Zu Druid 6


TL; DR: VIVID! Sean finally built one for himself.

In amateur astronomy, we have orthoscopic eyepieces. Orthoscopic optics are designed for absence or near absence of dimensional distortions in the optical view, and they use relatively few glass elements for high light transmission, scant aberrations and low-to-no light scatter. Orthoscopic eyepieces are the standard for critical visual astronomy of planets, due to the undistorted detail, minimal glass and resulting contrast rendering fine details observable at high magnifications. Newer optical designs emphasize other characteristics, particularly wide fields of view for a more immersive experience in observing the night sky, but designing for wide fields trades away some orthoscopic properties to gain something more spectacular and useful in a different way, to the point where intentional spatial distortions are introduced or accepted in order to tame worse ones when field of view goes very wide.

Not wanting to go all the way down another hobby’s wormhole here, I’ll leave the matter of orthoscopics at that as a way of shifting your mindset to orthosonics for a similar agenda to design for authentic sound in hifi audio. It’s more difficult than it seems.

Last year marked 50 years elapsed since I spent my first dollar of my own money on gear to replay music. 2018 also marked 50 years elapsed since I spent the first dollar of my own money on guitars. I’ve been buying recordings longer than both. I mention this because one thing has remained absolutely consistent in all this time, and counting: at any given time, and for any given category of products, there are only a small handful that are worth buying. There’s always lots of choice, but choice isn’t the same as worth. I am aware of the full panoply of audio gear but am undistracted by most of it, because….well…..most of it at any price isn’t compelling.

Especially loudspeakers, which mostly remain very far away from representing music and the instruments (including the human one) that produce the sounds of music. If mid-to-high-end hifi buyers were primarily driven by music concerns rather than gear, or what’s cool, or whatever makes the best success statement, or whatever else you’ve got that isn’t strictly endorsing of objective music replay, the entire market could be served by just two speaker makers: Audience with their ClairAudient line, and Zu Audio. I wish I could say otherwise, but these are the only makers of speakers fully delivering authentic music fidelity today, i.e. replaying music orthosonically. There are a few additional contenders who nearly get it right, at various price strata: JohnBlue, Voxativ, 47 Labs’ Lens, Quad with their electrostatics, and Konus are some who cover between 270° and 330° of the full 360° circle of fidelity. Which is great, and that much completion of the circle can deliver beautiful sound. But only Zu and Audience have mastered making speakers that can effortlessly deliver altogether holistic music fidelity, authentically.

Send your Magicos, YGs and KEF Blades to the smelter. Torch everything Wilson, Focal, Devore, Maarten, Revel and Dynaudio, let alone those horrible JBL Century 100 reissues we see rising from the dead now. Throw every crossover-intensive speaker into the woodchipper and send the ground-up mulch to your local toxic waste facility. Fake news is mostly a trumped-up distraction, but fake fidelity – that’s real. The orthoscopic authenticity cornered by Zu and Audience is rooted in both companies having developed, within any practical considerations, uncompromised full-range drivers coupled to insightfully-engineered cabinets. In loudspeakers, adroitly-chosen materials, along with astute mechanical, resonance, acoustical, structural and construction decisions, preserve the essential simplicity of a full-range driver design, emitting music without exaggeration.

And that’s the whole distinction, because let’s face it -- most of the supply side of the hifi realm is in the exaggeration business. Moreover, much of the consuming public likes it that way! For every “hungry-ear” buyer who seeks the artificiality of being in the band or inside the piano, or gulped down by the singer to be a swallowed resident inside the body’s resonant cavity, there is a designer and manufacturer willing and eager to tilt the ratio of transient-to-tone, or the inverse, away from real and aggressively toward spectacle. It’s endemic, and buyers are as much at fault as the designers & sellers in the industry. For people who want more transient detail than is actually present in a performance or from an instrument, orthosonic speakers aren’t for them. If you want a Fender guitar amp running 6V6 tubes to sound like a Marshall stack, or if you think Johnny Cash sounding 12 feet tall is authentic, you don’t want a true-sound, orthosonic, hifi speaker.

If you need or want a surprisingly convincing speaker that can be held in one hand, buy a pair of ClairAudients. But if you want something with room-filling shove, you want Zu. So, I will leave Audience behind here, since this commentary is about Zu, particularly the Druid 6.

This year marks my 15th year of continual Zu in my hifi systems. I started with a pair of used Druids that had been updated by Zu to 2004 configuration. They turned out to be one of the first ten pair of Druids made back in 2000. Those Druids were the first convincing find in my then 30+ years quest for a convincing crossoverless speaker. The 2004-spec Druid was certainly not perfect, but it was a revelation. Imperfect because it was a bit of a narrowcaster, and was soft on the top end. A revelation for its completely coherent presentation, octave-to-octave balance, consistent transient behavior, striking intimacy, pinpoint imaging, absence of crossover-point pinching, plus it was a tone monster. Druid was effectively a dynamic driver Quad ESL-57 but with dynamic range, energy and willingness to be abused. It was the first speaker to ever pass my test for reproducing specific electric guitar/amp combinations with true fidelity. I immediately added an early pair of Definitions to another hifi system but kept those Druids on my secondary system until Druid 5 was introduced, along the way getting periodic upgrades installed, culminating in Druid 4-08.

