criterion 85-es

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Just came up with a set of 85-es speakers. Apparently the tweeters are not working. Anyone with a schematic for this speaker? Physical evidence points to the ps, but would be handy to have schematic. The supply is simple enough to reverse, but looks like some pieces are removed ?????, so again a schematic would be handy

Never done anything with electrostatics, so this is just to get boxes running, not to bash the quality or lack thereof.
 
I have reversed the pc board and have come up with a schematic. The ps is directly coupled to line voltage (120vac) and a doubler gives me 275 VDC out. The audio signal is transformer coupled to modulate the dc output voltage. The tweeters are single ended, a metal perfed grid with a plastic film over the top. Contacts for the grid and the film are good, no shorts between film and grid. I have 2 supplies and 8 tweeters.

I do get output from each tweeter and each ps. Audio levels are pretty much the same for all combinations. I am witnessing very low audio levels, however. Not knowing what to expect, the fact that both ps's and all tweeters work pretty much the same, I'm tending to think that this is normal. Would anyone care to speculate? (maybe a good 20db below a direct radiator connected to same port, I mean, it's quiet)

Being that these tweeters are single ended, much of the low distortion of the more typical electrostatic speaker has been design out. Since I have very little invested, any suggestions as to how I might go about (1) converting to a push-pull arrangement (2) improving on the efficiency.
Never once have I done a thing with electrostatics, so not sure what I might consider, if anything at all. Again, little invested, so let the good times roll.
I can supply photos and a drawing of schematic if that would be of productive benefit
 
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The only thing I could find is that they were made by ESS for lafeyette.
It sounds like it could be a fun project.
Drawings and photo's would be great.
However the time spent trying to convert the esl drivers one could build a complete new driver very easily.
My method uses plastic lighting grid and window screen coated with spray paint (clear acrylic).

here are just a few examples
http://www.diyaudio.com/forums/planars-exotics/158115-material-esl-2.html#post2074212

http://www.diyaudio.com/forums/plan...nstruct-cube-louver-acoustat.html#post2142851

http://www.diyaudio.com/forums/plan...truct-cube-louver-acoustat-2.html#post2162588

http://www.diyaudio.com/forums/plan...t-panel-angles-8-vs-9-panels.html#post2170405

jer
 
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Thanks, Jackson. Grand Ledge appreciates! Allow me to read over all you sent. At the diaphragms I have 280V. The output transformer is about 1:14. Built in crossover is about 5K. With no ac applied I get the same amount of volume as when there is power, both low. As there isn't any amplification, not surprising. I'm not detecting any difference in distortion however, and this is surprising, but with the low level and my nasty signal source (don't ask, please) not sure this means much. So who needs bias anyway (snicker, jeer).
 
OK, I'm back. First thing I noticed is the use of a couple of Radio Shack copper clad boards for the +/-stators. I have several 1.75 x 2.5 China perf boards. Too small for a first pass? Window screen should work, also. I have seen screen up to about a 1/2" grid. Would this been too far apart?

You mentioned a 500v bias, how about the 280v that I have? Too low? Caps that I have are 400v, so a tripler is out.

The diaphragm mat'l from my existing spkrs should be large enough, perhaps a recoating?

Need to go back and see what you use for coating, connectors, spacers and output transformer. The criterion xformer doesn't have a ct, so can't use it, unfortunately.

Hmmmm, just may be able to afford this. That'd be cool.
 
1/2" screen is to large I have seen 1/4" but I have not tried it and 1/8" has to be special ordered.

I use use common 14 x 16 or whatever happens to be on the shelf.

Some like to use preforated metal,but it is rather costly.
Lincane would be good for small drivers if you have any laying arround.
I saw some at menards a few weeks ago but it was over $40 for a small piece of it.

400v caps will work in a tripler or multiplier if the proper circuit configuation is used.
But it takes at least 2kv to 3kv to get good output on an average.
I push mine to the limit with a variable 0v to 7kv supply that I designed.

I never got to properly test the micro driver but it worked good as a headphone unit as this was its intent.
So Idon't know its limitation's yet.

