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ESL DIY  |  DIY construction of the Stat Panel  |  ESL Builds and Works in Progress  |  A Segmented Stator Desktop ESL
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Author Topic: A Segmented Stator Desktop ESL  (Read 6360 times)

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Offline geraldfryjr

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A Segmented Stator Desktop ESL
« on: November 02, 2012, 01:02:41 PM »
Hello Everyone !!!

Lately I have been working on another small ESL with a electrically segmented stator.
I am using 1/16" TIG welding rod for my stator material on this build.
There is a very good discussion started on this method here,

http://www.diyaudio.com/forums/planars-exotics/206816-segmented-wire-stator-esl-simulator-esl_seg_ui.html#post2908293

And the program that I am using to predict its performance is in the thread and a copy of the english version can be found here,

http://www.diyaudio.com/forums/planars-exotics/206816-segmented-wire-stator-esl-simulator-esl_seg_ui.html#post3192348

It will have a 3 5/8" X 10" size diaphragm size with 25 rods per stator in a 6-3-2-3-2-3-6 pattern.

The D/S is projected to be about 1.9 mm or less as it can be adjusted with a  3.589 mm (.140") wire spacing.
This allows for up to a 10mil  (.010") stator coating thickness with a open area of no less then about 40%.
A 10mil thickness stator coating should allow me to use some extremely high voltages without the risk of any arcing.

The build will be of a very open type and will allow me to observe the diaphragm actions at very high excursion rates.
Its projected performance is expected to be in excess of 105db to 110db at a .5 meter by using this ESL calculator,

 http://quadesl.nl/sim/

As well as other software's that I have that predicts the performance of such dipole systems mostly done in Excel Spreadsheet format.

The object of this build is to test the predictions of the software as well as the object of getting an equal horizontal dispersion of the frequency's through out its operating bandwidth.

Being that these will be used in the nearfield just as my first little panels they do have have a rising response of 6db per octave just as a larger panel has.
And the beaming is even more noticeable in such a close proximity of the panel when moving about the work area of my desk.

Electrically segmenting the stators has been proven in the past to help correct this effect on larger panels so lets see how this will work for a smaller one.

Also it is projected that this will tremendously reduce the load demand on the amplifier as well, and, quite possibly a safer low current HV direct drive amplifier may be feasible to develop for such a panel.

Here are some pictures of the Predictions, Plans and Templates for the build.

 Enjoy !!

 jer :)
   



Offline geraldfryjr

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Re: A Segmented Stator Desktop ESL
« Reply #1 on: November 02, 2012, 02:32:16 PM »
I got the frames done finally !!!

They are are made out of 8" X 10" X .050" Optiplex plastic common at any Home Depot.
Their overall size is 12" X 5" and it will take 4 of these frames for each panel plus two more for spacer's.
They need not be complete frames if one chooses not to go that route as they will be just spacers as shown in the previous drawing.
Two are for the diaphragm and one for each stator.

They are quite flexible so I don't know exactly what kind of plastic it is, it seems that acrylic is much harder and stiffer than this stuff so I will have to add some rigidity somehow but I have a few idea's.

I used superglue to glue them with and at first ,But , I was impatient and some of the bonds had a thick gap and they failed so I had to clean them up and start over.
Then I tried using 5 minute epoxy and this was even worse and peeled right off.
So, I went back to using superglue as I have done on all of my panels to date.
I didn't dress up the ends of the strips and make them all exactly the same size and perfectly square as this would have helped a lot, only I would have had to readjust my templates to do so.
Instead, I just glued them and this time I made sure that they were fully cured before I disturbed them.

You must let the superglue fully cure or the bond will bend and break at the joint!!!!

I also put my desk lamp on them for some heat and went about some stuff around the house and when I came back they were nice and strong.
I also built up each side of the glue joint with 2 or 3 applications of more superglue as well especially on the ones that had a rather large gap.
They can now be handled without breaking apart.

