My DIY electrostatic headphones
Mar 13, 2015 at 4:27 PM Post #1,726 of 4,063
Tried this to get rid of imbalance on my SR-5/NB :

 
Didn't work, don't use it for your DIY projects 
redface.gif
 
 
Ali
 
Mar 13, 2015 at 10:40 PM Post #1,727 of 4,063
Hi Ali,
 
Can you describe what you have done so far to fix the imbalance issue?  After you've applied the iClean, is the sound louder, quieter or same, same?  How do you apply it? 
 
Can you post some pictures of your SR-5?
 
Wachara C.
 
Mar 14, 2015 at 2:51 AM Post #1,728 of 4,063
I did not go trough the entire thread, so please forgive me if this was mentioned before. Material suitable for the graphite coating on plastic films is colloidal graphite in water,  commercial name Aquadag, what it used to be the company called Acheson, being somewhere along the way acquired by Henkel :
 http://www.henkelna.com/about-henkel/product-search-1554.htm?nodeid=8798046388225
For the ESL diaphragm coating, it can and has to be dilluted VERY MUCH - and you can control the resistance by either leaving it as it dries (higher resistance ) or buffing it GENTLY (lower resistance) - gently enough not to remove it altogether.
 
It was used in DIY project for ES headphones by Pollock in Wireless World - not only for the coating on the diaphragm, but in an almost undilluted state for stators as well; as graphite coating on acrylic perforated plate. The design allows for minimum stray capacitance, as the stator has conductive surface only over the actual diaphragm area and does not extend over the spacer area, which does not contribute to the output and its additional capacitance ( as in most metal stator designs ) detracts from the performance ultimately achievable, particularly in the high frequency response.
 
Mar 14, 2015 at 11:16 AM Post #1,729 of 4,063
  Hi Ali,
 
Can you describe what you have done so far to fix the imbalance issue?  After you've applied the iClean, is the sound louder, quieter or same, same?  How do you apply it? 
 
Can you post some pictures of your SR-5?
 
Wachara C.

Hi Wachara,
 
it's my first attempt to fix the imbalance. I've learnt two days ago how to open the driver, I've trained myself on my junk SR-X/mk3. I've to say I'm impressed by the smart engineering of these things : everything is small, but incredibly solid, well-adjusted and easy to service.
 
To apply the iClean, I've sprayed it on the microfiber, then extremely gently rubbing the driver against it, on both sides. I've been a bit generous, so it takes around one minute to dry, but I've waited 10 minutes before re-assembling the driver. The sound is exactly the same.
I've tried the same on the crackling drivers (no holes though, but 2-3 very small black points...arcing ?) of my SR-X, and the result is the same : no improvement, no worsening.
 
I plan to test another "real" antistatic product (or rinse aid...davidsh ?), and use some very light paintbrush for coating...but I'll listen to any of your experienced advice at first
redface.gif
 
 
I don't have pictures of my opened SR-5, but here it is :

 
The overall condition is very (very) good, so I really do want to fix them 
smile_phones.gif

 
Ali
 
Mar 14, 2015 at 12:19 PM Post #1,730 of 4,063
That looks to be a very good condition pair of headphones. 
 
It'll be a pity if you can't fix it.  I would really like to see the inside of the phones.  If I can see it, I can probably help you to fix it.
 
I'm sure there are 2 dust covers, 2 stators, 2 spacers and a diaphragm on each driver.  Can you tell me if the 2 spacers firmly glued to the diaphragm?  I just hope that the diaphragm is only glued to one of the spacer ring as it'll be a very difficult fix if the two spacers are permanently glued to both sides of the diaphragm.
 
Wachara C.
 
Mar 14, 2015 at 1:26 PM Post #1,731 of 4,063
There is no "free" spacer in the driver, both ones are making a sandwich with the diaphragm :

As you can see, there is a kind of rainbow haze on which the iClean had zero effect.
This new unmounting / re-mounting session hasn't change anything, no improvement (fair enough), no worsening (breathe...).
I'm pretty sure it has something to do with the coating I've used since it had also zero effect on my SR-X drivers.

Ali
 
Mar 15, 2015 at 11:05 PM Post #1,732 of 4,063
  There is no "free" spacer in the driver, both ones are making a sandwich with the diaphragm :

As you can see, there is a kind of rainbow haze on which the iClean had zero effect.
This new unmounting / re-mounting session hasn't change anything, no improvement (fair enough), no worsening (breathe...).
I'm pretty sure it has something to do with the coating I've used since it had also zero effect on my SR-X drivers.

Ali

 
That's the kind of design I don't like.  By the way, are those spacer rings metal?  Or are they made of PCB?
 
The problem could come from the coating deteriorates over time especially around the corner where it's suppose to contact with the charge ring.  If the rings are made from metal you might want to put more coating around the inner circle edge to help getting the bias voltage from the ring to the diaphragm.
 
By the way, I think your coating spray works just fine.  Otherwise, the sound should be softer as you have already cleaned out the old coating.
 
Wachara C.
 
Mar 16, 2015 at 8:28 PM Post #1,733 of 4,063
I also have some SR-X mk3 with an imbalance. When they arrived one of the diaphragms was stuck to a stator (a failure mode I see in a lot of old electrostats). I took it apart and very carefully peeled it off causing only one spot of minuscule damage to the diaphragm, not a tear. The balance was way, way off so I took them apart again and cleaned the diaphragms and put anti-static coating on just as I do in all my DIY drivers. They got a lot better, but the balance is still way off. Let me know if you figure it out! Since the diaphragm is permanently sandwiched between the two spacers, I don't know if it's possible to really get a good repeatable electrical contact to the coating.
 
