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Stax SR-009 Channel Imbalance Trouble / Driver Problem?

Discussion in 'High-end Audio Forum' started by gu sensei, May 28, 2011.
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  1. John Heng
     
  2. John Heng
    I will post up some photos to show here. As I am a new member to this forum, this forum platform does not allow me to upload photos for the time being.
    Once the round metal mesh and O-ring is removed, there is no more dust screen blocking the membrane on my model.
    When I can upload my photo, hopefully, this can be seen more clearly.
     
  3. Julez
    In this case there where a few little holes in the dustcover where dust entered th driver. The owner reported noise comming from the driver but no(!) imbalance. I opend the driver and found this. Even the other side had very tiny holes in the membrane. So I had to make new membranes for his 009.

    That's what I thought when reading the fix from John. How could this solve the problem? Maybe the membrane was partly stuck on a stator and got blown away by the hair drier.


    John. There is no change in design of the 009. Your black metal mesh is to protect the dustcover from beeing punctuated and your ears from touching the stators and getting a little electric shock and protection if anyone would touch the inside of the headphone. What you see on my pic is what is inside the white housing. On top of that on every side is a black metal mesh for physical protection. The round silver things with hexagonal structure are the stators and they need the holes so sound can pass through the stators to reach your ears as the membrane (that membrane that is coated and moves to make the sound) is sandwiched between the two silver stators. To make it very clear. The membrane that is burnt in my picture is sandwiched between two stators (that can be seen on the pic). These are sandwiched between two mylar dustcovers. All that is inside the white housing. On the outside the white housing is sandwiched between two black metal meshs. All that is put into the silver aluminium cup and closed up with the ear pads on the ear facing side. Maybe you google how a electrostatic driver is basically built. There should be some schematic representation that show the basic principle of how a driver is built. Most speakers don't have the dustcovers. But all electrostatic headphones I saw had dustcovers (JF, HE60, HE90, all Stax models).

    Please don't "wash" your Lambda Pro. At best it won't do anything. At worst it will destroy your Lambda Pro if water enters the driver and washes away or moves the coating.
     
  4. John Heng
    My stator plates look quite different from yours. Do see attached photo. My photo just shows the hex bars and the membrane above it. The hex bars are by themselves with no micro hole perforations besides it like in your photo. Does your stator plate look the same if it is flipped over?

    One possible theory is that the water may have neutralise any charge build up by the dust and hence 'reset' the membrane.

    If that is indeed the true reason behind this fix, then would firing a zero stat gun at the membranes achieve the same result without going thru the trouble of 'washing' the membranes.
     
  5. chinsettawong
    Hi Julez,

    That's pretty bad arc you have. Did you play your music too loud to burn your diaphragm? Have you fixed it yet?
     
  6. John Heng
    Here are the photos from my SR009 (right driver). Can see the hex bars with the membrane (diaphram) above it. So it was on this diaphram on my left driver that I had dropped water droplets on to 'wash' it.

    20170521_133530.jpg 20170521_133358.jpg The photo above shows the black metal mesh with the O-ring. Lift it up and the diaphram is exposed.
     
  7. chinsettawong
    Hi John Heng,

    Obviously you haven't opened up your driver yet. The diaphragm is sandwiched inside the two metal perforated screens inside the white plastic housing. You need to open up the plastic housing before you can get to the diaphragm.

    You have only washed the outside dust cover.

    Wachara C.
     
    J-Pak and Jones Bob like this.
  8. John Heng
    ok. thanks and noted. Yes, I did not go in further. Maybe the 'washing' the dust cover neutralise some static build up that was causing the imbalance. So then is not as dangerous as I thought as I was merely washing the dust cover. So why is the dust cover this clear membrane film over the stators? That means this membrane vibrates as the main diaphram vibrates?
     
  9. chinsettawong
    No. The earspeakers are worn next to your ears. They're prone the sweat, humidity and dust. Having these dust covers help screening out those dangerous things.

    Many ESLs, Martin Logan for example, do not put any dust cover on their speakers. The way they're built also prevent them to be disassemble and clean. That's why people give them a shower. It's simply because you can't take them apart without risking tearing the diaphragms.

    Wachara C.
     
  10. chinsettawong
    Why cleaning the dustcover, in your case, solves the problem is unknown. Did you solder out the wires and solder them back when you did the shower?

    I remember hearing some people say that they take the headphones up for a plane ride and the balance is back. :)
     
    Last edited: May 21, 2017
  11. Julez
    It is not my 009. It was sent to me to be repaired. And I sucessfully renewed the membranes on both sides. The damage was really bad. As there where little holes and some bigger dustparticels inside the driver I am pretty shure that the driver membrane destroyed because of dust particles that found their way into the driver and caused arcing wich burned the membrane.

    That happened a few times to my self made headphone as well before I used Licron Crystal as coating wich seems to leave a very thin protective isolating layer on the membrane (or the resistivity is too high to feed enough capacity into the arc to get hot enough to destroy the membrane while arcing).

    If you are interested more about the technical details there is a very good book by John Borwick wich is called "Loudspeaker and Headphone Handbook". There is a chapter about ESL and also in the headphone section about electrostatic headphones. But the ESL chapter is the one with the most interesting technical explanation about electrostatic drive theory. It is very long and detailed and has very complicated mathmatical equations to explain the matter.
     
  12. John Heng
    I did not unsolder any wires. Just gave the dust covers a wash. As well as the other side.

    Originally my imbalance issue gradually got worst over one month whether it stem from improper storage or our high humidity in Spore, I don't know . I tried searching for a solution when I stumble onto this block. Most of the postings were about returning to Stax under warranty. Mine was bought as 'used' condition from Amazon. Hence no warranty.
    As I had success 'washing' my ML speakers, I thought what the heck... nothing to loose... so give it a try. After 'washing' and drying thorougly, I was amazed at the result. The full glory of my Sr009 sound returned back.

    If it is just gentle 'washing' of the dust covers and does not involve the diaphram, then great. Still the process requires delicate work to do the 'washing'. Why it solves the problem for me, the jury is still out I suppose.

    Was just sharing my findings. Good to have this community caution me on where the danger areas are. Am grateful to those that replied to me.

    What you mention about taking the SR009 on a flight can be another possible reason why some return their SR009 to Stax and the find no fault. Worth investigating.
     
  13. J-Pak
    How long have your 009 been functioning properly since you washed the dust covers?
     
  14. John Heng
    Yes ,Still working fine.
    I suspect the dust on the dust covers create some static effect that screws up the treble info. I now keep my sr009 in a bag to keep the dust out.
     
  15. astrostar59
    I am glad your 009s are fixed. Take care with using a bag. The ear cups can get damp and then if kept in a sealed enclosure of any kind will encourage mould on the leather. My 007s MK2s did that.

    If you don't use them for a few days, I would put them in the Stax 009 wooden case.
     
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