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 88

post #1306 of 1585
The earpads. I couldn't find them in my purchase history. I think these are identical:-http://www.ebay.co.uk/myb/SavedSellers?ssPageName=STRK:ME:LNLK:MEFSX&_trksid=p3984.m2034.l3390 They look like what I remember, lots of detail in the advert, which is why I went with them. Pleather might give a better seal, but that's just a detail.

I do have some stainless steel wire gauze, but I've got the PCB stators cut already, I don't want to get sidetracked into experimenting until I've got working diaphragms with very similar sounds.

Yes, the whole thing is heavier than it need be. There is a lot of room for circular holes in the parts, but in my haste I pressed ahead with the simplest design that I felt would take the punishment and be adjustable. The arrangement of stacked rings means that installing moisture shields will be straightforward.

When I thought of using the nylon studding, I found a choice of colours, and I realised that I was in the throes of creating a design with a certain steampunk flavour, plus I have succeeded in reducing the headphone to a flat pack kit.

w
post #1307 of 1585
Thread Starter 

I've been thinking of doing something like this for a while, and now I'm seriously thinking of going ahead.  

 

 

The purpose of having this bigger hole in the center of the stator, IMO, is to reduce the push and pull force in the center of the diaphragm so that one can lower the diaphragm tension and / or lower the spacer thickness to get higher efficiency.  In ESL speakers, we often put a silicone spacer there for the same purpose.  

 

The hole, silicone dot, cover up that middle circle when applying coating material on the diaphragm so that the diaphragm in that area is non conductive, or etch out the copper in the middle region of the stator, IMO, would yield the same result?

 

Dude_500 is the only person I know who have made such a design on his test stators.  Can you share your view or experience on this?

 

Wachara C.

post #1308 of 1585

The membrane would move differently in the two scenarios:

 

With the silicon dot you're essentially putting a spacer in the middle, so the membrane moves like a vibrating donut.  The good thing about the dot is that you get more stability on the diaphragm but no sound radiating from that point.

With the empty hole in the stator you have a non conductive area but the membrane can still move there from the momentum generated.  The good thing about this method is that you still get sound coming through that hole, but you don't gain as much physical stability and there may also be additional distortion if the field is too weak there (hole too large). 

 

I think it will sound very similar in the grand scheme of things, though.  I would probably make the hole longer/skinnier to reflect the shape of the stator (distance from hole edge to stator edge).

post #1309 of 1585
Quote:
Originally Posted by chinsettawong View Post
 

Dude_500 is the only person I know who have made such a design on his test stators.  Can you share your view or experience on this?

 

Wachara C.

 

It doesn't seem to change sound quality. I haven't really tested stability. Instinct tells me it helped stability, but it could be entirely in my head without a direct test. There is no scientific reason it should help with stability other than the decreased surface area which is minuscule. I'm not sure it really matters, as according to actual measurements I did recently increasing tension does not decrease bass. Within certain bounds, I think that is all in our heads and fueled by placebo.

 

The only thing I know for sure that's really nice about it is that you can glance at it and instantly know visually whether it's gone unstable which is actually pretty hard to do in a traditional stator.

 

I finally got a decent way to measure my headphones with in-ear mics and I do plan to do some comprehensive experimental stator analysis at some point, but I'm moving out into the real world in a few weeks and won't have access to CNC equipment probably until I buy/build my own stuff so it might be a while.


Edited by dude_500 - 4/28/14 at 6:00am
post #1310 of 1585

Can't help thinking the best solution to get most stability + efficiency would be a curved stator which in turn would allow the stators to get closer to the diaphragm and make the movement of the diaphragm more uniform with lesser excusion in the middle and more around the edges relative to using 'flat' stators.

