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My DIY electrostatic headphones - Page 8

post #106 of 1522
Thread Starter 

Hi Philippe,

 

It's so nice to see you again.  I've been wondering where you are.

 

Thank you very much for sharing your DIY Stax connetor.  I'll try to source something similar here in Thailand.  :)

 

Since you are here, may you comment on my idea?

 

I've been playing around with the idea of making a 3 stators and 2 diaphragms headphone.  I've actually made the design and cut the parts.  I'm going to cut the enclosures soon.  What do you think?

 

Picture23.png

DSC_0725.jpg

 

The size of the stators is very similar to that of Stax 407.  I make the two outer stators from single sided PCBs.  The middle stator is made from a double sided PCB.  My spacers will be made of 0.5 mm plastic.   I expect that this design will yield much better efficiency and hopefully much better bass than the conventional single diaphragm design.  :)

 

Wachara C.

 

post #107 of 1522

With a CNC machine you could just make Stax sockets like we did for the DIY SRM-T2 project.  The whole piece is milled from a block of Teflon and the sockets are from the CMC octal tube sockets. 

post #108 of 1522

Really interesting and innovative work! Anxious to hear how your phones compare to a 407. I have a small hoard of the Amphenol 5 pin jacks that are used  in most Stax amplifiers.  As Spritzer says, you can probably make better, but I'd be happy to contribute a few towards your projects. PM me if you're interested.

post #109 of 1522
Thread Starter 

Hi Spritzer,

 

Thanks for your info. :)

 

Wachara C.

post #110 of 1522
Thread Starter 

Hi FrankCooter,

 

Thank you so much for your kind generosity.  I'll PM you.   :)

 

Wachara C.

 

 

 

post #111 of 1522

 

It is indeed a very interesting idea.
 
Are you going to use some kind of crossover (low-pass filter) with the outer diaphragm? How high frequencies reflections between both diaphragms interact?
 
Best regards,
 
Jose
post #112 of 1522
Thread Starter 
Hi Jose, I've never thought of using a crossover. Anyway, that seems to be an interesting idea too. I'll try to make them sing first. Then we can think of how to play around with them later. Wachara C.
post #113 of 1522

This is incredible. After you iron out whatever small stuff you want to fine tune and find a build you are happy with======> Have you thought of offering this in a D.I.Y. kit form of unassembled parts/instruction manual for tech minded people to assemble themselves? I am sure you would have a positive response. Having a D.I.Y. set of these would make a person proud.

 

Truly inspiring.

post #114 of 1522

Dear chinsetawong,

 

Why not build a headphone that is no longer available but has a unique design like the Stax Sigma:-))

 

Regards Georg

post #115 of 1522

 

That arrangement is really food for thought.

 

I was wondering if you would need to pull out the diaphragms with a very accurate force. If they stay unevenly stretched, you might have distortion.

 

I was wondering if the PCB (woven glass epoxy?) shield is enough to isolate the outer layer and the inner layer of the second stator.

 


First Stator

Outer Diaphragm

(+ fixed bias polarity)

Second Stator Outer Layer

Second Stator Inner Layer

Inner Diaphragm

(+ fixed bias polarity)

Third Stator

+

(Fa >) +

-

+

(Fa >) +

-

-

+ (< Fa)

+

-

+ (< Fa)

+

 

 

What happens if you chose to supply inverse bias polarities? You would also invert + and – signal connections in the inner balanced arrange. For instance:

 

First Stator

Outer Diaphragm

(+ fixed bias polarity)

Second Stator Outer Layer

Second Stator Inner Layer

Inner Diaphragm

(- fixed bias polarity)

Third Stator

+

(Fa >) +

-

-

(Fa >) -

+

-

+ (< Fa)

+

+

- (< Fa)

-

 

 

I was wondering the magnitude and direction of all forces and the resultant/net force acting not only in the diaphragms, but also acting in the stators. The second stator seems to be neutral in both arrangements, right?

 

I was wondering also resonation on the second stator. I do not think the air enclosed between diaphragms cause resonation, but what if you choose to make an imperfect vacuum there? Is there a way to do that? Perhaps it would be a sealed duct within the spacers so you can always reinforce the vacuum and try different air pressures. 

