[Jazzman53]

The psychosis continues:   

I’ve started an insane new DIY speaker project-- a hybrid electrostat with selectable dispersion modes.  It could be the holy grail or I could fall on my face.
Each stator uses a vertical array of (132) copper coated .035 diameter TIG welding rods glued onto a black plastic egg crate support (florescent light diffuser).

The conductors are physically segmented into (11) discrete groups of (12) rods, and electrically segmented into (6) discrete groups (center group + 5 outer group pairs).     

In narrow dispersion mode, all wire groups are directly coupled to the amps/transformers; driving the diaphragm uniformly across its entire surface and the panel radiates a planar wave front giving a tightly focused sweet spot for best imaging and slam. 

In wide mode, dispersion is achieved the same way Peter Walker did it in the Quad ESL 63; using electrically segmented conductors receiving sequentially delayed signals via a resistor/capacitor delay network.  But where the Quad 63 used concentric rings of conductors in a delay line, driving the diaphragm from the center outward, as a point source radiating a spherical wave front, my panels use vertical wire groups driving the diaphragm from the centerline outward, as a line source radiating a cylindrical wave front.   
         
The stators are insanely tedious to build; especially considering that the 536 welding rods are only 36” long and the panels are 48” so I have to butt and solder/splice each one to 48” length. 

No sane person would go thru this… two stators nearly done and two more to go:

[persisting1]

This looks like a lot of work! Keep the photos coming 

[SteveFord]

I'm pretty sure you'll get this to work to your satisfaction.
Keep us posted, please.

[josh358]

Beautiful work!

[a.wayne]

Jazz,

Getting bored ..? Thats 2000+ rods per speaker pr , maybe an electrostatic "tympani" like speaker with 3 panels might do the trick , imagine   6000 rods ...

[TF1216]

Gnarly!  I am subscribed!! 

[avahifi]

What are you doing for a high voltage power supply and step up transformer?

Interesting project, I hope ends up being worth the effort.


Frank Van Alstine

[josh358]

BTW, have you considered using time delay a la Quad rather than a crossover? I've always thought someone should make a time delay line source electrostat. You wouldn't need miles of cable, you could delay the signals digitally (or with an all pass filter if you don't want to leave analog) and drive the segments independently . . . If I could design an ideal speaker, I think it's the approach I'd take.

Also, I'd aim for ideal dispersion within a dipole radiation pattern, the reason being that you can't steer the beam effectively in a speaker of practical width, so that's the only way to get good polar response which is critical for realism. If you aim for directionality it will only be effective where wavelength is smaller than speaker width so the highs will be more directional than the lower frequencies and that will skew the tonal balance. Since it's a dipole it's pretty easy to deal with early reflections, you just have the first reflection point on the front wall to deal with, and the second reflection at the corner.  You can orient the speaker to null out the lateral first reflections or compromise between nulling the first front wall and side wall reflections and make up for the fact that you're off axis by steering the array.

[Davey]

Awesome!  The polar response configuration-changing scheme is interesting, but the setup allows to experiment later with the configuration and not be locked in.
I suspect you'll end up leaving these in the "narrow dispersion mode" 99% of the time.

Definitely not insane.  Excellent ingenuity.

Dave.

[Hank]

Creative idea, Jazzman53!  I look forward to your progress and hope you get the sound you quest for.  I'll soon be upgrading the interfaces on my Acoustat Model 3's.

[Jazzman53]

Update:

I got the wires glued down on two of the stator egg crates.  I also have the
wires for the other two stators spliced, the end connections soldered, and ready to
install.

It was then that I had a brainstorm about not painting the egg crates for the front stators, as they are most visible and would look much better without painting them (even with a clear coat).

So, for the front stators I'm painting the wires before I install them on the egg crates, and leaving the nice black egg crates unpainted.  Where the horizontal supports will be placed, I tacked on some 1/4" strips of wood with double-sided tape to hold the rod spacing and hung the rods up to spray them. 

I just sprayed on the first coat of clear acrylic lacquer and taking a break to post this update.
 

[SteveFord]

Nobody is going to say eggcelent in their Mr. Burns voice?

[Jazzman53]

Update 2/13:
 
Hi all,
I've been down with bronchitis for a while but the project is now back on. 
 
All four stators are completed, the diaphragms are tensioned and bonded to the front stators, and minutes ago I sprayed the conductive coating on the diaphragms (shown still wet in the photo).  I will let the coatings dry overnight, then assemble the panels in the morning. 
 
And then I'm off to spend Valentine's day and the rest of the weekend with my China Doll... love that sushi 
 
Jazz

Photo1 - Stator being bonded to tensioned diaphragm (on stretcher jig)


photo 2 - Completed front stator with diaphragm installed:


photo 3 - Front stators with diaphragms masked off and conductive coating applied (Licron Crystal ESD):

[hi5harry]

Fantastic work Jazzman! Your projects are first class. What are your plans for the frames?

[JakeJ]

Kudos, Jazzman!

I'll also be following this build thread.  Are you documenting it in greater detail and posting that on your blog?  I made a quick and dirty search for the book but it appears to be out of print and those who have a copy are asking a pretty penny.

So I take it the plan is to time delay the 11 segments such that the array acts as a line point source?  If so very interesting.

Cute trick using threaded rod to space the stator rods.

Here's hoping this project "pans" out for you.  (Yeah, yeah, bad pun intended.)

[Jazzman53]

. What are your plans for the frames?

I'm not building whole new speakers here, only the ESL panels.  These new, segmented wire stator panels will
replace the non-segmented perf-metal panels in my existing beam-splitter hybrid ESL's shown below:

[Jazzman53]

Kudos, Jazzman!

I'll also be following this build thread.  Are you documenting it in greater detail and posting that on your blog?  I made a quick and dirty search for the book but it appears to be out of print and those who have a copy are asking a pretty penny.

So I take it the plan is to time delay the 11 segments such that the array acts as a line point source?  If so very interesting.

Cute trick using threaded rod to space the stator rods.

Here's hoping this project "pans" out for you.  (Yeah, yeah, bad pun intended.)

The threaded rod idea has been around for a long time... not sure who came up with that.  I will add this build to my blogpage if it works out as I hope.  The build technique is already well documented in Ken Seibert's web page here:  http://kenseibert.com/www/kenseibert/esl/

Roger Sanders' Cookbook I believe is out of print and others are selling copies at extortion prices on Ebay and elsewhere.  However, if you were to do a Google Search using the search words "Electrostatic Cookbook" + "PDF", I would not be surprised if you found a free download of the entire first edition.  I only point this out because the book is out of print so you would not be cheating the author.   

[JakeJ]

Thanks for the link and the search tip. 

That new build that Ken Seibert is doing might be interesting to follow too.

[Jazzman53]

The panels are completed.   When the resistors from Digikey and the Soviet military rotary switches from Belarus arrive, I can build the resistor networks to make these panels switchable between narrow and wide dispersion modes.

   

[dB Cooper]

Thanks for sharing your project. You are probably right that no sane person would go through this; but an audiophile would!!! Good luck!