In parallel, I made the Definition > Definition 2 > Definition 4 migration, yet the Druid never lost relevance. Definitions favored scale; Druids favored intimacy and they both overlapped on tone, coherence, speed, holistic transient and tonal behaviors and both excelled in delivering shove – that quality of musical dynamism that gives music projection and reach. In Zu’s case you get shove without gobs of power.

Druid 5 updated and expanded on the core Druid proposition but extended the top end for more harmonic completeness (courtesy of the Radian compression supertweeter replacing the older Zu tweet), deepened bass response, added greater agility and speed to the main driver, upped transparency, broadened the spatial presentation, boosted shove and put the Druid form factor in league with Definition by further killing cabinet talk. Druid 5 was the first Druid that had sufficient scale to double as a movie speaker, if the room wasn’t too big. Frankly, when Druid 5 debuted, it struck me as nearly perfect in practical terms, and about as much as one could expect from that form factor. Beyond Druid 5 lay incrementalism.

Or so I thought, then.

Enter Druid 6. Why has it taken me seven months to write this commentary? Because Druid 6 may as well be ground zero for a new vector of Zu. It completely unshackles the single-FRD / no-sub form factor of the Griewe – Druid configuration from the physical limits of its original form. Definition 1 had scale and a lot of cabinet talk. Definition 2 sacrificed some spatial scale to slay the cabinet talk. Definition 4 restored the spatial scale and tamed the cabinet talk to deliver a notably more objective speaker. Druid 6 has the spatial scale of Definition 1, which original Druids couldn’t come close to. It has the tone density trademark of all Druids and beyond what any Definition delivers. Snap and dynamic shove set a new Zu standard. Nuance and transparency Windex the entire presentation. Druid 6 is unbelievably quick, with the dynamic agility of Tiny Archibald confusing basketball opponents in his prime. And there is a fairly dramatic improvement in bass depth, character, impact and texture. I never had a real impulse to add subwoofers to any of my Druids, but then I had another system with Definitions and their powered sub-bass modules to satisfy deep bass cravings. Still, it just seemed counter to the simplicity and elegance of Druid to clutter the room with more boxes or towers to get bass fundamentals few recordings actually include. It’s probably only a half-octave further bass extension over Druid 5 but it sounds so convincing and fundamental that a sub is really only called for by a bass fetishist. All this adds up to a speaker that is a larger improvement over Druid 5 than Druid 5 was over v4-08. Which is saying quite a lot.

If you’ve traipsed through the Druids sequence as I have, that might not be your first conclusion, because on everything most obvious – high frequency response, neutrality, greater shove and improved bass, Druid 4-08 was left behind and there wasn’t a single aspect in which Druid 4-08 was better than Druid 5, other than you could buy a pair for much less cash. Druid 6 improves all these particular aspects over Druid 5 somewhat less so than the last generational shift, but that all sums, along with a specific and new Druid quality, to a new speaker that makes the greater leap over its predecessor. The new quality is “vividity." “ Yeah, that’s not a word, but I’m using it here. My TL;DR for this assessment is “Vivid.” And that is what slams your mind when you wire up Druid 6, especially after the 100 – 200 hours burn-in period needed when new.

Basil Hayden bourbon is 80 proof. Technically, that’s a little short for the category. But if I’m having whiskey before the sun is down, I often start there. It’s easygoing and doesn’t front load you for the evening. Druid 5 was like Basil Hayden. Forgiving, convincing, mellow. Works with almost any mood, music, room, aesthetic, amplification. Druid 6 is more like a 137 proof George T. Stagg bourbon. You need to be ready for it, and it’s going to seem a little loud on your palate. If you leave everything the same and just wire ‘em up, a pair of Druid 6 will hit you like a hot whiskey. Burning, flavorful….vivid. And unfailingly revealing. Druid 6 is a deity’s-honest truth of music presentation. So much so, some of you Druid aficionados out there might (will) prefer Druid 5. Depending on what you have today, Druid 6 will force upgrades, or at least changes in your system, upstream of the speakers. The most likely change Druid 6 will force is in amplification. Depending on how your DAC is voiced (don’t kid yourself, they’re all voiced) you’ll be contemplating a change there too. Phono cartridge? Could be, but less likely than DAC. Preamp, least likely to require a change unless a change in power amp argues for it. In my case, Druid 6 brought to a halt 15 years of Audion SET amplification with Druids, and really a total of 20 years of continuous SET listening in my secondary system. Why? Because the extra half octave or so of bass response is just a bridge too far for really clean, bloat-free bass from any zero-feedback SET amp I know of. SET works well with the deeper-plunging the Definition series because in the Def, a solid-state plate amp has a grip on the sub-woofer driver(s). The tonal qualities of the sub bass are derived from the power amp outputs (and characteristics) but the actual sub driver control is a product of the plate amp’s damping and grip. In Druid 5, the ~34 Hz bottom limit doesn’t reveal the limitations of low-damping factor, SET bass. My Audion Black Shadow 845 amps have excellent bass on Definitions and Druid 5. On Druid 6, bass extension is just enough further to bring SET deep bass control deficiencies to the forefront. Same with SET & PSET 300B.

