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Old 27th September 2007, 09:42 PM   #21
gvy is offline gvy  Belgium
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Quote:
Originally posted by MJ Dijkstra



Hi,

Martin Logan does! So it must be possible

Maybe you can avoid electrical segmentation (= crossover in the most sensitive range of human hearing) with a curved design
Martin Jan.

Martin Logan does (with plate stators and with 1000 of panels in a production process)....
I know that it is done by diy ers also....

But lets be honest to each other..... all of us , more experienced diy builders, know also that the change of building successfully a curved wire stator, with high efficiency, thus thight tolerances, by someone totally new in diy ESL building, is very small.
I just wanted to help Skyseeker , by pointing out what is really important in the building process of a good efficient stator.

It is even so that Martin Logan curves its stators with a reason of structural stiffness, more ,than the reason of the limited wider dispersion pattern.

A wire stator can be segmented to get the same effect.
No need to try to get a curved one.

Anyway , just my opinion in this of course


Geert
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Old 28th September 2007, 05:38 AM   #22
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Thanks guy's, you are a big help!

Geert: I already have "a few" years of experience in DIY. I am not afraid of a curved design.
The reason for wanting to build a curved design is that I expect a better balance between the highs and the mids without EQ'ing, as well as having the highs available to the whole couch (2 seater) instead of just one. I know that the stereo image will be compromised though for one of them.

Since you are right about being new to ESLs, I have decided to first build a half hight flat panel. That should get me up to speed. Next I will build a half hight curved panel. I will measure the two and compare them. If I find that curved does indeed bring the expected advantage, I will then build a curved full hight panel.

Calvin: My current room is 2.4m high. Even with a 1.8m and 0.3m blanks on top and bottom I will only just cover the whole room hight. Besides, 8 speakers of 8" (0.2m) with just a little space in between also need 1.8m.

I got a very nice quote from partsexpress for the speakers, converted into euro's its almost a laughable price :-)

Btw: If there is someone in Holland/Germany/Belgium who also wants to order from partsexpress, I would be willing to combine shipments. You can use the PM feature. I want to order next monday, so you will need to be quick. To convert USD into EUR, be sure to add approx 22% taxes. Shipment costs will be split according to ordered value as long as you do not order something prohibitively big and/or heavy.
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Old 28th September 2007, 06:25 AM   #23
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Quote:
Originally posted by gvy


Martin Jan.

Martin Logan does (with plate stators and with 1000 of panels in a production process)....
I know that it is done by diy ers also....

But lets be honest to each other..... all of us , more experienced diy builders, know also that the change of building successfully a curved wire stator, with high efficiency, thus thight tolerances, by someone totally new in diy ESL building, is very small.
I just wanted to help Skyseeker , by pointing out what is really important in the building process of a good efficient stator.

It is even so that Martin Logan curves its stators with a reason of structural stiffness, more ,than the reason of the limited wider dispersion pattern.

A wire stator can be segmented to get the same effect.
No need to try to get a curved one.

Anyway , just my opinion in this of course


Geert

Hi Geert,

I agree with you, building a curved one is not a good start. Making a good flat one is difficult enough for most diy.

I don't agree about the statement that curving is mainly done for structural stiffness. I've build a small curved wire esl (+/- 25 degrees dispersion, so 50 degrees total, closely matching ML) and the sound is not comparable with a flat one. The flat one being shouty and spitting, the curved one smooth. Unfortunately construction of the curved one is troublesome indeed and I have to solve several problems before it is good, but I like that kind of a challange as I've build several flat ones already.
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Old 28th September 2007, 06:46 AM   #24
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"The flat one being shouty and spitting, the curved one smooth"

Bingo. That would match my expectation on theoretical grounds. And more, I believe that the effect slightly offset from the optimum position would be even bigger.

The more I think about this, the more I get convinced that a flat ESL is actually one of the worst possible shapes for a sound source, UNLESS it is going to be used as a "headphone at a distance". In the later case flat is the way to go, and close up the the right listening position.

