[arnaud]

Dude500, looks awesome.

If you can get your hands on some leather pads (and make sure the earpad cavity is well sealed), you might gain in bass region (unless the rolloff is due to your microphone and not an actual illustration of back wave concellation due to transmission through the porous pad). However, whatever you may gain in the LF, you'll get even less sound absorption so the MF/HF response will get even more tilted up.

The most effective method would probably be the foam layer agaisnt the driver on the ear side. It might quickly get dark sounding (and the soundstage width suffer), but surely it will tame the highs. With the very large diameter perforations, I suspect you get little damping from the thin air layer, which may seem like a good thing at first but end up hearing the diaphragm's resonances.

Awesome DIY stuff though, really enjoying reading you guys updates!

 

[bidoux]

Quote:

 
Yes, a capacitor. The capacitance is dependent on the plate area. If you have charge distributed on both sides of the diaphragm instead of one, you effectively double the plate area. For any given voltage the charge will be doubled. This is why the foils in capacitors are rolled up, to take advantage of both sides of the plates.
 
w

I have read another time the way you put the diaphragm's movment into equation, and I still don't see how you can account for coating both sides of the diaphragm. The only change it would induce is a better symmetry but that is 5µm of diaphragm thickness regarding to the 500µm of DS spacing, so it is not really an issue.

The force one stator applies to the diaphragm is F_E1, given by  :   (F_E2 is the force applied by the other stator to the diaphragm)
 

 
where Σ is the surface of both, e is the distance from stator to diaphragm, U_0 is the bias voltage, u is the drive voltage and x is the distance from the middle between both stators to the position the diaphragme actually is (so it measures the diaphragm position from where it would be if there was no force at all)
 
Here you have a change in sign because you have two stators so there is a symmetry.
 
If you sum these two forces and say that the diaphragm is more or less a resilience (which has a certain constant named k), add a force induced by the air friction (which is, in the end, responsible for sound) also given by a constant h you end up with this equation, after simplifying a bit :
 

M is the mass of the diaphragm. That is the equation I was talking about a few posts earlier, you only have to consider voltages, the charges are hidden underneath

 
Maybe that explains a bit better why you can't think in terms of charges, it will lead you nowhere. If you read Roger sander's book, you will see he has the same opinion ; that is about double coating the diaphragm, he doesn't explain the equations I have just given, and they are not taken from his book.
 
(iirc the foil in a cpacitor isn't rolled to take advantage of both sides, only to manage to fit a lot of surface into a given volume but that is not really relevant here)
 
 
And of course, if you want to try to double coat your diaphragm, go ahead and let us know what you find out

 

[chinsettawong]

Quote:

And of course, if you want to try to double coat your diaphragm, go ahead and let us know what you find out

 

 

[dude_500]

Quote:

 
You used to make much larger active diaphragms.  Why do you make them smaller this time?  
 
With the driver of this size, you won't get much bass and the sound would certainly be brighter - due to less capacitance.  
 
How muh weight have you put on this time?  If I were you I would increase the bias voltage instead of lowering the tension.
 
This was how much weight I used with my 3 microns Mylar with active diaphragm size of 78mm x 118mm.  The spacer thickness was 0.5 mm and 580V bias voltage.  The tension was only barely enough.  If I were to to it again, I would use use a few more water bottles or increase the weight of each bottle to around 1 kg (1000 ML).
 
 
Wachara C.

I think I have something like 8-10lbs of total weight on it. Haven't checked the weight of the weights for a while and don't remember precisely what they are. It's the identical weights I used on my 78mm SR007 clone diaphragms. Those operate on the edge of stability, whereas these are far beyond stability (as expected, since the diaphragm is a bit smaller in these new ones).
 
This is the largest diaphragm the HD600 earpads can support. As seen in this picture, all the area is active (could maybe squeeze in a couple more millimeters, but nothing of any significance):
 

 
 

If you can get your hands on some leather pads (and make sure the earpad cavity is well sealed), you might gain in bass region (unless the rolloff is due to your microphone and not an actual illustration of back wave concellation due to transmission through the porous pad). However, whatever you may gain in the LF, you'll get even less sound absorption so the MF/HF response will get even more tilted up.

