chinsettawong
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Posts posted by chinsettawong
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7 hours ago, Kung said:
It started with repairing a badly damaged shangri la jr driver 2 years ago, I almost rebuilt the set from the diaphragm to the stators，and of course the dust cover😦
The first thing I discovered is that the 'nano-technology' used by hifiman actually comes from the covering used by indoors aircraft model enthusiasts，the name is OS film and it is still available on ebay or https://www.indoorffsupply.com/shop/os-film-25ft-roll-1
the driver of the hifiman estats is completely glued which is similar to the early stax lambdas, but hifiman glue is significantly worse...after opening the driver i found that they only use OS film for their dust cover, the diaphragm is another PET film ~ a little bit thicker but with much better strength. In order to repair the diaphragm, I found a seller on Alibaba who can provide samples of Toray PET film with thickness below 2 microns at an acceptable price，and use the inner tire stretcher to stretch the film like any other diy estats ，Then test it with a 10" subwoofer and minidsp umik-1 to find proper F0.
conductive coating is another serious problem，I've tried quite a few methods including antistatic agents like licron crystal, ANTISTATIK100，floor cleaner，carbon-based coatings such as graphene, and alcohol-soluble nylon, even tried nano-silver wire solution and metal evaporation...Some of them are sensitive to humidity, some arcs，some are ridiculously expensive, some have uneven surface resistance distribution, and some are sensitive to temperature changes. Yah~ finding the proper conductive coating is the most difficult part especially for a layman. unexpectedly, I tried to search for hifiman patents, hoping to find something useful... here's a patent showing that they used some kind of metal oxide nano particles as conductive coating for their estats. emmm，very interesting...🙄 By consulting with chemistry professionals, I decided to try a solution called ATO (antimony doped tin oxide), there are many antistatic agents I have used before have ATO ingredients though. I got some ATO alcohol solution at concentration around 10~15%, it works really well, and coating appearance is somewhat identical to hifiman diaphragm!
The last thing is to repair stators. hifimans probably use #150~300 brass mesh and solder their edges to a 2mm thick aluminum base plate PCB board, then glue the rest of middle part. I've tried tensioning those brass mesh with embroidery frame and manual screen stretcher，but it is not tight enough to stretche brass mesh in this way, the mesh itself is too strong to tighten it up... then I found some brass sieves with different meshes on taobao and these machined copper screens are perfect for making DIY mesh stators...
after everything's ready，i desoldered OG brass mesh, cleaned the copper foil, applied low temperature solder paste, and carefully soldered the new brass mesh with a heat gun.
During the process of repairing shangri la jr, I started planning to make some bigger mesh stator estats... of course，the target is its big brother shangri la SR😈I received a set of the first batch of shangri la sr made in 2016，here is the headphone inside，yap~inherited the tradition of hifiman with such horrible workmanship...😱 however，SR sounds not as technical as the X9000 though，but with more pleasant and passion. SR uses 3mm thick aluminum base plate PCB instead of 2mm on JR version，2 black things in the middle are to prevent the diaphragm from attaching stators，The D-S gap is around 0.7~0.8mm(thickness of glue included) which is identical to JR version，active area is close to 6400mm² ，that is pretty large diaphragm size for a commercial product though，but less 5300mm² of area on stator allows air to pass through.
I tried to use the 3mm FR4 board as mesh holder at first time，however，mesh stator disassembly is not an easy job...therefore，I changed to use 1.5mm brass plates as the mesh holder and glued the copper mesh to it , brass mesh is also replaced with higher # red copper mesh for more convenient adhension. I spent most of time adjusting the tension of the diaphragm and finally found the tension needed for F0 similar to OG SR ,the clone driver has a slightly enlarged diaphragm(6839mm²) ，0.73mm fr-4 pcb spacer， and everything is screwed to the housing cover.
The frequency response of clone and SR are generally similar，but the sensitivity difference between the two is about 1.5dB actually，SR is more diffused...clone one sounds a bit more clearer. SR has obvious recession between 1-2kHz，it may be caused by a sealing problem in the space between the driver and the earcup.... It's unlikely to be solved without EQ, but it doesn't sound as bad as it looks from the graphics.
one more thing...
Every shangri la must have a throne , so I made one for my mutation🤣
Very interesting! I am very curious to learn about your coating. Where do you buy it from?
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Maybe he was referring to the DIY headphones he was testing.
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Congratulations Kerry! It’s about time! Wishing you a big success.
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1 hour ago, JoaMat said:
Thank you.
Eventually I found it, among a lot of other stuff. A test board for the battery module. I probably did it in spring 2020.
Left heat sink has FJPF2145 (org. T2 it's 2SC3675) and right has 10M90S current sink set to 5 mA. Just find +250V and -560V and you are ready to go.
I only wish I can understand what you are making.
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I’ll buy one now too.
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Happy birthday, Joachim!
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I love those purple color wood stripes. Are those Purpleheart?
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Call it JoaMatron! 😄
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6 hours ago, Kung said:
From the picture you posted, there are some flocs have been inserted into the driver house，yea, it is more difficult to clean up for the mesh stator...😬
Good eyes!
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Nothing bad should happen. It could probably be the loosen wire connections. You might want to try resolder all the soldered joints first.
Well, some small dust could also be a problem. Check and clean the stators and the diaphragm could solve the problem too.
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10 hours ago, JoaMat said:
Until trusted person gives a reliable review here, you might study the interior of the new Stax SR-X9000.
I let the pictures speak for themselves.
Thanks for sharing the pictures. Have you a picture of the other side of the stator, the side that faces the diaphragm? What is the material and thickness of the spacers?
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The quality of the GB PCB was pretty bad too.
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Are they using felt as the dust cover?
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I really like to try to make some wire stators for my DIY electrostatic headphones. I've bought some wire mesh, but I have no idea how to stretch it so that it's absolutely flat and tight. Any ideas?
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Happy birthday!
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15 hours ago, spritzer said:
Those look great and reminded me to post this, a possible cable for DIY electrostatics:
https://www.aliexpress.com/item/1005002121174291.html?spm=a2g0s.12269583.0.0.67082dbcJ5CL0I
I just got some but have as of yet not done HV tests on it or anything but it's nice and supple, if a bit thin. Well worth a punt and reminds me of the Koss wire but not double insulated.
I’ve used something similar with one of my headphones for a while now. It’s been OK. Yes, it’s not double insulated and it’s not as soft as the Koss cable.
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Finish a new pair of electrostatic headphones today.
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It’s funny that the size of the transducer is exactly the same as my DIY headphones - 120mm x 90mm.
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This is my version - 3D printed using ABS filament.
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Happy birthday, Kerry!
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When I went and bought, I didn’t check the differences in price and quality. It’s what’s available in my area and I needed it quickly.
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I use SCT3080KLGC11 in my Grounded Grid power supply and it works well.
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Happy birthday, Kevin!
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A DIY Shangri-la headphone for HIFI-Xmen
in Headphones
Posted
Beautiful work!