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Kung

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Everything posted by Kung

  1. Don't worry too much about it , below 10V or even 20V is acceptable.
  2. yes,old ones are brass. i have considered carbon fiber or PMMA as mesh holder, after comparing the metal materials, I think the metal mesh holders have better looking though...
  3. Assembled a new pair of drivers with aluminum mesh holders,the headphone now weighs less than 360 grams which is a lot more comfortable for my neck
  4. Just to repair my own headphones, cause I have not only hifiman cans but also several other old estats of Stax and Sennheiser. it will be more reassuring to play with these old stuffs if I can do some repairs myself.
  5. According to 007t schematic, if the transformer outputs 270VAC, the voltage doubler circuit will give you 500VDC bias. If the transformer outputs 310VAC, you will have a standard 580VDC pro bias. because there is no voltage regulator, the turn ratio of transformer will be conservative for wider range of voltage fluctuation.
  6. It is likely that the #80 mesh is not easy to make a stator by hand, which leads to the failure of the omega driver, and the driver housing made by resin at that time was not as strong as later 007 009 though. There are some DIY estats such as Perun and Phenomenon in Russia, they use much lower number size copper mesh as stator. I have owned a pair of perun, the stators are made of about #10 copper mesh, the mesh itself is very strong actually, and is glued to the PCB holder with structural adhesive. As for the glass stator of the HE90, the glass is indeed rigid, However, as a stator, it does not play the role in the Sennheiser advertisement at all. The only thing I can expect is that the glass is chemically stable and not easy to be corroded or oxidized, and Manufacturing microporous glass plate is extremely expensive which also leads to the insane price of the HE90... Unfortunately, Sennheiser is now not planning to stop, they use even more expensive ceramic based PCB stator on HE1.😦
  7. Updating more DIY mesh stators. Glue the brass holder to the copper sieve with ERGO 5500 or 5900 then cut off the excess copper mesh with a nicking tool. Stators mesh size in the picture below ranges from #180 to #400,It is better to use a higher number mesh for making DIY mesh stators, the mesh with lower number size is difficult to glue...This may be the reason why stax no longer produce the original omega . Both omega and x9000 use about #80 mesh for their stator, and it is not easy to fix #80 mesh by hand, x9000 solves the problem by using thermo compression bonding...
  8. I bought a 711 clone rig on Taobao, here is the link: https://item.taobao.com/item.htm?spm=a230r.1.14.18.b2407a72U22HcB&id=41416109881&ns=1&abbucket=3#detail Contains a clone coupler based on IEC-711 standard, a preamp, a silicone pinna and a calibration file based on B&K4128C. the clone coupler has been confirmed by the headphone factory to perform almost the same as the G.R.A.S RA0045. Unfortunately , the silicone pinna is not a standard pinna clone from G.R.A.S or B&K, resulting in an additional 5k~6khz attenuation in the frequency response diagram.
  9. I did make X-men round driver which has a similar stax 009/s driver housing but a bit larger,and all X-men headbands actually are made with hifiman's damaged headphone parts, however, the yoke is aluminum 3D printed...😈 for comparison, the one on the right is the same size of 009/007 driver housing , the left one is the X-men with 1.5mm brass holder and #200 steel mesh stator in a 110mm driver housing. the stator can cover diaphragm diameter range from 84~92mm,the currently installed spacer is for 90mm diaphragm. I'm now running into some tolerances and earpad material problems....compared with perfectly matched sgl clone, the round estats have about 1dB consistency difference in sensitivity, and breathable fabric earpad causes roll-off of low frequency. this estat is currently on hold...🙄
  10. A small bottle of sample I took from a local college friend, the ingredients included ATO powder with a particle size of 20-30nm, some surfactant, and the rest was some kind of alcohol solution. I was told to mix extra anhydrous alcohol at a ratio of 1:3 to dilute it for coating, but I didn't dilute it, just sprayed it on the sponge to apply the stretched film, and there were some traces of liquid on the surface of the film after drying , it looks the same as the hifiman's. that shangri la jr driver was later used as a test driver for testing different thicknesses of films.
  11. 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🤣
  12. oh my😆,just as predicted,headphones retailing for $10,000+ are coming.
  13. I got the X9000 for about a month, and I also feel that the imaging of the X9 in the depth direction is a bit different from other stax headphones. The area near the middle is more concentrated and the rest is more diffused.I've tried a similar outside baffle with a deflection angle on my DIY estats,which has a little effect on the sound, but not what it sounds like on the X9.
  14. wow~ brass housing... I just simulated it on solidwork, the weight of each is over 300 grams, it is a disaster to wear this stuff on the head 😶
  15. it seems very odd,do you mean that the sound of 007 is different after 717 modification? for all I know,only 727 negative feedback modification, never heard of 717's(CCS mod?),717 is pretty a kgss and should be no problem driving 007. Providing headphone frequency response or some amplifier tests should make it easy to find the cause of the problem.😶
  16. Here are more pictures of PCBs that may be an early version. They look identical in terms of layout.
  17. I saw a portable estat amplifier on a Chinese e-commerce platform and it looks very similar to kevin's amplifier, Is this the commercial version ?
  18. 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...😬
  19. hell,so far as I know,tokyofansile is a japanese distributor of JR Audio on taobao,JR Audio has built many clone version of spritzer amplifiers and shipped them to japan,vietnam and thailand🙄
  20. bk version sounds similar to the standard SR-009, maybe a little bit more distant and tighter bass due to the new thicker earpads.
  21. I have made a t8k input stage board for my bh,with a little bit tweaking,they've been working for 4 months,and T2 input stage can work fine as well. ?
  22. chinese bhse from taobao jr audio。。。
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