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Regardless of which model one might choose, all of Feastrex's drivers represent, according to our U.S. Distributor Mr. Joseph Cohen, 'an embarrassment of riches.' He lauds them from the heart, saying, 'Choose any driver and you will have deep fulfillment. Feastrex Drivers For Sale. Minus- K (Advanced and custom isolation platforms for turntables and CD players) Monarchy Audio. DIY Turntables. Redpoint Audio Design (A further development of the Teres DIY Turntable Project)Teres Audio (DIY High- Quality Turntables)Turntable Belts- Elex Atelier (A source for rare turntable belts)Manufacturers. Feastrex D-9e Type-II speaker drivers Few photos of the Feastrex D-9e Type-II field coil drivers with gold plated top plate. Type II uses Permendur for the entire top plate and pole in combination with a pure malleable iron yoke.Mid-January 2007DIY Loudspeaker ProjectFeasting on the Feastrex full range driverand Augie woofer.Review By Dick OlsherClick here to e-mail reviewer
If you have read my recent review of the VISATON NoBox kit(see review by clickinghere), then you already know about my passion for open baffle designs.One key point is baffle size. It's easy to get the impression that bigger isbetter, but that is not necessarily so. An extreme baffle introduces asignificant reflecting surface into the listening environment. It can interferewith the distribution of reflected energy (especially rear-wall reflections) inthe room and may adversely impact the soundfield at the listening seat. A largebaffle is also more likely to flex and resonate due to the action of the woofer.And there is always the domestic spouse acceptance factor. The largest bafflesize one could imagine is an infinite open baffle, which can be approximated bymounting a woofer into a listening room wall so that it vents into another roomor the great outdoors. The downside, of course, is that the backwave is totallylost from the listening room. Much of a dipole's rich ambiance in fact comesfrom rear-wall reflections, which means that an infinite baffle's in-roombehavior would resemble that of a large closed box. Clearly, too small a baffleis counter productive, unnecessarily giving up bass extension due to front-backcancellation. In my view, the VISATON NoBox baffle meets the Goldilockscriterion: its' not too large nor too small. Approximating in extent thecritical 100Hz half-wavelength, it's just right! Since it makes for an ideal OBlaunching pad, the decision was made to embrace it as a platform for evaluatingvarious woofers and wide/full range drivers for OB applications.
Cast of Characters
The Hawthorne Audio Silver Iris Augie Woofer
There is more to Kentucky worth writing home about than merely Bourbon andhorse racing. I am thinking specifically of Eminence loudspeakers, headquarteredin Eminence Kentucky. And that is where Darrel Hawthorne, the progenitor ofHawthorne Audio, turned to for the design and manufacturing of his driver line.The Silver Iris line consists of a 15-inch coaxial and the Augie – a 15-inchwoofer intended for OB applications. The Coaxial driver came first. Darrel tellsme that following on its success, he wanted to offer a bass augmentation driverthat could extend frequency response low enough in an open baffle contextto fully enjoy almost any genre of music with minimal compromise. And so hewent back to the engineers at Eminence with a wish list in hand to develop theAugie.
The Augie is a well-built woofer incorporating Pro features such as a castbasket, a Kevlar reinforced paper cone, a long-excursion poly/cotton clothsurround, a vented 2.5-inch voice coil, and a copper shorting ring. Powerhandling is said to be 225 watts RMS. Three parameters are essential for idealperformance in an open baffle: a high driver total Q (Qt), a lowfree-air resonance frequency, and a generous excursion capability. The Augiedelivers on all three counts. Maximum cone excursion is a very decent 7 mm.Free-air resonance is 27Hz, and the Qt is 0.92. The latter parametergives the dipole woofer 'wiggle room' to compensate for the baffle step decreaseof 6 dB per octave down to its resonance frequency. The ideal Qt forOB applications is somewhat debatable, with some designers favoring a valuearound 1.0. Bob Carver's 'Amazing' loudspeaker comes to mind as an extremeexample. The speaker, when it was under review in Stereophile's listeningroom, featured a line array of inexpensive dipole woofers whose chief claim toinfamy was a Qt of about 1.2.
