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Lance A. aka Chopper 87 on the forums

This is the second chapter of a report whose first chapter can be read here.

Feastrex D9e-II:
I had opportunity to live with and compare the Feastrex D9e-II 9-inch to a prototype Lowther America 8-inch field coil driver for a while. This Feastrex is second from their top. At the time of my evaluation, it retailed for $42,000/pr. It requires a separate power supply to energize the rather large electromagnets. Recommended supply voltage is 10 to 15V. I powered the Feastrex with a pair of Mastech HY1803 DC regulated power supplies rated to output from 0 to 18V at 0 - 3A.  Joe Cohen of  The Lotus Group USA imports and supplied the Feastrex drivers plus an upmarket PSU suggested by the Japanese manufacturer as being sonically superior. Alas this power supply did not function properly by the time it reached me. What do the designers and manufacturers give as the reason for their driver’s claimed superiority? It all seems to boil down to paper. I wondered how many ply. 

"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 paper maker. (A skilled paper maker will be able to maintain a high level of consistency within his own manufacture.) It is impossible to know how a particular type of washi will sound until it is actually tried. Even then the sonic results will vary depending on how the washi is implemented as speaker cone. Here at Feastrex we have tried many different kinds of washi from all over Japan. As a result of extensive research, we decided to ask the master washi craftsman Mr. Ichibei Iwano for his cooperation in developing a paper ideally suited to our speaker building needs. Despite the extreme demands we ended up placing upon Mr. Iwano, he has very graciously striven to give us exactly what we needed. In our opinion his paper deserves to be considered a treasure of the highest order. We think there is nothing that can compare anywhere in the world."

I must admit to being a bit surprised at the thickness and rigidity of the D9e-II’s cone. I expected a light weight and thinness to the point of translucency as is common to all Lowther cones. Not. Although I was more than a bit hesitant to touch the cones on these super expensive drivers, I just had to. The cone appears to be very light in weight but comparatively thick and far from see-through - almost like a very dense yet very light cardboard.  Of course this oversimplifies a type of paper few of us in the West have ever handled. 

Although there are measured specifications for frequency response and other common driver stats for some Feastrex drivers in cabinets,  I found no free-air resonance figure for the D9e-II. Here are some Feastrex specifications and design characteristics that define and separate specific classes of their drivers. "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 to create his own sound. In the case of all field-coil drivers, the extremely high permeability of the magnetic circuit means that 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. Our Type 1 field-coil driver uses a single-piece (monococque) yoke and pole piece made entirely of iron and an iron face plate for a magnetic permeability of 4,000mu 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 10,000mu and a magnetic flux density of 20,600 Gauss. The expressive (resolving) powers of the Type 2 driver are superior to the Type 1 driver. Finally, the Type 3 driver uses a construction identical to that of the Type 1 but in an all Permendur construction instead of iron. It represents the ultimate in luxury, resolution and expressive power."

The D9e-II drivers fit nicely into my baffles normally equipped with Supravox 215-2000 EXC Eight field-coil drivers and RAAL 140-15D ribbon tweeters. For this evaluation the tweeters were disconnected. The Supravox drivers are not fitted with whizzer cones and therefore benefit from the addition of a very good tweeter. These Feastrex drivers like all Lowthers have whizzer cones and are in my opinion in no need of high-frequency augmentation. On-baffle bass duties were handled by one 16-ohm Alnico 16” Altec 416 woofer per side. These woofers were powered by a vintage Fisher Sa-16 EL84 push/pull 15wpc stereo amplifier. This little gems’ input sensitivity very closely matches that of the widebander amplifiers used to evaluate all full-range open baffle drivers. I can pad down the 416’s bass output with the Fisher amp’s input-level pots. I crossed in the woofers at 135Hz with a 1st-order 6dB/oct. slope using one 12MH and one 6.8MH toroidal inductor connected in series. This is a very personal choice. In the same baffles the Supravox field coils are often crossed at 212Hz using only the 12MH inductors. The D9e-IIs just felt right with on-baffle bass augmentation no higher than 135Hz. Again, this was personal preference.

The baffles under discussion were 20” wide by 48” tall. They are slightly tilted back with side-mounted supports which are 24” tall and tapered to 14” deep at the base. The Altec was centred at 11” off the floor whilst the widebander cutout centered at 31.5” off the floor. Why did I use these particular baffles when I had others of various dimensions on hand?  The Feastrex nine-inch drivers fit the Supravox cutouts like a glove.

I was expecting a 25wpc FirstWatt J2 amplifier to drive the 92dB efficient Feastrex D9e-IIs. Unfortunately UPS had other plans and I had no choice but begin the evaluation with my long-time reference, the 45-based Yamamoto A08-S amplifier. Its 2wpc rating really did not match the Feastrex requirements on paper but in the real world of experience, I was very pleasantly surprised. In my 13.5’ x 20’ listening room, this speaker/amplifier combo reached intolerably high volumes with plenty of dynamics for an unexpectedly copasetic match. It means those trying to - um, save money can drive their $42,000 D9e-IIs with a $3,000 amp! The rest of my system consisted of an S&B-based Bent Audio TVC with remote control; an MHDT Havana DAC with Locus Design Nucleus USB cable from PC to DAC; DIY fine silver interconnect cables throughout; Audience Au24 and 24E speaker cables; a 4-tier tier Mana amp stand and a PS Audio 300 power regenerator for digital sources only. It’s a very simple and clean system just the way I fancy them.