The stator of that driver is actualy aluminium duct tape smoothed to the flat side with all of the holes poked through with a toothpick and I used an etching method aswell.

I coated with clear acrylic and sanded it flat on a peice of glass and some 600 grit sand paper and coated it again until I got a perfectly flat finnish.
This was critical because daigphram to stator spacing ( d/s ) was in the order of .025" to .035" as I used some gift credit cards for the spacers.
Then the whole thing was assembled with scotch double sided transparent tape.

If you have a micrometer handy it is priceless tool to keep every thing symmetrical but if it isn't perfect it does not mean that it won't work.

The best diagphram material to use is mylar I have some .25mil but it is hard to find.
.5mil is common some have even used some types of food wrap and shrink wraps sucsessfuly.
The thinner the better but mylar is the best to use due to its mechanical stability.
I used monokote on my first build with great sucess.

The coatings I have used are licron and licron crystal.
Don't waste your time trying to rub in graphite.
Some use a diy formula that uses white glue thinned with water.
I have experiment with this method but never actualy used it on a diagphram since I have the licron.
However I have made a nice conductive paint using the same method and mixing in some powdered graphite .

The transformers you have could probably be made to work but performance would be marginal.
Alot of us have discoverd using toriod power transformers in reverse and I did a big write up on using this method.
I personaly (as others aswell) don't have any issues about sound quality using this method but a ground up build could yield far better result aswell for reasons explained in that thread.

I have spent around $200 in research of different materials and if your resourceful
you could do it for well under $100 or even $50.
The most costliest part is the bais supplies and transformers.
The drivers them selves are next to nothing (under $20).

This is the cheapest method I could devise and I get great results from the panels I have made so far.
I was so blown away with the sound of one panel that I didn't even take the time to hook two up in stereo yet.

This project doesn't cost hardly any thing if your resourceful enough.
I have gotten companies to send me free samples of stuff like glues ,plastic films and thats how I (and others) got the licron which cost $30 to $40 a can.

Somtimes you can find some busted up pieces plexiglass to cut into strips for spacers.
The mylar used to cover windows or frozen food trays could possibly be used aswell if it is thin enough. jer
 
OK, I trash what I have, build from scratch. While gathering mat'l for panels do I build up power supply, seems to me that the spacing between diaphragm and stator is determined by supply voltage, correct? If so I can build up a supply of 5-7kv and build panels to match.
 
Yes this is correct.
The breakdown of air is in the order of 80v to 100v per mil.
Plus the insulating factor of the stator coating.
But keep it on the low side to prevent any arc over.
So a 4kv supply will be suffiecent For a 1/16" d/s.
Most only use about 2kv to 3kv.
Making a variable supply is a nice feature.
You can make it variable by selecting different taps along the mutiplier string.
Once you get a feel of the construction process and material characteristics you can start pushing the voltage limits to try to squeeze as much effeciency you can.
However ,there are limits where nothing more can be gained.
I pushed one too far and arc over caused the panel to catch fire, but this was not caused by the bias supply.
Luckly it did not destroy the panel and I was able to make simple repair. jer
 
Don't invest in any paint coatings that have any pigments as these conduct at high voltages.
This is the most expensive part of building the panel so use what is cheapest as they are all pretty much the same as it will take many many coats to get sufficient coating thickness.
If you look up the msd's you will find this to be true for the most part as each company has to have their own variations of course.

The first layer with color is okay if you perfer to have a preference color after that stick with a clear coating.

Polyurathane or acrylic enamel is fine but don't mix the two as one will cause the other one to bubble and this causes problems.
I'm not sure if a primer coating will make much if any difference.
This is a subject that is currently being researched as they contain talc and its properties could raise the dielectric strength and dielectric consant factors,this is good.

Polyurathane from a can is to thick and needs also to thinned to be useable and is quite messy.
I am working on this process as well since spray cans of it are very pricey.

The white panels where made using the spray bomb method.
They were the first ones I did so they have a little bit of everything on them.

