#electrostatic speakers

[nobrashfestivity]

Speaking of Faye's Quad speakers, in real life they look like this

or this (Faye looks like she has the light grille-cloth)

Or if you don't like 16 ohms but love spending money you can do what i did and stack a 4 of them (a quad even).

My stands aren't as fancy but same thing.

"No I think our loudspeakers are very poor."

Peter Walker, inventor of the Quad ESL speaker

[audio-luddite]

Trolling the market.. DANGER!

I saw an ad for a rare, once very high end, set of speakers. They were local (yikes), quite cheap,( double yikes ) and have a hidden danger.

A very long time ago I built big electrostatic speaker arrays. They sounded remarkable. Around that same time there was a product called the Dayton-Wright Electrostatic Speaker. It was made in Eastern Canada and was one of the really good ones.

Recently a small company has been buying up old D-Ws and refurbishing them to sell in a VERY expensive speaker system.

These speakers are the ones that inspired me to build electrostatics. I knew a lot about them.

Some people (as once I did) consider electrostatics as the best concept for an audio speaker system. I have discussed before the limitations of all planar speakers.

Electrostatics are dangerous. Sometimes. D-Ws were about the most dangerous. They had an unseen danger.

They function with high voltages. Very high voltages. It can be extremely low current. I mean I have zapped my hand on a doorknob after crossing a carpet. That is not dangerous. A speaker can have substantial current. I once fried my hand with a speaker bias power supply. Once you have done that tube amplifier voltages seem modest.

This voltage is limited by how much the air at various humidity levels resists arcing. At enough bias you get sparks bouncing between the diaphragm and the stators that make the speakers work. That damages the diaphragm and can be scary. Dayton Wrights were done with very clever engineering where the drivers were held inside a containment that was flooded with a gas. That gas enabled much higher voltages and that facilitated better performance.

The ad in the Canuck Audio Mart never mentions any gas, but still claimed they worked OK. One danger for me is the fact the price was so cheap. I got buying it twitches. But the other is this gas.

Sulfur Hexafluoride is a clear, odorless, almost totally benign gas that has a very high dielectric constant. It is an insulator. It is used in high voltage power switching for one thing. It is also very heavy about 5 times heavier than air. It is not poisonous, but it will accumulate in low areas and displace air so it can suffocate people and pets. As it is heavy it lowers resonant frequencies. It can be used as a "party Gas" like Helium to make your voice sound really different. But you can suffocate. Oh and if it does find an arc it can produce an extremely toxic poison gas. So Much Fun.

I expect that over the decades this has been forgot about.

Back in the old days users would need to keep a tank of this stuff around to fill the speakers as they ran low. They always leaked. The gas is available from industrial supply shops, and is easy to get. Probably not good to set up in a basement though.

[audio-luddite]

Electrostatic Speakers.

They are out there. There are things I like and things I don't about them. Many years ago I thought they were the best you could have. And that is what I wanted. Full range from low to high no cross-overs, seamless sound. The large surface area couples almost ideally to the air in the room so converting electrical signals to sound waves is very efficient. Mostly true then and still today.

The down side is dipole radiation so the back wave bounces around and can cause weird effects. Some of those are very pleasant. Placement in the room is difficult. Another thing is limited low frequency response as the wavelength approaches the size of the speaker. Not so bad if you make them BIG. Bwah Ha Ha Ha!

Ironically they are the easiest to build from scratch. Mechanically they are so simple. I had a basic design from a 1970s issue of "Audio Amateur" and I was off to the races. Two sheets of perforated metal each with a thin frame of polycarbonate and a sheet of mylar with a conductive coating in a sandwich. A bit of work, some funky jigs and a lot of epoxy was all it took. I was turning out an 18" by 48" by 1/4" panel every week. I needed 6 of them.

The principle is very simple. You polarize the membrane with a thousand volts DC (more or less). Attach the outputs (high voltage) of an audio quality transformer to the front and back with the center tap on the polarized sheet ( think through a capacitor to block deadly levels of DC ) and physics does the rest. Execution is not so simple. I needed transformers and the logical source was out of a tube amplifier. More logic told me to buy operating tube amps and hook up the primaries to the speaker poles.

In the end I had two huge wood frames over five feet square, (not five square feet ) each holding three of my panels. I had a tube amplifier on station beside each frame operating as full range ES speakers.

It did not go perfectly smoothly. I found I needed to limit the width of the free membrane to prevent arcing so there was some trial and error. I almost blew myself up with the polarizing power supply. I had a hard time tracking down those tube amps too. But it all worked in the end.

And yes there was a severe roll off in the deep Bass, but a big woofer cabinet took care of that with a cheap used transistor amp. The cross over was a trick, but it all ran nicely. Audio nirvana was mine.

The sound was amazing. Thing is when you invest a lot of work and worry into a thing it does skew your opinions. There were flaws but I did not mind them so much. They were huge and imposing. That is the image of a hardcore audio nut isn't it? A chair, two huge speakers, wires all over the floor, and a stack of records. Been there.

