Julez
Member of the Trade: (Repairs Stax headphones)
I am also planning to build my own electrostatic headphone. I want to make a huge Jecklin Float type headphone.
My plan is to go with 100x120mm active area. The drivers will be made of PCB in 1 or 0.5 mm thickness. I want to
make a 3d printed housing and be able to move the drivers into proper position (distance and angle to the ears) as
every head is different.
I have allready started to repair Stax drivers from an SR-5, SR-Omega and a 507 Lambda (the glued drivers are a
pain as it is practically imposible to disasemble the divers if there is a problem). SR-Omega and SR-5 are screw
together and can be easyly reopend. I use a frame that was cut at the corners and can be pressed apart with screws.
I glue the Mylar (1.5 micro) with doublesided tape to the longer sides of the frame and tighten it with the wooden
latch to the frame with a protective ducktape between the Mylar and the latch.
I was successful in making drivers from my SR-Omega that are working fine without any dustissues for a few months.
But as Wachara said before: It was a trail and error to get the proper tension. I use 1.5 micro Mylar and stretch tight.
Then I use a head gun and warm the mylar to about 150°C and stretch it again. I do this two or three times. At the end
I try to get the tension nearly the same over the whole surfcae checking it by knocking with my fingernail to different
parts of the membrane. The I glue the metal rings onto the mylar by putting a glassplate exactly underneath the mylar
and then another glassplate on top of the metal rings. I use some heavy books to have good pressure on the metal rings
while the glue (I use Pattex 100% glue without solvant). It takes about 1-2 hours to dry enough to flipp the stretcher and
I do the same with the glassplates to put pressure on the rings when gluing the spacers to the other side of the Mylar.
After another 1-2 hours. I have tried diffrent types of glue and had the problem that many epoxy glues or contact
cement where drying to fast form me and therefore did not stick properly in the end. The Pattex has another advatage
in my opinion. It is strong enough to hold the Mylar when dryied but can be cut open again without too much hassle.
Another thing I had when gluing mylar with glue containing a lot of solvent was that some parts of the Mylar where
affected and turned milky.
When the glue is dried I cut the membrans out with a soldering iron that I also use to carefully remove the rest of the
Mylar around the drivers. I coat the membrans on both sides (as Stax does it) with a thinned antistatic agent applied
with a sponge. I make shure to also coat the inner side of the metal spacer as this is where the bias gets to the
membrane (the glue is an isolator). I tired to measure the resistance of the dried antistatic but my meter showed
nothing (It can measure up to 2gigaohm with up to 1000V). So I think my resistance must be higher than 2 gigaohm.
My experience with the Omega is that it has no charging time to reach full volume and it is of corse equally loud on
both sides. I also reworked an old non working Jecklin Float with this method. Of corse I did only coat one side of
the Float membrans because of the design. It has only one metal stripe to connect to one side of the membrane.
And as there are no seperate spacers (they are integrated in the stator) I could not coat the membrane on the side
faceing the stator. I just coated the opposite side and then (still in the stretcher) put the other stator on the coated
side (after coating was dried) and screwed both together as Wachara does this with his designs. I had to manipulate
the stators and drill bigger holes into it to be able to use screws. Again it allows for better maintainance if there is a
problem with the driver. Sorry but I forgot to make pictures of the Float drivers during the work. But here are pics of
the Omega and Lambda drivers:
Basically I found out what Wachara allready stated. 1.5 micro Mylar is very tricky to handle and
it takes a lot of trail and error to get the right tension. I never had too much tension on a driver.
Only not enough. You are right if the tension is nearly maximum and another tiny bit of stretching
and the Mylar would rip apart. I only got the right tension with heat treatment. With the coating it
is another story. Like I said I could not measure the resistance. I am not really shure it was because
of too high resistance or bad contact. The agent I use is not commercially available. It is a basic
solution for making commercial antistatic. I used 20 parts alcohol (in Germany called Spiritus) and
one part antistatic and applyed a thin layer of the mixture (as thinn as possible but covering the
whole Mylare surface). When the coating has dried I apply it to the other side and let it dry again.
Then I use a very soft brush when assabling the drivers to clean everything carefully (including
the membrans on both sides). Ready. Or there is noise and I have to open the driver again and
clean everything. Sometimes serveral times.