The black ones where double powder coated and later refurbished with clear acrylic.
This seemed to be one of the best and easiest methods I have tried.
But there are problems with inconsistency's and cracks in the coating (hence the reason I had to recoat them with the clear acrylic).

Both panels performed the same with the exception of the black panel was able to withstand the higher voltages I was trying to shove into it.
At those levels one could not stand to be in the room at that level for very long.

It seems like alot but price some preforated metal and compare,IMO. jer
 
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OK, now, if I choose to go to a large panels is there a link you'd recommend that explains things such as distortion, frequency response, polar response, what ever else I didn't mention, that is important to consider.

I realize the forum as an invaluable tool, but so is just flat out asking.

Here's where I am: Retired recently, living on ss plus what my wife earns. Dollars very precious, needless to say. Experimentation is expensive, can't afford too many "try it" 's. I have in my possession a number of low frequency drivers already, have started looking at various forms of woofer, sub- woofer configurations with integration into a set of full range high-end speakers. ( I am accustomed to music at the "WHO" db level) I am lacking in drivers for about 100 Hz on up so will need to come up with something. I have dismissed esl's because of cost perceptions. Building them may change all that. What I first need to do is determine how do I distribute the frequency range ( do I use a single full range panel?) How much surface do I need, What are power requirements, what do I need in terms of amplifiers, crossovers, etc. What will all this cost, (can I get there without a bunch of failures stacked up in the closet) If the costs analysis is favorable, then comments that I have read about how good they sound will make the final judgement call.
 
That input transformer!!!!

I would think that I am now going through the same entry level stuff that all go through: reading posts, making lists of what's needed, so on. Managing to get a grip on most things but input transformer is just a pistol.

In an alternate universe, direct drive would be great, in this one, well, I can buy a car for the cost of the amp, just for those with more resources than I have, let's say that.

One complaint I've read about is the very high turns ratio needed to step up the low impedance to the high impedance of the stators, and the accompanying stability issues associated with that.

I thought of this alternate approach, but being ever the newb, not sure if its been tried and dismissed, so before designing an output stage around this idea I thought I'd ask

Let's use a transformer, but with a 1:10 ratio, say. Simple enough in concept, the ct'd primary is the collector (drain) load on a complementary pair. This is not new, actually rather old school, anyone recall a McIntosh 2105? There is still concern with other transformer issues, but the stability issue may very well disappear. How it would sound??? Well, maybe some of you could speculate.

Haven't done a transformer coupled output stage for a few years, could be sort of fun.
 
A direct drive amp is the ultimate goal.
I have a collection of schematics of different topologies ranging from tubes to soild state,some proven and some semi proven and still on the drawing board.

It is very hard to get a discussion going here on the subject due to the saftey issues involved as an amplifier of that magnitude is quite dangerous and deadly if extereme precautions are not respected .

However it can be done inexpenisvely using modern day components.
A design that I have been working on consists of a couple of opamps and some fets powered by a micro wave oven transformer.
This design should produce a 6kv to 8kv peak to peak which should be suffecient for the average listener (using a large panel).

But if your anything like me more is always better.

I have already proven that the design concept works using a lower voltage of 150v using 100v IRF510's commonly found at radioshack and I will be using the design to power some es headphones (using a higher voltage of course).

Last summer I had asked the forums (in a round about way) what the absolute maximums would be and all I got was speculations, theory's and warnings of embarquing on such an endevor.

So, I set out to find out for myself.
I have calculated it will take about 1000 watts of power to fully drive a 1' X 4' panel to its limits with a 20kv to 25kv peak to peak voltage swing across the stators with a d/s of 3/32".

I choose this spacing to allow for greater excursion down to 200hz to 300hz.
Most use 1/16" d/s and a crossover frequency 500hz and as high as 1200hz.
I personaly prefer the lower frequency range due to the naturality of the sound of vocals and guitars and bass guitar aswell as the snap of percusive instrument start in that range.

Many like to argue over this, but like I had stated it is a matter of preference and panel design.

Mostly the width dimension is what determines the lowest pheasable frequency to be reproduced by the panel due to dipole cancelations and there are several ways to combat this.