While bass extension was commendable, the quality of the bass was lessdesirable. Carver himself characterized the bass quality as 'rolling' andclaimed that he preferred it that way. To my ears, the bass was simplyill-defined, the opposite of tight; the wrong compromise in my book – quantityover quality. Dipole bass confers certain advantages such as freedom from boxyresonances, but attention to proper damping is still an issue as it is withconventional box woofers.
There is, unfortunately, no free lunch. Increasing a woofer's Qt isaccomplished by scaling back the size of the magnet, which reduces sensitivity.The only way to maintain both a high sensitivity and a high Qt is toincrease the woofer's resonance frequency. Thus, a woofer with a high Qt and a low resonance frequency offers at best only medium sensitivity. Itis not surprising therefore that the Augie's sensitivity is only about 89dB.
Measured in the VISATON baffle, the Augie produced impressive low-frequencyextension. The following Figure shows its near-field response which is extendedclear down to the resonance frequency of 27Hz. Very impressive extension indeed!
I suspect that the ideal open baffle Qt may well be in the rangeof 0.6 to 0.7, as I found it necessary to slightly damp the bass range byshunting the woofer with a 25 Ohm resistor. Tuning the bass damping may well bea function of the room and personal preference, but I can report that whentweaked as described above and driven with the EAR 834T integrated amplifier,both bass impact and pitch definition were superb. It seems to me that manylisteners confuse bass weight with bass extension and opt for a subwoofer whenbass weight is lacking. The problem typically lies in the upper bass, the octavefrom 120Hz to 240Hz where much of an orchestra's foundation and acoustic powerresides. This is the octave that box woofers have a hard time coping with,basically managing to sound boxy through this range. In contrast, the Augiemanaged to shine here, elucidating instrumental fundamentals with consummateclarity and 3D realism.
The Augie's performance was so open-baffle friendly that I decided to use itas a foundation for several full range drivers. The OB2 finds the Augie matedwith the fantastic Feastrex D5nf. Future projects will feature the Lowther DX55and C55, as well as the new Jordan JXr 6HD module.
The Feastrex D5nf 'Naturflux' Full Range
This innovative Japanese full range represents a collaborative design effortbetween Mr. Akiyama, the president, and Mr. Teramoto, the builder. While severalother models are under development, including field coil versions, the D5nf(permanent AlNiCo magnet) is said to be their most perfect transducer and coreproduct for some time to come. I had seen a version of this driver at the 2006CES, and it has, in the interim, undergone a slow maturation process. The designwas finalized during the summer of 2006; the most notable production changebeing the addition of a phase plug – ala the Lowther full range.
While from the front this driver may look like an ordinary variation on thetwin-cone full range, the view is radically different from the backside. Thelarge domed iron yoke is the crux of the Naturflux magnetic circuit.Conventional speaker yoke designs produce sharp bends in the flux distributionand fail to optimize the flux in the voice coil gap. Whereas the Naturfluxcircuit is said to focus magnetic flux more efficiently within the pole pieceand voice coil gap, reaching a gap flux density of 16,000 Gauss in the case ofthe D5nf. Sensitivity is specified as 95dB to 97dB.
The cone material is custom paper from one of Japan's premier paper makers,manufactured to exact specifications under controlled conditions. Total mass ofthe moving assembly is an astonishingly low 2.5 gram per unit, and drivers areassembled in pairs with precisely matched cone assembly masses.
The low moving mass and large gap flux density results in an explosiveacceleration factor. Transient speed is superb and the overall presentation isboth dynamic and detailed. The D5nf can unravel complex musical passages withcrystalline clarity, which is no doubt a function of its controlled transientdecay. It is capable of erecting a titanic soundstage with palpably focusedimage outlines, at least when mounted on the VISATON open baffle. And to top itall of, this is the smoothest sounding twin-cone I have heard to date. No EQnetworks needed here. Cone break up resonances are well controlled. There is nofly in the ointment in the form of a prominent presence region shout or harshlower treble. The phase plug definitely does its job - the upper treble beingextended to 20kHz, at least on axis. Of course, the extreme treble beams, so beprepared to toe in this driver toward the listening seat. Though, at the otherfrequency extreme, I would not want to push it below 100Hz, at least on an openbaffle. And, as many of you know, I am not a fan of rear-loaded horns. It wouldbe a crime in my book to imprison a driver with the musical integrity of theD5nf in a box!
