Here are som caculators that might help you out.
They seem to be fairly acurate from what others say as I don't have an SPL meter right now.
http://quadesl.nl/sim/index.php#sim
http://www.fuzion.co.uk/Support/System_Calcs/Calcs/whatspl.aspx?Title=SPL Level at Distance Calculator
http://www.linkwitzlab.com/spl_max1.xls
There is a revised linkwitz spread sheet some where in a thread of last year just for planar drivers but it is the same as far as suface area and xmax is concerned I have also found these calculations to be true when using Winlsd by observing area(sd),cone excursion and spl charts.
when I find the the other spreadsheet I will post that link as well.
jer
P.S. 3.5meters (aprox 18 feet) you lose 10db of spl right off of the top,which is the main reason I prefer nearfield listening.But it is some thing to consider when it comes to larger rooms and living rooms and such.
They seem to be fairly acurate from what others say as I don't have an SPL meter right now.
http://quadesl.nl/sim/index.php#sim
http://www.fuzion.co.uk/Support/System_Calcs/Calcs/whatspl.aspx?Title=SPL Level at Distance Calculator
http://www.linkwitzlab.com/spl_max1.xls
There is a revised linkwitz spread sheet some where in a thread of last year just for planar drivers but it is the same as far as suface area and xmax is concerned I have also found these calculations to be true when using Winlsd by observing area(sd),cone excursion and spl charts.
when I find the the other spreadsheet I will post that link as well.
jer
P.S. 3.5meters (aprox 18 feet) you lose 10db of spl right off of the top,which is the main reason I prefer nearfield listening.But it is some thing to consider when it comes to larger rooms and living rooms and such.
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My fancy Dayton-Wrights are perfectly matched in quality to hi-fi 1975 electronics, if they meet the driving requirements. Cone speakers are the limiting condition even with far older amps.
ESL typically radiate from both sides and you get a quality of room-filling sound which many people favour. And not much is lost by cancellation. Even down low where theory says there should be cancellation, there just isn't anything like theory suggests.
If you are a respected guru, then maybe, just maybe, you are entitled to be as "abrupt" with replies as brsanko was at the start of this thread. But if you are a beginner, more seemly to be polite.
ESL typically radiate from both sides and you get a quality of room-filling sound which many people favour. And not much is lost by cancellation. Even down low where theory says there should be cancellation, there just isn't anything like theory suggests.
If you are a respected guru, then maybe, just maybe, you are entitled to be as "abrupt" with replies as brsanko was at the start of this thread. But if you are a beginner, more seemly to be polite.
geraldfryjr> Imho that first calculator isn't quite self explanatory. (Not to me at least)
I've looked at it before and come to understand it somewhat (I think).
The drive voltages are given as Vrms. Would this meen the resulting graph is depicting average dB (C) SPL?
Is there a way to estimate if/when the diaphragm will hit the stators?
What will be max peak SPL?
When you look at measurements they don't usually look like that, what gives?
Those are some questions just from the top of my head. Unless you know how to interpret the graph it can be kind of confusing.
Some of this I think I know but it's a long way before I'm certain.
If there are other n0obs out there besides me I think we would all be grateful for some clarifications.
I've looked at it before and come to understand it somewhat (I think).
The drive voltages are given as Vrms. Would this meen the resulting graph is depicting average dB (C) SPL?
Is there a way to estimate if/when the diaphragm will hit the stators?
What will be max peak SPL?
When you look at measurements they don't usually look like that, what gives?
Those are some questions just from the top of my head. Unless you know how to interpret the graph it can be kind of confusing.
Some of this I think I know but it's a long way before I'm certain.
If there are other n0obs out there besides me I think we would all be grateful for some clarifications.
Yes I agree,I am not sure exactly what is meant by a current drive vs voltage drive but I have a slight idea,So it would be difficult for me to explain and give the correct data.
But by playing with it for a while you can get the just of it as the output data is very close to the linkwitz spreadsheet.
There are a few more that I know of and I will find them and post them later.
But it is a start.
I believe that the voltage drive depicts the way an esl output given a constant voltage input.
And the current drive depicts driving on esl with a constant current source and as the frequency rises the impedence drops and therefore the drive voltage drops by the same rate thus flattening the frequency response.
Anyhow that is my guess,anyone whom knows the correct description of this please feel free to chime in.
jer
But by playing with it for a while you can get the just of it as the output data is very close to the linkwitz spreadsheet.
There are a few more that I know of and I will find them and post them later.
But it is a start.
