Friday, December 21, 2007

DIY Electrostatic Loudspeakers / ESLs - Stators and Supports

In the initial step of the build, you are required to glue the white and black spacers to the support structures, but this was already done for me by ER Audio. This probably saved me a day or 2. Next the steel grids that formed the stators had to glued to the support structure.Here I have the Support Structures and Stators laid out in a dry run to make sure everything fits.... and it does, perfectly. It also helps me figure out where everything goes. The picture shows the narrower treble panels. The large white bottle that you see is the polyurethane glue that will be used to attach the stators to the support structures. The glue takes 24 hours to cure and is very very strong. Good stuff. Also shown in the picture are wooden strips that will be used as pressure pads. These pressure pars will be used to push the stators and the support structures together to ensure a good bond during the curing process. I also lay out the stators for the full range panels. Notice that the screws that will transfer the +ve/-ve charge to the stators are 'brazen' in place. Again, a very elegant and simple design.There are 2 treble and 4 bass panels, in total 12 stators and 12 support structures to glue. This could get tedious. So I setup a 'production line' where the polyurethane glue is rolled onto 4 stators at one time. The polyurethane glue is rolled onto on the entire stator, this serves 2 main purposes; 1. to glue the stators to the support structure; and 2. to dampen the stator from vibrations and ringing as it is only 0.6mm thick. The Polyurethane layer applied is very thin usnig a mini paint roller. The polyurethane is applied over the entire surface on one side of the stator only. The stator side that will eventually face the diaphragm is left clean. If you are thinking that the polyurethane serves as an insulator, I cannot be sure of how well it will serve as a insulator, especially with so much voltage running through it. Best is still to avoid coming into contact with the speakers when it is in operation.
The Support structures are laid out on the table, ready to accept the stators once the glue is applied. There are in total 8 full range panels and 4 treble panels to be glued. So I do it in 3 runs of 4 each, thats 3 days of gluing, curing and waiting.... ho hum. After rolling on the polyurethane glue, I place the stators on the support structure. And the I use the pressure pad and weights to ensure a good bong all along the surface of the panelI found a way to weigh down 2 panels at a go... The next picture shows the first batch of 4 panels fully cured after more than 24 hours of bonding under pressure. While applying the polyurethane, the roller brush left many tiny bubbles, shich you can see in the picture. For the 2nd and 3rd runs, I worked out a simple brushing technique that got rid of the bubbles very effectively. You learn real quick when doing this.After gluing all the stators to their support structures, I place them all againt the wall for a dry run fitting using the channel clamps.This is how a completed side of the ESL would look like... a treble panel sandwiched by a full rnage panel on either side.A closer look at one of the full range panels fitted with the channel clamp. Remember that a panel is made up of 2 support/stators, I attached the channel clamps to the front and rear support/stators that make up one panel. As expected the clamp is very tight and also serves as a well insulated frame so that the completed panel can be handled safely. The only concern here is that because the clamps are so tight, I may damage the diapharms when I finally assemble the completed panels. Guess I need to practice this somemore before I do it for real.

ext I install the clips and copper strips. The clips will be used to connect the wires to the EHT aupply that will eventually bring electric charge to the diaphragm. Here is the clip installed on the support structure. I attach the clip first so that I know where the copper foil needs to exit the air gap spacer on the other side. The copper foil will come into direct contact with diaphragm, thus delivering the EHT charge. Before I attach the copper foil, I lightly sand the air gap spacers so that the surface is smooth and free of any adhesives that may be left over from the production process or from the previous tasks. Once done I clean the air gap spacers with some thinner. Only after I am sure the surface is clean and smooth do I attach the copper foil to the air gap spacers.This is a relatively simple task but one must be very careful with the foil as it is very thin and can snap as you fold in 90 degrees at the corners.So that's it, the stators/support assembly is completed.

The next step is the Installation of The Diaphragms

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