
Home  Forums  Rules  Articles  diyAudio Store  Gallery  Wiki  Blogs  Register  Donations  FAQ  Calendar  Search  Today's Posts  Mark Forums Read  Search 
Planars & Exotics ESL's, planars, and alternative technologies 

Please consider donating to help us continue to serve you.
Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving 

Thread Tools  Search this Thread 
15th September 2007, 07:52 PM  #1 
diyAudio Member
Join Date: Aug 2007

ESL Capacitance calculation
The formula for the capacitance of an ESL is given by:
C = (8.85E12 x A) / d Where C is in Farads, A in square meters and d in meters. My question is, what should "d" be? The D/S spacing? but the diaphragm is at constant charge. The audio signal is applied to the stators. Thus should not "d" be the distance between the stators? The books I have seen use D/S, but that seems wrong to me. Is there an explanation why D/S should be used? 
16th September 2007, 08:58 PM  #2 
diyAudio Member
Join Date: Sep 2006

An ESL is a very complex load, i think that formula is just a good approximation.
Capacitance increases with area and decreases with spacing. But the spacing is always changing during operation. Edit: There would be stator/stator capacitance also but it would be small and most likely insignificant. 
17th September 2007, 09:22 PM  #3 
diyAudio Member
Join Date: Nov 2004
Location: close to Basel

Hi,
basically it dosen´t matter which distance You choose! The formula gives an idea about the capacitance value under nosignal conditions. In a symmetrical ESL the distance between statorstator is twice the distance statormembrane. The capacitance between statorstator is one half of that of statormembrane. This is equal to a series connection of two identical caps....the value is halved. But since the diapgragm is usually coated with a high ohmic value material, it is difficult to measure the statordiaphragm capacitance. The lowimpedance stators You can easily measure. This value is more interesting because it is the one that the amplifier sees (through the transformer). jauu Calvin 
18th September 2007, 09:49 AM  #4 
diyAudio Member
Join Date: Aug 2007

> The lowimpedance stators You can easily measure.
> This value is more interesting because it is the one > that the amplifier sees (through the transformer). Exactly, that is why I was surprised to see the D/S capacitance used in the books. (Sanders, Wagner, Fikier) Have you ever compared the measured and calculated capacitances of your speakers? 
19th September 2007, 04:59 PM  #5 
diyAudio Member
Join Date: Nov 2004
Location: close to Basel

Hi,
Yes,odf course For the sheet metal stators I use the ststcapacitance is nearly the same as calculated. jauu Calvin 
Thread Tools  Search this Thread 


Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
crossover calculation  conket  MultiWay  3  11th May 2009 11:54 PM 
Max SPL calculation?  Ignite  MultiWay  17  9th April 2007 09:38 AM 
Calculation  aguantesoda  Solid State  5  31st December 2006 10:02 PM 
Parametric Q Calculationhelp, please  tocs100  MultiWay  3  2nd January 2006 01:21 PM 
Heatsink calculation  wuffwaff  Pass Labs  2  24th December 2002 01:39 PM 
New To Site?  Need Help? 