An Unconventional Loudspeaker system Latest change 2019-01-22
Electro Static Loudspeaker, New Design
In january 2019 it turned out that some of the Solosound ESL
modules had some damage. Not suprisingly, they are over 30 years
So I decided to start a project to construct new ESL tweeters.
This is a project in itself and will take many months.
I have a construction in mind very similar to the Solosound
modules but with one module covering the whole area.
A board size of 200 x 150 mm is beyond the capabilities of my
Eagle licence, but I gave it a try with the feeling that the
limitations might only apply to placing components.
And indeed, I can make a single layer board of 200 x 200 mm
with only holes and copper pour. The schematic is empty
because there are no components.
I defined a hole with drill 157 mil = 3.988 mm and a cirle of
200 mil = 5.08 mm in layer 41, tRestrict for the solder mask.
The area inside the red dotted outline will be the copper
Screenshot from Eagle brd. Square layout.
This layout has an "openness" of nearly 0.5
Detail showing the holes and the copper area.
The copper stops at 0.5 mm from the edge of the hole.
The solder mask will cover the board upto the edge of the
holes, and so functions as an insulator, the same way the
laquer does on the Solosound boards.
I have to find out whether this is sufficient or whether more
insulation is required.
Screenshot from Eagle brd.
Simulation of the Electric Field.
With FEMM (Finite Element Method Magnetic, but it does
electric fields too) I made a simulation of the electric field
near one of the holes.
Simulation of field strength.
We see a cross section throug a 4 mm wide hole. At the bottom
sits the Membrane, modelled as a conductor on 5000 Volts. 1mm
higher is the FR4 material of the stator, (εr
= 4.4) also 1 mm thick. The copper at 0 Volts is under the
laquer layer (εr = 3) and
approaches the hole to 0.5 mm.
We can see that in the vicinity of the membrane the
fieldstrength is fairly constant. Also, no regions exhibit
extreme field gradients which might lead to sparking.
Legend for the field strength.
A new Transformer?
A new High Voltage unit?