The series resistor(and the high resistance of the diaphragm coating for the matter) do limit the current for a stator to diaphragm discharge.
But, the more destructive arcing occurs stator-to stator.
I have spent much time performing destructive testing of panels to see exactly what the mechanisms are and what affects the voltage thresholds. The destructive stator-to-stator arcing occurs nearly at the same voltage no matter what the diaphragm bias voltage…even if the diaphragm is completely removed.
Nope. If a 3-5mm gap with un-insulated stators is a good idea(say for an ESL woofer) then a 3-5mm gap WITH insulated stators is even a better idea. If the insulation is properly chosen, there really isn’t any drawbacks. SPL will be the same, and you are now protected from any potentional arcing. Well, I guess there is one drawback…build difficulty. Obviously un-insulated stators are easier to build.
No. PVC is a much better conductor than air…about 1000 times better for most formulations used for insulating wire. So, the insulation “eats up” bias voltage 1000 times slower than the air gap.
Another point is that, as you previously mentioned, increasing bias voltage is easy to do. So, even if some of the bias voltage was lost across the insulation, you can easily bump up the bias supply voltage to compensate and get the voltage across the air gap to where you want it.
So, bias voltages losses are minimal and can be easily compensated for.
The quanitatively more detramenta loss in the insulation is the AC signal loss, which can't be easily compensated for. Depending on the formulation of the insulation, the dieletric constant is usually somewhere between 5 - 8. So AC signal is "eaten up" 5 - 8 times more slowly than in the air gap. With typical D/S of 1 - 3mm, and insulation thicknesses < 20 mil in almost all cases...losses are still less than 1dB.
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Very well put,Bolserst.
I like the way you put things in such detail and yet in understandable format.
In my experiments last year I have come to the very same conclusion.
As I had mentioned I had gotten to a larger level of sound pressure with the panel that could hold 6kv of bias than the panel that could only hold 3kv of bias.
This is obvious,but the deal breaker is that both panels were exactly the same size and had the same D/S spacing as well.
Like I had stated, The better one of the two also did not suffer any burn holes in the mylar either.
As I had pushed the panel to the point of ionization the worsening sound quality was more attributed from the amp clipping and diagphram clipping to the stator.
And when turned enough even the ionization from the high bias voltage did seem to be much of a detriment to the SQ infact some of the little purple flashes seemed to cause no change in the sound at all, unless the peaks were high enough.
I didn't get to observe this more because this is when the edge of the panel ignited and this excited me more the than the little purple flashes. he,he,he
Now I am not even sure if I want to waste my time and materials building a non-insulated panel.
But I may as the cost is nil just to find out for myself I guess, and, as a control for the rest of my tests.
jer
I like the way you put things in such detail and yet in understandable format.
In my experiments last year I have come to the very same conclusion.
As I had mentioned I had gotten to a larger level of sound pressure with the panel that could hold 6kv of bias than the panel that could only hold 3kv of bias.
This is obvious,but the deal breaker is that both panels were exactly the same size and had the same D/S spacing as well.
Like I had stated, The better one of the two also did not suffer any burn holes in the mylar either.
As I had pushed the panel to the point of ionization the worsening sound quality was more attributed from the amp clipping and diagphram clipping to the stator.
And when turned enough even the ionization from the high bias voltage did seem to be much of a detriment to the SQ infact some of the little purple flashes seemed to cause no change in the sound at all, unless the peaks were high enough.
I didn't get to observe this more because this is when the edge of the panel ignited and this excited me more the than the little purple flashes. he,he,he
Now I am not even sure if I want to waste my time and materials building a non-insulated panel.
But I may as the cost is nil just to find out for myself I guess, and, as a control for the rest of my tests.
jer
An un-insulated panel is a good "control" when testing out different insulation materials.
Just be sure to have current limiting resistors in the primary(between amplifier and transformer) or secondary(between transformer and stators) so you don't accidently destroy your amplifier if an arc occurs during testings.
I usually also add an in-line fuse to protect the amplifier when testing a new un-insulated panel configuration for the first time....just in case.
yes ,I agree, I do have a much bigger amp now since then.
I was using my Crown DC300a when I did that test.
I had not got back on the forum at that point in time as it was about september of last year.
Even when it turned into an arc welder I was able to keep it going for nearly 10 minutes with that amp untlil it triggered the thermo switch in the amp.
I have done this alot with that amp and it just keeps chugging along.
It handles my current speaker load of 1.6 ohms very nicely.
And sounds very nice even when it is not cranked up all of the way
It is a very nice heavy duty amp even though it is quite aged by today's standards.
jer
I was using my Crown DC300a when I did that test.
I had not got back on the forum at that point in time as it was about september of last year.
Even when it turned into an arc welder I was able to keep it going for nearly 10 minutes with that amp untlil it triggered the thermo switch in the amp.
I have done this alot with that amp and it just keeps chugging along.
It handles my current speaker load of 1.6 ohms very nicely.
And sounds very nice even when it is not cranked up all of the way
It is a very nice heavy duty amp even though it is quite aged by today's standards.
jer
bolserst, You mentioned that by increasing the amount of insulation it ultimately reduces the D/S distance. If you are insulating perforated panels ESL's, and if you were using double sided tape after the insulation coating, it will be elevate to same distance above the insulation as if it had no insulation and conversely the the distance from the diaphragm to the surface of the insulation will be at the distance of the insulation.
Please correct me if I am wrong, it seems I had this conversation before and this was my opinion.
Doc
Please correct me if I am wrong, it seems I had this conversation before and this was my opinion.
Doc
Can you point to the post where I said this? I can't seem to find it.
It doesn't sound right to me, so either I wrote something wrong or wrote it poorly such that it was easily misunderstood.
Bolserst,
My apologies, after re-reading your response I failed to see the last word you wrote when you were formulating your response... "1) When adding insulation, are you taking up precious air-gap space that is needed for diaphragm motion?
No."
I thought I was getting a pretty good handle on ESL construction after building nearly 20 panels over the course of a year, I thought that this information was as important issue to seek clarification.
Regards, and
Happy Holidays,
Doc
My apologies, after re-reading your response I failed to see the last word you wrote when you were formulating your response... "1) When adding insulation, are you taking up precious air-gap space that is needed for diaphragm motion?
No."
I thought I was getting a pretty good handle on ESL construction after building nearly 20 panels over the course of a year, I thought that this information was as important issue to seek clarification.
Regards, and
Happy Holidays,
Doc
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