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My DIY electrostatic headphones - Page 57

post #841 of 1487
Hope to listen to Mr. Wachara's DIY e-stats when I go to Thailand this MAY!! FINGERS CROSSED!
post #842 of 1487
Quote:
Originally Posted by Chazman View Post

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
 

 

The HE90 stators were etched glass and most of the sound comes from how they were made.  Also why there is a huge variation between sets and the reject rates were sky high back in 1991.  The stators were then coated to become conductive.  Gold plated diaphragm is just marketing BS. 

 

Quote:
Originally Posted by chinsettawong View Post
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.  wink_face.gif

 

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

 

Wachara C.

 

That would work but I'd try the "ear pad" setup use don the later Floats where they have a leather L shaped back at the back and bottom. 

 

With drivers this big I would remove or just bypass the output resistors on the T2/KGSSHV.  I'll check my data to see if Precide ever used any resistors on their sets... 

post #843 of 1487
Thread Starter 
Quote:
Originally Posted by spritzer View Post


That would work but I'd try the "ear pad" setup use don the later Floats where they have a leather L shaped back at the back and bottom. 

 

With drivers this big I would remove or just bypass the output resistors on the T2/KGSSHV.  I'll check my data to see if Precide ever used any resistors on their sets... 

Hi Spritzer,

 

I'm just having this itchy feeling after seeing many people posting about how great the new Jacklin Float sounds.  To me they are just big, and I'm sure that the size does matter.  It would be fun to try and see how good they can sound.  I can play around with the bias voltage to see what the most suitable voltage should be.  Without earpads, I'm sure that the headphones need to play a lot louder in order to sound decent.  By the way, do you think that the diaphragm size of 120 mm x 100 mm is close enough to the real thing?

 

Using series resistors shouldn't be a problem.  When I built my ESL speakers, I used 20 mega ohms series resistors.  They are just to prevent the possibility of large current going through.  I'm sure they won't hurt.

 

Wachara C.

post #844 of 1487
Quote:Spritzer
The HE90 stators were etched glass and most of the sound comes from how they were made.  Also why there is a huge variation between sets and the reject rates were sky high back in 1991.  The stators were then coated to become conductive.  Gold plated diaphragm is just marketing BS.

Ah that makes sense, did wonder if there was actually anything in that rather than just "Look at my gold bling headphones"

 

So I have opted for the more traditional set up, basics are going to be:

 

- Oval drivers - total size 105mm x 75mm (took some steer from my HD-580's in terms of size and personal fit) with an active area about 93mm x 63mm (6mm basic clearance space for screws and spacer area), using 2mm holes with a total of 462 holes per stator - 63% open on 1mm thickness 35um PCB glass fibre board.

 

- 0.5mm PCB spacers and will try to source some 2um Mylar. Still not sure on what anti static to get (in the UK that is) but open to personal suggestions on this? Do we reckon about a 1-2% stretch is a good place to start?

 

- Cherry wood oval cups with 15 area on back side which I will put a grill on and possibly play with various damping materials about the sound when I have put them together. 5mm lip on the front side of the drivers so I can get a really nice fit on the pads which I intend to make with thin leather running along the inside to help with bass exntension and then soft material next to the head.

 

I will try to get a snap shot of the CAD at some point and post it but having the stators made in the next week and hopefully the cups and spacers in the next week or two when I get the materials I need.

 

So just a couple of questions for the forum:

 

- Cabling, good to find a Koss extension cable to start with?

 

- Amp, right so I have not yet got round to making an Amp, I want to eventually make myself a tube amp for these but in the mean time I was thinking of trying to source something like a Stax type thing. Any help on this would be amazing, based on the dimensions and expereince what do you guys think would be a good place to start (I am not going to lie I am an electronics novice, I have some experience but mostly in IC's rather than passive type stuff)....

 

- Gluing the diaprham to the the spacers, how is this best done to ensure there is an electrical connection?

 

Again many thanks to the experts :-)

 

Chaz

post #845 of 1487
Quote:

- Cabling, good to find a Koss extension cable to start with?

 

- Amp, right so I have not yet got round to making an Amp, I want to eventually make myself a tube amp for these but in the mean time I was thinking of trying to source something like a Stax type thing. Any help on this would be amazing, based on the dimensions and expereince what do you guys think would be a good place to start (I am not going to lie I am an electronics novice, I have some experience but mostly in IC's rather than passive type stuff)....

 

- Gluing the diaprham to the the spacers, how is this best done to ensure there is an electrical connection?

