I've been meaning to post these for awhile but haven't gotten around to it...
All DIY Electrostatic headphones and tube energizer
I'll start with the energizer;
The circuit is taken from here;
http://www.tubecad.com/november99/page8.html
I have owned a few Stax "earspeakers" and associated energizers and wanted to build something that was pure tube (well, except for the rectifiers). I wanted to build the circuit first and get it working before I tweaked anything so no boutique parts were used in the first run. I used good quality parts but no copper foil in oil coupling capacitors; JJ electroyltics, Sprague orange drop, and carbon film resistors in signal path.
A shot of the underside before installation in the wood (ipe) frame.
Another of the top plate installed in the base...
With the headphones I had a little help. A friend of mine in Thailand milled the stators and stator spacers on his diy CNC machine from 1mm circuit board material. This proves to be an excellent stator material as it is totally flat, has one conductive side, has a very consistent thickness and is easy to mill. The small tooth at one end of the stator gives a place to solder the cable to.
He also milled the stator housing from a plastic known as Sintra here in the states. Sintra is a vinyl with a slightly foamed core. Here is a picture of the stators, spacers, stator housings and headphone frame. I used a donor headphone frame from an old pair of headphones.
Stretching the diaphragm is a little tricky so I made a simple mechanism for tensioning it evenly. The clips grab the edge of the ultra thin mylar (.9 microns). The mylar has to be cut with a hot tool (soldering iron in my case) otherwise it just tears. Cutting it hot creates a very small bead along each edge that reinforces it and keeps it from tearing during the tensioning process. You can see the lead fishing weights underneath that provide the stretching force in each direction.
While the mylar is tensioned I applied the graphite solution. This is just a mixture of graphite powder, pva glue and water. Once the graphite layer is dry I spray the diaphragm stretcher (also made from 1mm board) with Super 77 and gently lay it on the stretched diaphragm. Working around the perimeter of the stretcher ring I ensure that the mylar is securely attached. Once I am sure I have a good bond I trace around the edge of the stretcher with a soldering iron cutting the assembly away. Here is a picture of the two diaphragms on their stretchers.
A picture of completed headphones. They are a little fugly at the moment but I plan to beautify them a bit. The wrinkled plastic you see is not the diaphragm but a layer on each side that is not tensioned and acts as a vapor barrier (sweat!). I used Koss ESP 950 earpads which worked very well. I also plan on acquiring a Koss ESP 950 extension cable to use instead of the ribbon cable I have presently.
So, how do they sound? Damn good The detail one can achieve with electrostatic headphones is nothing short of amazing. I haven't heard anything that allows you to hear into a recording like a good electrostatic (headphone) rig. No room interactions means no room induced colorations. They are definitely unforgiving of crappy sources. My squeezebox sounds like Sh!t with them but a good cd player can be revelatory. I would say these sound a lot like the Stax SR-404, which has a little coloration in the upper mids. Right now I think the energizer is outpacing the headphones, but I have plans to make another pair...
All DIY Electrostatic headphones and tube energizer
I'll start with the energizer;
The circuit is taken from here;
http://www.tubecad.com/november99/page8.html
I have owned a few Stax "earspeakers" and associated energizers and wanted to build something that was pure tube (well, except for the rectifiers). I wanted to build the circuit first and get it working before I tweaked anything so no boutique parts were used in the first run. I used good quality parts but no copper foil in oil coupling capacitors; JJ electroyltics, Sprague orange drop, and carbon film resistors in signal path.
A shot of the underside before installation in the wood (ipe) frame.
Another of the top plate installed in the base...
With the headphones I had a little help. A friend of mine in Thailand milled the stators and stator spacers on his diy CNC machine from 1mm circuit board material. This proves to be an excellent stator material as it is totally flat, has one conductive side, has a very consistent thickness and is easy to mill. The small tooth at one end of the stator gives a place to solder the cable to.
He also milled the stator housing from a plastic known as Sintra here in the states. Sintra is a vinyl with a slightly foamed core. Here is a picture of the stators, spacers, stator housings and headphone frame. I used a donor headphone frame from an old pair of headphones.
Stretching the diaphragm is a little tricky so I made a simple mechanism for tensioning it evenly. The clips grab the edge of the ultra thin mylar (.9 microns). The mylar has to be cut with a hot tool (soldering iron in my case) otherwise it just tears. Cutting it hot creates a very small bead along each edge that reinforces it and keeps it from tearing during the tensioning process. You can see the lead fishing weights underneath that provide the stretching force in each direction.
While the mylar is tensioned I applied the graphite solution. This is just a mixture of graphite powder, pva glue and water. Once the graphite layer is dry I spray the diaphragm stretcher (also made from 1mm board) with Super 77 and gently lay it on the stretched diaphragm. Working around the perimeter of the stretcher ring I ensure that the mylar is securely attached. Once I am sure I have a good bond I trace around the edge of the stretcher with a soldering iron cutting the assembly away. Here is a picture of the two diaphragms on their stretchers.
A picture of completed headphones. They are a little fugly at the moment but I plan to beautify them a bit. The wrinkled plastic you see is not the diaphragm but a layer on each side that is not tensioned and acts as a vapor barrier (sweat!). I used Koss ESP 950 earpads which worked very well. I also plan on acquiring a Koss ESP 950 extension cable to use instead of the ribbon cable I have presently.
So, how do they sound? Damn good The detail one can achieve with electrostatic headphones is nothing short of amazing. I haven't heard anything that allows you to hear into a recording like a good electrostatic (headphone) rig. No room interactions means no room induced colorations. They are definitely unforgiving of crappy sources. My squeezebox sounds like Sh!t with them but a good cd player can be revelatory. I would say these sound a lot like the Stax SR-404, which has a little coloration in the upper mids. Right now I think the energizer is outpacing the headphones, but I have plans to make another pair...
Last edited: