Yet another ESL project

[jazzman53]

The insanity continues... more to come:

[Kingman]

WOW!!!! Looking good Charlie! An updated electrostatic panel.  Details?

[jazzman53]

This project is a segmented wire-stator type electrostatic speaker. 

The photo shows my stretching jig and stator wires being stretched about 1%.   Stretching the copper wires to plastic deformation renders them perfectly straight and also work hardens the metal such that the wires remain straight when the tension is relaxed. 

The stator wires will be supported in the speaker by an wooden lattice frame that will look somewhat like a ladder; consisting of side rails, two center rails and eighteen horizontal rung supports.

There are 90 wires total, which will be segmented into (15) 6-wire groups.  The center wire group will be directly coupled to the amplifier/step-up transformers; receiving the full frequency band above 200 Hz.  From the center outward, the paired wire groups to the left and right of center will receive progressively less treble.  This is accomplished by inserting resistors between the segments, which then couples with the wires' capacitance to form a first order filter that attenuates the treble downward and imparts a small phase shift that bends the wavefront into a cylindrical shape. 

The effect is that the flat panel electrostat now projects a cylindrical rather than planar wavefront; giving wide dispersion.   The polar response will be far superior to a curved panel (like ML) and even better than most conventional speakers, while still retaining the  magical ESL sound.               

[jazzman53]

BTW, I'm not smart enough to figure any of this out... but I have smart friends over at the DIY Audio Forum who provided me with an Excel spreadsheet calculator that does all the math. 

I just plug in the height & width of the panel, diaphragm-to-stator spacing, number of wire groups, and the low end cutoff frequency (where the woofer takes over) and the spreadsheet calculates the resistor values, max SPL, and frequency response curve.  Pretty cool! 

[MacGeek]

Very nice.  I wish you lived near Pittsburgh so some of us could hear them.

[RuralTom]

Very nice.  I wish you lived near Pittsburgh so some of us could hear them.

Agreed!

[schwarcw]

We have a new Sparky!!!  (long story  )

[jazzman53]

Update 3/9/16:

Most of the wooden pieces for the wire support lattices are cut. A few minutes ago I dry fitted the interlocking pieces for one of them (see below).

I plan to spray apply a coat of a light stain and a coat of satin polyurethane (while assembled, not glued). And then re-assemble and glue the pieces together, over the wires, in the stretcher jig.

The stators must fit within the frame of my existing beam splitter speakers and they had to be rather thin to clear the beam splitter during install.

It's a lot of work but I think they will look much better than my current welding rod panels.

[Sir Thrift-a-Lot]

That's dedication.

[jazzman53]

That's dedication.

It's a psychosis

[MacGeek]

Excellent work (and patience) nevertheless

[Sir Thrift-a-Lot]

That's dedication.

It's a psychosis

You'll only find enablers here.

[jazzman53]

Moving right along...

[Jim Pittsburgh]

what a great job.... congrats man.  Now we just need you to bring them to the 'Burgh" for a listen!

[jazzman53]

Update 3/24/16:

The stators are finished and the diaphragms were installed and conductive coatings applied this afternoon. The coatings need twenty four hours to dry and then I can assemble the panels. The resistors and bread boards for the RC networks were ordered today--- still gotta build the networks. I figure another week to wrap this up.


Below: Bonding stator to the tensioned diaphragm, on a pneumatic (bike tube) tensioning jig.  Diaphragms were tensioned to 1.4% elongation.


Below: Diaphragm installed