cdwitmer wrote:

If Very Knowledgeable Guy ever had an opportunity to do a listening comparison between a Feastrex Type II field coil driver, which has a Fe main yoke with a Fe49–Co49–V2 pole piece and a Fe49–Co49–V2 top plate, and a Feastrex Type III field coil driver, which has yoke, pole piece and top plate all made of Fe49–Co49–V2, he would no longer be laughing. He might recoil at the price, but his ears would not be telling him that there is no significant difference. There is a significant, very audible difference in the sound between the two drivers even though the only significant physical difference is the use of all-Permendur in one and Permendur plus Iron in the other . . .

cdwitmer wrote:

It would be irresponsible of me to attempt a detailed discussion of the sound because 1) I am not a well trained listener and analyst of audio…

Romy the Cat wrote:

cdwitmer wrote: It would be irresponsible of me to attempt a detailed discussion of the sound because 1) I am not a well trained listener and analyst of audio… Chris, with all due respect - don’t not you think that this reply sounds at least stupid? The Cat

OK, thanks. I would leave for others to decide what the “higher resolution image” might mean. It might be some kind of untranslatable Japanese folklore. The more vibrant color palette is definably a valid accomplishment, no one knows through if it is because the Permendur-made “main body of the yoke” as it might be another set of variant that impact the “color palette” of the Feastrex. However, if you inst that the Feastrex was methodologically-kosher in their research and the different between the old (let call them “color palette deficient drivers)” Feastrex driver and the new “color palette extended” drivers is ONLY in the fact that the new drivers use Permendur-made yoke then I would accepts the defeat of my cretinism and it the new drivers do have better color palette then it would prove your point.

However, this brings another interning angle.  The Feastrex is … 5-6-7-8 inch driver, I do not know, I never seen it specification. Let presume that it is 7” then the voice might be I would say 3”. This would make the “main body of the yoke” to be a cylinder of 3” by I would say 4”. This way the difference between the old $1000 driver and new $40.000 is in the 3” by 4” radial cylinder of Permendur. To make the external pole pieces and the electromagnet cores from Permendur the secretive Japanese Permendur-turners were able for $1000 but to add an additional 3”x4” cylinder they would need extra $39.000? Oh, pas do not insult me with stories about the precession of the surface: the Feastrex is soft-suspended driver that might not by design to use a very narrow gap.

Chris, I agree - I mock you and I do it only with one objective – to ridicule your desire to justify the $40.000 price tag with some kind of objective and rational reasons.  In reality those reasons do not exist and the ONLY reasons why you guys went for $50L range is because you know that spicing your driver with right literature you would be able to go away with it. There is no problem with it BTW but it is nothing then the “fuck off” approach that proposed above.

The point is that Robert above was correct suggest the there is an army full-range fanatics, all of those that I call “yellow drivers” users: Fostexs, Lowthers, Jordans, Feastrex and many others. There is nothing wrong with full-range idea if we make speakers for computer or something to build-it into a communication receiver. The question is why the hell we need a full-range driver if we pursue any more or less full-range sound reproduction? Here is where the fanaticism of full-range driver devotee takes over and they absolutely refuse to recognize the facts. And the facts are that there is a certain stop point from below and above where the use of full-range concept become juts to divesting for results. The very same Feastrex driver might be an excellent MF driver and if it high passed it at let say 500Hz then it might be able to care over 90dB sound pressure. I personally think that the recent tendency of full-range fanatics to go does “better” and “expensive” full-range driver is bad thing. I know that there was another 3” full-range driver at the show that was proposed for $65K. I am not saying that it does not worth it – I say that it worth only as a tribute to fanatism not as a tribute to the actual sound.