I hope this is helpful for anyone trying this at home! If there are still questions feel free to ask!
My plan is to go with 100x120mm active area. The drivers will be made of PCB in 1 or 0.5 mm thickness. I want to
make a 3d printed housing and be able to move the drivers into proper position (distance and angle to the ears) as
every head is different.
I have allready started to repair Stax drivers from an SR-5, SR-Omega and a 507 Lambda (the glued drivers are a
pain as it is practically imposible to disasemble the divers if there is a problem). SR-Omega and SR-5 are screw
together and can be easyly reopend. I use a frame that was cut at the corners and can be pressed apart with screws.
I glue the Mylar (1.5 micro) with doublesided tape to the longer sides of the frame and tighten it with the wooden
latch to the frame with a protective ducktape between the Mylar and the latch.
I was successful in making drivers from my SR-Omega that are working fine without any dustissues for a few months.
But as Wachara said before: It was a trail and error to get the proper tension. I use 1.5 micro Mylar and stretch tight.
Then I use a head gun and warm the mylar to about 150°C and stretch it again. I do this two or three times. At the end
I try to get the tension nearly the same over the whole surfcae checking it by knocking with my fingernail to different
parts of the membrane. The I glue the metal rings onto the mylar by putting a glassplate exactly underneath the mylar
and then another glassplate on top of the metal rings. I use some heavy books to have good pressure on the metal rings
while the glue (I use Pattex 100% glue without solvant). It takes about 1-2 hours to dry enough to flipp the stretcher and
I do the same with the glassplates to put pressure on the rings when gluing the spacers to the other side of the Mylar.
After another 1-2 hours. I have tried diffrent types of glue and had the problem that many epoxy glues or contact
cement where drying to fast form me and therefore did not stick properly in the end. The Pattex has another advatage
in my opinion. It is strong enough to hold the Mylar when dryied but can be cut open again without too much hassle.
Another thing I had when gluing mylar with glue containing a lot of solvent was that some parts of the Mylar where
affected and turned milky.
When the glue is dried I cut the membrans out with a soldering iron that I also use to carefully remove the rest of the
Mylar around the drivers. I coat the membrans on both sides (as Stax does it) with a thinned antistatic agent applied
with a sponge. I make shure to also coat the inner side of the metal spacer as this is where the bias gets to the
membrane (the glue is an isolator). I tired to measure the resistance of the dried antistatic but my meter showed
nothing (It can measure up to 2gigaohm with up to 1000V). So I think my resistance must be higher than 2 gigaohm.
My experience with the Omega is that it has no charging time to reach full volume and it is of corse equally loud on
both sides. I also reworked an old non working Jecklin Float with this method. Of corse I did only coat one side of
the Float membrans because of the design. It has only one metal stripe to connect to one side of the membrane.
And as there are no seperate spacers (they are integrated in the stator) I could not coat the membrane on the side
faceing the stator. I just coated the opposite side and then (still in the stretcher) put the other stator on the coated
side (after coating was dried) and screwed both together as Wachara does this with his designs. I had to manipulate
the stators and drill bigger holes into it to be able to use screws. Again it allows for better maintainance if there is a
problem with the driver. Sorry but I forgot to make pictures of the Float drivers during the work. But here are pics of
the Omega and Lambda drivers:
Basically I found out what Wachara allready stated. 1.5 micro Mylar is very tricky to handle and
it takes a lot of trail and error to get the right tension. I never had too much tension on a driver.
Only not enough. You are right if the tension is nearly maximum and another tiny bit of stretching
and the Mylar would rip apart. I only got the right tension with heat treatment. With the coating it
is another story. Like I said I could not measure the resistance. I am not really shure it was because
of too high resistance or bad contact. The agent I use is not commercially available. It is a basic
solution for making commercial antistatic. I used 20 parts alcohol (in Germany called Spiritus) and
one part antistatic and applyed a thin layer of the mixture (as thinn as possible but covering the
whole Mylare surface). When the coating has dried I apply it to the other side and let it dry again.
Then I use a very soft brush when assabling the drivers to clean everything carefully (including
the membrans on both sides). Ready. Or there is noise and I have to open the driver again and
clean everything. Sometimes serveral times.
I hope this is helpful for anyone trying this at home! If there are still questions feel free to ask!
