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How to construct a cube louver (Acoustat)
How to construct a cube louver (Acoustat)
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Old 14th April 2010, 09:47 PM   #61
geraldfryjr is offline geraldfryjr  United States
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"If you want to know if your insulation works without losses, you should setup an identical ESL without insulation to compare.

capaciti "

This is an experiment I would like to do someday.

The one thing that Roger Sanders told me ,that always stuck in the back of my mind, when we were talking about stator coatings (powder coatings was the subject) is " of course you want the highest dielectric strength but choose the one that has the highest dielectric constant even though it has a lower dielectric strength(volt per mil)".
Somehow I understand this but it is very confusing and I have never found any discussions of this or it being mentioned. jer
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Old 15th April 2010, 08:56 AM   #62
Capaciti is offline Capaciti  Germany
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Hi,

sanders is right, thats why e.g. for wire stators PVC is one of the favourible insulation materials, while teflon is not.

I am no expert in coated perforated metal stators, but i guess it took ML a long way to figure out the best coating. A simple laquer is certainly not the perfect one.

Capaciti
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Old 15th April 2010, 04:23 PM   #63
bolserst is offline bolserst  United States
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Quote:
Originally Posted by geraldfryjr View Post
" of course you want the highest dielectric strength but choose the one that has the highest dielectric constant even though it has a lower dielectric strength(volt per mil)".
Somehow I understand this but it is very confusing and I have never found any discussions of this or it being mentioned.
Both the Acoustat White Paper and the Janszen patent discuss desirable insulation properties for wire ESLs.
I don't think voltage rating for the wires are brought up, but once you understand the basics you can work it out for yourself.

The Acoustat White Paper can be downloaded a few places, here are two:
http://www.audiocircuit.com/A-PDF/AA...N2-941-ACO.pdf
http://www.integracoustics.com/MUG/M...technology.pdf

Janszen Patent US2631196
ELECTROSTATIC LOUD-SPEAKER - Google Patent Search


Referring to the attached figure taken from the Acoustat White Paper:

DC voltage
Ria & Rd form a resistive voltage divider for the applied bias voltage.
For a given bias voltage, you will maximize the voltage across the airgap if Rd is much smaller than Ria.
So you don't want a really good insulator for your insulation like teflon, otherwise most of the applied bias voltage will appear across the insulation rather than in the airgap.
PVC or Kynar are pretty conductive as far as insulation materials go.

AC voltage
Cag & Cd form a capacitive voltage divider for the AC voltage(music) applied to the stators.
For a given AC voltage, you will maximize the voltage across the airgap if Cd is much larger than Cag.
To make Cd large you want an insulation with a large dielectric constant like PVC or Kynar. Again, teflon would be a poor choice.

Voltage rating for wire insulation
If you choose a wire insulation that is somewhat conductive and has a high dielectric constant, the working voltage the insulation has to withstand (in a constant charge ESL) may be much less than you might think.
With Rd & Cd fixed by the insulation properties, the percentage of the applied voltage that appears across the insulation is a function of the airgap size. For ESLs with airgraps of roughly 1/16"(1.5mm) most PVC forumlations will have only 10%-15% of the applied DC & AC voltages appear across the insulation. So voltage ratings of 600V should be more than adequate for most PVC wire ESLs.
Kynar appears to be even better than PVC with both lower resistance and higher dielectric constant. But, it costs more and is not as readily available.
Attached Images
File Type: gif wires.gif (55.2 KB, 472 views)

Last edited by bolserst; 15th April 2010 at 04:33 PM.
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Old 15th April 2010, 04:51 PM   #64
geraldfryjr is offline geraldfryjr  United States
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Thanks,Steve,that helps me understand alot better. jer
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Old 15th April 2010, 07:36 PM   #65
moray james is offline moray james  Canada
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The first set of panels that I built and dropped into My Acoustat 0ne plus 0ne's were Kynar 28 gage wire wrap 12 wires per linear inch. They worked perfectly and sounded much better than the stock panels had. They played for a couple of years till one of my kids decided to experiment with poking the cubes with a Popsicle stick and was creative enough to get a step stool to reach up high and poke up there too. A calm conversation about all the hard work daddy had done and would have to to again was all that was required, we never had a problem of that sort ever again. She is in University now and has a set of Stax in ear monitors of her own. Really surprised me at the time as even though I was upset about it I never had a thought to get angry. It's a good memory that I like to keep in mind.
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Old 15th April 2010, 07:43 PM   #66
hella356 is offline hella356  United States
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Fortunate she didn't use a metal object! I've gotten used to warning people upon their introduction to the Acoustats that they have DEADLY voltages present and don't even THINK about touching them. The healthcare debate here in America has found me a great name for the speakers: Death Panels.
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Old 15th April 2010, 08:32 PM   #67
bear is offline bear
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How to construct a cube louver (Acoustat)
Nothing terribly deadly in a stock Acoustat with the Mk121 interfaces. High voltage, low current.

Strickland specifically stated that he used PVC because it is "leaky". He explained that he had built a version using 'good' insulation (ptfe) and they worked fine in relatively high humidity situations and not at all in very very dry (arizona) climates...

Fyi.

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Old 15th April 2010, 08:47 PM   #68
moray james is offline moray james  Canada
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Bear did you build with that film yet or are you just wrappin your lunch with it?
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Old 15th April 2010, 09:26 PM   #69
bear is offline bear
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How to construct a cube louver (Acoustat)
lunch... yummy.

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Old 15th April 2010, 09:42 PM   #70
moray james is offline moray james  Canada
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Say it can also be used as a fine prophylactic but the heat shrinking can be tricky. Good bear's need to build a speaker that sounds as sweet as honey. Go bear go.
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