OK why talk about this now? Two reasons. One is my last post was about a review of an amplifier and one of the speakers used in the test was the KLH 9. It is a full range electrostatic speaker from I think 1958. I think they started to make them again. Those looked a lot like my version 2 electrostatics. I thought about those for the first time in a long while.

Way back when I met a girl. I married her and we moved a couple times. I moved those big ass speakers once and promised never again. I took them apart and packed away the bits for the future. In the meanwhile I built a few simple small speakers in boxes and was impressed how they did not sound all that bad compared to the monsters.

Version 2 arrived after a few more moves when I decided to resurrect the beast in a reduced form. One panel per side rather than three. Simple frame, everything else about the same. Still sounded pretty good. There is always a but.

The flaws in the ES concept are several. Dipoles have equal output front and back. There is a lot of cancellation, and a lot of the signal is reflected about. The narrower the dipoles the worse that is. The membrane is like a drum skin and has a fundamental resonance very similar to a large drum. Bong! Dispersion of the high frequencies gives you a head in a vice sweet spot for listening. And finally the Bass roll off is inevitable, but you sort of forgive that as your brain is fooled by the initial transient. You still hear the drum it just does not rumble. Low pedal organs likewise do not work well. That is what subwoofers are for but they are far from perfect.

Finally they still take up a lot of room. You need to set them well away from the wall or they sound like crap. Looked cool though. Not unlike the KLH 9.

There are other things like having hundreds of volts of electricity around toddlers and related safety issues. Fabric covers only help a bit. So I put them away again and went back to box speakers. Once again not bad compared to the deadly lightning beasts. I also went back to a big transistor amp. I built it from parts left over from when Dynaco went under. I did not strictly follow the plans. And compared to my tube amps which I still had it was much better. Not just different, better!

This is a journey after all. You explore and learn things. What I thought then is obsolete. The really interesting thing is I am sure what I have now is actually much better than that old dream system.

This is supposed to be fun so be sure to enjoy the experience.

[audio-luddite]

Speakers a guide.

I have designed and built a few. That includes very large full range electrostatics to small single driver boxes. I have tried everything. I have done sealed boxes and vented and dipole and all that.

I know what worked and why, and what didn't work so well. Basically I will describe factors and methods and how they may affect the sound. I want you to be able to make your own judgement.

First thing is that if you put a signal into any speaker sound will come out. There are natural resonances and filter effects in the driver and its connection to the air be that a fiber cone or a plastic membrane. Almost anything will sound reasonable within its limits.

Most of what you hear is in the Bass and mid range frequencies. Information like the tone of a voice, or an instrument is in the lower frequencies. A soprano sings up to about a 1050hz fundamental. That is often all woofer in a two way system. A piano's lowest key is around 27hz and the highest is 4186hz. Middle C is 261 hz. The parts of the speaker that present that determine the voice of the unit.

Treble is like a spice on top. It is the upper harmonics of the voice or instrument. It has to be clear and balanced with the lower part of the spectrum. Young humans can hear up to 20 khz. My current limit is 15 kHz as I am old.

There are many types of tweeter and most work fine. The most common driver for the lower frequencies is a cone of some kind.

In a typical cone some frequencies are accentuated, and others are attenuated. If you tap the cone with your finger you will hear the sound of the cone. Some cones are paper or plastic or even metal. They all have a voice. The less you hear the better. In a plastic membrane like a large electrostatic you cannot tap the membrane without a serious shock. You can tap the frame around it and usually hear the sound pretty much like a drum. Well it is a drum actually.

That is one of the two reasons I no longer like electrostatics.

When I check out an unfamiliar speaker I pull off the covers and tap the cones if they have them. I also tap the sides and other surfaces of the box if it has one of those. The less you hear the better again.

The character and voice of a speaker is the sound of the driving surfaces. The Advent speaker had a recessed polite sound because the cone was felt based and deliberately absorbed certain sounds. That was to avoid papery resonances. Better to take things out than add them. But it also takes out some of the signal.

Another thing is how many drivers and how are they arranged. I see photos of respected units with several midrange or even tweeter drivers mounted side by side. That is always bad. If the speaker is pointed right at you it may be OK, but move side to side a bit and there is an interference pattern between them. Some are arranged in a vertical line. I have done that a few times. That avoids the side to side problem, but you may have a similar issue with multipath reflections off the floor and ceiling. Very expensive models may mount an array on a curved surface so at the center of the curve you mount your head in a vice and have perfect alignment with the signal.

I hope my description communicated my opinion of that.

Several speakers have drivers shooting backwards to reflect sound off a wall and add aire to the presentation. I did that once. I had the rear tweeter adjustable. I adjusted it off fairly soon.

Bass is a big problem. Boxes have size limits and good bass usually means BIG boxes. It also aggressively reacts to the room shape and dimensions. Room placement is a tricky problem and unique to every different speaker. With few exceptions speakers have to be set to dominate a room, which is hard for a wife to deal with. One reason that man caves are popular.

