DIY010 headphone

This was an attempt to create a DIY version of the Sony Q010-MDR1 (Qualia 010).
My design is quite janky, I don't really recommend making this.

Please note aswell that due to the huge cups and low profile headband with lengthy Beyerdynamic metal bow this headphone is unfortunately not suitable for small heads. I need about 8 notches on the HD 650, with the DIY010 I use the smallest setting.

About the inspiration:
The Qualia released in 2004 for 250000 yen as part of Sony's high-end Qualia brand.
It used a unique construction with the highlights being the 50mm composite driver, the lightweight magnesium/carbon fiber frame and a fully open acoustic design that utilizes a hollow earpad (suspended leather) with a self supporting porous baffle framed by the bridge-like earcup.

With this I tried to recreate it using the popular and easy to source HPD-50N25PR00-32 from Peerless/Tymphany.
The baffle is no longer self supporting, instead using a filtermaterial glued to a stiff former. Depending on the filtermaterial used the pressure chamber induced gain can be adjusted.

Instead of the drumskin pad I use the Fostex T50RP MK3 earpad. People usually throw those away because they are too shallow for almost anything but it is actually a high quality earpad that fits this perfectly because thickness isn't needed and it happens to be a perfect negative offset of the Qualia's cup profile.
The headband uses two Beyer springsteel bands with a 3D-Mesh wrapping. It has two spring plungers that push against the yoke from the inside, centering it. This makes for a nice clicky adjustment.
Uses the same LEMO connectors as in the Qualia, other connectors may fit with an adapter.

As seen in the FR measurement there is a massive peak around 5800 Hz. This is in line with the original Qualia and caused by a standing wave between the driver and the headplane. Getting the driver closer will push the standing wave upward, increasing distance lowers it. Due to the very open design the resonance is especially pure and therefore rarely activated. Nothing you can do about it except trying to quench it with heavy non woven dampers or building a specific resonator.
I simply use a digital parametric Equalizer (APO) to get rid of the peaks and to lower the low-mid. The result is suprisingly good turning the headphone from unusable to excellent. When using a dense resistor/filter for the baffle make sure that everything is glued/sealed properly to avoid channel imbalance at low frequencies.