So, I have to replace my beloved Audion Golden Dream monoblocks (300B PSET) to enjoy Druid 6 without distracting and illusion-undermining, zero-negative-feedback bass bloat. More on that near the end of this commentary.

But, if you’re forced into an electronics revision once in 15 years because of a significant loudspeaker advance, one can’t really complain. For the first time since first exposure to Zu Druid, I recommend alternatives to single ended triode amplification. As I will outline in a topical addendum at the end of this, I recommend single-ended pentode/tetrode, push-pull triode and some high-coherence push-pull tetrode and pentode amplifiers. Or if you’re tube-phobic, some solid-state amps one might want to consider include, Pass, First Watt, 47 Labs Gaincard, M2Tech Crosby, etc.

Druid 6 is the first Druid to serve as a convincing transducer for symphonic music. With the right amplification it will even play viciously intense metal without choking like you’re trying to squeeze toothpaste from its tube too quickly, forcing the tube itself to burst. No prior Druid could quite do that. On the other hand, Druid 6 loses nothing to prior Druids in the lone-performer-with-guitar genre, in fact drawing you into closer intimacy with the tone and textures of expression while maintaining the right spatial distance. It doesn’t exaggerate like the bulk of this industry’s loudspeaker offerings, inflating definition like you’re inside the instrument to feign intimacy.

Druid 6 is also easier to set up than any prior Druid. It might be more demanding of amplifier matching but the formerly-fussy floor-to-plinth gap height adjustment is much less hyper-critical now, for attaining correct bass. Because of its dispersive scale, getting a convincing soundstage is a less obsessive proposition in placement and toe-in. There will be rewards for taking the obsessive route, but you don’t have to. And one of the best small touches is that Druid 6 default footers are flat discs, layered with a thin polymer, and attached via a ball-mount that threads into the plinth. You can spec the plinth to be drilled through so the height of the feet can be adjusted from above with a hex wrench! Fantabulous. But the big advantage sonically is that the ball mount acts as a bearing for resonance dissipation. You can get spikes to anchor the speakers to a firm flooring under thick carpet, but for hard floors the default ball-mounted, top-adjustment, polymer-interfacing flat-disc footer is the bee’s knees, sonically and ergonomically. And it’s kind to your floors.

The design and execution emphasis on Druid 6 was the cabinet. The full range driver is improved and I won’t say that’s not important, but the complete revision to the cabinet materials, construction and the mounting of the drivers (including the FRD’s torque-tensioned anchoring to the rear of the cabinet, complementing the baffle attachment and its beefier surround), and the massive plinth are collectively a major advance in Druid resonance control, energy channeling and, by extension a murderous spree annihilating cabinet talk.

Figuratively Druid 6 wastes nothing from the signal in its transducing obligations. Of course it does waste something, but compared to what’s come before, it sounds like it doesn’t. Druid 6 is direct, declarative, clear, orthosonic. It snaps and crackles like real life sounds. Instruments and people have body and breath in correct proportion. Vocal fry sounds exactly like its coming from the Millennial voice behind it. Real acoustic guitar (if amplified, microphoned, not piezo-electric) sounds authentic in tone and in attack : resonance proportion. Voices, instruments and people are sized realistically. Everything is in high resolution in a natural way, without faked detail. Presentation is bursty and serene, strong and laid back, as is authentic to the performance.

It sounds perfect, but there’s a backside to the coin. Druid 6 is not forgiving of bad recordings, cheesy mixes, idiotic mastering. It lays bares faults in performance, recording decisions by the engineer, mastering, pressings (if vinyl). It is intolerant of runaway digititis. The manic sawing of digital compression loses the loincloth producers try to cover it with. The nasty bits of degraded fidelity traded away for expense reduction are naked for all to see.

You can ameliorate the relentless truthfulness of Druid 6 by choices upstream. A more forgiving phono cartridge or more sonically elastic phone preamp or DAC. Get the right tubes for your new configuration. Back off sheer resolution a trace with Zu Mission cables instead of Event 2. Or not. Go for the unmitigated, all-nude, vivid Druid 6 experience. Hear the beauty and the beast in modern recordings. You’ll thrill to music recorded in the pre-multi-track, pre-all-solid-state studio era. Recordings from the days of vacuum tube consoles and mics, with performers in the same room, have a holistic, tuneful sound mostly lost today, except for recordings from a few performers. Those recordings have a vividness perfectly transduced by Druid 6 and projected into your domestic space. With Druid 6, a modern, congested, over-processed, excessively-compressed assault is revealed for the noisefest it is. If you can’t handle that, you need Druid 5 or you need an obfuscating amp for poor recordings, and another amp for great ones.