 

 

From what I've heard, yes the Koss cable is good. I just use generic ribbon cable, but I've had it go bad with broken connections inside the wire near the headphones after a few months of use. Also they're not the safest option, although at these voltages honestly they have plenty of insulation for realistic safety.

 

 

I've always glued the mylar to a spacer that has no copper on it at all, then put the conductive coating on after gluing, and sandwich a copper covered spacer down onto the mylar. This leaves the mylar with 0.5mm on both sides as desired, and the mylar is contacted without having to glue it to copper.

post #846 of 1487
Thread Starter 
Quote:
Originally Posted by Chazman View Post

Ah that makes sense, did wonder if there was actually anything in that rather than just "Look at my gold bling headphones"

So I have opted for the more traditional set up, basics are going to be:

- Oval drivers - total size 105mm x 75mm (took some steer from my HD-580's in terms of size and personal fit) with an active area about 93mm x 63mm (6mm basic clearance space for screws and spacer area), using 2mm holes with a total of 462 holes per stator - 63% open on 1mm thickness 35um PCB glass fibre board.

- 0.5mm PCB spacers and will try to source some 2um Mylar. Still not sure on what anti static to get (in the UK that is) but open to personal suggestions on this? Do we reckon about a 1-2% stretch is a good place to start?

- Cherry wood oval cups with 15 area on back side which I will put a grill on and possibly play with various damping materials about the sound when I have put them together. 5mm lip on the front side of the drivers so I can get a really nice fit on the pads which I intend to make with thin leather running along the inside to help with bass exntension and then soft material next to the head.

I will try to get a snap shot of the CAD at some point and post it but having the stators made in the next week and hopefully the cups and spacers in the next week or two when I get the materials I need.

So just a couple of questions for the forum:

- Cabling, good to find a Koss extension cable to start with?

- Amp, right so I have not yet got round to making an Amp, I want to eventually make myself a tube amp for these but in the mean time I was thinking of trying to source something like a Stax type thing. Any help on this would be amazing, based on the dimensions and expereince what do you guys think would be a good place to start (I am not going to lie I am an electronics novice, I have some experience but mostly in IC's rather than passive type stuff)....

- Gluing the diaprham to the the spacers, how is this best done to ensure there is an electrical connection?

Again many thanks to the experts :-)

Chaz

-Seriously, if you can make your drivers bigger, then do it. I would stick with active area at least 70x100 mm.

-3 micron Mylar is the best one for me so far.

-I don't like to have any damping on my headphones. I feel they sound better that way. But you can try.

-I did post a picture showing the configuration of my driver a few posts back. Please have a look, and you should understand how the Mylar is glued to the spacer and how the other spacer is used as a charge ring.

Wachara C.
post #847 of 1487
Quote:
Originally Posted by chinsettawong View Post


-Seriously, if you can make your drivers bigger, then do it. I would stick with active area at least 70x100 mm.

-3 micron Mylar is the best one for me so far.

-I don't like to have any damping on my headphones. I feel they sound better that way. But you can try.

-I did post a picture showing the configuration of my driver a few posts back. Please have a look, and you should understand how the Mylar is glued to the spacer and how the other spacer is used as a charge ring.

Wachara C.

 

- Thanks, I have pushed the space envelope quite a bit (in terms of the number of holes and spacing, so its actually a bit over the number I said in places) and tried to make sure they would be pretty rigid. I will see how these ones go and then play with the active area on the next pair, also I did some measurements on my head, perhaps I have quite a small head but this was already quite a bit bigger in size to my HD-580's which are pretty big on my head.

 

On an interesting note I spoke to an Acoustics engineer about the stators and if there would be any advantage to putting minor radiuses on the non copper side of the stators - offical word was with over 60% open (these will be 63%) they are considered acoustically transparent and putting little horns on them effectively would increase the distance of the holes and take more energy from the sound wave. Additionally I am not sure I want to put tiny 0.2mm rads on 1848 holes!! :-)

 

- I can not for love nor money find a readily available source of 3um Mylar that I can get in the UK. Where do you get yours and I might be able to see if I can get I shipped over? What stretch do you put on your sheets?

