I have just completed another DIY project of mine and I thought I'd just share it with everyone. So here's the story, I always wanted a pair of planar magnetic headphones but I am broke and I couldnt put down any money for them, so I decided to DIY my own pair of planars and drivers based on the information I found around the internet. I guess some might not consider these to be "true" planar magnetics since they only have one set of magnets below the membrane as opposed to some which have two sets, one above and one below the membrane. Sound wise they are not perfect, but I would say it turned out better than I expected.
The completed headphones, I used a collapsing earmuff which I found on amazon. I removed all the stuffing and put the drivers inside.
Here's the view from the inside, there is one rectangular driver per side, each measuring about 6 x 4 cm.
A view of my DIY planar driver, It has 7 rows of n50 neodymium magnets arranged with a thin membrane which has aluminium traces running perpendicular to the magnetic field. The black lines are actually aluminium traces which I have covered with a black marker pen (more on that later). For the membrane I used ordinary plastic cling film.
Here is the back view of the drivers, I had to use a clip to bind the wires to the membrane as I could not solder the wires onto them because the cling film cannot withstand the heat of the soldering iron. I used a metal plate glued onto a piece of acrylic as the frame for the magnets to sit on. I did not use a full metal plate like some others because I wanted to reduce the weight of the drivers.
This is how the membranes look like underneath. The width of each aluminium trace is about 1mm and the separation between each trace is 1 mm. I am using the episilon layout which was implemented so well by Henry of Diy audio (http://www.diyaudio.com/forums/planars-exotics/200038-analysis-epsilon-17.html). Out of making the headphones, I found this part to be the most difficult, as most of the resources available for the membrane are for full sized speakers which involve cutting thin strips of aluminium and sticking them manually to the film. I tried that approach but I could not go below 2 mm and unfortunately with my less than dextrous hands I cannot align them parallel to one another. That resulted in a really bad membrane, so I came up with this method to make the membranes by etching the aluminium foil.
Here is how I made the membrane, I glued a piece of aluminium foil to the plastic cling film which I wanted to use as the membrane. Then I used a permanent marker to draw the pattern of the aluminium traces which I would like to keep. The marker acts as a mask which protects those regions from being etched. After that I soaked the membrane into ferric chloride (pcb etchant) and it would dissolve all the aluminium except for the masked parts, producing the membranes.
Thats all... thanks for reading =).