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Tips on building full range ESLs
Tips on building full range ESLs
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Old 21st April 2021, 08:01 PM   #1
thermionicvinyl is offline thermionicvinyl
diyAudio Member
Join Date: Nov 2018
Default Tips on building full range ESLs

After experimenting with building planar magnetic speaker, I have become increasingly intrigued with the idea with building an ESL. Specifically a full range one that doesnít require a conventional woofer to produce decent bass. Iíve assembled a list of questions regarding such a speaker design:

What dimensions/area should I use for a panel that goes down to 50Hz?

What about the spacing between the Mylar and stators?

What bias voltage to use, how to generate it?

Turn ratio of audio transformers for stepping up the signal?

Best place to get the materials? Mylar, transformers, coating are the ones Iím mostly wondering about.

Lastly, for anyone who has built a full range ESL panel: what was the experience like? Are you satisfied with the sound quality?
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Old 21st April 2021, 08:45 PM   #2
mattstat is offline mattstat  United States
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Join Date: Oct 2009
Dimensions are going to be heavily influenced by your expected listening distance, SPL, and music. If your output requirements are modest (around 90 dB peak at listening position) and the distance is around 8 feet, something in the 16 inch by 48 inch range can get down to 50 Hz, but the panels and design need to be quite good for this level of performance at this size. Most people going for full-range output wind up building bigger panels than this. Looking at commercial designs and their reviews can give you an idea of the size range that's typically required for reasonable market acceptance and the real-world limitations. A few designs with Stereophile reviews: Quad ESL-63 and ESL-989, etc.; Martin Logan CLS; Audiostatic ES-100; Sound Lab A-1 and A-3.

Bias voltage is typically 50 volts per mil of diaphragm-to-stator spacing (1 mil = 0.001 inch).

Maximum peak-to-peak audio drive voltage should be twice the bias voltage (or a bit more, depending on your insulation). Your transformer and amplifier choices need to be made with this in mind.

I've built full-range panels. Getting OK performance is quite a bit easier than getting really good performance. I think I burned a mile of wire building various prototypes before I got reasonably happy with my last ones (Acoustat style panels). A lot of this was me covering ground on my own though, as DIY designs/advice weren't as readily available then. In general, a lot of trade-offs are involved with full-range ESLs. You need a more thorough understanding of the limits of the designs to pull them off vs. a midrange/treble panel.

Last edited by mattstat; 21st April 2021 at 08:52 PM.
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Old 22nd April 2021, 02:29 AM   #3
thermionicvinyl is offline thermionicvinyl
diyAudio Member
Join Date: Nov 2018
Thanks for all the info. Itís amazing what information you can find if you dig deep enough.

How do you stretch a membrane thatís so large? Like 1í by 5í big?? Do you use a bicycle inner tube like many other diyers use? Or the heat gun method?

Iím wondering what the resonant frequency should be and how that corresponds to tension levels
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Old 22nd April 2021, 03:09 AM   #4
mattstat is offline mattstat  United States
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Join Date: Oct 2009
Heat shrinking always seemed easiest to me, so that's what I did the vast majority of the time. I got a large supply of Mylar years ago, so my film and mounting method were consistent, which meant resonance was fairly predictable as well. A good temperature-controlled heat gun makes things a lot easier also.

There are equations to calculate resonance if you want to apply a specific tension. If you're heat shrinking, you can also work backward from a certain panel size/resonance and calculate the tension that way. You can get in the ballpark this way, but I typically wound up adjusting things because I was trying to get pretty specific results.

There are other mechanical ways to stretch diaphragms, but they're typically pretty involved.

Resonance is a decision point. Uncontrolled ESL resonance isn't really usable. The peak level and Q are both very high/unnatural.

You can use a single resonance below the intended frequency range and then filter it out so it's not excited.

You can also distribute the resonances across multiple frequencies within the intended range of the speaker, which helps if you want to use them to boost bass response. This is often not enough on its own to produce natural sound, though.

My most refined designs used multiple resonance frequencies and different kinds of damping to produce a more natural sounding low frequency range. If done carefully, you can maintain some of the bass boost while also not getting too aggressive with the damping and screwing up the midrange/treble.

Last edited by mattstat; 22nd April 2021 at 03:13 AM.
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Old 22nd April 2021, 02:01 PM   #5
geraldfryjr is offline geraldfryjr  United States
diyAudio Member
Join Date: Feb 2008
Location: Jackson,michigan
Hi There !!!
May I Welcome You to this Wonderful Technology of ESL !!!

Here are just a few links to some links help get you started,

My current design methods,

Bookshelf/Desktop ESL's

and much much more,

Help, Advice, Information, Reassurance... ???

DIY electrostatic speakers for dummies

ESL High Voltage supply

A most excellent build using my stator coating methods,

High strength Dielectric Coatings, fact or fiction

First time ESL builder

First ESL build - Full Range .


ESL speaker build photos


ESL Diaphragm material, Anyone tried different?

Amp design,

Isobaric ESL alternative

And the Very Most Important, Electrical Segmentation !!

Optimizing my DIY full range esl

I have complied several of these lists through the years, if there is anything that you don't understand here Please Do Not Be Afraid to Ask !!!
Cheers !!!

And, Enjoy !!!


