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?