 


With summer coming up, one of the major reasons for this build was to have a pair of electrostatic headphones to go to when I just can't take leather anymore. I really dislike leather earpads

 

[chinsettawong]

Let me correct my mistake.  The latest oval shape headphones that I made has 74 mm x 104 mm active diaphragm area.  It's been a while and I forgot.  

 
I've been doing an extensive listening comparison between my Omega clone and this oval shape one, and I really like the oval shape one better.  Not only that the bass goes deeper, the sound stage is wider with very good treble.  And it's just more relaxing and fun to listen to.
 
I also compare them with my very first oval shape version.  They have slightly smaller active diaphragm - 70 mm x 100 mm.  Again the oval shape ones are more relax to listen to.  With the spacer of 0.6 mm, they are a little less efficient.  But with a powerful amp such as KGSSHV, they sing out really well.  
 
So I strongly recommend those who want to make headphones make the oval shape and try for yourselves.  I'm sure one of the reasons why they sound better is that they have bigger diaphragm area.  So, if you can make them even bigger, go for it.
 
This is the picture of the three headphones I'm talking about:
 

 

[spritzer]

HD600 pads are a bad choice for planar duty as they leak... a lot.  HE60 pads would be a far better fit and they are the same size.  Here is a HE60 I built from spare parts and a HD650 capsule holder... 
 

 
Different mounting fixture though.  If you want 100% velour then look into the Hifiman pads as they use a much denser foam to achieve more isolation.  Dirt cheap too... 

 

[Chazman]

Hello!
 
Long time reader (especially as this thread is soooo massive) and all this talk has inspired me to make my own headphones after getting a pair of Koss ESP-6a's and restoring them to their former glory. A number of years ago I was very lucky to be able to try a full Sennheiser HE90 / HEV90 set up and was blown away by them so I am going to base my designs on the basic design of those with Oval drivers in the 100 x 70mm ball park and want to try to use some premium materials in persuit of a great sounding pair of phones!
 
So I have a couple of questions (and I sincerely apologies if they been asked before but been trying to digest my way through all this amazing information):
 
- I have access to CNC capability so going to have the cups machined out of wood, was thinking Spruce, Rosewood or Mahogany. Any opinions on these for this purpose?
 
- After reading details of the HE90's it appears the stators are made with a gold coating, has anyone tried cutting the fibre board and laying gold leaf on it? Any opinions on this? The electronic engineers at my work suggested it might be good due to the low resistance and ability to get quite a lot of material off thus reducing potential capacitance.
 
- On the gold leaf topic I was wondering if you had the boards cut and then lay the leaf on top and when trimming out the holes cut them a tiny fraction bigger than the holes in the board - theory being it would be like the etching to remove the sharp edges and reduce arcing - crazy / stupid idea?
 
- I suspect that I may end up going for machining PCB board to make them in the end and a really novice question (mostly for Chinsettawong - You are an inspiration by the way!) when using the PCB as the spacer & connection to the diaphragm do you use 0.5mm board as in your early posts you suggested you used the same type of 1mm board you did for the stators (single sided obviously) but wouldn't that mean there was a 1mm gap to one side and a 0.5mm on the other or am I missing something? On this topic what is the best way - get 0.5mm fibre board for the spacers and put some thin foil type material to get the contact to the diaphragm (sorry know this is a stupid one!)?
 
Again an inspirational thread and thanks in advance for any assistance!
 
Chaz
 

 

[chinsettawong]

Hi Chaz,
 
If you have access to a CNC machine then go for it.  I'm sure you'll like what you make a lot.
 
I think any wood is fine.  Just pick the one you like best.  I personally use whatever hardwood I can find here locally.  I really like zebra wood, but can't find them here.  