Transformers really have gotten a bad rap through the years (from myself aswell until now) due to mediocore design and inferior materials.

This is not the case in todays times.

Lets face it E-I cores are a thing of the past as proper core material is very difficult to source and very pricey when when found.

It is a PITA to try and figure out how fit the windings in the winding area while maintaining proper wire gauge for the current demands with adequete insulation to withstand the highvoltages required while maintaining balance of the resistance of the windings.

Many times I have seen months of work in design and construction go up in smoke do to one flashover.
And much to there demise is the arguement of which method is easiest to do.

I have been wanting to build my own esl's since the very early 80's when I had found Roger Sanders articles in the libary.
He had also described a direct drive amp aswell, this intreaged me very much.

But It wasn't until 2003 after much research and when this forum was still very much in its infancy that I had finaly built a pair out of one sheet of egg crate material.
I was blown away at the quality with such simple construction and cheap materials.
Being unemployed and having just moved back up here from florida, I, was obsessed with the idea and was determined to find the cheapest way to build them.
Everywhere I went ,everything a saw, I would say to myself I could make one out of that or this (Recently I started I design of a 360 degree round driver using plastic cups).

That set my goals to bring it to the mass public.
Cheaply, so that anyone could afford them.

The pair of transformers I was using at that time were 6V6 OPT's from an old maganvox stereo chassis that I had saved from the junk mans pickup route.

I soon realised after one of them started to give out that they weren't going to cut the musturd at the levels I was seeking.
All of the panels I have running at this time were built then, 8 years ago.

I will find the thread explaining this first experience and post the link.

So,then the whole thing was put on hold because of life issues due to stupidity and lack of a proper way to drive the panels.

Which brings me to a year ago.
As I was reading these forums I found that good results were found sucsessfully by using off of the shelf toriod power transformers.

It is now the trend of many diy'ers today.
That is when I had set out to find the how and why's aswell as how to improve such a method.

I have found that the material used in the high quality E-I cores of yesteryear are now a common place for todays toriod cores, which by the way were a hard find even within the last 5 years until now.

Since I had 10 of these things laying around doing nothing, that I had picked up cheap from parts express, I decided too give them a try.

I added my own new pirmary of 10 turns to get the ratio I needed, and, much to my amazement it worked far beyond my expectations.

I won't go into all of the details now as they have already been documented.

Then one day while I was contemplating a super paralled chip amp to handle the low impedence drive required for my rather high transformation ratio of 1:215 and higher,It dawned on me.
If this thing has to be transformer coupled,why not design a simple common high current class b push-pull output stage that is common to tube amps and susan parkers design using fet's.
Aswell as some high power soild state amps used for public adress systems in the 60's and 70's.

Then a few months later I made the trip back to florida to get the rest of my equipment and power amps weren't an issue anymore.

However I did not scrap the idea and had recently developed a few such designs using circuit maker with no errors.

I can post the schematics if you like but they have not been built and tested yet. jer


http://www.diyaudio.com/forums/planars-exotics/161485-step-up-transformer-design-2.html#post2101604
 
geraldfryjr
There is no such thing as magic bullet or free cheese.
HV X-formers existed since Tesla times.
Professional advise as well as design are well known.
Sometimes it requires more than pure will...
One needs proper materials, procedures and, often unfortunately, equipment... see attachments
Third picture is the real life implementation of picture#2 design.
P.S. Single air void would nullify all your efforts with, as you said, "single flashover"
 

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Oh yes, so very true Alex,as I haven't even begun to start on the issues of proper transformer design.

I remember that transformer in the picture.
It is a true work of art and very massive.

If my memory serves me correct that transformer as a frequency response well into the sub audio range.
And it is what originaly inspired me to make my own from scratch.

But I haven't been able (untill recently) to find a source for such massive high quality iron.

In 2004 the only iron I could find was some m4 (or a slightly lesser quality there of).
From a local shop was willing to part with enough E-I's to build a couple 6" to 8" stacks for $50.

But,like I said it was just common iron used for motors and power supply transformer and I never pursued it. jer
 
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