Head-Fi.org › Forums › Misc.-Category Forums › DIY (Do-It-Yourself) Discussions › My DIY electrostatic headphones
New Posts  All Forums:Forum Nav:

My DIY electrostatic headphones - Page 15

post #211 of 1486

ED1.jpg

There are some stax difusse field equalizers eg Stax ed-1 (pro/signature) and they provide a special equalization for the related earspeakers.

Rhere is also the SRM Monitor which has the equalizatuin included.

 

For recent models pawel acoustics makes a equalizer.

 

Regards Georg

post #212 of 1486
Quote:
Originally Posted by chinsettawong View Post



Hi Birgir,

 

To DIY a pair of headphones for personal use, I think the difficulty isn't that much.  But, yes, if you want to go commercial or making a kit for the mass, it's another story.

 

I have no idea what a fully balanced Stax diffuse field EQ is.  Could you kindly explain?

 

Wachara C.

 


My issue was getting consistent results when people have no experience stretching and gluing mylar.  This would be a 100% DIY project but I believe that it isn't worth the bother if anybody with the minimal skill and basic instruments can't build it.  It also prevents Kevin and I from going way too deep down the proverbial rabbit hole... redface.gif

 

Diffuse Field EQ is a way of expanding the soundstage of headphones and minimize the issues all headphones have i.e. being so close to the ears.  Stax did indeed make a few boxes that did this but they are all single ended and tuned for old Lambda models.  I believe the Pawel box is just a clone of what Stax did plus adding crossfeed but the pix I have are rather poor.  The problem with DIY boxes are the tools needed to adjust them but if something like this could be done in DSP then that would be far easier to implement. 

 

post #213 of 1486
Thread Starter 
Quote:
Originally Posted by spritzer View Post


My issue was getting consistent results when people have no experience stretching and gluing mylar.  This would be a 100% DIY project but I believe that it isn't worth the bother if anybody with the minimal skill and basic instruments can't build it.  It also prevents Kevin and I from going way too deep down the proverbial rabbit hole... redface.gif

 

 



I will think of a simple and effective way to stretch and glue Mylar for you.  I actually have an idea.  Let me go back and do some experiments and I will post a step by step procedure with pictures for you.

 

Happy New Year!

 

Wachara C.

post #214 of 1486

The most simple way I used was a piece of glass and some tape with a strain gauge to measure how much force I used on the film.  Simple and very effective. 

post #215 of 1486
Thread Starter 

Hi Birgir,

 

That surely is one of the simplest and effective ways to tensioning Mylar.  There is another way that I would like to suggest. In this case you use a piece of glass and predraw some scales on it.  Let's say for each 1 mm you draw a line.  You cut Mylar just big enough to make a pair of headphones.  You tape the four corners of Mylar on the glass.  Draw a line on Mylar to indicate your prestretch starting point. Then you hand stretch your Mylar to your target point by observing the line on Mylar against those on the glass.  When you get to your target point, you simply tape it down. Do the same for all four sides of Mylar. I have some pictures below to show what I mean.  It's basically the same principle of how I stretch Mylar for my ESL.

 

  DSC03632.jpg

 

DSC03635.jpg

 

P8080021.jpg

 

These pictures are taken when I use a rubber tube tensioning jig for my ESL.  It's the same principle I use here.

 

As for gluing Mylar, I haven't found anything better than rubber glue.  I use a piece of sponge to help me apply the glue evenly.

 

DSC_2706.jpg

 

This is how I tape Mylar.  I use a soldering iron for cutting Mylar. 