I believe that the voltage drive depicts the way an esl output given a constant voltage input.
And the current drive depicts driving on esl with a constant current source and as the frequency rises the impedence drops and therefore the drive voltage drops by the same rate thus flattening the frequency response.
Anyhow that is my guess,anyone whom knows the correct description of this please feel free to chime in.
jer
It works for both.
If voltages are considered Vrms, then SPL is dB(average)
If voltages are considered Vpeak then SPL is dB(peak)
You can get an estimate of peak possible SPL by setting bias voltage and stator to stator drive voltages using equations in Section 3.3.2 of the Baxandall paper.
For a given diaphragm spacing d, the optimum Vbias and V(stator-stator) are:
Vbias = Emax x d / 2
V(stator-stator) = Vbias x 2
Where Emax is the field strength for air ionization, and is roughly 3kV-4kV/mm
For an ESL with 2mm spacing between diaphragm and stator you will maximize SPL with:
Vbias = 4000 V
V(stator-stator) = 8000 Vpeak = 5657 Vrms
Taken from:
http://www.diyaudio.com/forums/planars-exotics/161485-step-up-transformer-design-18.html#post2139266
These equations are also integrated into the spreadsheet I posted here for line sources:
http://www.diyaudio.com/forums/planars-exotics/48120-experiences-esl-directivity-9.html#post2218526
I think rereading posts #49 & #51 from the current drive thread will jog your memory.
http://www.diyaudio.com/forums/plan...rrent-vs-voltage-drive-esl-5.html#post2353154
Thanks,Steve,that was the other spreadsheet that I was looking for.
I am going to recompile all of those very important links and post them in the permenant favorites thread as I am constantly having to refer to them and as time goes on they keep getting buried further and are getting hard to search out when they are needed.
jer
I am going to recompile all of those very important links and post them in the permenant favorites thread as I am constantly having to refer to them and as time goes on they keep getting buried further and are getting hard to search out when they are needed.
jer
My memory is is very poor due to resons best left alone but I would like to thank everyone for being patient with me.
I really have huge problems remembering specific facts and where to find them. Most of the time I know that I've read it somewhere but I can't recall it or where it was.
So, thanks for taking the gentle approach in reminding me.
Does anyone have a pdf of the Baxandall paper? A few months back I spent an anfternoon in the library scanning it but two computer crashes later I can't seem to find it anywhjere.
I really have huge problems remembering specific facts and where to find them. Most of the time I know that I've read it somewhere but I can't recall it or where it was.
So, thanks for taking the gentle approach in reminding me.
Does anyone have a pdf of the Baxandall paper? A few months back I spent an anfternoon in the library scanning it but two computer crashes later I can't seem to find it anywhjere.
Since I had fell out of the scene around june of last year I had stated that I had some catching up to do.
The "current vs voltage drive" thread was one of them.
After reading it, it was mentioned how adding a resistor in series it then becomes a current drive it all made sense to me and my description is therefore correct.
I now completely understand the difference between the two.
As the resistor becomes the constant current source compared to the varing impedence of the panel with frequency.
Thanks again guys! jer
The "current vs voltage drive" thread was one of them.
After reading it, it was mentioned how adding a resistor in series it then becomes a current drive it all made sense to me and my description is therefore correct.
I now completely understand the difference between the two.
As the resistor becomes the constant current source compared to the varing impedence of the panel with frequency.
Thanks again guys! jer
This is a very thinly desguised personal blow and insult. I am quite suprised the moderators tolerated it. Is there some reason you think I am a beginer? I've been on this forum 5 years longer that you have, and I have been studying speaker and audio design for far longer than that. Perhaps I am not as well known on this forum (mostly due to the narrowmindedness of some menmbers and the effect it has on my temper) but I am certainly considered an audio, and especially speaker guru to anyone who knows me personally. So keep your rude personal comments to yourself and stay off my threads.
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I kept meaning to go back and try to clarify this point concerning horn loading an ESL since things had gotten kind of sidetracked while discussing the sensitivity issues of the ESL itself. No losses are happening when horn loading an ESL at mid and lower frequencies. The SPL will be essentially the same with or without the horn.
Suppose you are driving an ESL panel such that the SPL @2m is 90dB. Then you add a horn that increased the airload on the ESL by a factor of 10. The result would be that the ESL diaphragm would now move with only 1/10th the amplitude it had been before the horn was added. But, the horn now couples this smaller motion to 10 times the area of air. The end result would be an SPL @2m still pretty darn close to 90dB.