Next I sanded each side of the glue bond's on my glass work surface with some 320 grit (or finer) emery paper.
They are now ready for drilling (a step the that I forget on my templates but will add later) the holes to mount the stator's and sandwich the whole thing together.

However I will use Epoxy to mount the mylar diaphragm to one of the frames as I have done in the past.

Next I will be building the stators and here are some pictures of the frames in the building process.

 Cheers!!

 jer :)
« Last Edit: November 02, 2012, 02:45:21 PM by geraldfryjr »

Offline Dochungwell

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Re: A Segmented Stator Desktop ESL
« Reply #2 on: November 04, 2012, 09:21:59 AM »
Wow, Thank for your post and and research on this project. It really is amazing that the size of any speaker is essentially "hardwired" to dispersion angle. The issue of gluing the diaphragm down was a topic a while on DIY Audio. In my opinionI have researched this issue and found a rather simple alternative by using a double sided 3m contact tape......good luck with the build and  Protect your ears my friend!!! [size=78%]  [/size]

[size=78%]Doc[/size]

Offline geraldfryjr

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Re: A Segmented Stator Desktop ESL
« Reply #3 on: November 06, 2012, 03:44:58 AM »
Yes Doc,I would like to try using some double sided tape in one of my more permanent builds some time.
I did use it on my micro ESL and it worked great although there was not much tension to deal with.

Epoxy is nice that it easily peels of with a razor blade should I ever have to replace the diaphragm.
I have never had any issues of the mylar losing tension once it is mounted and set although it is quite messy to work with.

Once it set's, as it is pressed to the glass, It comes out very flat smooth and a little heat is all that is needed to take out any wrinkles in the Mylar and makes a nice even tension on the diaphragm.

It is also possible to use some transparent type double sided tape on a smaller panel like this and I have been wanting to give it a try as the tension is not that high.

Today, I finally got the Stator PCB pattern and frame drilling template done and finalized.
Next is to make the PCB's and drill them and the frames.

Then I can start cutting the stator rods out of some copper plated 1/16" l TIG steel welding rod and simply solder them to the PCB's.

MY drawings are made in Traxmaker a PCB layout program that comes with Circuit maker 2000 an electronic CAD/Simulator.
It allows me to draw with an accuracy to 1 mil and it gets printed out with perfect dimensions on my Samsung ML-1865W laser printer.

I also use this same printer using some photopaper to do toner transfer to make PC boards for circuits as well.
I picked it up on sale for $50 at Office Max last year and it was what I used to make my Variable HV Bias supplies PCB's.

Here are the drawing that I have been working on.

Jer :)

Offline geraldfryjr

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Re: A Segmented Stator Desktop ESL
« Reply #4 on: November 06, 2012, 05:28:05 PM »
Okay I got the stator supports etched today and they came out much better than I had expected !

I used some "hp everyday photo paper", product #q1976a .
I ended up having to do it three times before I got a transfer that was acceptable.
I don't think that my iron was hot enough but it worked.

I also ended up only taping down one end of the paper (unlike the photo) as the heat was causing it to bubble and lift prematurely leaving little or no toner on the board.

It was the end's that weren't coming out right as this is where my drill dots and alignment lines are located and I really needed those to be there.
The lines are only .012" (12 mil) thick and will be ground off once the holes are driilled.
The drill dots are only .030" (30 mil) in diameter as well.

Soon, I will be ready to start cutting and soldering the rods to the supports.

Here are the photo's of today progress !!!

Enjoy !!

jer :)

Offline geraldfryjr

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Re: A Segmented Stator Desktop ESL
« Reply #5 on: November 07, 2012, 03:13:13 PM »
Everything is starting to take shape now !!! :)

Right now, I am just using some short pins cut from the TIG rod to hold every thing together.
Later, I will drill the holes bigger for some 6-32 screws and nuts.

At this time, I will use the pins to keep everything aligned and take the time to square up the insides of the frames and one of the ends.
They are not to bad but just enough to annoy me a bit.
Clamping them in a vise and a few swipes with a fine metal file will solve this.
I can now also grind off the alignment lines on the stator supports as well.