Which means Druid 6 isn’t for everybody, and that’s a good thing. Because Zu can’t make as many of them as it can build Druid 5 in the same period of time. And Druid 6 costs about twice as much as its esteemed predecessor. Hence both are in the line concurrently. And this makes sense. In my TL;DR I noted “Sean built one for himself.” Sean has visited me often enough that I’ve had many hours of listening with him present. I’ve seen Sean spin vinyl of music he loves irrespective of recording or pressing quality, able to note the sonic offenses and still set them aside to let himself be infused by the tunes. And when the worst disk is done playing, he thinks about how to get more out of it.

This makes Druid 6 its own contradiction. It is the least forgiving Zu speaker ever, and yet the most fun. It’s seductive and off-putting in equal measure, depending on the quality of the source material. And yet its uncanny PRaT pulls you in to ignore what’s wrong with the source and revel in what’s right.

Zu’s finish quality is higher than ever, running with the best. The jewelry adorning the cabinetry is all functionally mandated, designed to look fab and is perfectly machined. While it sounds like this is as good as Druid can get, there’s no doubt Sean will take Druid further in coming years, but Druid 6 is a high plateau on which it can be parked, bought, enjoyed and admired while another speaker in the Zu line gets the new foundation of materials and build techniques laid down by Druid 6. In the meantime, in Druid 6, Sean Casey is making the one, true, full-range, orthosonic speaker. It doesn’t exaggerate, nor does it shade the truth. It neither spotlights nor romanticizes. It doesn’t make rough, wooly music silken, and it won’t make velvet sounds abrasive. Druid 6 presents Tom Waits and Maria Callas with equal authenticity. Yo Yo Ma and Joe Satriani are equally convincing. Frank Sinatra and Hound Dog Taylor are nothing but themselves.

A (lengthy) note on amplifiers for Zu.

If you’ve read anything prior I’ve posted here about Zu, you know I regard the amp-speaker interface and combination the fulcrum of fidelity for any Zu-based system. As I referenced earlier in having to abandon SET amps with Druid 6, buying this speaker requires careful consideration about the mated amplification. In the past 18 months another development required a complete revision to my power amplification in my Definition 4 system as well, so I have put extended effort into surveying alternate amps for both Zu systems over the past year or so.

In 2017 I had solar panels installed on my roof, and then later that year added Tesla Powerwall batteries. The panels were installed on the area of the roof directly over my living room where the Zu Definition 4 system lives. It’s a one-story rancher, wood construction house, so not much other than air, wood and sheetrock umbrellas my Definition 4 system from the shower of solar RFI. Apart from any RF emissions from the panels, the system has two wireless internet connections: a Wi-Fi connection to my mesh network by the Tesla Powerwall controller, and a cellular connection by the solar system inverter. At the same time, to accommodate the exterior Wi-Fi needs as well as prepare for wireless Roon endpoints to two separate systems, I changed my house Wi-Fi from a Google wireless router to an Eero mesh network.

The result was that my SET amps in the Definition 4 system proved perfect antennas for the shower of RFI bathing my living room, and no tactic for quieting that worked. The first step was to get an active preamp out of the system, so I sold off my crazy-good Melody p2688 tube preamp, which removed about half the problem. It was replaced by the splendid Luxman AT-3000 TVC from the early 1990s – a real work of magnetic art. Once that was added, I had quiet with push-pull tube and solid-state amps. At the time, I still had Druid 5 on the other system, and its location sharply contained the new RFI problem, so my Audion SET amps could still be used there. Then Druid 6 arrived to undermine my commitment to Audion SET. So, now what, for amplifiers?

About a year ago, after years of great difficulty finding a phono preamp that can make an Allnic Puritas phono cartridge sound correct (Allnic’s own phono preamps do not), I ventured a radical experiment to try the M2Tech Joplin Mk2 phono ADC, which I mated to the M2Tech Young Mk3 DAC, both powered by the Van der Graaf linear power supply. For this signal, The ADC converts analog to 24/192 digital and the DAC converts the processed phono analog digital signal to analog at 24/192 decoding. With RIAA done in the digital realm, and gain adjustable by 1 db increments, and a good range of options for cartridge loading, I finally got the Puritas to sound musically convincing. This led me to take a flyer on the M2Tech Crosby power amplifiers as a temporary fix to my Definition 4 power problem so I’d have something good to listen to while I took my time trying alternate tube amps. I bought two Crosby to run as bridged monoblocks. These are Class D amps using ICE modules with an M2Tech proprietary input section for better sound than most ICE-based amps. Into 8 ohms, one Crosby outputs 60w/channel. Run as a bridged monoblock, Crosby outputs 180w. Into the Def4’s 6-ohm load, Crosby should be good for ~270w each.

With a pair of Crosby amps and the Luxman TVC in the Def4 system, I had a quiet system again. In fact, dead-quiet. Quieter than ever! Without the RFI-induced gurgling, sputtering, spitting and whirring coming through my RF-antenna SET amps, I could listen in peace and embark on a tube amp odyssey as I had time.