In the case of a dynamic driver, when the horn is added the amplitude of the cone motion isn’t reduced much at all since the added airload is not significant compared to the mass of the cone. Therefore the acoustic output is increased by the ratio of the horns output and input areas. By making the throat smaller than the driver diameter(sometimes called compression loading) it is possible to increase the airload on the driver to the point that it starts to reduce the amplitude of the cone motion. This technique yields maximum efficiency from the driver. Reducing the throat diameter beyond this point and you run into the same situation you have with an ESL and you gain no further increase in output.
If you are familiar with compression loading and horns, perhaps this simplified comparison will make the ESL case make sense to you.
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Putting ESL's in a compound configuration has been used before for bass panels.
Although I have not tried it, I do have plans for such a system.
The only thing that I can see where it would be useful is only in the bass area and that it would allow larger controlled excursions (Lower THD) of the diagphram thus possibly reducing the size of the panel because of the higher excursions.
In order to get more bass without including the effects of dipole cancellations is to increase this displacement of the driver and/or its width.
To do this one must increase the surface area or the excursion of the driver.
This is true for any type of system.
Remember that ESL's are open type driver's so the idea of compounding them is only good for bass systems as the added mass will make them suffer on the high end.
But it may be feasible for a high excursion panel for a bass system.
I mean excursions of at least .125" or more just for any thing below 200HZ.
To do this would require extremely high voltages.
It is very difficult to deal with voltages so high and has been the area of where I have been experimenting with.
Depending on the size of the room one could actually build such a system that could work very well and still be compact.
I have some building to do !!!
I do understand what you are thinking when it comes to more force and the impedence matching to the horn.
I have thought about this myself.
But if you can't get more excursion than the usual 1mm than compounding the panels is not going to make any benefit.
Once you hear an ESL and experiment with it you will quickly find out how things close to the diagphram will effect its sound and sound quality from the back pressure loading on the diagphram.
This is the main reason why I like messing with a smaller panel.
It is smaller so it cost less but surface area rules.
The width of the panel is the main factor of a wide dispersion as well the low frequency cut off.
This is the same reason that tweeters are in the 1" range ,and midrangres are in the 3" to 5" ranges and woofers are,well, for bass frequency's.
This is true even for dynamic drivers only they have a much more excursion factor to make up the difference in SPL.
Then you have to add the phazing effects of the refelections off of the walls of the horn as the sound wave travels through it.
Once you hear an ESL you will be awed by its clarity.
But I still think that the two worlds can be used in a high output situation although the dynamic driver in this type of situation is very very hard to beat on a large scale.
The question of putting an ESL in an enclosure has been discussed many times over.
It all depends of what you are after.
One DIYer had enclosed the back of his MartinLogan's and caught hell from many, but, Hey if it works for him then all of the power to him,It all depends on ones particular situation.
As soon as I get my new mini panels built I will try some different baffle and horn techniques.
Now that the weather is finally starting to be nice I can now start to work on them before it starts getting humid,because paint is envolved
The other method of widening the dispersion is to use segmentation of the stator elements and I will be building two sets of similar sized panels inorder to test the dispersion of the two types.
And then mess with some kind of horn flare as well.
My biggest factor that I seemed to have tackled over the winter is how to contain over 15KV of voltage on the stators without any arcing or burn through in a .070" D/S spacing.
This is very hard to do and what was required to even have enough sound output to even consider the effects of a small horn.
jer
Although I have not tried it, I do have plans for such a system.
The only thing that I can see where it would be useful is only in the bass area and that it would allow larger controlled excursions (Lower THD) of the diagphram thus possibly reducing the size of the panel because of the higher excursions.
In order to get more bass without including the effects of dipole cancellations is to increase this displacement of the driver and/or its width.
To do this one must increase the surface area or the excursion of the driver.
This is true for any type of system.
Remember that ESL's are open type driver's so the idea of compounding them is only good for bass systems as the added mass will make them suffer on the high end.
But it may be feasible for a high excursion panel for a bass system.
I mean excursions of at least .125" or more just for any thing below 200HZ.
To do this would require extremely high voltages.
It is very difficult to deal with voltages so high and has been the area of where I have been experimenting with.
Depending on the size of the room one could actually build such a system that could work very well and still be compact.
I have some building to do !!!
I do understand what you are thinking when it comes to more force and the impedence matching to the horn.
I have thought about this myself.
But if you can't get more excursion than the usual 1mm than compounding the panels is not going to make any benefit.
Once you hear an ESL and experiment with it you will quickly find out how things close to the diagphram will effect its sound and sound quality from the back pressure loading on the diagphram.
