly. A little goes a long way, no more then 1 cotton ball per cup imo. Get a ball and pull it apart so you have a very fine wad of cotton in the cups. This will make the driver 'see' a larger enclosure.
If you over do it then it'll just make the volume of the cups smaller and kill your bass (boomy, lacking extension).
 
I haven't had any luck with felt lining. It's not dense enough to dampen without reducing the volume of the cups too much. Blutack/plasticine is perfect because it is very dense, so you don't need much of it.
 
To be honest i wouldn't bother opening up the grille. Looks like it's already at least 50% open. Kramer mod was only effective because the standard grille was like <30% open, and was positioned very close to the driver creating an air lock of sorts.

 

[Pingupenguins]

Thanks TMM!
Yes I noticed the horribleness of a filled cup. I won't go big or go home next time. I'll use a little cotton each time. Any thoughts about removing the foam from the exterior? Should I put dynamt on the interior behind the driver?
 
Thanks.

 

[Armaegis]

Don't bother with dynamat on the rear; the plasticine should be more than enough and it looks like you've done a good job there already.  Maybe put dynamat on the front if you take the foam off, but try to keep it intact in case you want to reverse it afterwards.
 
Getting rid of the hard spot directly behind the driver in theory reduces the strongest high frequencies from reflecting back out. The simplest way to do this is to just stick something on the cup directly behind the driver. I've used sticker felts (like the kind you put under a vase so it doesn't scratch the table) or even just a piece of hockey tape. These probably won't look very nice though, since the Aviator has semi-transparent cups. I think just some light filler like cotton or polyfill should be sufficient, or you could even try "floating" a felt disc behind the driver or attached to the arm.

 

[Pingupenguins]

?
 
So if I put a streched out cotton ball inside id ALSO have to put some sort of dampener directly behind it too?

 

[Armaegis]

No, just the cotton should be fine.

 

[Pingupenguins]

Ok. So if i didn't got the streched out cotton route, as in the cup is empty then I should place some soft object behind the driver

 

[Armaegis]

Yeah, that should in theory help mellow out the treble (assuming anything needs to be done in the first place).