I've learn something new, the design game of the frame and enclosure is all about vibration (not just removing it, but to use them in a positive way, like using wood) and balancing the pressure between the front and rear of driver.
To use double baffle,the stiffness increased and there is less vibration I can hear.
To balance the pressure between front and rear, some manufacturer use vents on the baffle, however I found that backwave might affect the sound negatively, and as a result sound to bright.
I prefer the solution used in fostex or sony r10, basicly they use an earpads that offer good seal (pleather/leather) then adjusting the sound by vents on driver side using foam. It is in a way like using very thin velour earpads, then use leather earpads on top ( in a very simple explanation)
My design use huge gap between the double baffle and cover them in micropore tape. By making the back side open or semi close, you change the pressure back side, then you have to adjust the pressure on the front side as well, thats why normally just making your originally closed headphones open (and vice versa)doesn't always sound nice.
I made new prototype in seashell oval shape.
I have added some damping on the 3d printed cup, and the gap between 2 baffle is 6mm, covered in micropore. Compare to my previous open prototype, on some tuning it offer rumbling bass but the mid is thick, and if I add more damping material, the treble really stand out and come alive without sounding harsh. But still thick mid annoys me. And the bass is a bit loose, and sound not too tight and fast, so I got my old wood cup out and back to the design board.
I present to you all the ultimate steampunk, with Iris door mechanism. I can transform between open to partially closed. The iris leafs were hand cut from brass, so the tolerance is very large, so it doesnt look very professional, but I dig it. Due to my bad skill, the iris can close maximum like in photo. The gap between 2 baffle is now 9mm and covered in micropore again. The wood cup is rosewood epoxy coated.
I dont put any foam or damping in the cup, because it will increase back pressure and IMO counter the point of making large ear cup. Without foam damping, the mid often sound too thick, thats why many people put foam damping. But you can solve it by reducing the pressure on the earside, making it further away from ear and let some air out by using porous tape (Micropore)
Now the vibration of the plastic cup is gone, sound very tight and clean. I like the most closed setting of the iris. Space and imaging is still there compare to the open (black ) version, but mid sound even tighter, treble surprise me the most. I can hear ever metallic "cling" and guitair metal strings sounds sooo sweet now. I did not expect that.
THe bass is quite expected, sound more punch and slam, and punchy, not even one bit punchy. It sound soo powerful and lots of energy now, but I have to get used to it for a while because the black open version sounded soft and laid back.
The drawback is only the look, now it is screwing huge!!! This is definitely something you enjoy holding in your hand and put on and enjoy music, not caring how you look like
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