This is the main reason why I like messing with a smaller panel.
It is smaller so it cost less but surface area rules.
The width of the panel is the main factor of a wide dispersion as well the low frequency cut off.
This is the same reason that tweeters are in the 1" range ,and midrangres are in the 3" to 5" ranges and woofers are,well, for bass frequency's.
This is true even for dynamic drivers only they have a much more excursion factor to make up the difference in SPL.
Then you have to add the phazing effects of the refelections off of the walls of the horn as the sound wave travels through it.
Once you hear an ESL you will be awed by its clarity.
But I still think that the two worlds can be used in a high output situation although the dynamic driver in this type of situation is very very hard to beat on a large scale.
The question of putting an ESL in an enclosure has been discussed many times over.
It all depends of what you are after.
One DIYer had enclosed the back of his MartinLogan's and caught hell from many, but, Hey if it works for him then all of the power to him,It all depends on ones particular situation.
As soon as I get my new mini panels built I will try some different baffle and horn techniques.
Now that the weather is finally starting to be nice I can now start to work on them before it starts getting humid,because paint is envolved
The other method of widening the dispersion is to use segmentation of the stator elements and I will be building two sets of similar sized panels inorder to test the dispersion of the two types.
And then mess with some kind of horn flare as well.
My biggest factor that I seemed to have tackled over the winter is how to contain over 15KV of voltage on the stators without any arcing or burn through in a .070" D/S spacing.
This is very hard to do and what was required to even have enough sound output to even consider the effects of a small horn.
jer
Hi,
the useable frequency range depends on the distance of the two parallel situated diaphragms. The second diaphragm introduces a phaseshift which needs to be small enough. After a Sony patent it is useful up to a range of ka<1.4 (k and a related to radiation impedance and dimensions of the diaphragm). I found it useful in a range of 100<f<4kHz.
In a hybrid-ESL it may reach magnitudes that no equalizing counter measurements for dipole cancellation are required. Besides the increased efficiency in the lower freq-range less Equing raises dynamic headroom and THD is lowered.
jauu
Calvin
the useable frequency range depends on the distance of the two parallel situated diaphragms. The second diaphragm introduces a phaseshift which needs to be small enough. After a Sony patent it is useful up to a range of ka<1.4 (k and a related to radiation impedance and dimensions of the diaphragm). I found it useful in a range of 100<f<4kHz.
In a hybrid-ESL it may reach magnitudes that no equalizing counter measurements for dipole cancellation are required. Besides the increased efficiency in the lower freq-range less Equing raises dynamic headroom and THD is lowered.
jauu
Calvin
The Dayton-Wright bass approach is kind of like a horn/transformer. The ESL panels are mounted as the dividing wall inside a sealed box which is filled with heavy gas. The ESL membrane drives the larger meter-square box membrane. Good bass down to 60 Hz and below. (Elsewhere, and often, I have argued that good bass to a surprisingly high low-cut-off is surprisingly good.)
Ben
Ben
Yes, as geraldfryjr and Calvin already mentioned, putting two closely spaced ESLs one behind the other doubles the obtainable force per unit are. Theoretically this would give you a 6dB boost in SPL output for the same input voltage. When I tested this concept I was never able to get the full 6dB, usually more like 5dB-5.5dB. But, a very useful bump in output.
Martin Logan uses this technique in the woofer portion of their CLX.
KOSS made same ESL in the 70s with woofer modules that used a stack of three diaphragms for triple the force.
Patents on the concept include the Sony one Calvin already mentioned: US3941946
Patent US3941946 - Electrostatic transducer assembly - Google Patents
and: US3136867
Patent US3136867 - BRETTELL - Google Patents
For reasons Calvin already discussed, multiple diaphragm ESLs would not be useable as a full range transducer. But, if used as a woofer the increased drive force would provide more output. However, doubling the number of diaphragms doesn't change the fact that the moving mass at low frequencies is still dominated by the airload. So, hornloading will not provide increased output at low frequencies even for multiple diaphragm ESLs.
At first I was agreeing with you, but actually it seems that in a hornloading situation where the issue is that there isn't enough force from the electrostaic charge to move the airmass it should work for low frequencies. In fact if you crossed it over at say 200hz or lower and stacked a bunch of panels together and loaded the horn to push a whole lot of air with very little diaphram excursion it should work fine. There would be a ton of math and lots of expense envolved and I don't necissarily know if it would be a big improvment over a dynamic driver but it should work.
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