 

- I have heard a few people say they don't any damping and some that do but its all pretty easy to put them on and off the back side of the phones so might as well give it a go (based on the closed back Koss ESP-6A's which have felt and paper backing to stop the rear wave, of course they are closed completely so not the same but maybe a middle ground)

 

- Thanks, I have gone back and with Dude_500's response below I have stopped being stupid and worked out how you did it, for some reason I had it in my head to glue both spacers on to the sheet but of course you only need to do one and just put the other on! Again apoogies for being a bit slow! :-)

 

Quote:
Originally Posted by dude_500 View Post

From what I've heard, yes the Koss cable is good. I just use generic ribbon cable, but I've had it go bad with broken connections inside the wire near the headphones after a few months of use. Also they're not the safest option, although at these voltages honestly they have plenty of insulation for realistic safety.

 

 

I've always glued the mylar to a spacer that has no copper on it at all, then put the conductive coating on after gluing, and sandwich a copper covered spacer down onto the mylar. This leaves the mylar with 0.5mm on both sides as desired, and the mylar is contacted without having to glue it to copper.

 

 

I have emailed the distributer to find out if I can get one - I am clearly in the wrong country to get hold of anything to do with Electrostatics, they don't even stock the 950's in the UK apparently!!

 

- Anybody got any advice on the Amp side of things?

 

Thanks,

 

Chaz

post #848 of 1487

Wachara C - Also how are you getting on this those enormous Jecklin Float type phones you mentioned a few posts ago? The drivers on them look instanely big jecklinsmile.gif

post #849 of 1487
Thread Starter 
The place to get 3 micron Mylar is at www.eraudio.com.au

if you want, you can also get the diaphragm coating material from them too. I've heard that it works well too.

About the Jecklin Float type headphones, it's just an itch I have right now. I might or might not build it. But believe me, for electrostatic type of headphones or speakers, size does matter. smily_headphones1.gif

Wachara C.
post #850 of 1487

If you want to know anything about DIY electrostatic amps just ask away.  Tubes, SS or crazy transformer hybrids... we've done it all.  redface.gif  I have one planned which has only two triodes in total for a fully balanced amp.  Not cheap and probably will sound quite... ehhh... special. 

 

Quote:
Originally Posted by chinsettawong View Post

Hi Spritzer,

 

I'm just having this itchy feeling after seeing many people posting about how great the new Jacklin Float sounds.  To me they are just big, and I'm sure that the size does matter.  It would be fun to try and see how good they can sound.  I can play around with the bias voltage to see what the most suitable voltage should be.  Without earpads, I'm sure that the headphones need to play a lot louder in order to sound decent.  By the way, do you think that the diaphragm size of 120 mm x 100 mm is close enough to the real thing?

 

Using series resistors shouldn't be a problem.  When I built my ESL speakers, I used 20 mega ohms series resistors.  They are just to prevent the possibility of large current going through.  I'm sure they won't hurt.

 

Wachara C.

 

The real thing was originally designed around RTR tweater panels and they were something like 5"x5" so 120x120mm is very close.  The biggest issue is the limited baffle range so that lack of bass that goes with it.  They don't go deep and the bass is all over the place. 

 

With the talk of cloning the HE90 I finally tried to install the present I got from you on Christmas yesterday and they are just a bit too big to fit in the HE90 frame.  I trimmed the connection tabs a bit and with the drivers mounted like the stock HE90 units (connections at the top) there is no way for the cable entry to work.  I'll try it the other way around and see if I can make it work but it is very tight indeed.  

post #851 of 1487
Thread Starter 
Quote:
Originally Posted by spritzer View Post

The real thing was originally designed around RTR tweater panels and they were something like 5"x5" so 120x120mm is very close.  The biggest issue is the limited baffle range so that lack of bass that goes with it.  They don't go deep and the bass is all over the place. 

 

With the talk of cloning the HE90 I finally tried to install the present I got from you on Christmas yesterday and they are just a bit too big to fit in the HE90 frame.  I trimmed the connection tabs a bit and with the drivers mounted like the stock HE90 units (connections at the top) there is no way for the cable entry to work.  I'll try it the other way around and see if I can make it work but it is very tight indeed.  

 

Thanks for the info on the Jecklin Float.  I understand that without good seal the bass won't be that good.  But it would be nice to try to see just how good they can actually sound.  To me, they're very easy to build since I don't have to find them the proper ear pads. :)

 

I'm sorry about the HE90 clone not fitting into the cup properly.  When I had my hand on HE90 the last time, I didn't want to open them up since they weren't mine.  So I did my best guess of how the drivers should be.  I think I must have made them a little bigger than the real thing. 

