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Reviewer: Srajan Ebaen
Source: Zanden Audio Model 2000P/5000S
Preamp/Integrated: ModWright SWL 9.0SE; Bel Canto Design PRe2; Eastern Electric MiniMax; PrimaLuna Prologue 3 [on review]
Amp: First Watt F1; PrimaLuna Prologue 5 [on review]
Speakers: Zu Cable Druid Mk4; Zu Cable Method [on review]; Lowther Medallion III with 16-ohm DX4 [on loan]; The Horn with modified Fostex 108E Sigma [on loan]
Cables: Zanden Audio proprietary I²S digital cable; Stealth Audio Indra; Zu Cable Ibis; Crystal Cable Reference power cords; Z-Cable Reference Cyclone power cords on both powerline conditioner
Stands: 2 x Grand Prix Audio Monaco four-tier
Powerline conditioning: 2 x Walker Audio Velocitor S
Sundry accessories: GPA Formula Carbon/Kevlar shelf for tube amps; GPA Apex footers underneath DAC and amp; Walker Audio SST on all connections; Walker Audio Vivid CD cleaner; Furutech RD-2 CD demagnetizer; WorldPower cryo'd Hubbell and IsoClean wall sockets
Room size: 30' w x 18' d x 10' h [sloping ceiling] in long-wall setup in one half, with open adjoining living room for a total of ca.1000 squ.ft floor plan and significant 'active' cubic air volume of essentially the entire (small) house
Review component retail: $1,995; Medallion III $2,500 assembled, $1,600/kit; The Horn $775/pr
Why is an amplifier's first watt so important? Watts are cheap. Don't wurry, be 'appy. In a very fundamental way, the answer to this innocuous question determines the sound of your speaker. Be that an 87dB or 101dB design, all you're getting past the first watt is a logarithmically smaller and smaller contribution. Nothing past the first amplifier watt will ever remotely approach its initial and whopping output contribution. In fact, the inverse is true. More and more power achieves less and less. A jump from 100 watts to 200 watts accomplishes no more than proceeding from the first to the second watt: a 3dB increase in gain. It's the first watt that gives you the mondo turbo-charged power boost of anywhere between 80 to 110dB depending on your speaker sensitivity. Beyond that, advances are slow, costly and inefficient. This incontrovertible fact is cleverly exploited by high-efficiency loudspeakers. They achieve all of their playback levels from that first watt (or even a fraction thereof as in my case).
Consequently, the dynamic range and sonic flavor -- of how an amp will interact with your speakers (any speakers) -- are all encoded in that puny first-born (but disproportionally powerful) watt. Better make this number-one watt CEO of your company then. Let him personally run all things. That's precisely the credo of Nelson Pass' FirstWatt outfit. It's a spin-off from his main company Pass Labs, which caters to the less efficient speakers that predominate today's market. Built in limited editions of 100 units, FirstWatt amplifiers instead focus on micro power specs and the speakers served by them.
Nelson's sonic amplifier universe divides into 2nd- and 3rd-order distortion amps. This refers to their respective THD focus. The former is typical of tubes, the latter the domain of solid-state (unless deliberately shifted as with his Aleph amps and now the F2 and Pass Labs XA series - XA100 below). FirstWatt's F1 debut was a 10wpc Class A current-source or transconductance amp in the 3rd-order camp. The new 5wpc Class A current-source F2 is a 2nd-order champ, based closely on the original Zen amp but without feedback.
This family resemblance occurred to a poster on the diyAudio forum. "I assume that the F2 uses a lower supply voltage (between 25-30V) and a higher bias (3A perhaps?). It is yet unclear whether it uses a buffer or nor but I have some indications that it is built without a buffer, one Mosfet only. Now, it makes me wonder which device Nelson employed: IRFP044? Or maybe something else like a 2SK1529?" If you don't already know it, Mr. Pass is highly supportive of DIYers. For years, he has made available detailed schematics for his various Zen amps. Besides being a creative outlet for unconventional amps the mainstream could never embrace, First Watt of course also has commercial aspects. Its designer simply can't divulge all secrets before a particular incarnation has sold out (which, incidentally, is rapidly approaching for the F1, meaning service schematics will soon open the book on how to build your own F1).
