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Old 4th March 2016, 06:59 PM   #1
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Default Yet another segmented ESL

Hi all,
I’ve highjacked Bengel’s thread enough already so it’s time to start a new one for my new segmented wire hybrid ESL project. All help and/or immoral support are appreciated.

Status:
I’ve completed a wire stretching jig and got the wooden support lattice drawn but I also have a mile long honey-do list impeding my progress. Still, I hope to start making sawdust within a week.

Panel open area will be 10.5 x 46.5 inches with two vertical spacers dividing the diaphragm in to 3 sections. Each section driven by (30) 20awg single strand copper wires with .010 XLPVC insulation & .052 O.D.

The (90) wires will be segmented per symmetrical configuration 2 and consist of (15) 6-wire groups in (8) electrical segments (center segment + 7 segments on the left & right).

Total wire area is equivalent to 8.7” x 48”, the d/s is .062, sections are 8 and the X-over freq is 220Hz.
For these inputs, Bolserst’s calculator gives the feed resistor value at 120.41 Kohms.

I will use the 76:1 tandem 50VA 230V/2x6V toroids and 2.7KV bias supply that I already have, with a 1 Ohm resistor in front. Question: Will I still then need the .75R feed resistor on the center section?

Regarding stator mass:
I figure a perfect stator would have infinite mass for its charge to react against, driving the diaphragm. The much heavier steel perf stators I’ve built in the past vibrated when playing so my new and much lighter copper wire stators will no doubt vibrate even more and I’m wondering if the effects will be audible. Any thoughts on that?

Regarding the wave front:
Just wondering if my understanding is correct: While I grasp the relationship between emitter width and wavelength to dispersion, I’m not sure if the resulting wave front is truly being altered from planar to cylindrical, and if so, by the frequency dispersion alone-- or is the RC line progressively phase shifting the emitter sections and this is altering the shape of the wave front? I figure phasing can’t remain constant down the RC line. I would really like to understand how the wave front is shaped.

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Last edited by CharlieM; 4th March 2016 at 07:14 PM.
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Old 5th March 2016, 02:48 PM   #2
WrineX is offline WrineX  Netherlands
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Nice jig !!! The Whois does not bend under load ? I had aluminum
Profiles bending more then I dared. In mm what mm2 ur using ? I used 1 mm2 and that gave allot of strain on the jig.
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Old 5th March 2016, 07:57 PM   #3
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Hi WrineX,

The jig bends only slightly under the load. It probably would not bend at all if I had exactly centered the axis of pull in the frame.

The wires are .052" outside diameter, including the .010 thick insulation. .
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Old 10th March 2016, 02:45 AM   #4
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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.

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Old 10th March 2016, 03:50 PM   #5
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Charlie,
as hardwood flooring exercise tells me you would not be able to disassemble well fitted wooden pieces even after a light PU coat. The thing flows into minute slot(s) with such an ease. I would rather do parts separately with subsequent light sanding before final assembly. You have to sand first coat anyway do not you?
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Old 10th March 2016, 03:54 PM   #6
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Quote:
Originally Posted by CharlieM View Post
...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.
Looking good
I wonder if you painted the two inner vertical spacers flat black to match the wires if it would impart a cleaner look to the panels?
The idea being that you would see wooden crossbars against a black background, rather than a lattice of wooden crossbars and spacers. I'm not sure....
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Old 10th March 2016, 07:32 PM   #7
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Quote:
Originally Posted by alexberg View Post
Charlie,
as hardwood flooring exercise tells me you would not be able to disassemble well fitted wooden pieces even after a light PU coat. The thing flows into minute slot(s) with such an ease. I would rather do parts separately with subsequent light sanding before final assembly. You have to sand first coat anyway do not you?
All good points, Alexberg.
Applying the stain/paint with the pieces assembled may indeed bond them together.

The intent was to keep the stain/paint off the bond surfaces by applying it with the pieces assembled. To that end, and keeping in mind the points you made, I may attempt, on one lattice first, to mist the stain on so lightly that it sits in place without flowing, wait 8 hours and then mist on some thinned down satin poly in the same manner. Unlike a typical application on furniture, I won’t be sanding and applying a second coat, as I’m not concerned so much about sheen or wear thickness—just a light cosmetic seal to make the grain pop. The side support rails can’t be seen once the panel is installed so I could just mask those off. The center spacer supports will be the issue.
If that doesn’t work, one lattice is firewood.
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Old 10th March 2016, 07:37 PM   #8
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Quote:
Originally Posted by bolserst View Post
Looking good
I wonder if you painted the two inner vertical spacers flat black to match the wires if it would impart a cleaner look to the panels?
The idea being that you would see wooden crossbars against a black background, rather than a lattice of wooden crossbars and spacers. I'm not sure....
I had given that some thought. On my old perf-metal panels, I think the vertical spacers were a nice contrast so I'm thinking likewise on the wood panels.
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Old 12th March 2016, 06:56 PM   #9
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Oh No Charlie: Another cool project! Looking forward to reading about your impressions when you fire these up. My Jazzman Mark Vs are still alive and doing very well, thanks to you again, but I may have to rebuild them. I've noticed the stators are pulling away from the tape in several spots...The segmented panels with the rods and removable diaphragms by Ken Seibert look very interesting. I may have to try them. Hope you are well!
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Old 14th March 2016, 09:44 PM   #10
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Quote:
Originally Posted by waldtraut View Post
Oh No Charlie: Another cool project! Looking forward to reading about your impressions when you fire these up. My Jazzman Mark Vs are still alive and doing very well, thanks to you again, but I may have to rebuild them. I've noticed the stators are pulling away from the tape in several spots...The segmented panels with the rods and removable diaphragms by Ken Seibert look very interesting. I may have to try them. Hope you are well!
Yes, the psychosis got the best of me and I'm at it again. There is no cure.

If a perf metal stator isn't perfectly flat, any local high spots can cause it to separate from the spacer tape. But you can still save those panels:

In the center of the spacer, where it's separating, insert a hot awl or small nail thru a stator hole to burn a hole thru the foam tape spacer. Do this in two adjacent holes, then insert a small plastic zip tie thru the holes and pull it tight from the backside to close the gap.
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