Be aware: this is just conjecture on my part. Not having build an ESL jet.

Btw MJ, 50 degrees is a BIG opening. Have you done that with a single diaphragm?
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Old 28th September 2007, 08:40 AM   #25
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Quote:
Originally posted by SkySeeker
[BBtw MJ, 50 degrees is a BIG opening. Have you done that with a single diaphragm? [/B]

Hi,

It's not that big compared with ML!
It's a single sheet of Mylar® as well.
The trick is to tension only vertically (very high tension) and almost zero in horizontal direction.

ML has a horizontal spacer each 12 cm (sequel2) but you could reduce that distance and use thinner Mylar. I am planning to use 4 micron with 3 to 4 cm distance between the spacers. Spacing will be around 1,5 mm or slightly more.
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Old 28th September 2007, 03:57 PM   #26
Calvin is online now Calvin  Germany
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Hi,

having built both, flat wire as well as curved sheet metal successfully I don´t see why it should be more difficult to build a curved stator than a flat one.
It is a lot of work to get all (!) the wires perfectly straight.
There is the risk to tear the wire apart or to get a failure point in the insulation while pulling it straight. Next possible points are the numerous glue joints (its quite a task to get here a precision of 0.1mm)
that have to be of equal thickness, etc. etc.
Building a curved stator is just ordering the stator sheets, have them insulated and build a simple curved stretching jig for the membrane.
Everything else is just prescision handcrafting.
There are small sonic differences between segmented flat wire panels and curved sheet metal panels and those ly within the dynamic performance which is slightly superior with the curved panel (tonality is equal when both types are equed precisely and in the correct way). Efficiency is highest with curved panels too. The only ´drawback´ against flat panels is their restriction to the midhighs (i.e. Hybrid-ESLs)

jauu
Calvin
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Old 28th September 2007, 04:55 PM   #27
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Hi Calvin,
Didn't you have problems with insulating the metal sheets in a reliable and durable way?
What did you use?
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Old 29th September 2007, 11:10 AM   #28
Calvin is online now Calvin  Germany
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Hi,

I had my panels powdercoated with the powder I chose before.
They looked perfect, but I feared the thickness of the coating to be a bit too low (it was safe when testing with the nomnal expected voltages, but I liked to have reserves in this special case).
So I added several layers of a clear 2-component PU-laquer since the coating reached the thickness I wanted. PU has very favourable features for this kind of insulation.

My panels work very well with this insulation and are absolutely safe within their intended voltage range and with lots of reserves above that range. (otherwise I very probabely couldn´t wrte these words ;-))

jauu
Calvin
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Old 13th February 2008, 06:05 PM   #29
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Default Woofers almost finished

Now that I have assembled my woofer for the first time, I though to post a picture.

Thanks to Calvin for helping me out with a few idea's when I needed them :-)

Btw: I first needed to build the woofers, so that I can check the stator spacing on the ESL design. Now that that is finished I will build the amplifier next (from HiFi-Akademie) then the pre-Amp then the stretcher then the ESL prototype and finally the big ESL. Still quite a long way to go.

Woofer spec: 8x Dayton RS225S-8. Total height about 2.18m, width 29.5cm, open baffle type A, with sides angled outward at 10 degrees.
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File Type: jpg woofers - eye level view.jpg (15.3 KB, 237 views)
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Old 14th February 2008, 08:15 PM   #30
Few is offline Few  United States
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Looks great! I have 12 of the same woofers still packed in their boxes as I work on plans for my own OB design to go with a flat, segmented, stretched wire ESL. I have a few questions about your woofer array, if you don't mind:

1) What sort of series/parallel wiring scheme did you adopt for the woofers?

2) Did you do any comparison between a simple flat panel and the final form you built, perhaps while in the prototype stage? I'm leaning toward a flat panel at the moment but am open to other ideas.

3) Do you have any measurements of the response of the 8-speaker array?

Keep us posted on your continued progress. It looks like you're at the beginning of a very nice project.

Few
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