I am about to start building my first ELS, and am somewhat confused by the description of ELS panels when referred
to as segments. In some cases the description appears to refer to actual physically separate panels, and sometimes
to large panels divided by spacers, can anyone give me an answer?
I assume that when a large panel is divided by spacers that the spacers are glued to both the stators and the mylar.
Can a large panel divided by spacers still be regarded as a single panel for calculations and response?
Finally ( probably not ) given the same approx area and disregarding stray capacitance would there be much sonic
difference between a single panel and say three separate panels?
All replies and advice gratefully received
Thanks MIKE 😕
to as segments. In some cases the description appears to refer to actual physically separate panels, and sometimes
to large panels divided by spacers, can anyone give me an answer?
I assume that when a large panel is divided by spacers that the spacers are glued to both the stators and the mylar.
Can a large panel divided by spacers still be regarded as a single panel for calculations and response?
Finally ( probably not ) given the same approx area and disregarding stray capacitance would there be much sonic
difference between a single panel and say three separate panels?
All replies and advice gratefully received
Thanks MIKE 😕
There are two types of segmentation that you are referring to here.
First, There is mechanical segmentation.
This is has to do with the individual physical sectioning of the diaphragm that make up the complete width of the panel.
This has the effect of having several panels lined up together end to end such as some of the Acoustat models that are in a vertical fashion or horizontally divided like the Martin Logan's and other similar design's.
Some of reason's for this type sectioning is for stability issues and some are for an attempt at creating several distributed diaphragm resonances rather than having one main diaphragm resonance to contend with.
This is typically associated with whether or not you are trying to create a full range panel.
Most of the DIY'er builds I have seen only know about the stability issues of the diaphragm and typically it has been found (and stated in Rodger Sander ESL Cook Book) that the width of the panel should not exceed 100 times the Diaphragm to Stator spacing (D/S).
Typically I use 1:40 to 1:70 for my panels as they are narrower and I will explain why in a minute.
What happens is that if you are over this range (smaller D/S compared to width) you can run in to stability issues with the diaphragm collapsing into and sticking to one of the stator's.
Also having adequate tension has a lot to do with this as well.
This is more difficult to achieve if you are using a material that is quite thin such .25mil Mylar and section widths larger than 6" to 9".
If you only have .5 mil Mylar then this may not be as big of an issue, I have made a few with diaphragm thickness in the range of .6 mil to 1.2 mil as well.
But generally I have always used my .25 mil stock for the most part.
I did have quite a time getting my first 7.5" wide panel to be mechanically stable at First but eventually, I did it.
I use the heat gun method to tension my panels, others have gone through the trouble of building a mechanical stretcher.
I never got as far as building one yet since I have only been build small desktop panels so far.
I like to have just enough tension as this keeps diaphragms the resonant low and below the crossover frequency.
Second, And the most important thing that most DIY'ers are not aware of (as it took me quite some time to find the answer as well) is that the width of each of the section plays HUGE role in the High Frequency Dispersion Quality's of the panel, or better known the Beaming Effect.
The wider the diaphragms radiating area is, the more Beaming Effect you will have at the higher end of the audio frequency bandwidth.
Here is my description of this from this thread at ESLDIY as found here,
Login
It goes like this,
"When the section width equals one wavelength the dispersion pattern is of the familiar doublet figure 8 pattern, and, any frequency below this point becomes more and more Omni Directional with a Circular wave front.
Above this frequency, The wave front begins to form into a beam and sometimes with some extra lobes shooting out from the sides."
So, As I said most DIY'er only use the guide lines for stability reasons I choose to use smaller widths for the sections.
This difference between my 7.5" wide diaphragm and my 3.25" wide diaphragm was huge and made big difference of not having to keep my head in a vice in order to enjoy the stereo field!!
Thus I have kept to the smaller size ever since.
Now remember that D/S Ratio?
Since my panels are narrower I like to have a bit more excursion room for the diaphragm at the lower range down to about 200Hz to 300HZ or so.
I have been using approx .072" to .090" for my D/S and then I just compensate for this increase by using a higher bias voltage.
This is also the lower limit if you are using a common Power Toroid Transformer's in a step-up configuration
This works out very nicely as it takes displacement to produce the lowest frequency's.
And since they are Omni-Directional anyhow due to the diaphragms radiating area's width, Displacement rules!!
This brings me to "What is electrical Segmentation?".
Well it is a method to be able to have that Wide Diaphragm for to be able to produce those lower frequency's and not have (hardly) any of that Beaming Effect at the high end of the spectrum!!
