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Old 16th May 2016, 04:03 AM   #1
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Default Curved Electrostatic Speaker Build

Hello!
A couple months ago I completed my first ESL: A single 12" x 12" panel with 12 micron Mylar and a PVA glue coating. I was pleased enough with the results to make some more! I have started construction on two 12" x 24" curved ESL panels again with 12 micron Mylar, but now with Licron Crystal as the coating. The 12" x 12" panel got pretty loud so nearly 4 times the surface area and better sound dispersion should make these new panels rock!

I hope I'm making making thread right...
Anyway, enjoy!
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Old 16th May 2016, 04:17 AM   #2
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Default Curved Electrostatic Speaker Build

I received the sheet metal about a month ago and I just got to rolling it last weekend. I don't know exactly what the curvature of the metal is but no doubt it will be better than a flat panel in terms of dispersing sound. I've attached some photos of the flat metal and the bent metal.
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File Type: jpg IMG_20160325_154317.jpg (1.06 MB, 446 views)
File Type: jpg IMG_20160510_180705.jpg (1.01 MB, 429 views)
File Type: jpg IMG_20160510_180719.jpg (812.0 KB, 414 views)

Last edited by DriedChalk; 16th May 2016 at 04:34 AM.
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Old 16th May 2016, 04:42 AM   #3
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Default Curved Electrostatic Speaker Build

After soldering the wires onto the stator I hung the panels up for some coats of primer and a just a few coats of black polyurethane spray paint. The black paint is super economic at less than a dollar a can from Home Depot. I just started painting today and should hopefully be finished by the end of the week.
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File Type: jpg IMG_20160515_152055.jpg (943.4 KB, 398 views)
File Type: jpg IMG_20160515_213042.jpg (979.6 KB, 394 views)
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Old 16th May 2016, 09:52 AM   #4
Calvin is offline Calvin  Germany
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Hi,

You did a nice curvature, though a little too much for my taste.
It'll become difficult to tension the membrane.
Also it looks as if the cuts in vertical direction are not done well.
In the first pic the left edge (top or bottom edge of the panel) looks well cut with no sharp edges.
The side edge though (upper edge in pic) starts quite smooth from the left corner and becoming more rough towards the right corner.
The sharp pin-like structures that appear when less than half of a hole is cut are prone to flashovers and should be avoided as they are also difficult to insulate properly.
Best would be of course a solid rim like the one visible at the lower edge.
Besides insulation issues a solid rim is also advantageous regarding glueing spacers and the membrane to the stator.
Especially the glue joints at the top and bottom rim of the stator must take serious amounts of force from the tensioned membrane.
I hope things will go well, but I'm afraid Your panels required a bit more pre-painting preparation.

jauu
Calvin
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Old 16th May 2016, 11:09 AM   #5
Calvin is offline Calvin  Germany
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Hi,

just found a pic I made ages ago explaining the issue of sharp edges and holes.

jauu
Calvin
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Old 16th May 2016, 01:27 PM   #6
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Hi calvin,
Thanks for the advice. On the edges with the pin-like structures I tried to grind them down so that instead on a sharp edge pointing inwards it was a smoother curve. Aside from grinding the metal itself, do you not think that many layers of paint and electrical tape wrapped around the edges will stop arcing?
Thanks,

Ben
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Old 16th May 2016, 02:27 PM   #7
tyu is offline tyu  United States
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Thanks for the input...an pic.....your panels look great.....looking for your input...on what you think of the Licron as coating...an sound output.....good luck
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Old 16th May 2016, 06:07 PM   #8
Calvin is offline Calvin  Germany
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Hi,

good to see that You are sensitive to that little but important detail
Many layers of laquer are not neccessarily the way to go, as a thick layer builds up only around the pin structure where it is not only not needed, but may alter the d/s value (with low d/s hybrid panels think in 1/10mm precision range rather than 1mm range).
The buildup at the peak structure itself may still not suffice if its a very sharp pin as the field strength is the strongest here.
Even if the flashover treshold of the insulation is high enough at the beginning, it may age faster and lead to a premature breakdown.
A layer of tape is a good measure to raise the flashover treshold and to protect the edges, but of course should rather be used as an 'add-on' detail, not as a neccessary part of the 'prime' insulation.
Clear singlesided PVC or PP tape (e.g cheap package tape) comes in well tolerated thicknesses around 0.1mm (PP also has self-healing characteristics) and is mechanically quite strong.
Spacers made from 3Ms foam and VHB tapes stick well to PVC tape.
A point that requires Your attention, as the mechanical forces on the glue joints in vertical direction are high and permanent for years.

jauu
Calvin
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Old 16th May 2016, 06:55 PM   #9
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Hi Calvin,
Thanks for your reply. I was thinking of using electrical tape that wraps around the edge of the double stick tape and the stator on each side. Of course on the side with the Mylar I would wrap it over the edge of the Mylar and the stator. If I were to use the PVC tape or packing tape would that go underneath the foam tape and around the edge of the stator to give more surface area for the foam tape to adhere to or over the foam tape and Mylar just like I was planning on doing with the electrical tape?
Thanks,

Ben
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Old 16th May 2016, 11:50 PM   #10
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Did you do the curve yourself? How so?
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I enjoy my organic shapes.....
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