Hand Built Full Range Drivers of the Highest Caliber

Feastrex fixed magnet drivers are priced from $4300 a pair and field coil drivers from $5900 a pair.

 

New From Feastrex: The Nf 5ex 5" Naturflux field coil driver - Ultimate Purity at an affordable price - a remarkable achievement

 

A message from Haruhiko "Hal" Teramoto
builder of Feastrex speakers

The incomparable D9e 9" Field Coil Full Range Driver

The D9e defines transparency, is the king of microdynamics and the emperor of inner detail. It operates at speeds not normally experienced by ordinary folk and deals in unlimited space as a sideline. It tickles and warms, but cracks like lightning. It says, "I am what you didn't even know to ask for, but when I show up, you know what I am."

There is a legend about two master sword makers. Both could create a blade capable of sustaining the sharpest, most perfect edge. In all respects, save one, their swords were equal, but this one difference alone meant they were worlds apart. What was this difference? You could face the first maker's blade towards the current in a leasurely stream and the blade was so sharp it would cut a gently floating leaf in two. Aiming the second maker's equally sharp blade in the same fashion yielded an entirely different result: as the leaf approached it was gently buffeted around the blade. This was because this maker had built his compassionate heart into the sword.

"We are the bearers of a tremendous responsibility -- toward our suppliers, toward our customers, and toward the musicians and composers and recording engineers of the world, whose music we intend to reproduce. Everyone else has done their part to the best of their ability, and when I build these speakers it is up to me to do my part well, so that the efforts of all these other people can bear fruit. Thus I am in a never-ending battle with myself, to more fully master and perfect my craft, and to be able to translate the passionate spirit of all these people into beautiful sound bringing great joy to lovers of fullrange speakers throughout the world." - Haruhiko "Hal" Teramoto

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The D9x Family of Loudspeaker Drivers

"Among the various Japanese technologies in these speakers, the most important is undoubtedly the "washi" paper used in the cone assemblies. Each local region of Japan has its own distinct types of washi, and each type of washi will vary according the individual papermaker. (A skilled papermaker will be able to maintain a high level of consistency within his own manufacturing.) It is impossible to know how a particular type of washi will sound until it is actually tried, and even then of course the sonic results will vary depending on how the washi is implemented as a speaker cone. Here at Feastrex we have tried many different kinds of washi from all over Japan. As a result of our extensive research, we decided to ask the master washi craftsman Mr. Ichibei Iwano for his cooperation in developing paper ideally suited to our speaker building needs. Despite the extreme demands that we ended up placing on Mr. Iwano, he has very graciously striven to give us exactly what we need. In our opinion, this paper deserves to be considered a treasure of the highest order. We think there is nothing that can compare with it anywhere in the world."

"Just as in the case of the D5x family of drivers, each driver in the D9x family has its own special attractive points. Within this product group, in terms of cost vs. performance ratio, the D9nf (965g AlNiCo 5-7 magnet) stands out; it has truly impressive performance. The magnetic flux density of the D9nf is about 16,000 Gauss (actual measurement). The D9 is probably the king of this family; with the D9 you can hear information that you can't hear even with the D9nf. This is to be expected since the AlNico 5-7 magnet weighs 2600g and the voice coil gap is surrounded by Permendur pole pieces -- the magnetic flux density of the D9 is about 20,000 Gauss (actual measurement)."

"With the field coil drivers, changing the power supply can affect the sound just as much as changing the amplifier. Varying the voltage applied to the field coil can also have a huge effect on the sound by changing the damping of the driver, allowing the user to achieve a wide range of effects with every type of enclosure from horn to open baffle. The user can obtain a huge degree of freedom in creating his own sound. In the case of all the field coil drivers, the extremely high permeability of the magnetic circuit means back electromotive force forms in the voice coil, for powerful electromagnetic braking and a significant reduction of excess motion in the diaphragm. As a result, transient response is excellent. The Type 1 field coil driver uses a one-piece (monococque) yoke and pole piece made entirely of iron, and an iron face plate, for a magnetic permeability of 4,000 mu and a magnetic flux density of 16,000 Gauss. The Type 2 field coil driver uses a yoke made of iron with a precision interference fit Permendur pole piece and Permendur face plate, for a magnetic permeability of 10,000 mu and a magnetic flux density of 20,600 Gauss. The expressive (resolving) powers of the Type 2 driver are better than the Type 1 driver. Finally, the Type 3 driver uses a construction identical to that of the Type 1 driver, but uses all Permendur instead of all iron. It represents the ultimate in luxuriousness, the ultimate in resolution, the ultimate in expressive power."

The D9 Monster Alnico

The D9NF NaturFlux Driver

The PB9 Passive Radiator

D5 Monster Alnico Magnet

"I can tell you that my goal is to design a speaker that will be capable of beautifully playing all music. That is the only kind of speaker that we at Feastrex are willing to ship to customers, and if it can't do that there will be no point in making it -- there are already any number of speakers that can do an unsatisfactory job . . . there would be no need for yet another." Haruhiko "Hal" Teramoto Feastrex Yamanashi, Japan

 

 

 

 

 

D5e Field Coil Driver - All Permendur

Driver Dimensions:

D5nf
D5 Monster Alnico
D5e
D9nf
D9e

Recommended Enclosures

5" driver Feastrex Original Enclosure

more info

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Photo of torn washi paper by Clark Blumenstein

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