This is done by having several separate stator sections that are isolated from one another by a resistor.
With the individual capacitance of each stator section, fed along with each its own individual series resistor forms a low pass filter that cascades on down the whole width of the panel.
Therefore only the highest frequency's will be radiated from a thin strip of of the complete width of the diaphragm, and as the frequency is lowered the effective width of the radiating area becomes larger.
Therefore keeping a constant and wide horizontal dispersion pattern throughout the audio band that the panel is producing.
This paper is a must read for more and complete information on this subject,
http://home.kpn.nl/verwa255/esl/ESL_English_2009.pdf
Found Here,
Elektrostatic Loudspeakers
I hope this helps you and hopes to see your build soon!!
Cheers and Keep on DIYin' !!!!
jer 🙂
First, There is mechanical segmentation.
This is has to do with the individual physical sectioning of the diaphragm that make up the complete width of the panel.
This has the effect of having several panels lined up together end to end such as some of the Acoustat models that are in a vertical fashion or horizontally divided like the Martin Logan's and other similar design's.
Some of reason's for this type sectioning is for stability issues and some are for an attempt at creating several distributed diaphragm resonances rather than having one main diaphragm resonance to contend with.
This is typically associated with whether or not you are trying to create a full range panel.
Most of the DIY'er builds I have seen only know about the stability issues of the diaphragm and typically it has been found (and stated in Rodger Sander ESL Cook Book) that the width of the panel should not exceed 100 times the Diaphragm to Stator spacing (D/S).
Typically I use 1:40 to 1:70 for my panels as they are narrower and I will explain why in a minute.
What happens is that if you are over this range (smaller D/S compared to width) you can run in to stability issues with the diaphragm collapsing into and sticking to one of the stator's.
Also having adequate tension has a lot to do with this as well.
This is more difficult to achieve if you are using a material that is quite thin such .25mil Mylar and section widths larger than 6" to 9".
If you only have .5 mil Mylar then this may not be as big of an issue, I have made a few with diaphragm thickness in the range of .6 mil to 1.2 mil as well.
But generally I have always used my .25 mil stock for the most part.
I did have quite a time getting my first 7.5" wide panel to be mechanically stable at First but eventually, I did it.
I use the heat gun method to tension my panels, others have gone through the trouble of building a mechanical stretcher.
I never got as far as building one yet since I have only been build small desktop panels so far.
I like to have just enough tension as this keeps diaphragms the resonant low and below the crossover frequency.
Second, And the most important thing that most DIY'ers are not aware of (as it took me quite some time to find the answer as well) is that the width of each of the section plays HUGE role in the High Frequency Dispersion Quality's of the panel, or better known the Beaming Effect.
The wider the diaphragms radiating area is, the more Beaming Effect you will have at the higher end of the audio frequency bandwidth.
Here is my description of this from this thread at ESLDIY as found here,
Login
It goes like this,
"When the section width equals one wavelength the dispersion pattern is of the familiar doublet figure 8 pattern, and, any frequency below this point becomes more and more Omni Directional with a Circular wave front.
Above this frequency, The wave front begins to form into a beam and sometimes with some extra lobes shooting out from the sides."
So, As I said most DIY'er only use the guide lines for stability reasons I choose to use smaller widths for the sections.
This difference between my 7.5" wide diaphragm and my 3.25" wide diaphragm was huge and made big difference of not having to keep my head in a vice in order to enjoy the stereo field!!
Thus I have kept to the smaller size ever since.
Now remember that D/S Ratio?
Since my panels are narrower I like to have a bit more excursion room for the diaphragm at the lower range down to about 200Hz to 300HZ or so.
I have been using approx .072" to .090" for my D/S and then I just compensate for this increase by using a higher bias voltage.
This is also the lower limit if you are using a common Power Toroid Transformer's in a step-up configuration
This works out very nicely as it takes displacement to produce the lowest frequency's.
And since they are Omni-Directional anyhow due to the diaphragms radiating area's width, Displacement rules!!
This brings me to "What is electrical Segmentation?".
Well it is a method to be able to have that Wide Diaphragm for to be able to produce those lower frequency's and not have (hardly) any of that Beaming Effect at the high end of the spectrum!!
This is done by having several separate stator sections that are isolated from one another by a resistor.
With the individual capacitance of each stator section, fed along with each its own individual series resistor forms a low pass filter that cascades on down the whole width of the panel.
