Role of ESL stator insulation?

[Few]

Perhaps I should know better than to ask a question like this when I'm tired on a Friday night, and enjoying an end-of-week beverage, but I'm seeking insights into the role of stator insulation in ESL design and operation. There have been several threads on different types of insulation, and the effects they might have, but what is the real reason to insulate the stator?

For the moment let's assume we have another method in place to prevent anyone from simultaneously licking the two stators . I'm focusing on the stator-diaphragm gap. If another design feature were in place to prevent the high resistance diaphragm from contacting each low resistance stator, would there be a need for insulation?

There have been some recent discussions about the use of fine netting to damp diaphragm resonances. If the netting were placed between the diaphragm and the stator so that the two couldn't come into contact, would that eliminate the need for insulated stators? Could we get away from concerns about high resistivity stator coatings and time constants and humidity sensitivity? What am I missing?

Few

[WrineX]

well it not always that the diagraph hits the stator, the problem is conductivity of air! if im right air wil conduct and the spark can jump 1 mm with 3 Kv so 6 kv 2 mm etc, i mean without insulation most panels with 1 mm spacing wil arc everytime you listen music. wich sounds crap and also burns holes in ur mylar.

then you can either lower ur voltage and get lower SPL or increase stator distance wich wil do the same lower you SPL

[chinsettawong]

Don't forget the safety measure that you might come into contact with the stator while the music is playing. The zap can kill you.

Wachara C.

[MJ Dijkstra]

And what about dust (conductive) coming between the unisolated stator and the Mylar.
That would make an arc even without music playing?!
Insulation is not that bad to sacrifice reliability and safety

[Few]

Thanks for the replies. Wachara C., I didn't forget the safety issue. That's why I said "For the moment let's assume we have another method in place to prevent anyone from simultaneously licking the two stators."

I'm not sure I follow your logic WrineX. If you add insulation such that it prevents arcing (by dropping some of the voltage through the insulation instead of the gap), you end up with the same sensitivity reduction you would have gotten by reducing the bias voltage.

I guess I can see that a large amount of dust could form a bridge between the stator and the diaphragm so some form of dust cover could be used. Nonetheless, I'm left wondering if using fine netting to prevent diaphragm-stator contact might be a viable alternative to insulating coatings--especially if some builders end up wanting to add the netting to damp the diaphragm's fundamental resonance.

Few

[WrineX]

i think it depends on the insulation properties. if an insulation of 0,5 mm will arc at 6000 just assuming here, it is at least higher then air, so when ur create 1 mm spacing with air only it will arc at 3000, using the insulation the conducting stator will be 0,5 mm further away but you can use twice the current, i thinks that would be win!. by the way o,5 mm is pretty thick for a insulation but ok, in dream land we wnat conducting stator with a verry verry thin insulation but verr verry good , like rated 10000 or whatever. explaining stuff in english is not one of my favorites i think

but i have to check if doubling voltage is giving you the same spl as decreasing the spacer by half

[audio.ESL]

Originally Posted by WrineX

well it not always that the diagraph hits the stator, the problem is conductivity of air! if im right air wil conduct and the spark can jump 1 mm with 3 Kv so 6 kv 2 mm etc, i mean without insulation most panels with 1 mm spacing wil arc everytime you listen music. wich sounds crap and also burns holes in ur mylar.

then you can either lower ur voltage and get lower SPL or increase stator distance wich wil do the same lower you SPL

You are 100% correct.
I just tried my ESL whose stator without insulation inside.
4000VDC and 2mm spacer,I see the spark.

But the sound from ESL is really good,very transparent.

[WrineX]

well go get some paint and paint it like 5 times crappy job but hey no sparks

[audio.ESL]

Originally Posted by WrineX

well go get some paint and paint it like 5 times crappy job but hey no sparks

I will send the new stators to the car paint factory,it's better and not expensive.
4PCS of 300MM*1200MM double sides, cost 70USD.
I choose the color of dark blue,just like BMW.

[Few]

i think it depends on the insulation properties. if an insulation of 0,5 mm will arc at 6000 just assuming here, it is at least higher then air, so when ur create 1 mm spacing with air only it will arc at 3000, using the insulation the conducting stator will be 0,5 mm further away but you can use twice the current, i thinks that would be win!.

The problem is that in your example the 6000 V is what you're applying to the stator but you have to take into account the fact that the insulation and the air gap act as a voltage divider; some of the applied 6000 V drops across the insulation rather than the air gap so it is not experienced by the diaphragm. As a result you might be able to apply 6000 V to the insulated stator, compared to 3000 V for uninsulated panels, but that doesn't mean the diaphragm experiences a larger force in the 6000 V case.

but i have to check if doubling voltage is giving you the same spl as decreasing the spacer by half

Decreasing the air gap by half increases the sensitivity by a factor of four---it goes as the square of the distance.

Few