So, what do you get for 42,000 smackers? Being stunned! As soon as I mounted these drivers and prior to performing what usually is a lengthy baffle-alignment session, they had me glued to my chair. Keep in mind that the baffles usually fitted with Supravox field coils were pointed almost directly at me. This is something that until now was strictly verboten for whizzer’d widebanders. Now however I had no bite, harshness or artificial etching of voices and instruments. That was unexpected but not what kept me in my seat for the next four hours. I found myself daring these speakers to sonically transform my second and third-tier music – the kind of stuff I rarely listen to because the recording/engineering quality of the sound ain’t up to snuff. With the Feastrex in place, the usable portion of my PC-based music library was much increased.

I found these drivers amongst the most difficult to describe. They were so unique in their ability to make instruments and especially voices sound real that cliché terminology and outright gushing are hard to avoid. I will attempt my best to verbally paint a picture of what they did. These drivers were well run in before arriving at my place so what I heard was what they’re capable of. I am used to extreme clarity, lit-from-within life and 'you are there' coherence and presence already. My big Lowthers are champs in exactly those areas. However the D9e-IIs knocked ‘em out in the first round. The first thought through my mind was, how the hell did they do that?  Bass down to approximately 80Hz in these baffles had definition I never had before. I turned off the Fisher amplifier driving the Altec 416s to confirm that the  dramatically improved bass definition was from the widebanders. It was. I could hear and feel each vibration of the bass guitar and every nuance of a cello’s rolling growl as never before. That’s when I decided to lower the 416s' crossover point from 212 to 135Hz. The Feastrex drivers reached lower in these baffles and produced more bass refinement and detail than all previous candidates. I lowered the woofers’ crossover point to hear more of the D9e-II’s bass potential. This is one reason why I prefer to run my fullrange drivers unfiltered.

The life blood of all music is in the midrange. This is where presence and coherence live or die and precisely the focus of the Feastrex’s performance that prompted my almost immediate wtf response. I love vocals - Jazz, rock, classical, opera, the works. I thought that I had already experienced extreme vocal clarity with my existing drivers. But these Feastrex drivers pulled off a trick that bordered on the miraculous. They presented far more clarity with voices (proof that there’s always better) while being significantly smoother and more grain free than I thought my system capable. At 15 volts these drivers reached their sweet spot. I am accustomed to accepting a trade-off when ratcheting up the clarity of every other widebander previously evaluated. More clarity generally requires finding a way to tame the increased bite. Not here. Male and female vocals sounded as though someone had removed cloth-covered speaker grills. There was that lit-from-within quality—presence, coherence—and a spookier level of vocal realism at all volume levels. And, the darned things could point right at me. The advantage of this should not be underestimated. When forced to listen to a widebander off-axis, one often experiences more smoothness at the expense of the best midrange and HF qualities that driver is capable of. I could point the D9e-IIs directly at my listening position and enjoy their greater lucidity with none of the usual drawbacks. For me, these drivers set a new midrange standard on voices and instruments.

The high frequencies are generally where I am forced to spend the most time tweaking while listening to the more powerful widebanders available. One must often accept an intermediate area of baffle alignment (toe-in) to gain the most alive midrange presence without razor burns from the highs. Again, the smoothness, refinement and control that these drivers exerted on the mid and treble bands allowed me to aim them right at me to face the whizzers head-on. The highs were very delicate and refined, with just the right amount of energy. This was an exceptionally well-balanced driver. The Feastrex D9e-II highs were a quality match for my big Lowthers but their lack of peakiness and bite allowed me to enjoy a more state-of-the-art midrange quality on axis.

I never experienced imaging or imaging specificity quite like this before. It was not exactly as though these Feastrex drivers set new standards for image width, height or depth. There I’ve heard better. This may have had more to do with the largish baffles than the drivers’ raw imaging ability. What these did was to add flesh and bone, brass and strings to otherwise vaguely outlined musicians and instruments within a very billowing and open soundstage. Open baffles are famous for producing very billowing and dimensional staging between and behind them but are not as great at the sides or in front and behind the panel. And that’s exactly how the Feastrex behaved too. No surprises there.

The upshot was the most refined and detailed bass I have yet to hear from an 8” or 9” widebander. Not that it necessarily produced oodles of bass in these open baffles but extension exceeded all my other drivers and defined palpability was uncanny. I swear I could count the string vibrations on the cello (not really). Midrange? What more to say? This is the area of special strength that makes these drivers worth the price of admission. Their simply there level was exceptional, like someone continuously painting water colors between and behind my speakers. The HF smoothness and refinement allowed for an on-axis orientation while the boxless soundstaging was both rewarded and limited by the open baffle format. I love the nasal-passage-clearing openness of OB soundstaging. The D9e-II’s ability to paint palpable images throughout the midrange then added delineation and density to voices and instruments within that stage.

Dynamics and speed (PRat if you will) were aspects where the D9e-II was slightly bested by several of my other options. In any OB combination, the Lowther PM7, PM5 and PM2MKII are dynamic as hell and fast as greased lightning. The D9e-II did not snap quite as hard or fast. This was most noticeable on string plucks and strums, drum slaps, cymbal attacks and percussion in general. I adore the dynamics and speed derived from my Lowthers paired with 12-inch Tone Tubby woofers in OBs. So which one is the more accurate, Feastrex or Lowther?

My personal takeaway is that no driver and speaker is perfect. That said, the Feastrex D9e-II set sufficiently higher levels of performance to make it my new reference widebander. I thought that it would be nice to evaluate one of Feastrex’s sub $10K options. This would help determine whether the washi paper imparts a family sound to even their—comparatively—-affordable drivers. Good news on that front.  A pair of Feastrex Nf5ex 5” field-coil drivers are headed my way. They retail for around $8,000/pr when fitted with the company’s vaunted washi.

Feastrex website