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Test #2: F1, F2 and Decware Zen Taboo on 16-ohm Lowther DX4 in Medallion III cabinet:
My first up close & personal encounter with a Lowther in my own system came by way of the Second and Third Rethm. Architect slash speaker designer Jacob George from Southern India goes many extra miles to modify his Lowthers. For the DX4 of the Second Rethm pictured, he adds additional stationary (phase-plug mounted) and moving (cone-mounted) skirts aka whizzers with strategically perforated patterns. The elephant condom aka "expanded polystyrene wave guide" mounts to the magnet. It deflects the rear wave to prevent it from returning through the driver diaphragm which Rethm loads into a round tunnel. All Rethms employ consecutively more and more elaborate spiralled labyrinths or rear horns. These "transmission lines" extend bass response while the extra appendages upfront counteract the so-called Lowther shout - a rising upper midrange.


Imagine faux sibilance. Certain notes in both male and female voices jump out of the musical fabric in a piercing and shrill fashion. That's the shout. It's operative across the presence region which becomes hot compared to its surroundings and thus gets emphasized or pushed forward. Careful toe-in can play with off-axis response to minimize amplitude of the shout a bit. Nelson's compensation network for the F1 tilts the DX4's rising response at its 500Hz knee and brings it back to flatter. Naturally, this doesn't change the remaining squiggles of nonlinearities in the leveled-out response.


Another Lowther challenge has traditionally been to overcome bass shyness below 60Hz. How to add weight and extension to counteract the incisive nature of the driver's native coverage? My personal characterization of the raw DX4 is that of a caffeine-haggard speed freak - astonishing reflexes and detail coupled to major nervousness and raggedness. This is further aggravated by a pretty severe peak at 8Khz beyond which the driver rapidly falls off.


Put in those terms, things don't sound terribly appealing, do they? Nor do they explain why so many listeners keep chasing these qualities while simultaneously being fully prepared to engage immediate counter measures to tame and control them. As implemented in the Second Rethm, these driver nonlinearities have been rather successfully addressed in the mechanical domain. Still, the innate flavor of extreme speed and energetic openess remains. With proper in-room setup, the Second Rethm's forked rear horn which eventually splits into two ends of dissimilar lengths and mouth openings is good to around 42Hz. It retains useful though of course attenuated output into the mid 30s and doesn't mandate a subwoofer but could still benefit from one.
Naturally, I was curious how the stock driver would sound in the far simpler though voluminous cabinet of the Medallion 3, with transconductance drive acting as the "counter force" rather than
Jacob's mechanical devices and complex rear loading. Needless to say, my Rethm encounter lies well in the past by now. For a real comparison rather than faint recall of untrustworthy aural memory, I'd use the Zus. The differences between them and the stock and un-eq'd Lowthers proved to be pronounced and easily tabulated.

The Druid sounds like the far more linear of the two speakers, exhibiting merely a minor depression around 1kHz that translates as a slight veiling in the presence region. The Zu is distinctly more endowed in the bass and not at all bedeviled by peakishness. It has near triode-like body and percussive transients are followed by the full meat of the impact which becomes the focus. It's not the precisely timed flawless leading edge (which is there to be admired), it's the subsequent bloom and its weight that take center stage. It's the antithesis of a hollow sound - all outline, no center. It needn't be played loud to sound full but can be played silly loud without causing any unpleasantness (except for the airport sound pressure levels per se this eventually equates to). It's unbelievably non-fatiguing and satisfying though not as finely detailed above the upper midrange as my Avantgarde Duos, Gallo Reference 3s or the DX4.


The Lowther in the Medallion III cab is far more polite in the bass, nowhere near as oomphy or displacement-happy, flittier and somewhat thin. Its focus is on the vocal range. This emphasis translates as heightened -- but also spotlit -- detail. There's a tendency for sharpened leading edges conveying speed and incision but less follow-thru in the subsequent body department. The appealing bit -- at appropriate levels; louder exasperates the shout -- is hotwired dynamics and great projection power. It's as though a super-attractive singer on stage looked you straight in the eye. She maintains unbroken contact, time stands still and you're wired a wordless message down that magnetic animal attraction connection. The far less appealing part? After one album of Giannis Parios at normal volumes, my ears were ringing and my wife shouted "shrill" from upstairs (through the curtain that spans the archway separating her lair 8 steps up from my sound dungeon). At low volumes, these speakers sound a bit threadbare because everything from the midbass on down begins to recede and wash out. Finding the right volume becomes critical then and is a pretty narrow range.


So these Lowthers by themselves wouldn't set my world on fire - that much was clear early on. What's more, they'd require work to minimize what plainly is an unbalanced and compromised driver. 'Work' was just what the doctor ordered for today's assignment. After all, the issue really wasn't whether this Lowther loading sans EQ was for me or not (it's not - give me the Second Rethm with its modified DX4 any day of the week). The issue was how these specialty amps would redress tonal balance, bass extension and weight. Because voltage drive is the de facto standard in audioville, that's how I'd start out; a baseline reference for how most listeners would approach the DX4: with tubes and low power.

Intrinsic to the concept of the F-amps is the ability to insert a customized parallel filter network at the speaker inputs to perform some deliberate frequency contouring on single-driver speakers which tend to suffer variations on a theme - a rising midrange and attenuated treble.


According to Jon Ver Halen of Lowther America, the F2 doesn't benefit from any additional EQing for the PM2A in the Medallion III. Due to a mishap in communication, I understood this to be true for the DX4 as well (a driver Jon hasn't yet tried in this cabinet and with the F2). So while he sent me F1 networks implementing the values Nelson's personal testing on his Kleinhorns with various drivers (all published with curves in the F-amps' owner's manuals) recommends, I did not test the F2 with any networks.