The full-range drivers are great what they cost $300 and the entire speaker might be built in home-depot for 20 minutes. As the $50K solution the full-range driver is not only unfortunate but also dangers devise in my view. Let me to explain.  When Feastrex stop to sell your literature and publish the actual data on those drivers (I can believe that you market the sale of the raw drivers for years with no technical data– only the idiocy of DIY community can tolerate it) then one of the parameter will be power handling. This would be very interning to see, even those I would not believe in the number you will publish.  What I mend is that take a LOT of balls to connect $40K drive of medium sensitively to power amp without any high-pass filter.  I have seen how the stupid ceramic woofers were flying away from the speaker with any “puff” from amplifiers. I can give you names of the distributors who replaced many many many of those driver for their customer… in your case it will be $40K per pop… Wait until the hoodlums put OTL amps to drive your Feastrex…

Anyhow, I do feel that accept you guys seriously you need to come up with at least a complimentary bass driver of for your Feastrex. Then you might sell a set for those 50K to whomever like it. To promote a full-range driver for $40K is not what I see rational from consumer perspective.

I had once visited these sites:

"We make two different sizes of drivers: 5 and 9 inch. As can be expected, the 9 inch has a larger sound, the 5 inch has a slightly greater finesse in the high frequencies. Please choose according to your room size, though we should note that the "smaller" 9 inch drivers, I.E. the Naturflux units, can also work well in small/medium sized rooms. Also, the "larger" 5 inch units I.E. the Type II and III really shine when given a large room in which to breathe. In the end, it is all according to your taste in music reproduction. All of our full range driver units are the best at what they do. For advice regarding driver choice, please do not hesitate to ask us directly."

http://www.feastrex.com/products.html

and

"Paire de haut-parleurs Feastrex D9 "Naturflux", neufs 2800 € (prix neuf = 5600 €)

Z = 16 ohms
Fc = 63.8 Hz
Qts = 0.4
Mms = 24.74 g
S = 254.47 cm²
BL = 18.66 N/A
Efficacité = 1.33 %
Sensibilité = 93.3 dB/W/m (supérieur à 96dB/W/m en équivalence 8 ohms)"

Thanks, tuga, I never visited Feastrex site, in fact I thought that it is not available in English. In reality the Feastrex site is fine and gives quite eloquent information about Feastrex product and the Feastrex views.  In the Testimonials section the feedback from Floridian Toby White attracts my attention:

“My first full-range speakers were JBL LE8T drivers in small Sansui bass reflex enclosures.”

The JBL LE8T as a full-ranger?! Hm, that is original. As many time I used this driver I never used it under 70Hz and over 6KHz. The LE8T is very good driver but ONLY in the range where it is good. It is MF driver not the full-range driver. I think the same is with Feastrex.

serenechaos wrote:

A great match for Asian culture/music? Makoto Tanaka (Builder of the Nessie cabinet) was at the controls, playing bamboo flutes, bells & such.

And I am not kidding. Each time someone invite me and try to impress me with their new Lowthers speaker they unavoidably play the CDs by MA Records.

serenechaos wrote:

My wife requested a CD she was familiar with, and he played it, then a Nora Jones someone else had, and as the first track was ending, he turned to me, pointed to my bag and shrugged.  I gave him a Rachmaninoff CD which I was sure would push the little single driver over its limits, but I wanted to see how it handled it.  As the speakers started having trouble, he became very interested, ask to see the CD case, and wrote the name down.

Very funny.

serenechaos wrote:

He said that the 5" was the most expensive field coil driver, and the 9" was the least expensive.  AND, that pretty much everything in them was different...  The frames, the wire, the paper that the cones and whizzers are made from for example are processed ~200 times in the lower grade model, and ~400 times in the higher grade model.  --So, I wasn't just listening to "more permendur", and a larger driver, in a larger box, with a different amp, but a totaly different pair of speakers...

Well, it makes more sense.  I do like the Feastrex’s leaser suspension. Many movie companies did it in 30s and had some of those drivers – they were quite pleasant. With a good selection of paper and the most important the size of paper the result might be extremely good. I remember I used 8” and 10” Telefunken 1939 driver and was surprised: the 8” was OK but the very same 10” was garbage. The paper driver bend and a driver that it too large for the shoulder of the cone (+ angle and a few other things) does not sound good.

