I built a single electrostatic speaker two years ago with the very limited information I could find on the Internet.I just couldn't believe that those things could actually work! While the speaker I built wasn't pleasing to look at (it is made out of artist canvas frame, balsa wood, shiny perforated aluminum, a ton of epoxy, a tangle of wires and some parts from an electrostatic air cleaner) the fact that it made sound amazed me! It even sounded much better than I expected.
The first thing I did was gather as much information as I could on the Internet which wasn't much. Only one or two sites provided any useful information, but one in particular, authored by Mark Rehorst http://www.glmt.com/esl/ proved to be invaluable.He gives some basic steps on how to build ESL'S. However, some of the materials he used weren't readily available to me so I mprovised a little. Here is a list of materials I used and were to I found them.
- Two sets of artist canvas frame that I bought at a local art supply store.The wooden frames were about two feet (61 cm) high by about one foot (30.5 cm) wide.I used these two frames to hold everything together, one for the front side one for the back. They are very sturdy and inexpensive, and there are many sizes available.These worked especially well for me since I have no woodworking equipment and very little woodworking skills.
- Perforated aluminum sheets, they are usually sold at hardware stores, but it took me several trips to different stores to find somebody in my area who carried them. They are thin, easily cut with ordinary tin snips or even a good pair of scissors.I think the sheets measured36 inches by 18 or 24 inches wide.
- For the diaphragm, I didn't know where to obtain Mylar sheets soI bought a 3M brand insulating kit, which contains some double sided tape and a huge sheet of thin plastic. It is designed to cover a drafty window and then shrink tight when heat from a hair dryer is applied, thus insulating the window. I don't think the plastic is Mylar, but it worked fine and it is very easy to find in early fall through winter in any hardware store,also, it is very inexpensive. (One of my several of my shopping trips for parts led me to a hobby shop, and I noticed that they sell plastic in rolls used for covering wooden model airplanes, it is designed to stick to wood and shrink very tightly when heat is applied, I bought some but never used it, seems like a good idea for a diaphragm, but I don't know how well it would hold powdered graphite because the plastic has an extremely smooth surface on one side.)I taped the plastic to a table and rubbed in powdered graphite as hard as I could into the plastic, this I thought was the hardest part of constructing my speaker. later when the plastic was attached to one half of the final assembly, I used a hair dryer to shrink the plastic and make it taut as I could without burning a hole in it.
- Powdered graphite, that I bought at an auto-parts store. very inexpensive.
- Balsa wood.Available at any hobby store. It is used for making model remote control airplanes.I used them to space the diaphragm from the aluminum sheets, because they are extremely thin and very easy to work with. this was a little pricey, but I couldn't, and still can't think of a better way to space the aluminum sheets from the diaphragm.
- A roll of aluminum tape I bought this at Radio Shack, a store that sells all kinds of electronic stuff .It comes in rolls of about 25 feet long and is about a half inch wide and paper thin.It is used in home security systems for something but I have no idea as to what. Crutchfield.com sells a similar product but they use it as speaker wire that you can stick to your walls and paint over instead of trying to hide regular speakers wires along your walls.I used this to provide current from a wire from the high voltage power supply to the diaphragm by sticking some all around the outside edge of the diaphragm. I made sure some of the tape came out the bottom of the speaker and put a screw or a nail through it and attached the wire to it using electrical solder. The tape is a little expensive, especially since I only used a few feet of it.
- Ordinary speaker wire. Attached to both sheets of aluminum between the sheets and the wooden frame any way you'd like. I just stripped about a inch of insulation off the wire and spread the individual strands out as flat as I could and taped it to the each aluminum sheet than I put epoxy over it and the aluminum sheet and glued that side to the wooden frame.Probably not the best way to attach it but it did the trick!
- Epoxy,I used this to glue the aluminum to the frames, then the balsa wood spacers to the aluminum, and finally, the diaphragmto the two sides, holding it all together. I reinforced the bond between the front and back frames by putting screws in the corners of the frame being careful not to put a screw through the aluminum sheets and the diaphragm.
