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Old 16th February 2020, 02:58 AM   #11
CharlieM is offline CharlieM  United States
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Hello Grantin,

The attached schematics are for an earlier speaker design with the same panel arrangement. The new speakers will crossover a bit higher and use a 3.2kV bias supply.

Physically; the panel has three equal-width diaphragm sections, each driven by five (5) 6-wire groups. In total; 90 wires arrayed in 15 separate groups.

Electrically; the 15 wire groups are driven as: A single [six-wire] center group with seven left/right paired wire groups arrayed symmetrically on either side.

The center wire group is directly coupled to the amplifier interface and receives the full audio bandwidth above the crossover frequency. The paired groups on either side are powered in series through the center wire group.

Inserted between the wire groups are series resistors which couple with the wire/diaphragm capacitance (in parallel) to form a series of low-pass filters that progressively chop off the upper frequencies, toward the panel edges. This arrangement gives very smooth trending dispersion.

In effect; the panel's frequency/phase progression from the center to the edges approximates a line source projecting a cylindrical wave front. A couple of really smart ESL gurus on the DIY Audio Forum (a.k.a. "Boslerst" & "Golfnut") provided an Excel spreadsheet program which I used to design my panels.

Also; the segmentation scheme flattens the panel's frequency response, down to the low frequency cutoff. Whereas; an unsegmented flat panel tends to have a rising frequency response and very narrow sweet spot.

I plan to cross the panel over to the woofer at 235Hz using a 24db/octave Linkwitz-Riley filter slope. I will use a DSP crossover which gives a lot of tuning flexibility.

I built a similar OB woofer/ESL for a friend a couple of years ago (the one shown playing in the video) but I've never owned one myself or had an opportunity to audition them over time (I plan to keep one of the four pairs I'm currently building, though).

My current ESLs are also hybrids, with similar wire panels but they use 10" woofers in a transmission line. I'm looking forward to tuning the new OB speakers.

I figure the quasi-H baffle OB with a 12" woofer should be fairly adequate in bi-amp'd two way setup. But for my pair; I will use a tri-amp setup with Ripole subs handling the bottom two octaves.
Attached Images
File Type: jpeg Wire Layout.jpeg (61.0 KB, 86 views)
File Type: jpeg Figure 1.jpeg (25.2 KB, 88 views)

Last edited by CharlieM; 16th February 2020 at 03:26 AM.
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Old 16th February 2020, 05:12 AM   #12
gnnett is offline gnnett  Australia
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Join Date: Jul 2004
Location: Docklands VIC3008
Thanks for that Charlie.

I have been attempting something far less ambitious and failing for the last 4 years, but am now heading in the direction of using less Acoustat panels (2 per side) and handing over to Ripoles using the Peerless SLS drivers, 1 pair per side at about 60 to 80Hz. I will have to venture into the world of DSP I suspect as well, but that is some distance away.

Regards

Grant
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Old 16th February 2020, 06:23 AM   #13
carlthess40 is offline carlthess40  United States
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Join Date: Oct 2017
Location: Lake Mary Florida
Quote:
Originally Posted by CharlieM View Post
Hello Grantin,

The attached schematics are for an earlier speaker design with the same panel arrangement. The new speakers will crossover a bit higher and use a 3.2kV bias supply.

Physically; the panel has three equal-width diaphragm sections, each driven by five (5) 6-wire groups. In total; 90 wires arrayed in 15 separate groups.

Electrically; the 15 wire groups are driven as: A single [six-wire] center group with seven left/right paired wire groups arrayed symmetrically on either side.

The center wire group is directly coupled to the amplifier interface and receives the full audio bandwidth above the crossover frequency. The paired groups on either side are powered in series through the center wire group.

Inserted between the wire groups are series resistors which couple with the wire/diaphragm capacitance (in parallel) to form a series of low-pass filters that progressively chop off the upper frequencies, toward the panel edges. This arrangement gives very smooth trending dispersion.

In effect; the panel's frequency/phase progression from the center to the edges approximates a line source projecting a cylindrical wave front. A couple of really smart ESL gurus on the DIY Audio Forum (a.k.a. "Boslerst" & "Golfnut") provided an Excel spreadsheet program which I used to design my panels.

Also; the segmentation scheme flattens the panel's frequency response, down to the low frequency cutoff. Whereas; an unsegmented flat panel tends to have a rising frequency response and very narrow sweet spot.

I plan to cross the panel over to the woofer at 235Hz using a 24db/octave Linkwitz-Riley filter slope. I will use a DSP crossover which gives a lot of tuning flexibility.

I built a similar OB woofer/ESL for a friend a couple of years ago (the one shown playing in the video) but I've never owned one myself or had an opportunity to audition them over time (I plan to keep one of the four pairs I'm currently building, though).

My current ESLs are also hybrids, with similar wire panels but they use 10" woofers in a transmission line. I'm looking forward to tuning the new OB speakers.

I figure the quasi-H baffle OB with a 12" woofer should be fairly adequate in bi-amp'd two way setup. But for my pair; I will use a tri-amp setup with Ripole subs handling the bottom two octaves.


Those are gorgeous speakers, are you taking orders for them? Iím sure I could not afford them anyway. Lol
Great work and thanks for the pic of how the resistors are for
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Old 16th February 2020, 06:33 AM   #14
carlthess40 is offline carlthess40  United States
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Join Date: Oct 2017
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Quote:
Originally Posted by CharlieM View Post
I'll let you in on a little secret: Speaker designers love to show them off.
Carl, you have an open invitation to visit me in Savannah most anytime.

Charlie


Thanks Charlie
I just started reading your website, great information there, your a very modest man
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Old 16th February 2020, 11:41 AM   #15
CharlieM is offline CharlieM  United States
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Quote:
Originally Posted by carlthess40 View Post
Those are gorgeous speakers, are you taking orders for them? Iím sure I could not afford them anyway. Lol
Great work and thanks for the pic of how the resistors are for
I'll send my drawings and parts list to anyone who wants them but I'm swearing off building more speakers to sell... it's just too exhausting for an old guy like me.
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