I'm intrigued by the "inverted" esl's from FinalSound which, unlike typical esl's, applies the bias charge to the stators and feeds the audio signal to the diaphram. Their website says there is a sealed conductor inside the diaphram (as opposed to a surface coating?)--- so now I'm wondering; how did they do that?
Would the diaphram need to be less resistive in this case, since it takes the audio signal rather than a steady bias charge?
The design's impedence is said to be at least 3 ohms across the entire frequency spectrum (more amp friendly) and is implied to be inherently safer.
I hope that someone here more knowledgeable than myself (that would be most of you) will check this out (link below) and share your thoughts on it.
http://finalsound.com/
taichiguy
(charlie)
Would the diaphram need to be less resistive in this case, since it takes the audio signal rather than a steady bias charge?
The design's impedence is said to be at least 3 ohms across the entire frequency spectrum (more amp friendly) and is implied to be inherently safer.
I hope that someone here more knowledgeable than myself (that would be most of you) will check this out (link below) and share your thoughts on it.
http://finalsound.com/
taichiguy
(charlie)
The clue is their stated thickness for the diaphragm- 12u, about double the usual 6u thickness. It would appear that this is formed from laminating two films together, conductive side in. I haven't searched for their patent app yet, but I'll wager that this is the "secret."
What the actual advantage of this is, as opposed to the claims of the blitheringly stupid ad copy, is quite unclear other than, "it's different."
I would love to see the withering paragraph in Augsperger's JAES patent column. And to meet the marketing guy who came up with the rather ominous "Final Solution" slogan.
What the actual advantage of this is, as opposed to the claims of the blitheringly stupid ad copy, is quite unclear other than, "it's different."
I would love to see the withering paragraph in Augsperger's JAES patent column. And to meet the marketing guy who came up with the rather ominous "Final Solution" slogan.
Hi,
I am not a big expert , but i didn't like their advertisements.Stating that ESL directivity is an advantage ... More than strange.
Also , i don't understand how they overcome charge migration by this technology ...
I am not a big expert , but i didn't like their advertisements.Stating that ESL directivity is an advantage ... More than strange.
Also , i don't understand how they overcome charge migration by this technology ...
OK, I've found their US application and it's not as off-putting as the ad copy. But I'm scratching my head to try to see what's really new.
Hi,
there is a problem inherently to the inverter technology. Since the membran and the stators are very conductive, the ESL do not work in constant charge but constant voltage mode.
As a result the charge on the membrane will change when it comes near to one stator. As we all know this means non-linear movement and increasing distortions. Especially at lower frequencies the change of charge and the distortions will increase.
This technology has its advantage regarding safety and should deliver more sound pressure at lower frequencies at given audio input voltage. But as always, nothing is for free. Distortions are the limit for such a system.
regards,capaciti
there is a problem inherently to the inverter technology. Since the membran and the stators are very conductive, the ESL do not work in constant charge but constant voltage mode.
As a result the charge on the membrane will change when it comes near to one stator. As we all know this means non-linear movement and increasing distortions. Especially at lower frequencies the change of charge and the distortions will increase.
This technology has its advantage regarding safety and should deliver more sound pressure at lower frequencies at given audio input voltage. But as always, nothing is for free. Distortions are the limit for such a system.
regards,capaciti
I read the application, which appears to contain several little gaffes. I agree with Capaciti; this design does not appear to use constant charge operation. Furthermore, there is a claim of safety since high voltage AC is removed from the stator. But this design uses +/-3000VDC on the stators. The inventors placed a 10M resistor in series with each DC supply followed by a shunt 4nF cap to ground. While I doubt that the energy stored in these caps could injure or kill, I wouldn't want to touch a stator with my hand while another part of me is grounded. I doubt UL would approve.
Also, I think the use of concave inner stator surfaces is questionable on several grounds.
Also, I think the use of concave inner stator surfaces is questionable on several grounds.
Perhaps we can assume that the membrane does indeed have a necessarily low resistance but I am not sure that we can assume that the stators do too.....unless I have missed something.
Tim.
Tim.
Capaciti said:
Hi,
If we would make a membrane resistance constant and low , and allow some current to flow through it , like in a conductor , wouldn't this decrese charge migration ?
Regards,
Lukas.
Yes ,
But may be it is possible to make a current flow to one direction by making a slight potential difference between , lets say , top and bottom of diapraghm ?
But may be it is possible to make a current flow to one direction by making a slight potential difference between , lets say , top and bottom of diapraghm ?
The concave stators may be necessary to prevent arcing as claimed but wouldn't the non-uniform stator-to-diaphram spacing would cause the diaphram to be driven less strongly and possibly slower at its center? I'm invisioning some resulting undesirable wave modes on the diaphram here...
With the caveat that I have not tested their configuration, I don't see the concavity as being a good idea. A few minutes with a signal generator, amplifier, and strobe light convinced me that the diaphragm of a reasonably large area conventional e-stat moves in a planar way, i.e., as a flat sheet.
I think you both are right about the stator concavity. At very, very low frequencies the diaphragm's motion will be dominated by diaphragm material stiffness, more than air radiation resistance, and it will move as a bow (roughly a catenary shape). But at audio frequencies, air radiation resistance dominates and the diaphragm motion becomes planar, with all the bending taking place at the edges. As Taichiguy implies, the center of the diaphragm in this design will have a lower electric field than at the edges, creating a sort of inverse taper (to use an optics and microwave term) where the center has the least output. This works against the cited goal of greater dispersion. Also, the maximum electric field in a concave stator system will be limited by how much voltage can be withstood at the edges. Why not then open up the stator spacing to be the same at the edges as at the center, and increase the bias voltage accordingly? Finally, a fatter stator might have more problems with air resistance, turbulence and possibly resonance. Other than that, it's a great idea 🙂
Have you guys figured out the claim of 4 times greater voltage sensitivity?
Also, here's a section I don't understand: "Since film 68 [diaphragm] is connected directly to the high voltage AC audio signal supplied by audio step-up transformer 16, low impedances are avoided. This reduces load capabilities for the audio amplifier (i.e., a 4-9 ohm load instead of a 1 ohm load). This translates into a reduction in impedance by a factor of 4." Huh?
Have you guys figured out the claim of 4 times greater voltage sensitivity?
Also, here's a section I don't understand: "Since film 68 [diaphragm] is connected directly to the high voltage AC audio signal supplied by audio step-up transformer 16, low impedances are avoided. This reduces load capabilities for the audio amplifier (i.e., a 4-9 ohm load instead of a 1 ohm load). This translates into a reduction in impedance by a factor of 4." Huh?
Well, if there is a 4x sensitivity increase, the step up ratio can be proportionately reduced (for those of us not running 845-fired furnaces). So that could be why the claim is made about impedance.
Tim makes a good point about not assuming the stators are low-resistance. Patent page 4, claim #13 says the stators are non-metallic so I'm thinking they may be high-resistance (could be desirable for "inverted" operation). I'm curious about the diaphram's resistance, which I don't see stated in the patent.
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