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moray james 30th April 2008 04:47 PM

Make it worse to make it better???
this is just one of those "food for thought" postings. I have an idea and I have not tried it out so have no hard proof as to will it or won't it work but I can see no reason why this would not be a very interesting experiment. So if you try this and it works just give me credit for the idea and if it does not work just forget i ever mentioned it.
The Maggie is a very popular speaker and those who love it do so with a passion. Maggies are in fact high mass drivers and their dirve system is extreemly non linear (read never ever linear). That said they can and do sound very wonderful. So we have compared to an esl which is very very linear and low distortion ultra low mass a speaker that generates a ton of second order harmonic distortion. This pretty much amounts to the difference between a high % distortion tube amp and an ultra low distortion SS amp. People fall in love with lots of second harmonic distortion.
So I suggest that some one build up a flat ESL panel with different thickness stator spacers. I should think that if there was a difference in thickness of about 25% front Vs back stator spacers that should generate some second harmonic distotion and sweeten thins up so the ESL does not sound so sterile. Then you can also play the game of front side Vs back side listening as they will both be different (with maggies some folks prefer one way to the other). That it so if anybody tries this idea please let me know what you find out.

thinkbad 1st May 2008 08:07 AM


Interesting idea !

I recall a review in a scandinavian hiifi-mag of a american-made tube preamp with a measured second order distortion of almost 30%, the reviewer raved about the extreme transparency troughout the frequency range...

Well, a bit OT :eek:


moray james 1st May 2008 01:26 PM

JB: no not OT at all that was the point. ESL's and planar magnetics seem to share the same issues as tube amps and SS amps. The ESL (on paper) is light years ahead of any Planar magnetic loudspeaker. But just look at the huge body of died in the wool maggie users. I admit that the first time I heard a paie od SMGa's running on a Linn and all ARC electronics I was prepared to be very unimpressed and instead I was very impressed. In the same way that I was impressed by a tiny SE 3.4 watt amp (with bags of even order distortion). This hobby is not about right and wrong it is about the illusion of real music the emotion of music. Its kind of like we have been saying that HIFi speakers are better than PA speakers but it is not the case. The two are different that all they do different jobs. I have come across amplifier circuits that were intended to generate some extra even order distortion for just this very purpose. So why not sweeten up a set of ESL's a little and pump the illusion of the sound some?

el`Ol 1st May 2008 06:52 PM

Hello Morray!

Maybe that is even true when you compare the Maggies with "better" planar magnetics. I had the chance to listen to Magnepan and Analysis Audio speakers at the Highend in Munich this year and last year. I didnīt stay in the Analysis Audio room long enough last year, but this year I had the impression that the Analysis speakers are a class of their own in terms of dynamics (my recommendation for drum solos), but tonally a bit on the synthetic side compared to the Magnepans. I know I listened to the Maggies with Jeff Rowland electronics, while not having looked at the electronics in the Analysis room very carefully, but I think it was nothing well-known. A maggie critic at audioasylum (things exist between heaven and earth) told me it must have been the electronics.
About the asymmetric ESL: I played a bit with FEMM and the only way I see is building stators with different geometries and conductors on the diaphragms like in a magnetic planar to use the local non-linearities. My math teacher would have said: You can also drill a hole in your knee and fill it with jam. Why not get some nicely colored strong power amp? The Electrocompaniet NEMO is very nicely colored, I never heard their smaller ones.


moray james 2nd May 2008 08:34 PM

Well Ollie can you figure us ou of this mess?
What does Femm suggest will happen with a simple stator thickness difference front to back side in the order of 25% thicker one side Vs the other side? Thanks Oliver.

el`Ol 3rd May 2008 06:31 AM

Hello Morray!

As far as I know FEMM only allows defining lines as conductors, not blocks (I am currently using it for designing a magnetostatic speaker, not for electrostatic problems). A third outer stator with the voltage of the adjacent/opposite stator, as well as a dielectric on one side give only very slight non-linearities.

BTW, what I find boring about ESLs is mainly the transients and the poor integration with a dynamic bass. I would like to listen to a magnetic planar (not a muddy maggie) with ESL midrange.


Few 4th May 2008 07:39 PM

Perhaps I'm missing something, but I don't see how having different front-stator-to-diaphragm and rear-stator-to-diaphragm distances would introduce second harmonic distortion into an ESL's operation. The electric field strength experienced by the diaphragm should be independent of the diaphragm's position between the two stators. The electric potential varies with position, but the field strength does not. (The electric field lines between two ~infinite plates are parallel.) If that weren't true the ESL would not be capable of the low distortion output pointed out in the original post.

Second harmonic distortion can be a problem in a curved ESL panel because the forces associated with forward and backward motion of the diaphragm are not symmetric: diaphragm motion in one direction stretches the diaphragm while motion in the other direction reduces its tension. With a flat, two-stator ESL, though, the second harmonic distortion should be low no matter what you do with the diaphragm-stator distances.


el`Ol 4th May 2008 08:32 PM


Originally posted by Few
Perhaps I'm missing something, but I don't see how having different front-stator-to-diaphragm and rear-stator-to-diaphragm distances would introduce second harmonic distortion into an ESL's operation. The electric field strength experienced by the diaphragm should be independent of the diaphragm's position between the two stators.


moray james 4th May 2008 09:03 PM

An unbalanced drive will generate distortion...
as long as the diaphragm to stator spacing is balanced (identical) from one side of the speaker to the other then regardless of where in between the two stators the diaphragm is the combined forces pushing and pulling will always be the same. If you make one set of stator spacers thicker or thinner than the other side then the drive is off balance.
With curver ESL's yes you have some differing tensions forward to backward but for the most part you have tension in the length of the diaphragm which keeps it centred. Don't forget that you also have different front to back stator thicknesses. This is to accomodate large excursions where horizontal tensions will increase and so pull the diaphragm more flat thus drawing it closer to the rear stator. Push pull is low distortion because things are balanced and symmetrical. Skew the symmetry and the distortion goes up.

Few 6th May 2008 03:06 AM

The point I was trying to make is that since the electric field is the same at all points between the stators, drive symmetry is guaranteed no matter what combination of spacer thicknesses you use.

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