Chalk up the M2Tech Crosby Class D amp as wonderfully-Zu compatible. This is the best Class D sound I’ve heard, period. Maybe only rivalled by the 47 Labs Gaincard, which has much less power. I prefer these to most bi-polar solid-state amps, only a few of which have somewhat better musicality, usually at less output. Such amps are generally associated with Nelson Pass. So if you are tube phobic or have any other reason to need or prefer a smooth, bursty, dynamic, musically-convincing, high-definition, solid state amplifier for Zu, consider the relatively affordable M2Tech Crosby.

Back to tube amps. At the same time I was considering tube amp alternatives to my long-time Audion SET amplifiers, I also have to note that I regularly am contacted for advice on affordable tube amps for Zu speakers as well. Now, I have a pair of Quad II Jubilee monoblocks, which were the last edition of Quad II amps produced in the UK. They sound quite good on any Zu speaker, so when I got Druid 6 and found them not ideal for SET in the bass region, it was easy to slip them in the Druid 6 system, or to move them over to Definition 4 when I wanted some tube-amplified music. The Quad II pair are always a great backup amp for me, and the closest-to-SET seamlessness I’ve heard in a push-pull amplifier, simple circuit and all that.

But Quad II is built for KT66, with 6L6 an alternative. I had mine pretty tweaked through tube selection: Tubestore Preferred Series 274B rectifier, Mullard mesh plate EF86, Sylvania NOS 6L6 long ago sourced from Mesa Boogie in the form of their legendary STR-415 power pentode. As an alternative I also used cryo’d Tube Doctor KT66. The Quad II sound seriously good but still only 12-15w and the pair could be more elastic. I would love them to have more of the Plasticman kaPow! reach & slam that my Audion Black Shadow 845 SET amps muster.

My system racks are setup for monoblocks, so all stereo amps are ruled out. Meanwhile, as I started my tube amps odyssey, more requests for affordable amp recommendations trickled into my email. Which is why I want to let you know about Ling Xiao Nan and his hand-built, affordable, amplifiers. Xiao Nan designs and builds his amps in the Guangzhou region of China. He is self-taught on the subject of vacuum tubes and amplification, and been building amps for over a decade. He’s also a guitar player, but he’s proud to point out that he is a “full-time amp builder.” You can find Xiao Nan offering amplifiers on eBay under his Tube Fantasy brand, but that’s only a fraction of what’s possible with him.

Online, Xiao Nan generally sells clones of vintage circuits, particularly pre-war and post-war German cinema amplifiers, the Quad II and the Williamson designs. The circuits are faithful with only a few component value deviations for modern speakers, particularly in cathode capacitors. When he is cloning an amp circuit, he builds his transformers to the original electrical spec but uses his own preferred winding techniques. Xiao Nan machine-winds his transformers on his least expensive amps, and hand-winds them in everything else not-very-much-more expensive. He keeps cost down first by building in China, but also by keeping to a Quad II-sized chassis for most of what he offers, in black or natural aluminum, or a similarly-proportioned upsize for designs with larger transformers. Ling Xiao Nan builds monoblocks.

I first learned about Tube Fantasy when I was out on my patio on a cold-for-Los-Angeles night in December with a glass of Corbin Cash Rye, Tidal on my iPhone through my i.am+ Buttons, idly flipping through tube amps on eBay. A listing for a Quad II clone pair at a ridiculously low price stopped me cold, especially since I had gotten a request to recommend a cheap tube amp for Zu earlier that day. They were so inexpensive I decided to do the Zu community a public service to evaluate them. If someone was selling a pair of Quad II clones for a few hundred bucks, I had to hear them, for better or worse.

I’m going to comment on those Quad II clones shortly, but in email correspondence about the sale and in asking some questions I had about the amps, I quickly got to know Xiao Nan beyond the usual eBay transaction, and in doing so I learned about other amps he makes. Perfect. I now had a custom amp builder to let me affordably tour circuits and tube types to bracket myself and zero in on where to finally land in replacing my Audion SET amplifiers. This led to me acquiring the following monoblock pairs in the span of 3-1/2 months: Quad II clone, Williamson push-pull, 2a3 triode push-pull, Klangfilm KLV-204 clone (F2a beam power tetrode-based) single-ended tetrode, LS50/GU50 single-ended pentode, 300B-or-2a3 push-pull. And I am considering getting a pair of Telefunken V69 clones.

At some point, some of these amp pairs will be sold, but the luxury of auditioning a range of circuits and tube types on a relatively modest cash outlay is considerable. And you know what? Xiao Nan might make you a pair of stepping-stone amps, or he might make you the last pair you need. He certainly can. Xiao Nan tends toward simpler circuits, high quality parts, emphasis on transformers and pentode/tetrode designs, though he builds triode push-pull anytime you want. He is quick to build, his soldering is clean and careful. Nothing is needlessly bulked up for faux masculine appeal.