 
Don't try to do a gold coating by yourself.  I don't think that you'll get a good result.  Actually making the stator very low resistance doesn't help.  I find it's better to use copper cladded PCB for the stators and coat them with a few very thin layers of Acrylic paint to be the best.  The paint insulates the stator which protects them against rusting and possible short in case some small dusts find their way into between the stator and the diaphragm.
 
I use 1 mm PCB for my stators and 0.5 mm PCB for my spacers.  The copper sides of the stators are facing each other with two spacers sandwiching the diaphragm in the middle, so the spaces between the diaphragm and the two stators are the same on both side.  Please look at my arrangement from this picture.
 

 
You want the 2 spacers to be of equal thickness.  So, using a fiberboard as spacers and putting a foil in between isn't a good idea.
 
Wachara C.

 

[chinsettawong]

By the way, I also did a listening comparison among HE60 and all my DIY headphones.  Unfortunately HE60 just isn't good enough to be in the same league.  It's now back in the box. 

 
Wachara C.

 

[wakibaki]

Quote:

And of course, if you want to try to double coat your diaphragm, go ahead and let us know what you find out

 
Exactly. Like I intend to try with one stator unperforated.
 
 

 
CNC machine arrived today.
 
w

 

[chinsettawong]

What do you guys think of something like these?
 

 

 
 
With simple enclosure and headband, they could very well be something very similar to the Jacklin Float.  I'm targeting a spacer of 0.75 mm and a bias voltage of 1000V - 1200V.  They should be able to be driven by my KGSSHV and DIY T2.  

 
By the way, the active area on this design is 100mm x 120mm.
 
Wachara C.

 

[Chazman]

Wachara,


Thank you very much for the advice!!

I will go for the pcb material idea then (though struggling to find 0.5mm board that isn't pre sensitised, which I am sure isn't good is it?), another possibly silly question, when you sandwich your 0.5mm pcb board spacers I assume you face them in to the diaphragm so you get a contact on both sides and assume you glue it down? If so how do you do that and get a good connection?

I was thinking when I make them to sand the side facing the ear of the cup by a couple of degrees downward (in towards the ear canal) to help reduce any standing waves inside, good idea?

Again sorry for the novice questions but don't have access to the cnc machine for long so need to plan these bits before I get making. Will post some basic plans when I have drawn them up....

Thanks,

Chaz

P.s. which ones are you favourite out of your army of phones?

 

[ayaflo]

CNC machine arrived today.

 
how much did you get that for?

 

[dude_500]

Quote:

I will go for the pcb material idea then (though struggling to find 0.5mm board that isn't pre sensitised, which I am sure isn't good is it?), another possibly silly question, when you sandwich your 0.5mm pcb board spacers I assume you face them in to the diaphragm so you get a contact on both sides and assume you glue it down? If so how do you do that and get a good connection?
 

This is the place to get 0.5mm and 1mm copper clad: http://www.ebay.com/itm/Copper-Clad-Laminate-PCB-Printed-Circuit-Board-Material-/120664289524?pt=LH_DefaultDomain_0&var=420018556366&hash=item1c1826f0f4
It's a bit expensive, but I think its the best you can do without ordering in bulk from a supplier.
 
 
How do the floats work? Isn't there zero seal since they 'float' over your head without any sort of earpad at all? I'd think the open air resonance would be completely present and they'd sound like total crap (like how it sounds when you hold the earpad of standard electrostatic headphones a centimeter away from your ear).
 
 
Regarding more listening, the new headphones are much more enjoyable to listen to. My old pair sound so flat now in comparison. Probably won't have a chance to try until at least the weekend, but hoping for more bass from lower tension.

 

[Chazman]

Dude_500 - thank you, another forum legend

I am in the UK so will have a look about on eBay and see if there is anything like that a bit more local. On that note is there anyone in the uk who would like to see some Mylar , I have found some (2um) on eBay but I don't necessarily need 20m of it?!

I was not thinking of them floating they would still have a pad as per normal but if you imagine it is normally a tube that is perpendicular to the side of your head these would be angled a little so the driver does not face head on and might help reduce any standing waves inside the cup. I will draw a quick image later to better describe.

Thanks,

Chaz