So this is how Nelson replied to the above inquiry: "24V; 2.7A; no buffer; IRFP240 (gain) / IRFP9240 (ccs); 5 watts into 8 ohm; 15.5 dB gain; -1 dB @ 100 KHz; 20 uV noise." To which the poster retorted, "oh Nelson, it seems you are describing a low-voltage original Zen with no FB." And Nelson's crafty reply to that? "Seems that way, doesn't it?" In a further explanation, he added how "the F2 has the same supply voltage but since the F1 operates balanced, its bias is split between the 2 halves and you can expect to deliver only half of the total bias to the load at best. In the F2, the single-ended circuit gets all the bias so the available current is quite a bit greater."
As a current source like its F1 sibling, the F2 deliberately focuses on crossover-less speakers that won't invert their network values from their usual interaction with voltage-source amps. Speakers with crossovers will likely require some compensation, something Nelson has dedicated an entire white paper to. From what I've gleaned, it seems likely that future FirstWatt installments will transition into voltage source offerings that are copasetic into the usual crossovers. For now, the focus is still on full-range drivers like the Fostex 208EZ and 168EZ and units by Lyeco, AER and Cicada, all Lowther clones which Nelson presently experiments with. If your speakers fall into this single-driver camp (including 2-ways with an add-on tweeter), the F1 and F2 were designed for you. Ditto for my Zu Cable Druid Mk4s and -- of course -- any true Lowthers like the DX55 and DX4.
|In an e-mail long since deleted, Nelson once shared how based on his experience at Pass Labs, there's a nearly equal number of listeners who favor 2nd-order or 3rd-order harmonic distortion. One sounds sharper, more articulate, precise, fast and PRatty; the other is warmer, more relaxed, bloomier and somewhat romantic. Rather than betting the family farm on either flavor, Mr. Pass has always strategically designed products for both audiences. This lets individual music lovers follow their bliss rather than have the designer's personal preferences forced on them. It's like serving chocolate and vanilla ice cream. Your customer base instantly doubles. Where the F2 is concerned, its design brief reads unapologetically "solid-state amp for tube lovers". Is that why I got this review sample? If so, excellent strategy on admiral Nelson's part. I'm such an easy read - though Nelson is quick to point out that his F amps weren't designed to substitute for tubes, "doing certain things better than tubes and other things not quite as well." What they do|
|clearly better is voice-coil control. They faithfully translate any input voltage into its equivalent output current rather than an output voltage on which each speaker draws its own arbitrary current relative to frequency and amplitude. Current drive means precise voice-coil tracking and cone acceleration. Too bad 99.9% of all speakers are designed for conventional voltage-source amps. Otherwise more people could enjoy the special favors of transconductance, including its blasé disregard for overpriced designer cables (or as Nelson puts it, "...wire, connectors, the inductance of the voice coil, the resistance of the voice coil vs. temperature - all that stuff...").
Unlike the 80-ohm output impedance of the F1 that resulted in a damping factor of 0.1 to not prematurely roll off LF extension of extreme self-damped high-eff drivers, the F2 offers a Z-out of 15 ohms via a deliberately placed resistor for a slightly higher damping factor of 0.5 ohms. Removing this internal resistor produces the amp's native 700-ohm output impedance. Input impedance is ca. 50kOhm. Based on the above graph of a 10kHz square wave at 3 watts, the F2 is also hellaciously fast. And, every one of them is bolted and soldered together by the maestro personally, tested and listened to in his system. Unlike the balanced F1 with its three current sources driving a differential pair of output transistors to produce cancellation of 2nd-order distortion, the F2 is a single-ended, single-stage zero NFB Class A design operated from a constant current source. Its gain is a low 15.6dB. As a high-biased Class A design, it consumes 200 watts during operation and requires adequate ventilation. Like the F1, operational noise is essentially non-existent and lives barely above ground zero - at about 100 pico-watts if you need to know (and one pico watt is a trillionth of a watt). This makes the F2 and F1 perhaps the quietest amps on the market. For owners of conventionally networked speakers, Nelson Pass has revisited the Aleph 3 in a new iteration called the Aleph J. This latest incarnation benefits from 12 years of ongoing experience since the original was launched. The Aleph J is being introduced jointly with the F2.