 

You would avoid air resistance inside the second stator mesh and may compensate occasional differences in the stretch forces applied to the diaphragms during the manufacturing. There would be also an impact in high frequencies interactions between both diaphragms as there would be little air to conduct sound.

 

But then there would be no air to push forces between both diaphragms, which was you first disign criteria (improve sensitivity).

 

Do you think this (air pressure between both diaphragms) is some way relevant?

 

I know sometimes engineering goes in practical models, but I love to simulate or anticipate things...

post #116 of 1522
Thread Starter 

Hi Jgazal,

 

Wow, that's a lot of thoughtful thoughts.  I have been thinking only doing the really easy triple stators and double diaphragms design,  I've no intention of vacuuming the air between the two diaphragms.  I want to keep it simple and try to see if it will work.  Thanks for sharing your thoughts though.

 

I will most likely try the configuration as your first chart:

 

 

First Stator

Outer Diaphragm

(+ fixed bias polarity)

Second Stator Outer Layer

Second Stator Inner Layer

Inner Diaphragm

(+ fixed bias polarity)

Third Stator

+

(Fa >) +

-

+

(Fa >) +

-

-

+ (< Fa)

+

-

+ (< Fa)

+

 

 

Unfortunately, I haven't had the time to cut the enclosures this weekend.  So, the assembling and testing will only come next weekend at the earliest.  I'll keep you posted of the results.

 

Wachara C.

post #117 of 1522
Thread Starter 
Quote:
Originally Posted by nick n View Post

This is incredible. After you iron out whatever small stuff you want to fine tune and find a build you are happy with======> Have you thought of offering this in a D.I.Y. kit form of unassembled parts/instruction manual for tech minded people to assemble themselves? I am sure you would have a positive response. Having a D.I.Y. set of these would make a person proud.

 

Truly inspiring.


Hi Nick N,

 

Thanks for your interest.  At the moment I am still experimenting with my different designs.  I hope my work inspires people.

 

Making stators from CNC milled PCBs is just one of many possibilities.  A few people have successfully made their ES headphones out of some commonly found stuffs.  So, please do not be discouraged if you do not have access to a CNC machine.  If you need some guidance on how-to, I'll be more than willing to help.  :)

 

 


 

Quote:
Originally Posted by schorsch View Post

Dear chinsetawong,

 

Why not build a headphone that is no longer available but has a unique design like the Stax Sigma:-))

 

Regards Georg


 

Hi schorsch,

 

I might just come to that one day.  Thanks for your suggestion.  :)

 

Wachara C.

post #118 of 1522

 

One last thought now on stator’s temperature.

 

I was reading those comments on C32 done by a Stax engineer who said they had a concern with the stator temperature so that they made a hole right in the middle of the mesh (stator). According to him that would improve air circulation (I wonder if it also improves the reproduction of certain high frequencies that will not reflect at the thinner mesh; do higher frequencies originate from the middle of the diaphragm or they come from the whole surface? A laser vibrometer would be useful to trace that…)

 

I think woven glass epoxy boards are less prone to temperature variations than the full metal C32 stators (different specific heat capacities on the materials). And the PCB copper layer is not thick enough to increase temperatures or accumulate so much heat energy.

 

But given the fact that your second stator will be air isolated, it would be nice to monitor its temperature along certain usage time.

 

I am looking forward to hearing the results from you. It is a very exciting project.

post #119 of 1522
Thread Starter 

Hi jgazal,

 

Personally, I do not think that there will be any issue with the temperature.  Even if it does, opening a bigger hole in the middle will not help much, IMO.  I haven't noticed any changed in temperature on the stators or headphones regardless how long I am using them.  If there is any, the temperature should more likely come from the person who wears the headphones.  It shouldn't be any higher than a person's body temperature. 

 

Let's keep moving and worry about all these details later.  :)

 

Wachara C.

 

post #120 of 1522

The heat would really only be an issue with a T2/BHSE pushing (relatively) massive amounts of current onto the stators and even so, only with prolonged periods of that.  Still all metal stators are more sensitive to the ill effects of temperature drift than the PCB based units. 

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