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My DIY electrostatic headphones - Page 74

post #1096 of 1471
Thread Starter 
With your thick spacer, you should try them at 900-1.2 KV. You might find them even more interesting. smily_headphones1.gif

Wachara C.
Edited by chinsettawong - 10/14/13 at 6:54pm
post #1097 of 1471
Here is a very nice stretcher:-http://www.ebay.co.uk/itm/24x24-Screen-Stretcher-Mesh-Stretching-Tension-Too-3-yards-Silk-Fabric-as-gift-/160965481632?pt=LH_DefaultDomain_2&hash=item257a4a54a0, but very expensive. I'm thinking I could maybe make something like this, maybe with a couple of vices screwed to a piece of board, or maybe even just some threaded rod and make some pieces with the milling machine...
post #1098 of 1471
Thread Starter 

Hi Wakibaki,

 

That kind of stretcher is too good for our application.  It's too big too.  I spent less than US$10 into making my inner tire stretcher.  I went to a bicycle shop and asked for the smallest inner tire that they had available.  It costed me only around US$3.  I then searched around my house and found some scrap woods.  I cut, glued, and put everything together.  Even with this cheap stretcher, I still think that it's too good.  The problem is that I don't really need to stretch the diaphragm that much.  If you can find a helping hand, I think the stretcher using clips and weights is better.  It's easier to repeat the process too.

 

Wachara C. 

post #1099 of 1471
Yes, of course that stretcher is overkill, but it shows a technique and a machine design that can be copied. I want to try making a stator with that fine stainless steel mesh I found, I want to be able to apply some force to pretension it because I think that it'll be possible to make a more rigid structure that way, in the same way that aircraft have stressed skins. This is how I was hoping to avoid the problems with stator flexing that were brought up.

I looked at your inner tube stretcher, but I couldn't tell exactly how it worked from the pictures. Perhaps you could write a short description of how it works to make things clearer for the rest of us, if it's not too much trouble.

After some experimentation with spindle speeds, depth of cut, feed rate, and particularly lubrication, I've succeeded in getting my CNC to cut the 1050 aluminium plate that I bought. It's taken me a long time, but I'm hoping to have a finished headphone in a week or so. Because I'm still recovering from surgery and chemo, I'm tired a lot of the time, so sometimes days go by and I get nothing done, but it means that I've had time to think about the mechanical design and modify it. I'm a bit more confident that the cups will actually hug my ears now.

I ordered a pair of velour covered pads 100 mm diameter, they fit the cups perfectly. Cool. Something I don't have to make from scratch.

I've also done some CAD drawings of the amplifier case. I found a digital voltmeter to display the bias voltage which I've decided to make variable. With the CAD drawings I think I have reasonable hope that everything will fit together, even though it's taking me forever to get it done.

w
post #1100 of 1471
Thread Starter 

The inner tube stretcher is very easy and cheap to build.  First off, you need to build a wooden frame.  The frame is just big enough to fit your inner tire. 

 

To use it, you simply cut the Mylar sheet larger than the size of the frame.  You wrap the Mylar to the back side and tape it down to the frame.

 

 

 

You then inflate the inner tire and the Mylar should be stretched evenly in all direction. 

 

 

You apply glue on your spacer and glue it down on the Mylar.

 

 

Release the air form the tire and cut out the diaphragm and you're done.  Even though this method works well, you tend to stretch the diaphragm a little too much. 

 

 

It'll take a few trials and errors to know exactly just how much tension you need.  With too much tension, you don't have good bass.  With too little tension, your diaphragm won't be stable.  :confused_face:

 

I hope you get the idea.  I'm sorry that I mix up pictures of the small and big stretcher.  The principle is the same.  I use this big stretcher to make my full range ESL.  :L3000: 

 

post #1101 of 1471

^Woah, that's pretty wicked. Nice, indeed

post #1102 of 1471

 

Hello!

 

I have STAX 507. Could someone suggest where I can buy damaged membrane for one drive?

post #1103 of 1471
Thread Starter 

Hi bbest,

 

We really don't have a concrete idea of what material exactly that Stax is using to make the diaphragms for its 507.  If you really want to replace the diaphragm, you might need to replace the diaphragm in both right and left driver.  The diaphragm material that we are using is Mylar.  Any thickness up to 3 microns has been proven to be quite good.  I personally prefer using 3 microns Mylar.  You can find some sellers on Ebay.

 

Wachara C.

post #1104 of 1471

You prefer 3 microns? Any idea why Stax has chosen to settle between 1 and 1.5 microns?

post #1105 of 1471
Thread Starter 

I like it better because I have actually tried them all.  :tongue_smile:

post #1106 of 1471
Quote:
Originally Posted by chinsettawong View Post
 

Hi bbest,

 

We really don't have a concrete idea of what material exactly that Stax is using to make the diaphragms for its 507.  If you really want to replace the diaphragm, you might need to replace the diaphragm in both right and left driver.  The diaphragm material that we are using is Mylar.  Any thickness up to 3 microns has been proven to be quite good.  I personally prefer using 3 microns Mylar.  You can find some sellers on Ebay.

 

Wachara C.

 

ok - thanks for sugestion! But another question - how could I clean membrane from dust and hears's fat? With wich liquid can I do this (of cause without damaging membrane)?

post #1107 of 1471
Thread Starter 
Quote:
Originally Posted by bbest View Post
 

 

ok - thanks for sugestion! But another question - how could I clean membrane from dust and hears's fat? With wich liquid can I do this (of cause without damaging membrane)?

 

 

Are you sure you want to do this?  Blowing the dust off, gentle wiping, or bushing can all be done.  However, I'm not sure if it'll fix your problem.  Can you describe your problem and what you have already done?

 

For ESL, some people clean them with shower water.  But I really don't recommend it for the earspeakers.

post #1108 of 1471

Thanks, Wachara. That's clear now, and cheap and easy to do.

 

I ordered the rest of the parts for the amplifier from Farnell last night, so I will be able to check that the layout is correct and order the PCBs in the next few days.

 

w


Edited by wakibaki - 10/22/13 at 9:45am
post #1109 of 1471
Quote:
Originally Posted by chinsettawong View Post
 

 

 

Are you sure you want to do this?  Blowing the dust off, gentle wiping, or bushing can all be done.  However, I'm not sure if it'll fix your problem.  Can you describe your problem and what you have already done?

 

For ESL, some people clean them with shower water.  But I really don't recommend it for the earspeakers.


I simply take off dust from membrane with cotton pads. It is all ok with sound. 

In damaged drive, in defending film of stator, was small hole size of match head. This hole I taped with glue. And this drive became airtight. 

post #1110 of 1471
Thread Starter 
Quote:
Originally Posted by bbest View Post

 


I simply take off dust from membrane with cotton pads. It is all ok with sound. 
In damaged drive, in defending film of stator, was small hole size of match head. This hole I taped with glue. And this drive became airtight. 

Do you mean that the diaphragm has a small hole on it or is it the dust cover that has a hole?  It is very unlikely that the diaphragm has any hole - unless you really crank up the volume so much that the diaphragm is burnt through.  The dust cover on the other hand is very fragile.  I'm not so sure if taping up the hole can really cure the problem.  Try the headphones for a few days and let us know if the problem is really solved.

Wachara C.
Edited by chinsettawong - 10/24/13 at 7:15pm
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