The F1 + Druid combination is a marvel of rhythmic drive, across-the-board articulation and monster bass. In fact, the F1's endowment in the nether regions into such copasetic loads really drove home how the down-firing Griewe alignment of the Zus relies on just the right gap height to properly dampen the driver. A larger gap lowers extension and raises amplitude but also increases group delay and minimizes damping. Ordering Zu's blunted and shorter spikes (available for hard floors) allowed me to dial in this gap. The recommended height is that of two stacked jewel cases. The lowest I could go with the longer carpet spikes added well more than a 1/4" to the ideal height. The lower gap height now achieved audibly superior self-damping of the driver, especially welcome below 60Hz. Say hello to the meanest slap bass this side of Marcus Miller.
Using my ultra-linear and only very modestly tube-sounding and ultra-quiet ModWright SLW 9.0SE means the F1's 3rd-order signature occasionally veers too far into the sharply pungent aroma for my tastes. Substituting the ModWright with my Eastern Electric MiniMax's more overt 2nd-order THD spectrum (or the new PrimaLuna ProLogue 3) makes for my favored combination, this despite a subtle loss in resolution over the ModWright especially at low volumes. I was thus very curious whether the ModWright/F2 combo would give me the drive, control and microdynamics of the MiniMax/F1 duo, a slightly more voluptuous bloomier feel and the superior transparency of the SWL. Hey, some of us nutters want it all (and then some if no one's looking).
|That includes getting bass from a DX4 Lowther in a small box (the black superimposed L1 shown is specifically made to mate with the F1 only). Current drive to the rescue. With just the right kind of resistor across its terminals to optimize frequency response, the big Lowther Medallion III's rear-loaded horn with a front-firing mouth hidden behind a velcro-fitted grill had been submitted to demonstrate what Jon Ver Halen of Lowther-America has already publicly stated: The F1 takes Lowthers to places they haven't been before (shy of Jacob George's complex spiral horn in his Second Rethm).
|Lowthers are a strange anachronism. With decidedly lo-tech foam surrounds, paper cones that look as though they had aged in the sun, a whizzer cone and bullnosed phase plug in the middle, little gives away why they would enjoy their renown. Unlike the up-to-date|
|drivers in my Zu Druids, Lowthers clearly harken back to a date with down time - decades down. Hence, would-be usurpers to the Lowther throne are legion. Aficionados of their particular charms meanwhile continue to insist that despite their wrinkles and liver spots, Lowthers triumph over all comers in this field. Of course even those who really don't (know) know that Lowthers have problems. Devotees would call 'em demands instead, being fully prepared to cater to their whims to reap their just rewards. Take away the upper midrange peak, add bass to fill out those boots and stretch the waist line. Even detractors would concede that then, maybe we'd have something to write home about.
Jon Ver Halen added the following for the Medallion III: "The pair you have is the first one built. We tried a Cherry stain on Birch which penetrated the solid wood differently than the plywood, hence these cabs were downgraded for review/demo purposes. We'll sell the Medallion III both as a kit ($1,600) and fully assembled and finished ($2,500). Standard finish will be unstained Birch but optional wood veneers are available for a surcharge. Plans are given with drivers upon request and we probably give away 10 sets of plans for every pair we build. So it is more often than not a DIY home builder's affair.
The speakers work best about 2 feet from the rear wall (perhaps a bit closer for bass reinforcement) and 3 feet from the side wall. If Nelson's midrange correction circuit isn't used -- or if using a voltage-source amp -- the speakers sound best about 15 degrees off-axis. Most people prefer the axis of the speakers to cross behind the listener but a few prefer it with the speakers crossed in front of the user. Listening on axis with a voltage-source amp results in a peak in the upper midrange and lower highs."