- I made a power supply from a electrostatic aircleaner.These are about the size of a shoebox made to sit on top a desk or table.I think they are supposed to work by blowingair from a fan past sever thin metal plates that are under high voltage, and somehow this cleans the air that goes through it.Every once in awhile a piece of dust or something goes between the plates andthey will arc and make an annoying popping noise.These cleaners are expensive and I don't recommend buying one just to remove the high voltage power supply,I had one that was very old and the fan wouldn't spin anymore from all the dust that collected inside of it.Also, I couldn't find anyone back then who sold high voltage power supplies, So that was the only thing I could think of to use. Since the aircleaner used a/c electricity and converted it to d/c to operate the power supply internally, I cut a power cord off an old pair of computer speakers that plugged into an a/c outlet and converted the current immediately to 12 volts d/c. Theseinverters are used to plug in all sorts of things from cordless phones to the older Nintendos.I hope you understand what I'm talking about, anyway. . I used the cord to plug into the wall and change the current to d/cand then to go to the high voltage power supply and transform it to how ever many volts, I assume it was at least two thousand d/c volts but I have no way of knowing since I don't own a voltmeter.
- The only thing I didn't make from scratch was the matching transformer which I bought from a place called Antique Radio Supply in Arizona. Sorry, don't have the address.This was easily the most expensive part of my speaker and cost about $45.00.
That's pretty much how I constructed the speaker, after reviewing what I just typed I'm amazed this thing actually worked, as I'm sure you are too! Using some spring clip speaker connectors I bought from Radio Shack and a little wooden box in which I housed the transformer and power supply, I connected the power supply to the matching transformer and to the diaphragm, then the amp speaker outputs to the matching transformer and on to the aluminum sheets. Finally, I plugged the power supply in and turned the amp on. Then I put in a Queensryche CD...
Having a low power amp I can't say the music was loud but it sounded fine except for some hissing that I'm told was caused by applying too much graphite to the plastic.I was also told that eventually it would go away, but I never messed with it long enough to find out, as I only used it to amaze my friends for a few minutes at a time before my little amp would get too hot.later I connected the speaker toa Bose bass module (subwoofer) and with my graphic equalizer used to fine-tune. It sounded better than quite a few speakers I'd owned before (quite possibly because I've owned some cheap speakers), except for the constant hiss, which sounded like I was playing a old cassette tape, but you really couldn't hear when the music was playing.
This convinced me that I had to build a real pair of speakers the next time, and I will.Hopefully, I'll learn some tricks and tips from the ESL-Circuit site and pass along the ones I have as they come. One thing I will definitely do different next time is to buy a power supply from somebody instead of using the contraption I made. Here are a few things that might be usefull to anyone who decides to build ESL's the way I did.
- I do not consider myself an audiophile.I can't afford any of the high priced equipment,but I do appreciate the quality and sound reproduction of such equipment, and I love almost all forms of music. But, if someone is expecting a pair of Martian-Logan's building their ESL's like I did, they are going to be disappointed.
- I think the several thousand dollar per pair price tag for a pair ofelectrostatic speakers is outrageous since I built mine for about $100 dollars. And, I suspect that the pair I'm going to try and build next, with the help of some friends who can help me make them more pleasing to look at, should cost no more than a pair of ordinary speakers one would find at an electronics store, plus a couple of weekends to build.
- I have very limited skills with electricity or even building anything, for that matter.The speaker I built was ugly, but I was proud of it, and my friends thought I was some kind of genius, which I'm not at all. If I can do this with my very limited knowledge and skills, then anyone can. The key, I found, is to read as much as you can.I didn't have anybody to communicate withwhen I built my speaker, but I'm glad this will not be a problem for others since now there is The Audio Circuit, a resource for such information!
I'll answer any questions I can, but since this was my first ESL I might not always be able do so right away. Regards, Paul Parsley. You can contact Paul Parsley via The Audio Circuit.