I don't have the time to make a detailed building plan of this speaker, but if you follow the instructions below, and use some inspired thinking power, you will find it not too hard to build.
There are four water cut stainless steel frames,4 mm thick, with handmade 4 mm holes for the screws. Two of the frames are lined on the inside with 2 mm neoprene rubber for membrane gripping. Use rubber glue when gluing the neoprene to the steel. Mount the two frame halves together with all the screws and let the glue dry for a few days. Then take it all apart again.
A lined back frame is put on a big table, rubber side up. 12 uM mylar film, conductive side up, is placed over this frame and stretched with many 50 mm wide clear packing tape strips, 70 mm apart.
When stretching the film, pull the tape strips almost to the breaking point.
When you have placed stretched tape strips all around the perimeter, put the unlined front metal frame on top and start screwing. Pull the screws AHAP (As Hard As Possible).
The film I use is very similar to the M-L film, with a sputtered thin metal layer.
Done! Sounds easy, doesn't it?
Today I use a B&G Neo3 planar dipole tweeter for the top end. This allows me to drive the Esl with ten cheap ordinary, series coupled, 220/9 Vac, 40x40 mm, encapsulated, circuit board power transformers up to appr. 5 kHz.
These transformers are impossible to destroy with any amp!
The bias voltage is obtained by connecting a seven step ladder to the balanced output of the drive transformers via two 1,5 MOhm 2 watt resistors.
The input of the ladder is protected from voltage transients by a 220 Vac varistor. The output is connected to the front metal frame via six 10 MOhm resistors and three 1N4007 diodes in series.
Good Luck!
PS. I use my ears when building speakers, but I will do some frequency measurement with HolmImpulse when i find the time.
