HE Jade Frequency Response and CSD Waterfall Plots
BTW, just in case you didn't know, these are electrostatic headphones.
I've heard these before at an earlier meet and liked them somewhat. These remind me of the HD800s, especially in the treble. The HD800s have always been hard to describe for me. They kind of have a split personality. Sometimes the HD800 can sound lush or laid back, but other times they can sound brittle and bright. The bass on the HE Audio Jades extends down fairly well, but it's restrained. It will hit the low notes, but it's not explosive. The HD800s hit slighter harder and just as low. By no means is the Jade bass lite, unless you are a basshead.
The HE Audio Jades have less of the HD800's split personality. They don't have that sometimes laid-back nature of the HD800. They sound more neutral, but with a tip upward, with the same brittle hardness of the HD800 (can you say 6k peak?) Like the HD800s, they have a bit of energy from 6k onward, although it doesn't sound like there any major resonance modes, it does seem hot around 8k. Maybe some mods can correct this? I have some ideas already and will experiment.
EDIT: Now that the diaphragm has had a chance to charge up for a few hours, there's moar bass and lushness. (Have 007s nearby to make sure it's not brain burn-in.)
BTW, these headphones look extremely DIY. They do extract low level information extremely well. Better than the 007mk2.5.
CSDs show some moderately broad ridges between 5 and 9kHz. Somewhat similar to the HD800 CSD. Maybe that's why these remind me of the HD800s so much. It's now obvious that those notches in the FR graph above are really resonances in disguise.