 

Usually, I will cut a few more pieces of spacer rings. I like to try with different tensions and different thicknesses of Mylar.  :)

 

Wachara C.

post #216 of 1486

How do you heat treat the mylar?  That is indeed the biggest obstacle in making the drivers last for 50 years (how old my Stax SR-1 drivers are).  Quad used a special oven and I'm sure Stax uses something similar for the correct heat transfer properties. 

post #217 of 1486
Thread Starter 

Hi Birgir,

 

With enough mechanical tensioning, there is no need to use another heat treatment on the diaphragm.  On ESL building threads, there have been a lot of discussions about this topic, and it's pretty apparent that you can only heat shrink the diaphragm to a certain extend.  However, mechanical tensioning can do a much better job than heat. 

 

I don't think that the diaphragm is to blame for when the diaphragm looses it's tension.  Most of the times, it's glue that fail.

 

And yes, Quad did use an oven to do a heat treatment.  But, I'm skeptical about that.  They could have used heat to treat the coating material and not the diaphragm.

 

Wachara C.

post #218 of 1486
Thread Starter 

Here is an example of a failed ESL driver.  When I opened it up, I found that the double sided tape that I used gave up its strength.  This was after about 3 months of usage.  When it failed, the diaphragm would collapse to one side and the sound was very much distorted.

 

The diaphragm was initially stretched to 1.5% elongation on one side.  It's probably too much. 

 

DSC03639.jpg

 

Wachara C.

post #219 of 1486

Read this and the similar thread over at DIY Audio and I think I might have to have a crack at a set. Spent the evening on Sketchup and have began designing the stator and spacer.

 

stator.jpg

spacer.jpg

 

Ever so slightly ripped off from one of chinsettawong's designs. Do they seem ok so far? They're both 90mm in diameter so you have an idea of scale. 

post #220 of 1486
Thread Starter 

Hi Nixon,

 

Your design looks great. However, you also need to have a knob on your stator so that you can solder the + and - audio signal onto. 

 

What is the spacer thickness you intend to use?  I assume that you are going with 70 mm active diaphragm area, right?  In my last design, that is exactly the dimension I use.  But, if I were to do it again, I will increase the active diaphragm area to 80 mm.  This will give you better low frequencies response.

 

Wachara C.

post #221 of 1486

Thanks chinsettawong. Meant to add the knob on the stator but was  a bit knacked after making all the holes it and must have forgot. I'll tweak it tonight to increase the diaphragm area and add the knob. 

 

 

 


Still undecided on the spacer thickness, modelled it at 0.5mm but that's easy to change if you think that's wrong.
 

post #222 of 1486

Redesigned the spacer and stator to be 10cm in diameter. Going to have a go at the enclosure next.

 

 

strator 2mm.jpgspacer with tab.jpg

 

post #223 of 1486
Thread Starter 

That stator design looks interesting.  But I think that your long and unsupported opening will cause you problem.  The whole stator might not be strong enough.  You might want to reduce the length of your slots down to perhaps 2 -3 cm, IMO.  Otherwise, it looks really nice.

 

Are you going to use a PCB to make your stators and spacers?  Don't forget to etch out all the unneeded copper on the outer circle of your stator.  With the copper out, it really make a huge difference in high frequencies response.

 

Wachara C.

post #224 of 1486

I'll tweak the stator now. Plan to use PCB to make the stator and spacer and already planned to etch off the excess copper after reading about your test of it. 

post #225 of 1486

Hello, and sorry for the late reply.

I just recently completed a small electrostatic speaker (not a headphone, sorry.)

Good news is: SPACE BLANKET WORKED. Sounded great, played well, a little arcing didn't destroy it completely.

Bad news is: I am not an ESL professional. It sounded great, but I haven't ever heard another ESL. Also, I tensioned/assembled it very poorly. It was only stretched about 0.7% and there was a small wrinkle in the corner.

 

Setup: ~2500kV ballast with 15 megaohms of resistance and 1/16 inch d/s spacing on a 5inch x 7inch speaker.

Have a nice day:

Mike

New Posts  All Forums:Forum Nav:
  Return Home
Head-Fi.org › Forums › Misc.-Category Forums › DIY (Do-It-Yourself) Discussions › My DIY electrostatic headphones