Unlike some of the Fostex twin cones I have worked with in the past, whichfuzz over detail, the Feastrex delights in revealing detail. Though you hadbetter be prepared to drive the D5nf with a high-quality matching amplifier andfront end. And, for the record, I am still living happily ever after with theAltmann Micro Machines Attraction DAC. The OB2 was quite magical when drivenwith the EAR 834T integrated amplifier, as microdynamic nuances were given fullscope of expression. If you have a weak heart, I suggest you bypass the OB2 infavor of a lower resolution device. In summary, I am inclined to agree withFeastrex' claim of supremacy to the extent that the D5nf is presently the bestsounding 5-inch fixed magnet full range money can buy.
Driver IntegrationFeastrex Drivers For Sale Near Me
The task of blending these two fine drivers was guided by the KISS principle– Keep It Simple, Stupid – at least as simple as was possible taking thedrivers' needs into account. My goal was to maintain a full-bodied balancethrough the upper bass transition region without impacting bass or midrangeresolution, and as it turned out, that necessitated the use of second ordercrossover networks. That may disappoint some purists, but I did try the firstorder approach and was not satisfied with the results. The final network (shownbelow) makes me very happy and I believe coaxes the best sound possible out ofthe driver complement in the context of the VISATON OB.
Parts quality is a major factor in a speaker of this caliber. The capsselected for this project were the auricap metalized polypropylene type byAudience. For starters, this cap is extremely well built, and most importantly,my listening tests showed a clear preference for the auricap over the SolenFastcap. In general, the auricap appears to introduce less fuzz into the signalchain relative to the average metalized poly cap. Its sound could be bestcharacterized as smooth, yet detailed, with excellent transient clarity. Thecritical 48 μF cap in series with the D5nf was built up from three lowervalue caps: 30 + 15 +3. For the last measure of high-frequency purity, Ibypassed these caps with a 0.01 μF Teflon film cap by Relcap.
Some of you may have noticed by now the discrepancy in sensitivity betweenthe Augie woofer and the D5nf (89dB versus about 97dB) and must be wondering howis it possible to match these drivers without padding down the Feastrex fullrange? The answer lies partly in the subtlety inherent in the definition ofsensitivity, which is not referenced to an actual watt at 1 meter, but rather to2.83 V across the terminals of the loudspeaker. For an 8-Ohm load, thattranslates into 1 watt of power sunk into the load. However, in the OB2's drivertransition region, the Augie's impedance is about 6 Ohms while that of the D5nfis 16 Ohms. For 2.83 V across the OB2's input terminals, the Augie isdissipating 1.33 watts to the D5nf's 0.5 watts. The power ratio amounts to about8.5dB and means that the Augie is working that much harder to keep up with theD5nf. Add 8.5dB to the Augie's nominal sensitivity and you end up with 97.5dB.The proof is in the measured frequency response, which is shown below. These arein-room measurements (with the EAR 834T amplifier) at 1 meter for both the rightand left channels.The impedance curve for the complete OB2 speaker is shown below.AddendumIn view of the need to provide end user support, Feastrex conducts international business solely through established dealers. Feastrex has informed me that they have not established a fixed MSRP for various international markets and interested parties should inquire regarding local dealerships. Feastrex has recently appointed the Lotus Group as its US distributor. Please contact them regarding US retail pricing.Company InformationHawthorne Audio Silver Iris 'Augie' 15-inch wooferWebsite: www.hawthorneaudio.comCost: $165 ea. (introductory offer)Feastrex Naturfluxtm D5nf full rangeWebsite: www.feastrex.comCost: See above addendumFeastrex Drivers For SaleMadisound Speaker Components: source for coilsWebsite: www.madisound.comauricap by AudienceWebsite: www.audience-av.comFeastrex Drivers For Sale By Owner