 

Wachara C.

post #852 of 1487

Cudo's to you man, this is amazing!  I love it!  Making your own equipment.  Did you learn this stuff in school or are you a born tinkerer?  

post #853 of 1487
Thread Starter 

beyersmile.png  Let me know if you can find a school where they teach you to build all these.  wink_face.gif

 

Wachara C.

post #854 of 1487
Quote:
Originally Posted by chinsettawong View Post

 

Thanks for the info on the Jecklin Float.  I understand that without good seal the bass won't be that good.  But it would be nice to try to see just how good they can actually sound.  To me, they're very easy to build since I don't have to find them the proper ear pads. :)

 

I'm sorry about the HE90 clone not fitting into the cup properly.  When I had my hand on HE90 the last time, I didn't want to open them up since they weren't mine.  So I did my best guess of how the drivers should be.  I think I must have made them a little bigger than the real thing. 

 

Wachara C.

 

Forgot one thing about the Jecklin, it's not the ballast resistor in the bias supply that I'm worried about but the 5K1 output resistors on each of the four outputs.  These are setup for the Stax load and will cause issues with much larger drivers.  I would just jumper them as we would need to do a lot of testing to find a suitable value for Jecklin's.  I just checked the Ergo amp schematic and there were no resistors in that one.  They did use 32M for a ballast resistor though. 

 

It took some creative cutting of the connecting tabs and violating the HE60 cable but I got them to fit.  redface.gif  The connection tabs are now less than 1mm strips but that's enough.  The problem was that when I mount them the correct way (tabs at the top) there is no way for the cable entry to fit as the bottom of the driver is right next to it.  Shave 1mm off the driver all around (so 2mm from top to bottom, side to side) it will fit just fine. 

 

I fitted them with loose fitting PVC dust covers but I need to clean them out as they squeal a bit.  They do sound good though, a bit "slow" compared to the Lambda Nova drivers I had before but pretty good over all.  Nice amount of bass though it rolls off a bit down low.  Top end has some bite to it but it's otherwise nice a smooth.  Midrange good as well but a bit... vague, diffused if you will.  I just realized after I wrote that that I was pretty much describing the HE90, though in broad strokes.  tongue.gif

 

I do have one suggestion, you could apply more tension to the diaphragm.  It's nice and stable but the HE90 and the Stax Omegas use even more tension.  Now back to some more listening... 

post #855 of 1487
Thread Starter 
Quote:
Originally Posted by spritzer View Post

 

Forgot one thing about the Jecklin, it's not the ballast resistor in the bias supply that I'm worried about but the 5K1 output resistors on each of the four outputs.  These are setup for the Stax load and will cause issues with much larger drivers.  I would just jumper them as we would need to do a lot of testing to find a suitable value for Jecklin's.  I just checked the Ergo amp schematic and there were no resistors in that one.  They did use 32M for a ballast resistor though. 

 

It took some creative cutting of the connecting tabs and violating the HE60 cable but I got them to fit.  redface.gif  The connection tabs are now less than 1mm strips but that's enough.  The problem was that when I mount them the correct way (tabs at the top) there is no way for the cable entry to fit as the bottom of the driver is right next to it.  Shave 1mm off the driver all around (so 2mm from top to bottom, side to side) it will fit just fine. 

 

I fitted them with loose fitting PVC dust covers but I need to clean them out as they squeal a bit.  They do sound good though, a bit "slow" compared to the Lambda Nova drivers I had before but pretty good over all.  Nice amount of bass though it rolls off a bit down low.  Top end has some bite to it but it's otherwise nice a smooth.  Midrange good as well but a bit... vague, diffused if you will.  I just realized after I wrote that that I was pretty much describing the HE90, though in broad strokes.  tongue.gif

 

I do have one suggestion, you could apply more tension to the diaphragm.  It's nice and stable but the HE90 and the Stax Omegas use even more tension.  Now back to some more listening... 

 

Thanks for all the infos.  If I move ahead with the Float project, I might have more questions that need your help. bigsmile_face.gif

 

As for HE-90 clone, when I played with it, I used 0.85, 1, and 2 microns film.  When I stretched them too much, I didn't get good bass.  At that time, I didn't tried them with 3 micron film.  With 3 micron film, I can certainly tension it a lot more and still have good bass.  If you already have some differnt Mylars, please try them and see what you like best.

 

About the squeal, I really think that spraying the copper side of the stators with a couple layers of laquer paint helps a lot.  The paint also protects the copper against the possible oxidation.  Please try.  L3000.gif

 

Wachara C.

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