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My first impressions a about the “differences” of field-coiled derived form the time when I ran the Telefunkens war time drivers but at that time I had no reference how the same driver would act with permanent magnet. Also, the Telefunkens are the regular MF 8” drivers - the compression driver is totally different story. The only more or less illustrative indication about the compression field-coil driver I got from listening the Klangfilm Bionor with permanent manger vs. the set of it’s own electromagnet drivers. Still, since I do not like the results I heard from any of Bionors it was hard to say anything defiantly then.

This morning I spent another few hors this morning with field-coiled S2.  The entire speaker sounds horrible and the S2 field-coil sounds “strange” and “different”. I did have a chance to reconcile a little my feeling about it.

I have a constant sensation that the field-coiled S2’s sound remarkably reminds me the sound or OTL amplifiers. It has the same ability to super precise to follow the very minute dynamic fluctuation of signal and superb transient but those phenomenal qualities are not connected with anything else, primary it has no correct harmonic backup for the sonic events.  The instantaneous feeling of those “absentminded sounds” is very impressive and many people ignorantly fall for it  ythe long run or generally correct sound.

I sense that the field-coil, at least the one that I made, has a lot of common with OTL sound. It is very clean, it is electrostatic-like free from grain, it is very softly and very naturally enters the sonic stresses but it always, I mean always, always, always too thin, meaning it has no acoustic-like harmonic stricture. As the result it sound remarkably sonically imprecise and insultingly musically hollow and worthless.

I do like SOME deferential effects of the field-coil has but the biggest revelation I got this morning when I un-screw the S2 field-coil and put back the S2 with it’s default permanent magnet. 

Well #1:  the perfectly tonally and harmonically balanced sound went back to its normal state and the horrible honk that I got using the electromagnet completely despairs.

Well #2: to my big surprise the softness that very much impressed me with field-coil did not become an anti- softness with permanent magnet. The regular S2 did hold it’s own. It did not demonstrate “hardness”. Instead the S2 demonstrate it’s ability to be “stressed” to deeper level of impassiveness then the S2 field-coil. I find that S2 field-coil can not be aggressive or bold if the music calls for aggressiveness and the S2 field-coil mellows down the stress of impressionism aka act like electrostatics. Why the Mravinsky orchestra’s strings sound like Vienna Philharmonic and why Mravinsky orchestra woodwinds sound like Prague Philharmonic? Since then Russian brass sounds elastic and fertile but not nasal and bruttal?

Well #3: Harmonics, harmonics, harmonics … here is where all music lives. The very first note from the S2 permanent magnet immediately set the things straight.  Using adjectives I would characterize is as “rich” vs. “thin”. The S2 permanent magnet has large tone with beautifully-connected notes.   Each note is not juts a note itself but has a referenced via harmonics to what was before and after, It has sot of harmonic ambiance noise that dose slightly masks the appearance of the fundamental pitchers but without that harmonic noise the pitchers sound too contrived and artificial.  The S2 field-coil is less loaded with ambiance and the core note are more naked. Also, the tone is less grained and more hygienic.  It is very positive for sake of observation and dissection but it is slightly destructive as it makes listening less fluent but more intellectual.

Are the harmonics or distortions? I do not know. Is it possible to make the S2 field-coil to sound harmonically correct by injecting a long tail of upper bass channel. Possible.  Is it possible that using larger magnet the harmonics pattern of the field-coiled driver might be changed? Possible.

I do not know where I go from here, as well that I do not know how final my observations are. So, far I see a LOT of problems with field-coil and what I learned make me do not take seriously the experience of other folks who try to make the field-coils. For instance they are some Japanese, German and French speaker makers who try to make two channels field-coil speakers. Now I know that it is foolishness. The field-coils can not work well across a wide range and should operare only within a limited amount of octaves. The higher frequency is the more flux the driver want and the less frequency is the medium or low flux sound much more useful.

So, what will I end up using? Hm… I do not know yet.  The S2 field-coil “as is” is not correct direction and to get the most out of the concept the entire magnetic structure of the driver should be rebuilt to take care bout the heat dissipation. So far the conversions cost me ~$700. I have an idea how the S2 driver might be changed to run off the field coil. I would estimate that I would cost around $2500K. Then I need to change the entire Macondo configuration trying to make the field coil to sound harmonically correct.  I doubt that I would go for it, as I frankly speaking have no needs. I would like to inject into the regular S2 some softness but I am not wiling to change anything else in the sound of this driver. So far, at the level in whish I did it, a field-coil magnet does not sound to me like a useable solution to me. I will give more time to the field-coiled over the next few weeks but so far you have heard my preliminary observations…

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