Ling Xiao Nan and Tube Fantasy are in many respects the Sean Casey and Zu Audio of tube amps. Both represent strong points of view, are music-driven and constantly tinkering for better sound, and delivered value is high.

Here’s a sampling of Ling Xiao Nan / Tube Fantasy prices, monoblock pairs, shipped to USA (DHL), amps only, no tubes:

QUAD II Clone (18w), $499

Williamson Clone (25w wired triode / 45w wired pentode), $688

2A3 push pull triode (13w), $688

Klangfilm KLV204 Clone, single-ended-tetrode (10w), $688

LS50/GU50 Direct Coupled, Single-ended Pentode (13w), $1000

In cases where Xiao Nan supplies any of the tubes, he specifies so. Otherwise, you source tubes and stuff the amps when you get them. Every amp Xiao Nan builds gets burned in and listened to for five hours before shipping. All my amps have arrived trouble-free electrically. One had stripped transformer cover threads due to customs overtightening during disassembly-reassembly under inspection, and they also damaged a faceplate. Xiao Nan immediately ordered replacements for me.

Xiao Nan does not pot his transformers both for maintainability and because potting compromises high frequency performance. You may hear a trace more mechanical hum up close than from, say, a true Quad II. But music-on, this is irrelevant. The amps are quiet electrically. Common to all of Xiao Nan’s amplifiers is exceptional transparency, very high definition, fast transient speed, exceptional soundstaging and depth. For whatever reason, with any of his amplifiers, I am getting more spatial depth in the soundstage than with any amplifiers I’ve had connected to my Zu systems, regardless of price, and that includes the many amps visitors have brought to audition on Zu speakers. That fast, transparent, dynamic, tuneful sound I valued particularly in Audion SET is here. Further, in the push-pull amps, crossover notch grunge is vanishingly low. Some notes on specific amps:

Quad II Clone: Fast, open, dynamic sound. Because Xiao Nan winds the output transformer differently than Quad did, this also changes the feedback behavior somewhat. The result is greater audible difference between KT66, 6L6 and EL34 in the clone compared to genuine Quad II. With EL34, the clone is relentlessly revealing, hi-def and blindingly fast, which is great for excellent recordings/masters/pressings, but not forgiving of flawed wax or digitalis-digital. With KT66 the clone is closest to the original Quad II sound, which was not strictly romanticized but does possess some vintage warmth. The perfect balance is found with the NOS 6L6. With this power tube, the clone is smooth, defined, dynamic; delivering Druid-like tone density and lots of dynamic punch for its power. The amp takes some time to burn in and bloom. About 120 hours will do it. It will sound thin in the bass region until then, but progressively less so.

Williamson (Triode-Mode): Dynamically stronger than the Quad II or its clone. Refined, smooth, high definition, solid deep bass on Definition 4 or Druid 6. Same basic sonic difference between EL34, 6L6, KT66, as in the Quad Clone. Again, I settled on NOS 6L6. In the Williamson, the Quad II and QII Clone, my preferred rectifier is the Tubestore Preferred Series 274B. It gets the most tone, space, definition and dynamic punch from all three amplifiers. This is an exceptional tube amp, that lives up to the Williamson amp legend from shortly after WWII. In fact, it’s the best Williamson implementation I’ve heard and easily walks over a Marantz 8B.

2a3 Push-Pull: Inexplicably bursty and elastic for its 13 watts. And my pair have only 8 ohms windings. On 16-ohm Druid 6 they sound dynamically huge. Excellent bass discipline compared to any SET amp, while retaining all the triode magic, though still quite objective. No slow, lazy, old-school triode amp sluggishness. This amp, Xiao Nan’s custom circuit at my request, gives up nothing in definition, speed and punch to the tetrode and pentodes in his other push-pull amps. The rectifier you want is NOS 5v4.

Klangfilm KLV-204: This is an early post-war German cinema and studio amp. It was used as a monitoring amp in recording studios (so high definition required) and as a reserve amp for cinemas using the larger KLV-402 & 502 amplifiers. It lives up to its high definition requirements. I have known about the F2a tetrode tube for decades and never managed to get my hands on any of the Klangfilm or Telefunken amps that used it. I was excited to get a chance to hear the Shindo Cortese, which promptly disappointed me like most other Shindo amps I’ve heard. But this KLV-204 clone is exciting to listen to! Only 10 watts (I had my pair wound for 16 ohms to use with Druids), it sounds dynamic beyond its means. No detail gets past it. Midrange is tone-dense like a great triode but burstier. Among the quickest, most agile amps I’ve heard at any price. Like Druid 6, this KlangClone is vivid, tonally, dynamically, and spatially. With Druid 6 it is musically amazing on an excellent recording, but the x-ray truth of the combination can render a poor recording too distracting to listen to. Badly recorded or mastered bass, particularly, shunts the illusion of musicality. This is one of my favorite amps ever heard, but it is a specialist and Xiao Nan builds it affordably enough to use it selectively. The F2a tube, btw, is a German Post power tetrode built for 10,000 hours of life. They often go longer. As NOS and vintage tubes go, they aren’t cheap, but they aren’t ridiculously expensive, either, given how long they last.