Therefore only the highest frequency's will be radiated from a thin strip of of the complete width of the diaphragm, and as the frequency is lowered the effective width of the radiating area becomes larger.
Therefore keeping a constant and wide horizontal dispersion pattern throughout the audio band that the panel is producing.
This paper is a must read for more and complete information on this subject,
http://home.kpn.nl/verwa255/esl/ESL_English_2009.pdf
Found Here,
Elektrostatic Loudspeakers
I hope this helps you and hopes to see your build soon!!
Cheers and Keep on DIYin' !!!!
jer 🙂
Dear Jer.
Thanks for reply, very grateful for advice, clears things up.As you say it looks like the way to go at first will be a couple of panels that are around 4" width, and between 8" to 12" high. I can use the bass/mid in my existing transmission line speakers for lower frequencies.
I have found suppliers for all the bits. Very lucky with alu stators 1mm thick, 3mm holes, 50% open, at a good price and within a short drive, which should avoid bending in the post.
First try will be only one side, to avoid making more than one mistake at a time!
Also I have to make electronic Xovers and amps, and hope that 80-100 watts will do the trick. present amp only 15-20 watts.
If I need higher power will need to get ready made modules as my electronics are not good enough to make amp without ready made PCB. I have used Rod Elliot's PCBs for all my existing system ( ESP in Australia ) and the sound is really good.
Thanks again.
Mike (in UK )
Thanks for reply, very grateful for advice, clears things up.As you say it looks like the way to go at first will be a couple of panels that are around 4" width, and between 8" to 12" high. I can use the bass/mid in my existing transmission line speakers for lower frequencies.
I have found suppliers for all the bits. Very lucky with alu stators 1mm thick, 3mm holes, 50% open, at a good price and within a short drive, which should avoid bending in the post.
First try will be only one side, to avoid making more than one mistake at a time!
Also I have to make electronic Xovers and amps, and hope that 80-100 watts will do the trick. present amp only 15-20 watts.
If I need higher power will need to get ready made modules as my electronics are not good enough to make amp without ready made PCB. I have used Rod Elliot's PCBs for all my existing system ( ESP in Australia ) and the sound is really good.
Thanks again.
Mike (in UK )
Very Good!! 🙂
I get very good results from my desktop size of 3.25" X 9.75".
Using just an 80watt amp I can get +100db to about 105db with it.
This is enough that I can only get a 95db flat response down to about 50hz with my 5.25" woofer as this is all it can do on the low end to keep up with the panel.
Just make sure that you have ample amount of stator coating thickness as well, at least 6-8 mil or so, I used 10mil on my latest build.
See the link in this post for more info,
http://www.diyaudio.com/forums/planars-exotics/246846-first-time-esl-builder-2.html#post3766136
I love building the smaller ones for a few reasons,
They are cheaper to make for a First time builder and easier to handle.
It allows you to get your own building process down a lot easier and should you make a mistake or find a way to improve upon your system it is cheaper to be able to just start over.
Second once they are done you will find that they really do preform Quite well when it is done right.
http://www.diyaudio.com/forums/planars-exotics/109789-esl-diaphragm-coating-8.html#post2162068
Then you can easily apply everything you have learned to building a larger system if that is what you chose to do and not have to worry about it failing on you.
I can not stress enough how important the stator coating is for a successful build of any size for that matter.
Cheers!!
jer 🙂
I get very good results from my desktop size of 3.25" X 9.75".
Using just an 80watt amp I can get +100db to about 105db with it.
This is enough that I can only get a 95db flat response down to about 50hz with my 5.25" woofer as this is all it can do on the low end to keep up with the panel.
Just make sure that you have ample amount of stator coating thickness as well, at least 6-8 mil or so, I used 10mil on my latest build.
See the link in this post for more info,
http://www.diyaudio.com/forums/planars-exotics/246846-first-time-esl-builder-2.html#post3766136
I love building the smaller ones for a few reasons,
They are cheaper to make for a First time builder and easier to handle.
It allows you to get your own building process down a lot easier and should you make a mistake or find a way to improve upon your system it is cheaper to be able to just start over.
Second once they are done you will find that they really do preform Quite well when it is done right.
http://www.diyaudio.com/forums/planars-exotics/109789-esl-diaphragm-coating-8.html#post2162068
Then you can easily apply everything you have learned to building a larger system if that is what you chose to do and not have to worry about it failing on you.
I can not stress enough how important the stator coating is for a successful build of any size for that matter.
Cheers!!
jer 🙂
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