You may have noticed that my connection pads are covered by the stator frames as this was done on purpose in order to reduce any chances of arcing to the diaphragm at those points.
The connection to the pads will be done by drilling a hole from the back side of the pad just to the copper clad and a pool of solder will be form in the hole in order to make the connection to the pad.

This will allow the stator support PCB to lay perfectly flat to the stator frame.
This will also give the stator frame some rigidity across the width as both ends are designed to overlap like this.

The lengthwise rigidity support I have not decided yet as I am pondering a few different options.

Here are the pictures of today's progress.
Sorry that some of them are fuzzy as my camera doesn't do well at times.

Enjoy!!
 
 jer :)
« Last Edit: November 07, 2012, 03:32:49 PM by geraldfryjr »

Offline Dochungwell

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Re: A Segmented Stator Desktop ESL
« Reply #6 on: November 07, 2012, 07:42:00 PM »
Hey Ger,


Your build is coming a long nicely!! I like the way your are building this segmented stator and am looking forward to hearing you results. This should provide you with a pretty great divergence angle you are hoping to achieve.


What is the D/S distance and Bias voltage are you looking to use?


Doc

Offline geraldfryjr

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Re: A Segmented Stator Desktop ESL
« Reply #7 on: November 07, 2012, 08:09:28 PM »
Here is a excerpt from the Rough draft picture of the predicted SPL's at .5m and 500Hz.
Using a bias of 7Kv and a drive of 6160Vrms with a 28vrms (100watt) into a 1:220 thransformation ratio vs D/S in mm.

jer :)

Offline geraldfryjr

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Re: A Segmented Stator Desktop ESL
« Reply #8 on: November 09, 2012, 04:56:51 AM »
I have been holding my high speed grinder (Dremel tool) for nearly a constant 6 hours now and I have all of the stator rod cuts and sized to about 25.2cm.

I all that is left is to grind off maybe a little more and round the edges of all the ends and they will be ready for soldering to the stator suppot PCB's.

I also need to make one more set of the short stator supports for the middle of the rods as some of them aren't completely flat and have a slight bow in them.

A support in the middle will be ample although aesthetically two would look better.
But, That would be a lot of soldering as there is a total of 50 rods on this panel and I don't have a ton of solder right now.
This will also help give it some rigidity lengthwise as well.

Then all that will need to be done is glue the diaphargm to its frame and coat it, drill the holes for the connections and sandwich bolts and hook it up and hopefully it won't burnup !!! He,he,he,he

I will be testing the stator coating before I mount the diaphragm though just in case anyhow.

Here is what I have so far and they will be ready for coating in a day or two.

Enjoy !!

 jer :)

Offline chinsettawong

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Re: A Segmented Stator Desktop ESL
« Reply #9 on: November 09, 2012, 07:50:10 AM »
Wow, Jer!  You've made a lot of progress in just a few days. 

How will you insulate these rods?

Wachara C.

Offline geraldfryjr

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Re: A Segmented Stator Desktop ESL
« Reply #10 on: November 09, 2012, 02:45:35 PM »
Thanks Wachara !!

I will be using spray acyrlic enamel.
I really like the copper color but I may have to go ahead and use a primer though, as it is the process that I know that works well.
I may try one later without the primer to compare to after I build a rotisserie to keep the paint form running and let it cure evenly around the rods.

Here are the details of the coating process and tests,

http://www.diyaudio.com/forums/planars-exotics/200352-high-strength-dielectric-coatings-fact-fiction-2.html#post2893839

http://www.diyaudio.com/forums/planars-exotics/200352-high-strength-dielectric-coatings-fact-fiction-2.html#post2894427

jer :)

Offline chinsettawong

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Re: A Segmented Stator Desktop ESL
« Reply #11 on: November 09, 2012, 10:03:11 PM »
I've been thinking to do the same for years.  Insulation is only thing that holds me back.  I wonder if it is possible to epoxy glue the rods to a wood flame and then send the whole thing to do a powder coating.  I know that it takes high temp to do powder coating, and the heat might just melt the glue.  :(

Offline geraldfryjr

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Re: A Segmented Stator Desktop ESL
« Reply #12 on: November 10, 2012, 12:09:12 AM »
It may be possible I know that they do powder coat wood now.
The temps for powder coating is only 400 to 450 degrees Fahrenheit and only needs to be in the oven for as long as it takes for the material to flow out.