There is an interning subject with Feastrex – if they use their beloved Permendur to balance the field-coil problems. I still do not buy that Permendur narrative. The people who know Permendur cores advised me that Permendur core might be too fast for subjective listening, making transients ultra-fast, hard to possess by brain. Feastrex seems like pile up Permendur in the driver and Chris report “higher resolution”.  The higher resolution is in the same world as the faster transients but why Feastrex need faster transients of no one complained about transient’s deficiency before. Well, I think what happed is following. The perm magnets Feastrex drivers most likely are OK transients-wise. The electromagnet version of the same driver is mostly (like any other electromagnet version) is transient-softer. So, Feastrex found a way to get some speed of the transients by loading the driver with more Permendur.  (Let presume that more Permendur works). The top of the line AudioTechnica headphones are a wonderful example of sound that the Permendur has raped.

Anyhow, I personally do not feel that Permendurisation is the right way to go. Cost, difficulty to manufacture, a need of extra power supply, faster loose of bass on higher permeability (this is why it is not boomy anymore) are the penalties.  If the ‘as is’ field-coil Feastrex does need any help in transient department then why do not use this driver with higher transformer ratio and by more idling of output tube to get the transients back? 

Romy,
I was asking questions here, and @ RMAF because I'm trying to gather enough information to build compression drivers.  
At my day job I am a prototype machinist at Los Alamos National Lab.  I don't plan on going into production, just to build a few good ones.

I had planned on using field coils at first, (as adjustable magnets) to determine how strong of magnets would be most effective, like using pots in a circuit, then replacing them with good resistors. 
I was concerned about loss of transients after reading your experiments with converting Vitavox drivers, with no other changes, losing transients... 
I hadn't thought of it before, but maybe you hit on the reason for Feastrex using so much Permendur? 
Like Mundorf silver-in-oil capacitors.  The oil damps the otherwise overly bright silver sound. 
And yes, that sure sounds like the hard, expensive way to go about it. 

For what ever it's worth, I just remembered, they said the Feastrex cone paper was made from Mulberry bark.  What I did find interesting though, was next door, another guy from Japan had a few prototype compression driver diaphragms he had stamped out of pure Magnesium.  Very hard to stamp, but very light, and might have a good sound--not "ringy" like titanium. 
Robert

To understand why permendur, as reported elsewhere and  to my own little  experience, sounds different to soft iron as conductor of magnetism in loudspeaker motors one must look at permendurs  properties.

Two differences might contribute: Magnetic and mechanical.

The mechanical first:

I tried to with a piece of wood to tap the central pole piece of two otherwise identical loudspeaker magnets, one with only soft iron in the magnetic circuit and one with permendur pole pieces.

The permendur one had a much louder and longer lasting ringing sound, that correlated well with the impression of the two units when playing music.

The magnetic:

Take a look at the BH curves of permendur.

One will notice that it saturates easy and hereafter reaches the very linear saturated permeability area.

As long as the permendur is kept saturated it is very good and linear (distortion free) and the pole piece of the Featrex is undoubtably saturated in the magnetic gap.

Following the field lines in the magnetic circuit away from the magnetic  gap, the level of magnetism will decrease and might eventually reach the highly nonlinear regions of permendur, and unless the whole magnetic circuit is saturated  a can problem occur:

If the level of flux in the permendur is on the sharp transition between saturated and not saturated, any modulation of the field originating from the signal in the voice coil, will produce harmonics of the disturbing modulation. This in turn will be reflected back as a varying driving force into the voice coil and further into the radiated sound as distortion.

Soft iron does not have this sudden knee in its BH curves and will therefore be immune to the magnetic distortion mechanism described above.

If  both, or any of these factors are at play with the Feastrex is speculative, but distortions can produce the impression of richer harmonics, more vibrant etc.

hello to romy the cat- thankyou for the site.

"mystification....special (audio) clubs"

i am a diy guy, i am like this because i have to make my own stuff.

this talk of myterious clubs ...is there a secret handshake?

what about a hood with the eye holes cut out?