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-   -   Horn loaded electrostatic ?? (http://www.diyaudio.com/forums/planars-exotics/190023-horn-loaded-electrostatic.html)

brsanko 1st June 2011 05:23 AM

Horn loaded electrostatic ??
 
I have been designing rear loaded and compound horns for several years now and experimenting with different drivers and observing what makes a driver well suited to a horn enclosure. The conclution I have come to is that the most important qualities are a lightweight diaphram with excellent control and damping characteristics. Which is what brought me to electrostatics. The diaphram is nearly weightless, and stiffness isn't really even an issue because the stators control the entire surface evenly. I can't help but wonder what could be done with a small circular electrostatic say 3" - 6" in diameter in a compound horn enclosure. I guess the biggest thing I'm wondering right now is how much can a electrostatic diaphram move before it gets distorted and how would one measure or determine the T/S parameters or whatever the equivalent information of such a speaker. Anyone with any information or suggestions please pitch in. I welcome information from everyone, but please don't tell me it can't be done and enumberate all the reasons it's a stupid idea. I tend to get defensive and upset by naysayers and have been banned for a few days more than once for telling people to shut up. Please feel free to contribute any facts or ideas you might have but if your goal is to tell me I'm wasting my time, don't waste yours.

beun 1st June 2011 05:36 AM

I am not quite sure it would work, horn loading works by increasing the loading at the speaker and acts like an acoustic transformer. This then exchanges displacement for force. The electrostatic force is relatively week and I am not sure if you can generate enough force to make it work.

brsanko 1st June 2011 05:41 AM

Well if you don't have to move it much you can make the gap relatively small and use metal foil as the diaphram if need be. I need to do some more reading on the basic principles of ESs. I'm doing that now. Thanks for the quick response.

geraldfryjr 1st June 2011 07:43 AM

I been wanting to horn load my little panel too se how well it would work.
It has a 9.75" X 3.25" diagphram and gets extremely loud.
I run it at 5kv to 7kv bias with about 25kv p-p across the stators (maxed out).
So I have been trying figure out a horn design for it.
I don't think it would be pheasible for a wide panel but a small width one might work well.
I think it would be worth giving it a try. jer

Keith Taylor 1st June 2011 02:08 PM

A horn loaded ESL is unlikely to work for reasons discussed towards the end of this thread I started.http://www.diyaudio.com/forums/plana...ostatic+AMT%3F Basically ES forces are too weak and the membrane motion simply stalls when loaded by anything other than free air. I wish it were otherwise, but the laws of physics are uncompromising.

Keith

geraldfryjr 1st June 2011 02:29 PM

Yes, I have been thinking about that myself.
As I have run it to issues when trying to just dampen the backwave with some fiberglass insulation and I lost a bit of detail on the high if I got to close with it as it was loading up the diagphram.
But that was in mono and might not be noticeable to much in stereo.
But if I can come up with a size and shape it would be very easy to try as I already have the drivers and driver system made.
I think that it might actualy work good for a midrange system,But I don't think it will be loud enough for PA use though.
Yet my little driver is quite powerful when running at maxed out voltages not like your average esl running at a 2kv bias.
jer

markusA 1st June 2011 03:12 PM

It would be cool to see some experiments on this.
It could be done in several different ways I think.
Beveridge have the acoustic lens and an enclosure, Maybe one could do something similar modelled as a FLH?
It could be anything from a very narrow panel to a wide one?
A hornloaded line source sounds like fun. :)

Or you could keep the dipole characteristics and build it symmetrical front/back? I think I've actually seen some experiments on this but doing it without a chamber the size will get out of hand pretty quick if you widen the panel.

To bad if the laws of physica are working against us, it would've been interesting to see what could be done.

bolserst 1st June 2011 03:43 PM

Quote:

Originally Posted by Keith Taylor (Post 2591202)
A horn loaded ESL is unlikely to work for reasons discussed towards the end of this thread I started.http://www.diyaudio.com/forums/plana...ostatic+AMT%3F Basically ES forces are too weak and the membrane motion simply stalls when loaded by anything other than free air. I wish it were otherwise, but the laws of physics are uncompromising.


There is a way around the apparent inability of an ESL to drive a horn. The idea was published in an AES paper by Josef Merhaut.
AES E-Library Horn-Loaded Electrostatic Loudspeaker

Basically, a prisimatic waveguide is used to transfer the resistive impedance at the throat of the horn to a larger area ESL. The benefits are a purely resistive airload on the ESL diaphragm over the whole working range of the horn. The benefits are a very predictable flat response and no pronounced diaphragm resonance normally caused by the reactive air-mass loading on the diaphragm.

A few details were posted here when discussing diaphragm resonance:
http://www.diyaudio.com/forums/plana...ml#post2392743

He also received a patent(US3590169) for the idea, although it doesn't contain all the technical information provided in the AES paper.
ELECTROSTATIC HORN LOUDSPEAKER - Google Patents

brsanko 5th June 2011 05:56 AM

I was thinking of making a round panel as small as possible to achieve the desired frequency extension(80Hz-20Khz would be perfect). I like the idea of loading both sides of the panel but not symetricly but rather a front horn for high frequencies and a rear horn for low frequencies (crossed over somewhere between 200-500Hz).
The other thing I was thinking about was coupling them with a tube amp and instead of putting an output transformer on it to bring down the voltage and another transformer on the speaker to bring it back up again you could direct couple it to the speaker and even use a single ended amp and the tube bias could be the diaphram bias...maybe, just thinking out loud, er... in type.

geraldfryjr 5th June 2011 07:10 PM

Yes I was think of some sort of asymeterical design but don't know which method yet as that will take some experimentation.

Yes you can couple the panel directly to a tube amp as it has been done ,BUT,It takes some serious voltages to get to a very large SPL.

When I pushed my panel past its limit (to the point of ignition from an arc over through a mounting bolt) I was applying in the order of 25kv p-p across the stators.

With music the average person could not be in the same room and even I could not stay in the same room with a steady sine tone.
As I am quite used to it being loud.

Sadly my SPL meter does not work otherwise I would have a figure for you to post.


jer


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