Mar 17, 2015 at 12:09 AM Post #1,734 of 4,063
This is Awesome!!!  I have to ask a few questions though, what CNC mill do you have (bed size, tolerances, etc.), and how do you like it (would you get a different one if you had the chance)?  Does it have some sort of cooling system? I am looking to get one (maybe once I have a real job) for all my DIY needs.
tongue.gif

 
Mar 17, 2015 at 12:00 PM Post #1,735 of 4,063
  This is Awesome!!!  I have to ask a few questions though, what CNC mill do you have (bed size, tolerances, etc.), and how do you like it (would you get a different one if you had the chance)?  Does it have some sort of cooling system? I am looking to get one (maybe once I have a real job) for all my DIY needs.
tongue.gif

 
My CNC router table is about 1200 mm x 800 mm which is way too big for making headphones.  If I were to make a new one, I would probably make it 800 mm x 600 mm.
 
At the beginning I just use a simple wood router for the cutter.  But I have now upgraded it to be a variable speed spindle motor.
 
Wachara C.
 
Mar 17, 2015 at 5:16 PM Post #1,736 of 4,063
  I did not go trough the entire thread, so please forgive me if this was mentioned before. Material suitable for the graphite coating on plastic films is colloidal graphite in water,  commercial name Aquadag, what it used to be the company called Acheson, being somewhere along the way acquired by Henkel :
 http://www.henkelna.com/about-henkel/product-search-1554.htm?nodeid=8798046388225
For the ESL diaphragm coating, it can and has to be dilluted VERY MUCH - and you can control the resistance by either leaving it as it dries (higher resistance ) or buffing it GENTLY (lower resistance) - gently enough not to remove it altogether.
 
It was used in DIY project for ES headphones by Pollock in Wireless World - not only for the coating on the diaphragm, but in an almost undilluted state for stators as well; as graphite coating on acrylic perforated plate. The design allows for minimum stray capacitance, as the stator has conductive surface only over the actual diaphragm area and does not extend over the spacer area, which does not contribute to the output and its additional capacitance ( as in most metal stator designs ) detracts from the performance ultimately achievable, particularly in the high frequency response.

In Material Safety Data Sheet of Aquadag you can find:
 
"Incompatible materials:   Copper.Zinc.Aluminum."
&
"Conditions to avoid:   Keep away from heat, ignition sources and incompatible materials."
 
I am not sure if it is good idea to use it in ESL drivers.
 
Mar 17, 2015 at 5:25 PM Post #1,737 of 4,063
  In Material Safety Data Sheet of Aquadag you can find:
 
"Incompatible materials:   Copper.Zinc.Aluminum."
&
"Conditions to avoid:   Keep away from heat, ignition sources and incompatible materials."
 
I am not sure if it is good idea to use it in ESL drivers.

I did state the general materials of the ESL driver by Pollock. Aquadag does not come in contact with any of the mentioned materials. Even aluminium stators are either anodized or covered with high voltage resistant paint - there is no such thing as practical bare Al, Cu or Zn stator.
 
There is no heat in properly dimensioned ESL driver, there are no ignition sources either.  Should the driver arc for any reason, the result is burnt off portion where the arcing occured and not an open fire.
 
Mar 17, 2015 at 6:13 PM Post #1,739 of 4,063
  How do you connect coated mylar to BIAS source? I do it with copper on PCB or copper wire. But it is always copper or aluminum.

Just use a little dot of undiluted (paste) Aquadag between the stator and and coated mylar. It spreads over larger surface and creates less of a dimensional disturbance than any metal type contact would. 
 
I would have to check for the integrity of the ultimately copper wire/Aquadag contact (drivers in storage for over 15 years by now ) - but during the operation I do not remember any catastrophic contact failures. 
 
Mar 17, 2015 at 10:55 PM Post #1,740 of 4,063
Hi All,
Joined up a few hours ago.  I've been following the My DIY ELECTROSTATIC headphones thread for as long as it takes to read end to end and digest some of what I read.  My intention is to build a decent pair of electrostatic head phones. I'm a regular over on the DIY audio forum and have been heavily involved in the passive mechanical linear tracking tone arm development.  Back in the early 1960s I made successful electret microphone capsules using aluminized mylar film and charging the electret in an oven with polarizing potential applied.   Played around with ESL by throwing a window screen on the carpet with a two foot square of aluminized mylar on top of it and tying the conductive side of the mylar to the plate of a 6L6 output tube, and the window screen to ground. Polarizing voltage and audio all on one wire.  The sound was incredible for the time even though it emerged in a pencil thin beam directly over the center of the diaphragm. I fully expect that these crude early experiments will not be repeated and a real fine product will emerge.I am looking forward to participating in this forum. Best regards to Chinsettawong and  all you members whose postings I've been reading for some time now.
BillG 
 
I apologize for posting here if inappropriate.  I have been trying to determine exactly how this forum is set up and the correct way to participate..  Not the easiest thing to do. This thread seems to be where I will be and covers what I'm most interested in.  Please inform me if I'm out of line in any respect.
Thanks
BillG
 

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