I was going to do the same with my screen stator on a aluminium 3/8 C-rail frame and using epoxy had crossed my mind as well.
I did start looking into some high temp epoxies and I forget which ones but they are available.

At the time I didn't realize that the melting point for solder is much lower than the 400 degree range so that won't work at all.

 jer :)

Offline geraldfryjr

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Re: A Segmented Stator Desktop ESL
« Reply #13 on: November 10, 2012, 11:10:14 PM »
This afternoon I was able to finish one of the stators, Yeahhh !!

Being that it is the First one you know that it would be impossible to go along without some kind of Quirp or Two or Three or Four, almost didn't but it is just not expected.

The first one was that the center support was slightly off on one end making it not perfectly perpendicular to the frame.....Oh well.
This was just laziness and being impatient on my part.

I had set the supports on top of the frame in order to solder the rods to them using the same holes and pins to keep them aligned.
However ,I had forgot to secure them and one of the pins on the live side came out of its hole in the frame causing it to become cockeyed.

I did not notice this until I tried to reassemble it with the frame on top like it is supposed to be and found that it had shifted a 1/16".
I pondered just re-drilling the hole but it was not straight and you could see it.

Then as I was struggling to get the frame back off of the pins the end piece on the same end had snapped off !
No Biggy, I can just glue that back together.

So, I decided I could just easily un-solder the ends and re-solder it back on after re-aligning it, easy fix although time consuming.
As I was un-soldering the ends, Two of the pads had lifted and this destroyed the piece, So, I had to make another one.....More time wasted !!

While I was soldering the rods at first I had no spacer gauge to go by and I just eyeballed them but after the 8th rod this proved that my spacing was getting quite inconsistent and found myself having to spend much time going back over them and re-adjusting a few of them.

This is when I had found my little set of feeler gauges.
This worked perfectly only I had found that my pad spacing's were not where I thought they were at an expected .140" or .141" but .139" about 3mil off and this was relevant by the time I got to the 10th rod near the center.
After a swap of the feeler gauge size all is well and re-adjustment was as simple as re-heating the end of any rod that was in question.

I have built quite a few balsa wood model airplanes so all of those skills came in very handy for me.

All in all it came out very nice after I had fixed it with the new end piece.
Now, I have to find my little wire wheel in order to clean up the ends and take down a few high solder spots and it will be ready for coating.

I sure hate to cover up the pretty copper finish but that will be a subject of another build as I do have some 11" X 36" stators already made from the same TIG rod for some bass panels.
If this works well I will use this same type of construction for to match those bass pieces so that they will be a matching set.

If were to make a building jig these could be made very quickly and easily.
I like my window screen method as well as it is still cheaper to build but the object is to get a wider and even horizontal dispersion of the frequency's with this method.
The TIG rod is nice as it adds a lot of rigidity and is self supporting for the most part compared to a stretched copper wire construction that is so well known that has been used in the industry.

The copper clad is nice as well as this makes it so much easier to solder to the supports than a bare steel wire.
If there is any one thing that I would change is to use a smaller diameter wire.
This same wire can be found on spools called MIG wire and ranges about .023" to .045" diameter sizes,I will investigate this sometime in the future.
Since it comes on spools some kind of stretching may be involved to get them to be perfectly straight, But that will be another project.

And now for what you all have been waiting for............ The pictures of today's progress !!!

Cheers !!!

 jer :)

 

Offline chinsettawong

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Re: A Segmented Stator Desktop ESL
« Reply #14 on: November 11, 2012, 12:31:48 AM »
That's super nice! ;)


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