Last edited by geraldfryjr; 22nd April 2021 at 02:24 PM.
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Old 22nd April 2021, 10:37 PM   #6
thermionicvinyl is offline thermionicvinyl
diyAudio Member
Join Date: Nov 2018
Thanks for all the links! Itís really helpful for a beginner like me whoís wanting as much information as possible. After reading some of Roger Sandersí book along with some forum posts I complied a list of specifications for the speaker I want to build:

Panel Shape: Flat
Electrically Segmented: No
Frequency Response: 50Hz-20kHz +/- 3dB
Size/Area: 60in tall by 15in wide, 6.25ft^2
DS Spacing: 1/16in
Bias Voltage: 6.25kV
Audio Voltage: 12.5kV pk-pk
Diaphragm: 3um mylar
Sensitivity: ~85dB
Stator Material: Perforated Steel, 1/8in holes, 40% open area
Insulating Spacers: 1/16in double sided foam tape
Frame: 1in thick MDF

First of all, let me know what you think of these specs and if theyíre even achievable.

My main concern is diaphragm spacing, diagram tensioning and voltages:

What spacing should I use between the diaphragm and stator? Iím using foam tape as spacers but my only convenient choices are 1/8Ē and 1/16Ē.

It seems like heat shrinking the Mylar is the only practically method of tensioning for large panels. What are your thoughts? Is all Mylar suited for this?

Are commercially available HV generators any good? Where do I get audio grade transformers and what ratios should I use? Do I really need two per panel?
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Old 23rd April 2021, 01:25 AM   #7
geraldfryjr is offline geraldfryjr  United States
diyAudio Member
Join Date: Feb 2008
Location: Jackson,michigan
Your Welcome !!!
I have thought about rewriting that book several time but but This guy already did !!!

Frank Verwal,
His Most Excellent Info can be found here,

Elektrostatic Loudspeakers

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Old 23rd April 2021, 02:19 AM   #8
geraldfryjr is offline geraldfryjr  United States
diyAudio Member
Join Date: Feb 2008
Location: Jackson,michigan
That is your basic recipe but there is a lot wrong with it.
A 15" wide panel looks impressive but won't yield you the Best Performance without electrical segmentation and a panel that size will need at least 3" to 5" wide mechanical segment just to keep the diaphragm stable !

Even with that you will still have quite a narrow sweet spot due to the beaming of the high frequency's because of the large physical width.

Just like these panels that some may recognize (below) !!!
The build is found right in the links as well.

These links show the whole process of CharlieM and Mavric building his panels and what is exactly involved in building a Perforated Metal ESL.

it is fairly easy actually, may I suggest though you choose a smaller size build as your first build, until you learn your style of technique of building these things.
I started out small with super super results and it took me 10 years to develop them. Now I am working on a 4th gen version and taking those techniques to the next level of building a much much larger system than my Desktop ESL version's.

new esl start to finish build

different ideas for ESL panels

new esl start to finish build

Material for ESL

However they Do Rock especially when set out side they hold there own extremely well, but not an optimal design, I had some say so in this design, but I was just learning a few things at the time myself as well, as too what causes the bad horizontal dispersion in the First place in ESL's !!

I didn't much care for the large segment spacing in the First place, I had suggested something in the 3-4 inch range but it is what Maveric choose to do here they are again in all of their Glory, well taken care of !!!

Still don't have em setup yet. :headbang:

The large TIG stator will be the back stators of my larger ESL system in the making since 2006 I made 6 of those in the winter time with nothing to do, I still have to calculate and build the electrically segmented front stator pieces yet.


P.S. More links here,

Newbe Question: ESL bias power supply
Attached Images
File Type: jpg Big vs Small.jpg (59.2 KB, 186 views)
File Type: jpg Ready for The Diaphragm.jpg (168.3 KB, 187 views)
File Type: jpg ONE TIG STATOR a.jpg (185.6 KB, 190 views)
File Type: jpg esl.jpg (383.6 KB, 192 views)
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Old 23rd April 2021, 04:51 AM   #9
thermionicvinyl is offline thermionicvinyl
diyAudio Member
Join Date: Nov 2018
I'm excited to make a large panel when I am able to! What do you mean by mechanical segmentation?

Also I took a look at that link from your other post. The E. Fikier looks really good but it's in dutch. Do you know if any english version exists?
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Old 23rd April 2021, 10:04 AM   #10
geraldfryjr is offline geraldfryjr  United States
diyAudio Member
Join Date: Feb 2008
Location: Jackson,michigan
Well You see those panels of Mavric's up on the right?

Those panels are quite large so lets try and analyze and predict their performance a bit without going overboard as I really love these things for what they are !!!

Their history is in these threads and I finally will be able too have the time to test em up Proper too show everyone one what anybody can do if the really want it bad enough !!!

This Not about its flaws, if there are really any at all !!!
We'll find out when those tests come.
One of the transformers is messed up and it took out my Ashley FTX2000 amp so I been kinda pretty pissed off at them but I guess I got some fixin' to do!!!
More on that later !!

CharlieM and Mavric did a fabulous job on these things and I just wanted to test them out and get them back running so maybe Mavric will get a space soon for them and set them up for himself to enjoy again.

Cheers !!!!
Mavric and CharlieM !!

I just wanted to make it clear to everyone what the deal was with these things and why they made a 1100 mile trip to me just in case they were wondering,
Maveric didn't have the space for them for a minute and where he had them stored they almost got destroyed !!
As you can see I don't have the matching TL woofers that he created for them as well, those are long gone......... Water ! :/

So I promised Mavric, that I would take care of them and when he gets setup we'll get them back set up at his place again amps and all !!

So that is the history on their Fine Example of a DIY ESL and I will get to the details of what to expect of such a build in the next post.

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