Yet Another DIY Electrostatic Speaker Project

[jazzman53]

Hi all,

I've retired from speaker building but I want to share this last ESL project. I don't know how I would top this one anyway-- It's the finest speaker I've ever built.

Others are building these now, using my drawings and encouragement. The labor is horrendous (no sane person would attempt it) but the journey and results are life changing.

Description:
This speaker is a flat panel wire-stator hybrid electrostat with dipolar bass from an Eminence KappaLite 3012LF woofer on an open baffle. The speakers + subs are 6-channel stereo with a DSP crossover.

The Eminence 3012LF woofer isn't optimal for low bass on an OB (low-Q & 56Hz Fs) but it doesn't need to be with the subs in play, and it blends superbly with the ultra-fast electrostat, and that was the priority.

The stators are state of the art 90-wire arrays, symmetrically segmented in 15 six-wire groups to function as a line source projecting a cylindrical wavefront. This setup gives wider and smoother trending dispersion than a curved panel ESL, or even most conventional speakers.

The details of how the segmentation scheme tailors the dispersion are given on my website below, along with several build videos:

Jazzman's DIY ESL Page
Jazzman MkIII Intro Video
Stator build video
Panel assembly video
* Video of the prototype playing

*The prototype had a different segmentation scheme and a lower quality woofer than the final version.

Below: The Jazzman MkIII ESL and matching Ripol subwoofer

Below: Back view showing the amp-interface assembly and Eminence 3012LF woofer.

Below: Sketch showing the wire lacing and segmentation layouts.

Below: Stator in the assembly jig with the oak support lattice glued down over the wires.

Below: Completed 90-wire stator.

Below: Front stator being bonded onto the diaphragm, on the bike tube tensioning jig.

Below: The amp-interface assembly (HV bias supply & tandem step-up transformers).

Below: Jazzman MkIII speaker with its magnetic grill covers on.

 

[ben_]

I have no technical insight on this, but that looks like an insane amount of work. Really impressive.

 

[Mikado463]

Jazzman, nicely done , congrats ! As a longtime Stat/di-pole lover I applaud your efforts !!

to this day some of my most enjoyable piano recordings have listened through Electrostatic speakers.

 

[dlaloum]

Nice .!

You system looks similar in concept to the ESL63 design, except rather than aiming for a spherical dispersion pattern, you aimed for a linear one, and you appear to have provided far more "steps" than the vintage 63...

 

[jazzman53]

Nice .!

You system looks similar in concept to the ESL63 design, except rather than aiming for a spherical dispersion pattern, you aimed for a linear one, and you appear to have provided far more "steps" than the vintage 63...

Yes; it's a similar concept implemented differently (line source vs point source).

Generally, more/narrower vertical segments (discrete wire groups) gives wider and smoother-trending dispersion in a cylindrical pattern, but there is no additional advantage in making the wire groups narrower than about 12mm (approximate wavelength of the highest audible octave).

My panel design was inspired by a white paper entitled "An electrostatic loudspeaker with zero-free polar response" by Dr. Rod White, a physicist/ESL builder in New Zealand.

I'm not good with math but fortunately, one of Dr. White's collaborators, Steve Bolser (aerospace engineer at Boeing) had translated Dr. White's info into an Excel spreadsheet program ("Segmented ESL Calculator") and posted it on the DIY Audio Forum.

With the Calculator doing the math, all I had to do was plug in the physical parameters of the panel (height, width, number of electrical segments, diaphrgm-to-stator spacing, transformer step-up ratio, low-frequency cutoff, bias voltage). From those inputs, the spreadsheet calculated the capacitance, the segmentation resistor values, and also generated plots of the frequency response and max SPL.

 

[Bobby Bass]

Hi all,

I've retired from speaker building but I want to share this last ESL project. I don't know how I would top this one anyway-- It's the finest speaker I've ever built.

Others are building these now, using my drawings and encouragement. The labor is horrendous (no sane person would attempt it) but the journey and results are life changing.

Description:
This speaker is a flat panel wire-stator hybrid electrostat with dipolar bass from an Eminence KappaLite 3012LF woofer on an open baffle. The speakers + subs are 6-channel stereo with a DSP crossover.

The Eminence 3012LF woofer isn't optimal for low bass on an OB (low-Q & 56Hz Fs) but it doesn't need to be with the subs in play, and it blends superbly with the ultra-fast electrostat, and that was the priority.

