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Since October of last year I've been toiling away on my biggest-ever ESL speaker project.  And in the coming weeks I will be posting some photos as the project nears completion.  

 

Several of my Carver Audio friends have been twisting my arm for years to build some speakers for them, but until now I've declined because my designs are exceedingly tedious and exhausting builds, especially for an old guy (66) like me.   I must have bumped my head somewhere because I finally agreed to do it. 

 

I'm about 85% through building four (4) pairs of an OB hybrid design that uses a 12" woofer mounted on a semi H-baffle.  The frames are red oak and the stat panels project a curved wave front using frequency and phased-array wire stators driving the diaphragm sequentially from the center-line outward.  The stator wires are 20 AWG, UL-1061 single-strand copper.   

 

Building eight speakers at the same time is a huge project but I think I've moved beyond the suicidal phase and starting to to see some light at the end of the tunnel.  

 

The video below shows a similar design that I built in 2018, along with my method of building the wire stators.  

 

The new speakers are a refined version of the design shown in the video, with a new 3.2kV bias supply, a different woofer, a slightly slimmer frame, and magnetically attached grills front and back.  

 

More to come, but for now-- enjoy the video! 

 

 

Edited by jazzman53
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Amplifier/ESL interface (high voltage bias supply and step-up transformers), located on the lower rear shelf of the speaker:

 

Interface.jpg

Edited by jazzman53
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Update  Tuesday March 3: 

All (8) ESL panels, power supplies & speaker frames are completed. 
Now assembling the (16) segmentation resistor networks. 
Still have to buy woofers and make the grills.  

Here's another video; showing the diaphragms being installed and the panels assembled: 
 

 

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  • 2 weeks later...

Update Saturday March 14, 2020:

The panels and segmentation resistor networks are installed in all eight speakers.  Today I installed Peerless SLS 12 woofers in one pair and they're playing tonight.  I delayed ordering woofers for the remaining speakers until I've had a chance to audition these.  My first impression is the SLS 12's will be fine.

I still have to build the grills but it feels good to be wrapping this project up after 5 months of toil.  

The photo and video below were made today.. enjoy!
 

 

 

 

IMG_2266.jpg

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I reckon this is an awesome achievement and one that can only be done by someone with real knowledge and experience.

So how many of these superb types of speaker have you crafted over the years? and where did the original design come from?

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Posted (edited)
15 hours ago, Grimmie said:

I reckon this is an awesome achievement and one that can only be done by someone with real knowledge and experience.

So how many of these superb types of speaker have you crafted over the years? and where did the original design come from?

I've been building ESLs since 2008, starting with perf-metal stators, then segmented welding rod stators, and a few years ago I started building electrically segmented wire stators.   I didn't invent wire stator ESLs or electrical segmentation-- I only applied those principles to my designs, which include this speaker.  I think the most innovative part of it was the wire stretching jig; as I've never seen one like mine.  

 

To the best of my knowledge Accoustat built the first commercial wire-stator ESLs and I'm not sure who first introduced electrical segmentation --- that might have been Audio-Static.  There are several companies making segmented panels now but they only use two or three segments, just to spread the highs.   It takes many more segments to create a smooth trending dispersion pattern.   Generally; down to 12mm, more/narrower segments gives wider/smoother trending dispersion (no advantage below 12mm which equates to the smallest audio wavelengths)

 

I'm not smart enough to figure all this out but I have very smart friends at the DIY Audio Forum to helped me along the way.  

 

My segmentation scheme is derived from a technical paper written by a physicist in New Zealand named Rod White (a.k.a. "Golfnut" at the DIY Audio Forum).  His collaborator Steve Bolser (a.k.a. Bolserst at DIY Audio Forum) created and Excel spreadsheet calculator program for designing segmented ESLs; which I used when designing my panels.  I just plugged in the input parameters (panel dimensions, number of segments, diaphragm-to-stator gap, bias voltage, transformer winding ratio, and low cutoff / crossover frequency)  and the spreadsheet calculates the resistor values, max SPL, upper frequency limit, and graphs the response curve. 

 

 

Edited by jazzman53
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Wow!

jazzman53, this really is next level DIY, High end craftsmanship here... 

Congratulations on this outstanding project, they look fantastic! I really admire your patience & precision with your work.

Thank you for sharing , i'll be watching closely.

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I admire your skill, they look very professional.  I'm sure they will sound as amazing as they look when completed. 

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Update 3/23/20:

All four pairs of speakers are fully completed except for the magnetically attached grills, which I started building today. 

I spent the weekend sound testing every pair, and they all play to ridiculous volume with no apparent issues. For a $77 woofer; I'm pretty impressed with the Peerless SLS-- I was concerned it wouldn't be up to the task so I only ordered one pair initially. I should point out that so far I've only sound tested them chopped off at 60Hz and crossing into a pair of Ripol subs with a 24db filter slope. Thus unloaded on the bottom end; the Peerless woofers rock pretty well without bottoming out at X-max. 

Parts Express had the black grill cloth but not the burgundy I want for my pair-- so I was happy to finally locate some 66" x 36" sections on Ebay. That order arrived today and it's only 54" x 36".  With the Corona virus lurking and me old as dirt, I'd rather lose the refund than risk the post office to return a package. 

Just one more delay in wrapping this project up...   

In the meantime-- here's some more porn for all you planar pervs:

 

IMG_2290.JPG

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Update 3/26/20:

Having a lot of problems with the grill frames.  They looked great the day I built them but they bowed after a couple of days and I'm having to redo them.  The first time I used white pine stiffeners on the hardboard frames, the second time I used poplar.  Both bowed but the poplar bowed a bit less.  So I'm cutting the stiffeners off and bonding new stiffeners on with the frames purposely bowed in the opposite direction, hoping they will bow back to near straight condition.  I may end up giving them a week or so to stabilize, then cross cutting slots in the vertical stiffeners to relived the bow, and then gluing on some strips to re-stabilize.  They will look nice if I can resolve the bowing issue:
 

 

x2.jpg

grill 0.jpg

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The Kingssound speakers use a frame of aluminium u section for the perimeter with aluminium rods as horizontal ribs.

The u section is 15 x 7.5mm, ribs probably 6mm.

Sockets inserted in the frame to accept pins in the speaker. Works pretty well.

Thanks for the updates. Maybe a closer look at the way you have wired the resistors might help.

I use open baffle 15" drivers in my Kingsound as well. Works well down to 40Hz.

Fly screen framing material could work. They have 90 deg corner joints. 

Regards,

kffern

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DSC_0146.JPG

Edited by kffern
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  • 3 weeks later...

Hi all, 

 

This project (all four speaker pairs) is finally completed, so this will be my last post on this thread unless it's in response to others. 

 

I resolved the issue with the grill covers bowing and they turned out great.  

I finally now have my dream speakers for life, and I'm sure the recipients of the other three pairs will feel the same way.  

 

I'll just leave you with a last VIDEO showing the speakers playing. 

 

Enjoy!

Charlie 

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