Also, increasing surface area of the stator will mean more force applied to the diaphragm, right? So I guess it's a compromise between surface area and acoustic transparency, eg. efficiency and transparency, when making 'stats assuming the dimension of the stators/diaphragm is known?

post #1311 of 1585

Long term stability does seem to be a problem here. My headphones aren't doing so well with spring weather. It's hot and humid today (more so than any day yet this year), and I'm practically down to standard bias to keep headphones stable that have been stable at pro-bias for a year and a half up to this spring (literally have been sealed up for a year and a half, only aging has affected it). These are all on 2um mylar from ebay. Glad I put adjustable bias on my amp! I wonder what the solution to this problem is...

 

 

Update: Upon further thought, I think the problem is the coating reacting with the temperature/humidity. Usually when I slam bias down to zero it takes a second or two for the sound to go away. Today, it instantaneously goes away implying the resistance dramatically dropped today, possibly to the point of causing instability. I can only imagine that all anti-static cleaner liquids would have similar properties, I've been using http://www.elexp.biz/chemical/1733.jpg


Edited by dude_500 - 5/1/14 at 2:44pm
post #1312 of 1585
Thread Starter 

About stability, once it fails, it's very difficult to fix.  I've tried many, many times and there's no help.  Even shrinking the diaphragm with hot air doesn't help.

 

The humidity can cause a problem.  But, I'm not sure if it's related to the diaphragm instability.  I have witnessed a lot of the noise problem during high humidity season, but not the instability issues.

post #1313 of 1585

Do you think there was creep in the contact cement?

post #1314 of 1585
Thread Starter 
Quote:
Originally Posted by n3rdling View Post
 

Do you think there was creep in the contact cement?

 

In my case, no.  

post #1315 of 1585

Anyone read this ?

 

 http://www.quadesl.org/index.php/hard-core/panel-coatings/original-quad-coating

 

http://www.ebay.co.uk/itm/Electrostatic-Speaker-Conductive-Coating-Elvamide-120g-/280534535726?pt=Vintage_Electronics_R2&hash=item4151294e2e

post #1316 of 1585
Quote:
Originally Posted by n3rdling View Post
 

Do you think there was creep in the contact cement?

 

Not this problem. I took one pair apart last night and the tension remains about the same as it was before. However, I switched the coating out to a very thin layer that takes 5-10 minutes to charge in winter, and it took about 3 seconds to charge. Today is a bit less humid and it's at about 10 seconds. So it's definitely the extreme atmospheric sensitivity of the coating that's causing my problem.

post #1317 of 1585
Thread Starter 
post #1318 of 1585
Thread Starter 
Quote:
Originally Posted by dude_500 View Post

Not this problem. I took one pair apart last night and the tension remains about the same as it was before. However, I switched the coating out to a very thin layer that takes 5-10 minutes to charge in winter, and it took about 3 seconds to charge. Today is a bit less humid and it's at about 10 seconds. So it's definitely the extreme atmospheric sensitivity of the coating that's causing my problem.

Have you ever measured the resistivity on the diaphragm? My headphones and all Stax headphones that I've tried can charge up instantaneously.
post #1319 of 1585
Quote:
Originally Posted by chinsettawong View Post


Have you ever measured the resistivity on the diaphragm? My headphones and all Stax headphones that I've tried can charge up instantaneously.

 

I've tried, never gotten anything to read less than max value on a meter. The ones that take a few minutes to charge in winter I tried to measure by putting 400V across the diaphragm and measuring current with a triple-darlington, which came up with something like 3*10^14 ohm/sq +- a lot. 

 

That's on the extreme high-end of what I'd ever do. But if I use my coating material sufficiently for instant-charging (basically put a bunch on and don't think about it), it's always going to be unstable even for unacceptably high tensions in this weather. Seemed to last through last summer although I was in a different climate.

post #1320 of 1585
Thread Starter 

Wow, that's an extremely high resistivity.  I doubt if your diaphragms can really be fully charged.

 

If I were you, I would go for a bit thicker spacers, and put on a less resistive coating. 

 

For my Float clone, I couldn't get the right tension and stability when using 0.5 mm spacers.  In the end, I cut a piece of 0.1 mm thick plastic sheet as extra spacers.  It's amazing to see how the extra 0.1 mm can help stabilize the diaphragms.

 

Wachara C. 

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