You can have the details, but consider the project a partial failure.
Size: 23x60 cm (approx.)
Spacer thickness: 1mm (approx.)
The material used is double adhessive foam tape. The configurations is 2 cm tape around the edges, a strip of 1cm tape in the middle.
The diaphragm is coated with rinse aid, which seems to work.
The diaphragm is made of food film ~11um
Bias voltage: Between 500-1000 volts
Step-up: 2x1600/1x200 in 3 phase iron core configuration, with small and very poor inductors used for general use in the physics class.
Also tried my SRM-T1 for driving the panel (580 volt pro bias).
I've got to look into electrostatic induction, somehow I thought the diaphragm wouldn't be subjected to any force when there'd be no potential between the stators as that'd mean no electric field between the stators eg. no forces acting on the charge of the diaphragm.
This seems to be wrong.
I find it difficult to understand this concept. Is it much to ask that you break it down (when there's voltage potential between the stators and when there is no potential) or refer me to some litterature?
OK - the truth and nothing but the truth.
ES drivers are in principle perhaps the simplest to make - of all the generating priciples.
They are equally the most difficult to make them work right. Because they have to be geometrically exact and have to keep that geopmetrical perfection to work - no matter what.
I will tell you the true anecdote regarding the ES headphones by Neil Pollock, published in Wireless World in late 70s ( I shared the link ). Three students , me included, saw the article the same day. One had his drivers made from phenolic prototype printed circuit board and driven by some transformers in two days - and it fared no better than yours, despite being much smaller in size. The second did a bit better, in about two weeks - also transformers - but to stay on the polite side, let's say he demonstrated ES could potentially work...
I had to get a pro forma invoice, order the Aquadag, wait till it arrived, cleared the customs - before I could do "anything", it was almost two months. Remember, that was in 1980-81, snail mail, Yugoslavia. I did prepare in between the acrylic stators, spacers, etc - but could only proceed after getting Aquadag.
First, I used transformer. It worked - but was not an improvement over Audio Technica ATH-7 electret headphones I owned at the time as I have hoped for.
Enter amplifier. It took me almost 6 or so years, building various amps, before I found something that finally did satisfy me. And better drivers, etc, etc.
If you can, I suggest going to see Quad latest ESL speakers - they differ from their immediate predecessors primarily in how the stators are strenghtened against curving, resonances, etc - and thus achieve even better loudness and better bass, while at the same time having less distortion.
In short, the very first thing an ES driver must NOT be is - a propeller. It should be one precise plane, not twisted and curved. And making this reality is hard - VERY hard. Sennheiser went to untold extremes in their Orpheus - Quartz Glass electrodes (gold plated for conductivity ) that are about the most plan/flat thing on earth, encased in some hard wood from Africa usually used for - propellers in aircraft. Because it resists the deformation better than almost anything else, regardless being hard to machine well. No wonder it was lots of $$$$$.
Regarding literature - http://www.amazon.com/Electrostatic-Loudspeaker-Design-Cookbook-Sanders/dp/1882580001 There was a series of articles on ES drivers in The Audio Amateur, later (reprinted) in The Speaker Builder ( google is your friend - perhaps they are still available as download ) - both by Sanders ( practical guy) and Ronald Wagner (scientific guy) http://www.hificollective.co.uk/books/bk5004.html - and it was more than a mild acrimony between the two. Yet both are very helpful at understanding why and how ES works and what can be made to make practical designs that can be duplicated by a dedicated DIYer.
You can wrap it any way you like - the EXACT method of
HOW it is made in top commercial designs that were and are successful in the market will most likely be
never revealed - it can be one's lifetime work to figure out how to make that driver that was just a bit "off" finally "perfect" - would you spend your entire work life just to be able to give everything away in a forum - for free ?
This is the primary reason why ES is not more widespread.
And we have not even touched the amps driving these drivers...