For years I stayed away from vented enclosures. My idea was that it took some time for the tuned resonance to come up and by that time the impact had passed. I used sealed boxes with large heavy woofers tuned very low. They worked well, but needed active cross overs and more amplifiers.

A popular concept is a pair of smaller speakers with an added sub-woofer. The subs are often self powered. It adds something that is missing from the compromise that small size force on the design. There are a few very respectable small speakers that exploit that. Another factor is that bass is power hungry so you can get loud with a modest amplifier on the small units and some horsepower in the sub. I am ambivalent about this. I think is degrades the image of the sound. I have done it.

A lot of my initial impressions of a speaker are from looking at it. What method is used here? One way, two way three way or more? Single drivers or an array? If it looks complicated I have strong doubts.

Important to your solution is your living accommodations. A house, or an apartment? If you share a wall or floor or ceiling with neighbors you need to be polite, or invite them to the party. I am lucky I have a house. I can turn it up. Small systems make for less problems with neighbors.

All that said there are OK many speakers out there. You have to judge for yourself by listening. Ideally if you can trial them in your home with your equipment you will hear what they really sound like. In a shop or dealer showroom that is not true.

I could go on for hours. I will stop here.

So Happy hunting.

[audio-luddite]

Don’t give me no Electrostatic.

There are many ideas about the perfect loudspeaker.  Many have serious flaws yet work pretty well in spite of them.

Electrostatics are a cool concept and can sound very nice.  The idea for those that do not know, is to place a high voltage charge on a thin film of conductive plastic that is set between usually two conductive perforated plates.  By varying the voltages (high voltages) on the plates the thin film will move back and forth between them based on the same mechanics that makes a charged balloon stick to your sweater or makes your hair stand on end when you scuff your feet across a carpet.

The scheme is that the surface area is very large and the film is very light so it can move quickly and in sensitive response to the music signal.  One great advantage is to work well the sheet must be large which means it couples well the the air in the room.  Another advantage is typically it can respond to very high frequencies. Ideally that means a full range response eliminating cross overs.  Those are good things.

The practical realities mess up the ideal quickly.  Large areas in narrow gaps rapidly become unstable.  If the film gets too close to the plates there can be a spark which puts a hole in the film though it can kill mosquitoes. The span of the film must be kept as small as possible which raises the lowest frequency.  You may see several types that use long and tall elements to keep the size up while keeping the supporting distance short.

There is the thing about high voltage.  Actually a bit dangerous. It also means you need to use tube electronics or impedance transformers to raise transistor voltages up ten or twenty times.  Those are extra parts.  Extra parts always get in the way a bit.

The famous Magnapan systems are based on getting rid of those extra bits and the high voltage.  Those are very seductive I must admit.

I built a few electrostatics.  I enjoyed them and tweaked them.  I needed a subwoofer to give me bass, but everything else was amazing.  But the flaws were real and serious.  My versions used perforated steel plates painted with insulating varnish.  If you tapped on them there was a definite “metallic bung” sound.  Kettle drums sounded really good, but for not a good reason. 

Every commercial electrostatic product I have auditioned does this.  Damping the sound out is very hard.

All of these are fundamental dipoles.  The marketing material will claim this is an advantage, but it is not.  Sound bouncing off your room walls from the rear radiation makes a nice effect, but it is not an accurate representation of the recording.  You could objectively claim that distortion is 50% due to that source alone.  That your hearing mechanism is more sensitive to the initial sound helps to mask the problem, but it is a huge problem.

I got tired of the equipment overhead and the imposing size and the flaws.  I moved on to other methods, all more satisfying.

If you look at old stuff you will find many respected representatives of this technology.  Many have been in production for decades.  The most famous is the British Quad ESL.  It debuted in 1957.  It was relatively small but I guess it was for small English rooms in the Olde Country.   They cannot be made to go loud as that will cause them to arc and often shut down. The traditional solution was to buy more and stack them to make them twice as loud for orchestral music. The newest versions are lovingly built to high standards of craftsmanship. They have had a long time to sort out the bong sounds and other stuff.  I am sure any owner of them will be pleased with his $12,000 purchase

But aside from the dipole distortion (still proudly there) there is another thing. This product uses an array of time delayed signals to simulate the effect of a spherical radiating source.  First bit of that is that is also a flawed concept as no real music performance emanates from a pulsating sphere.  The Second is that there are extra circuits and things in the delay system that do more than just slow down the sound.  Those things are distortion. They claim they measure vanishing levels of distortion in the lab.  They may, but the rear dipole radiation is 180 degrees out of phase and it is let loose in any real listening room.

Those are rare birds these days.

There are better solutions.  I know I have been working on them for a long time.

[wersitime]

Prototype of a Electrostatic Headphone. For more info join the Facebook Group Electrostatic Speakers. See how it is build: https://www.facebook.com/media/set/?set=a.1594170760662246.1073741865.100002080125887&type=1&l=60c9e93074

[bitmoreuk]

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