LS50/GU50 Single-ended Pentode: More like the sound of the Klangfilm KLV-204 than any of the others. Crisp, clear, fast and transparent. Also dynamic beyond what’s expected from its mere 13 watts output. Clean top-to-bottom. A little bass shy compared to the push-pull amps but there’s a remedy. In most tube amps, particularly those with cathode bypass caps, there is a trade-off between ultimate bass performance, and ultimate top end. When faced with this, Xiao Nan prioritizes top end linearity over bass linearity. But making adjustments to the chosen values for cathode bypass caps can land you in your zone. You can do this after getting the amps or if you communicate to Xiao Nan your general preferences, he can reliably adjust for the right value. You just have to communicate effectively. Overall, Xiao Nan’s LS50/GU50 single-ended pentode monoblocks are sonically in the same realm as the F2a-based Klangfilm KLV-204 clones, but not quite so MRI in unsparing revelation. The LS50 has more latitude in acceptable recording quality than the KlangClone. Given the Definition 4 sub-bass extension, Xiao Nan suggest snipping the cathode bypass cap on the E180F driver tube to bring bass performance into better balance with the speaker. But I have to say before doing that, the intrinsic bass from this amp on Def4 maybe a little light, but it is very well presented in terms of character, definition and attack.

300B/2a3 Push-Pull: I commissioned Xiao Nan to build for me a pair of monoblocks that can use either 300B or 2a3 output tubes, in push-pull configuration. I have a quad of KR 300B Balloon tubes held back from my recent sale of my Audion Golden Dream 300B monoblock amps, which I wanted to use in push-pull configuration with either my Druid 6 or Definition 4 system to make continuing use of those magnificent tubes. Xiao Nan indulged me with a custom design. Those amps are arriving in the next day or two. Comments pending if anyone is interested.

Telefunken V69 Clone: Probably last in my series of bracketing amps from Xiao Nan will be a pair of clones of the legendary Telefunken V69 Cinema amp. This is a full Class A, push-pull, tetrode amplifier using a pair of the F2a tetrode tubes in each monoblock. Like the Klangfilm KLV-204, input and driver tubes are the equally-revered EF-12 small-signal pentode. Class A output is 25 watts per monoblock. I will decide in the next day or two whether I will order these, put them in the mix and then vet the whole shebang for what stays and what goes.

You can find Ling Xiao Nan on eBay as seller “fatkit83-8.” If you private message me, I can offer his direct contact information for amp inquiries.

Of course the genuine Quad II remains a highly-viable tube amp for any Zu speaker. It is coherent, musical and also delivers more dynamic shove than its diminutive specifications might lead you to expect. Ling Xiao Nan gives you alternatives, and plenty of them, for less cash. And similar to like-minded Asian originators like mhdt (DACs), Jasmine Audio (phono preamps and amplifiers), and Melody (preamps and amps), all of Ling Xiao Nan’s implementations are informed by music listening and in-depth inquisitiveness seeking more fidelity than he previously delivered at any given time. Just like Sean Casey.

Ask questions if you have them.

Phil


213cobra
Marc,

I had a chance to listen to Nat 211 amps a few times in the past, even as far back as when I had Def2, and even earlier NAT amps using the VT4-C triode, well before I owned anything Zu. Certainly good sounding amps in the grand scheme of amplification choices; I just was not convinced of them relative to Audion Golden Dream and Black Shadow. I also didn't spend a lot of time with them because there were common QC complaints at the time. The range of choices in power tubes was also narrower for 211 than 845 and 300B. Overall, they didn't move me and did not sustain my attention. NAT have revamped their line since then and I haven't heard the current production. The Magma New using the GM100 certainly *looks* fantastic, and I'd be optimistic about its SQ if I were anticipating an audition.

Phil
Thanks to Marc for mentioning NAT amps. Higher powered SE amps could be of interest although some of the higher powered transmitting tube characteristics may be of concern. 
J, it was kinda a necessity. My old room was 800 sq ft/10,000 cub ft, a tall order for 25W Black Shadows to fully saturate. My Nats are 70W w serious Iron, and this may be an underestimate, closer to 90-100W.
Even 101dB spkrs w no energy-sapping crossovers don't say no to the extra helping hand Wattage.
Which NATs do you own? I couldnt agree more with the power thing and firmly believe that part of the problem with all SETs that I have heard is the lower power of these designs and distortion they produce at higher output. 
Hi J, the SE2SEs w 1948 GE 211s (not the current spec using GM70s). I would love to consider the Magmas w 170W transmitter tubes. But at £45k, a bit beyond me. IMHO, I'm not sure about the 120-130W Transmitters, they're a little too analytical for me. Tetrodes, not triodes, I believe.
As a Vietnam vet and infantryman the only thing M-60 means is the
U.S . Army’s deadly machine-gun .If this was done for a laugh, it ain’t funny.
The M-60 evolved out of the M-50 monoblock amplifier we introduced in 1991. We found that by installing the B+ power transformer for the MA-1 that the M-50s made 10 more watts and the M-60 became its new designation as the upgraded B+ transformer became stock.