The stators are state of the art 90-wire arrays, symmetrically segmented in 15 six-wire groups to function as a line source projecting a cylindrical wavefront. This setup gives wider and smoother trending dispersion than a curved panel ESL, or even most conventional speakers.

The details of how the segmentation scheme tailors the dispersion are given on my website below, along with several build videos:

Jazzman's DIY ESL Page
Jazzman MkIII Intro Video
Stator build video
Panel assembly video
* Video of the prototype playing

*The prototype had a different segmentation scheme and a lower quality woofer than the final version.

Below: The Jazzman MkIII ESL and matching Ripol subwoofer

Below: Back view showing the amp-interface assembly and Eminence 3012LF woofer.

Below: Sketch showing the wire lacing and segmentation layouts.

Below: Stator in the assembly jig with the oak support lattice glued down over the wires.

Below: Completed 90-wire stator.

Below: Front stator being bonded onto the diaphragm, on the bike tube tensioning jig.

Below: The amp-interface assembly (HV bias supply & tandem step-up transformers).

Below: Jazzman MkIII speaker with its magnetic grill covers on.

Wow they look amazing congratulations! Hope they sound as good as they look.

 

[dlaloum]

Another benefit of your line design, is the additional surface area, which should improve the bass I expect?

How did you go about matching to the woofer? I tried several times with different subs and my ESL63's but could never get a decent match... all in the days before digital electronic EQ became viable...

 

[jazzman53]

Another benefit of your line design, is the additional surface area, which should improve the bass I expect?

How did you go about matching to the woofer? I tried several times with different subs and my ESL63's but could never get a decent match... all in the days before digital electronic EQ became viable...

Achieving a seamless blend between a woofer and ESL is a challenge for any hybrid design. I opted to mount the woofer on an open baffle to obtain a matching dipole radiation pattern.

Typically, you would want a high-Q woofer with floppier suspension on an OB, to allow the woofer to play low without a lot of EQ boost, as needed to offset the dipole phase cancellation.

The Eminence Kappa-Lite 3012LF is not at all optimal for playing down low on an OB, due to its having a low-Qts / stiffer suspension.

But with the subs in play, the mid-bass woofer doesn't need to play low... it just needs good mid-bass thump (OMG the Eminence thumps!) and most importantly-- it needs transient speed (i.e. low inductance) and good damping (minimal overshoot) to blend with the ultra-fast ESL. The Eminence woofer on the OB provides the best integration I've heard in a hybrid ESL.

Of course, the characteristics of my hybrid ESL and your full range is ESL-63 are different. Still; both need subs for the bottom octaves, and achieving a seamless blend is even more difficult with subs.

I think a pair of dipolar subs would work best with your ESL-63's. And I think Ripol subs would be the best choice. I love my Ripol's (the cleanest, most non boomy subs I've ever heard).

 

[dlaloum]

Sadly WAF caused the ESL's to be replaced... (I had a 4.0 surround setup with ESL63's and ESL989's)

 

[jazzman53]

Sadly WAF caused the ESL's to be replaced... (I had a 4.0 surround setup with ESL63's and ESL989's)

Yeah, I had some WAF issues to deal with too. Problem solved now, though... I don't miss her at all !

 

[TLS Guy]

Sadly WAF caused the ESL's to be replaced... (I had a 4.0 surround setup with ESL63's and ESL989's)

That was sad, as Quad ESLs have been the reference point of how speakers should sound. That was the main reason Peter Walker designed them. He wanted a reference. He of course realized the power limitations, but it was the superb frequency response and balance and the total lack of coloration that set the standard and still does. You could really say, that you have no business designing a speaker unless you have spent time with Quad ESLs.

 

[dlaloum]

That was sad, as Quad ESLs have been the reference point of how speakers should sound. That was the main reason Peter Walker designed them. He wanted a reference. He of course realized the power limitations, but it was the superb frequency response and balance and the total lack of coloration that set the standard and still does. You could really say, that you have no business designing a speaker unless you have spent time with Quad ESLs.

Lots of speaker designers have kept a pair of Quads in the back as a reference...

The midrange purity of the original ESL57's is still astounding.... the 63's were good... but not quite as good in that midrange.

For years my dream was to set up a 5.1 system using 989's L & R, 57 Center and 63's rear/surround.

Never quite got there...