Looking at the published response curves in the manuals, the DX55 in Nelson's Kleinhorn [graph 2] is the more linear Lowther than the DX4 [graph1] which requires a lot more compensation to get into the ballpark of "flat" [the broken line is pre EQ]. In general, these EQ networks tend to work most predictably with sealed alignments. Backloaded horns and their various hybrids with transmission-line and tuned-pipe attributes will require more personal experimentation. This could mean derivative values and modifications to Nelson's simulation model above. In the end, certain such speaker designs might only benefit little if at all from the particular voicing options afforded by transconductance drive. Conversely, the sealed small L1 Lowther monitor available from Lowther America only works properly with the F amps. This is part of their unusual nature. When used with single-driver loudspeakers, user tweaking is not only encouraged but most likely mandatory to get the best out of any given combination. That's what the FirstWatt site makes no bones about - these amps not only aren't for everybody, they're for a very small niche group of listeners only.

Here's what I heard with the DX4 - small but more or less insignificant changes between the F2 and Taboo, most likely far more a function of different output devices than any pronounced superiority of current over voltage drive. The above descriptions of the un-EQ'd DX4 apply to both these amplifiers. With them, I consider the DX4/Medallion III far too flawed, non-linear, shrill and lean for any recommendation. If you're a reader deeply suspicious of day-and-night transformations, get ready for the firing squad. Aim your cross hairs right at my skull. Ready? The F1 with its custom-tailored networks had me not merely faintly intuit the Lowther's promise while suffering its nasty bite. I heard what I assume is its promise realized!


Shout, stridency and fatigue be gone (well, nearly - a whiff remained). Wimpy bass be gone - definitely. Thinness be gone - absolutely. Three strikes and you're in. Hello Dolly! By counteracting the excessive rising response above 500Hz, the F1 and parallel comp networks appeared to add significant (and well-damped) dBs in bass output to delay rolloff and increase extension and relative heft. The lifted midrange/lower treble leveled out and even top-end extension seemed increased by being better integrated. Inserting the Druids for comparison was educational. While extending lower still, the Medallions didn't trail by much. Bass quality wasn't quite as taut, tensioned and feisty as with the Zus but also mostly devoid of the peculiar hollowness or organ pipe resonances of certain backloaded horns. The Zus won the dog fights in the treble skies as well but again not by a massive margin. The main difference occurred in the vocal range. Here the Lowthers cashed in on renown and reputation. If you think of a voice like a many-petalled flower, the DX4 unfurled even the innermost virgin and dew-sealed petals for the ultimate in detail and the concomitant sense of greater intimacy.


I'm not at all certain what exactly it is about these wicked transducers except that the myth around them is true. They turn any singer into a lap dancer. The biological software program in us that recognizes voices simply locks and the warning lights go off: perfect match. It's really quite beyond analysis. Something in you just knows and accepts that the voices your system reproduces are real, not reproduced. Throats are wide open and the minor laryngitis imposed by lesser drivers is removed.

Granted, at happy levels, a modicum of forwardness reasserted itself - but I'm talking pretty loud. At sane full-length CD rather than single-track push levels, the Lowthers did their magic. I felt I had just passed an important test of secret audiophile initiation. You see, I have deliberately spent time at various trade shows to listen to the famous Quads only to not get them. Instead of honing in on what they did right to enjoy all their mythical qualities, I remained massively bothered by what they lacked -- dynamics, extension and funk factor -- and walked out an unconverted heathen. With the DX4, I now had seen the light.


My personal Road to Damascus experience in the single-driver realm came by way of the Zu Druids. At $2,800/pr, they set a mighty high -- and exceptionally well-balanced -- standard for all comers in this exotic segment. The Medallion III with the DX4 is more expensive [$4,200], less extended on either end -- though not objectionally so once tailored -- and cosmetically old-fashioned to be just another largish box. Once the F1 is optimized with the network, the DX4 loaded into the Medallion III blossoms. I assume the same holds true for the F2 whose network values would necessarily be adjusted versus the F1. The flip side? Without these transconductance amps -- i.e. driven by an ordinary amp like my Decware Zen Taboo -- the DX4/Medallion III is all over the place and, as far as I'm concerned, not really listenable.

It's really curious that vocal detail freaks would chase these qualities and be simultaneously prepared to engage protracted evasive maneuvers that span complex (and often very sizeable) loading schemes, driver modifications, setup and exotic ancillaries to redress what, in the DX4, is clearly a seriously imbalanced raw driver with a hefty financial price tag of $1,695/pr. When Jon Ver Halen asked me to remove the DX4s from the cabinets during return shipping so as to prevent their voice coils from getting misaligned, I nearly choked. Why bother with a bloody driver that's such a high-maintenance primadonna to potentially not survive a return trip while remaining installed in its cabinet? Someone less - er, committed to the L-world could be forgiven for investigating other wide bandwidth drivers (or massively modifying the Lowthers as Rethm does).


But let's return to the real purpose of this review - an evaluation of the FirstWatt amplifier. On the rear-horn-loaded Lowther America Medallion III, the F1 with the proper networks was the one. Mistaking Ver Halen's needs-no-network missive to mean the DX4 (rather than the PM2A in his personal Medallion III pair), I can only assume that the sonic distinction between the two F amps as described for my Druids earlier would transfer intact to the Lowther - once the F2 benefits from its proper network that is. Without that correction circuit, it was just as handicapped to undo the DX4's sins as was the SEP amp by Steve Deckert. Next stop? The Horne Shoppe's Fostex-ified Model 1.