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Old 10th June 2012, 12:17 PM   #11
uglykid is offline uglykid  Denmark
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Join Date: May 2009
Hi.

Charlie.

that was actually your homepage that inspired me to made some els again, i did a couple for about 15 years ago but they failed completed because off bad stator isolation and bad diaphragm coating at that time. I have tryed to separate my panel but with no luck, so i have now made a little test panel and that panel act like the big one with very low sensitivity but now i hopefully can figure out what there was wrong with the big panel.

I have tried my biassupply and i can not get a good spark even with 6.5kv i get a tiny tiny little spark then the wires almost touching each other, thats bad so i made another biassupply with a "good" spark and connected it to the test panel but no change.

bazukas.

my hole size is 4mm (3.5mm after coating) and 58% open area, i have tried another stator isolation on the little testpanel with same result so i dont think it is the isolation on the stators thats the problem, actually then i have coated the stators i tested them by putting them together with kitchen alu foil between (sandwich) connected the stepup trafo and turned the amp (150w) fully up to its clipping limit with a 1khz sinustone and the foil vibrated so much that i have to add earprotection that was insane loud.

calvin.

my diaphragm contact is made by cutting a long thin piece (5mm)of kitchen alu foil and put very thin dobbelsided tape on one side and place it on one of the stators so it made contact to the coating then i press the stators together, the foil goes up in both side of the panel.

you say a high conduktive copper foil over time eat up the coating... is it a good idea and use graphite (spray) instead? i mean add coating and then with masking tape made a connector of graphite and then maybe add a layer of coating on top of the graphite (sandwich).

you say that i have to test the coating before i put the panel together... how to? i have a x100 probe to my scope and i have a couple of good dvm and a couple of different powersupplys, actually i have a lot of measurement equipment but not a megger, can i use some of this?

the statguard polish is very easy to apply and it cover the diapgragm very nicely it´s a little soapy to use and it takes about a hour or so to dry, it sticks very well to the diaphragm i can not rip it of with the tapetrick and a fingernail.
i have tried to apply a very thick layer on the testpanel but still no change in soundlevel.

I´am sure i not have wrong trafo connection, have worked 22 years on transformer factory with testing trafos :-) offcouse i could have made a mistake but the trafo connection should be ok.

chinsettawong.

i think i have done like many others so i am very confused what is wrong, but maybe the varmason actually is a bad coating i really dont know, so i will try to use the dish soap on the test panel when i get home tommorow to see if it make any difference.


geraldjer.

like i wrote in my first post, the speaker keeps playing for about 20-25 minutes after i have disconnected the biassupply so the coating and isolation should be ok.

i will also try to raise the stepup ratio, but again i am confused other have a working speaker with the same D/S and stepup ratio like i have...hmmm maybe i am more deaf than i thought :-)


bentoronto.

my test amp clips with 150w but honest i havent mesurement the input voltage on stepup trafo... will do then home again.



i will be back soon.

uglykid
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Old 10th June 2012, 05:11 PM   #12
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Location: Toronto and Delray Beach, FL
Quote:
Originally Posted by uglykid View Post
snip
bentoronto.

my test amp clips with 150w but honest i havent mesurement the input voltage on stepup trafo... will do then home again.
uglykid
Aha! That's a perilous way to assess output voltage (which is what we should be talking about, not power). Yet that is the basic starting point in your query.

Quite possibly your amp is able to pump only a small voltage into your transformers.

Try to 'scope the voltage - computer software oscilloscopes are pretty good.
Ben
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Old 10th June 2012, 08:09 PM   #13
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As I had mentioned I believe that your coating seems to be functioning properly.

If you actually have 6.5kv being produced by your supply you should be able to draw an arc of at least 1/4" long even with a current limiting series resistor.

See this thread for reference,

how can test the stator insulation and mylar coating?

The only thing a current limiting resistor will due is limit the current and the thickness of the arc as there is still 6.5kv and still should jump the gap only not as often as it would without the resistor.
The test that is shown on that post was at about 5kv as shown on the meter.
I must mention the ruler that I was using was segmented in 1/5 inch increments as to avoid any confusions.


jer

Last edited by geraldfryjr; 10th June 2012 at 08:30 PM.
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Old 11th June 2012, 07:55 AM   #14
Calvin is offline Calvin  Germany
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Hi,

if the bias supply puts out good 6.5kV there should be a clean visible sparc over a few mm (if there are no or small valued current limiting resistors).
If You hold the wire of the supply down onto the membrane coating (the second bias-supply connection to gnd and the respective stator) the membrane should immediately and clearly recognizable be drawn towards the stator. If not, then either the bias-supply voltage is pulled down (leakage) or there´s no contact at all to the coating, or the coating simply isn´t working.

Thin strips of Aluminum foil are perfectly ok, though pure Aluminum tends to build up a insulating oxide surface layer. I always used the coating to ´glue´ the strips to the diaphragm. Then I additionally ´painted´ the strips with another thick layer of the coating, thereby creating a large contact surface and a environmental sealing of the strips. A press-on contact as You´ve done will also work, but may fail over longtime periods, because of corrosion of the contact metal and/or lowlevel corona eating up the coating.

Anyway, if You got high SPLs when testing the panels with an alu-diaphragm, the stators as well as trafo and bias-supply and their connection seem ok.
Then the missing output with the Statguard coating can only be due to a missing contact to the coating, or Statguard is unsuitable as coating or, as last possibility, the tranny might have died by internal flashovers whilst testing.

jauu
Calvin
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Old 18th June 2012, 09:02 PM   #15
uglykid is offline uglykid  Denmark
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Hi all.

Ok there at least one big fool in Danmark...it´s actually me...i have now tried every thing all your great guys have mention and nothing have work for me!!! so i have done some brainstorming to figure out that was wrong, then one night it hits me that i was trying to made.. a MID/HIGH els speaker..and not a full range, so i connected a crossover to my speakers in my living room ( a couple of old system audio 1070) and removed all frequences under 300hz with 24db/octave and magic happens i got very low level from them too and thats with the same amp i was using to test the els panels, the only difference was that the els play so much much better

So my speakers actually work like they should and i will go on and finish them.

I will post pictures of the stretcing jig and the speaker panels in a couple of days.

Thank you all very much for solutions and answers and for trying to help me the only thing there was wrong was me

Kind regards
uglykid
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Old 19th June 2012, 12:08 AM   #16
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You know, if you had just looked closely at the signal to the speakers at the start.....

Ben
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Old 19th June 2012, 05:11 AM   #17
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I am glad you figured it out !!!
It is amazing how how much sound there is once you add the lower registers !
I used to think the same thing with my little panels, even with just some little 5.25" woofers they just exploded in sound !!!

Then they exploded !!! He,he,he,he



jer

Last edited by geraldfryjr; 19th June 2012 at 05:13 AM.
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