I had no knowledge of ’M-60’ meaning anything else until reading this thread. Its a monoblock amplifier; that’s where the ’M’ comes from. Otherwise the amp is all triode and makes 60 watts into an 8 ohm load without the aid of an output transformer. The amps have gotten a lot of reviews over the last 25 years as well as awards; so far this is the first mention of this missive to my knowledge. So, in a nutshell, my comment wasn’t done for a laugh nor meant to be funny. We had Druids in the shop for a number of years and its a simple fact that the M-60s work great with all of the ZU lineup.
Ralph,
Of course you have never had a complaint until now and among the sane no explanation is required.


I believe Ford lost a lot of sales in Latin America when a fancy dancy name they gave a new model translated into Spanish came out close to "not quite a man who prefers to stay at home close to his mother" LOL NOT!
I heard the Wavac amps that used some of these transmitter tubes but cant remember how they sounded. Perhaps I was in shock over the price. 


Tbh, that could apply to many on forums incl myself LOL.
Who did you have in mind?
    Phil , thanks for a rather enlightening article on the new Druids . My system is “ Rife with Problems “ as I have older Zu Omens , but I very much enjoy them . The fellow Agoner I purchased them from has Zu Druid 4/5, Devore, and Voxative . He invited me to RMAF last year , but I was unable to attend . After the first day there , I asked him about the Zu Room . His description had “ Holy F$&@ “ in the reply . This is from a guy that has amassed a large collection of great gear and doesn’t swear . I’ve been craving a pair ever since . So thanks for your music history and the lengthy description of the Druids , as I’m living vicariously through you . Much the same as when my fishing pal purchased a CX 4000 Cobra . I should have finished college like my parents suggested ! So thanks for your share and I wished you lived in central California, so I could visit . Cheers , Mike B. 
As others have said all speakers have problems, I just pointed out that the older Zus have a number of significant problems that the newer Zus, have in part, addressed. The biggest example were the cabinets and how they were far too lossy. These cabinets needed thicker material and many additional reinforcements. Zu has shown that they are truly interested in improving their products and that they are evolving in meaningful ways. Great guys with a great product if your tastes parallel those of the designers. 


No question cabinet talk was a noticeable flaw in early Zu, until the Definition 2 and steps taken with the Druid v4-08 upgrades. You got around that by limiting SPLs or just putting up with it when you wanted to hammer your skull. It wasn't that the cabinets were too thin, but that they weren't stiff enough for the early MDF construction.

Def2 and the briefly-made Presence went to birch ply and more bracing, and if anything, the cabinets were overdamped. Cabinet talk was gone but some of the Def1 projection was truncated. In Def4, the combination of mixed materials and more sophisticated internals laid a new foundation for how Zu thought about energy management. Druid 5 saw equal advancements to the drivers and the cabinet. Druid 6 has taken the mixed-materials laminates and cabinet internals to a new high, augmented by integrated energy management techniques.

Whereas a lot of designers would have just gone down the path of adding mass through thicker sidewalls, Sean put the time into developing a more sophisticated approach to make the cabinet much more inert and to channel spurious energy to ground while maintaining the external dimensions of the Druid form factor, while *also* keeping to the internal working volume needed for full Griewe function. Thus, Druid 6 looks like the original but it has evolved a sonic light year since inception.

Phil
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Hello, I own a pair of Zu Omens and I agree with you on the merits of Zu speakers. As I have not heard the JBL l100 reissues I can’t comment on them but I own the new JBL 4312se monitors paired with a 505 Luxman integrated amp it’s a heavenly combination. One of the best sounds I have ever heard. Also I have a Line Magnetic 219ia 845 based integrated amp and some Klipsch heritage heresy III speakers and this combination is magical also. Both of these systems sound better with the respective speakers than with the Zu’s. I have owned most of the brands of so called high end , high resolution speakers and like you said they do not sound like real music. The Klipsch, JBL and the Zu’s sound like real music. I also have some JBL 580 horn speakers that sound awesome also.
In a few weeks I will complete my survey of amp circuits with Zu Druid 6 (and Definition 4). It will include evaluations of:

845 SET
300B PSET
300B Push-Pull
Quad II
Quad II Clone with transformer improvements
Williamson
2a3 push-pull
Klangfilm KLV204 (F2 single-ended tetrode)
Telefunken V69 (F2 Push-pull)
LS50 SEP
LS50 PSEP
EL156 SEP

Phil
Phil,
I'm happy/sad that I found this thread today.  I'm moving onto my 3rd set of Zu speakers and taking delivery of Druid VIs at RMAF in September.  I thought that I had my amp decisions all figured out.  I was going to finally treat myself to Audion Golden Night 300b Monos.  Looks like I'll be watching what your impressions are moving forward.  Thank you for all your input.  Will you be at RMAF this year?    
There is certainly latitude in the matter of SET bass on Druid 6. I'll say that even with Druid 4-08, the relative lack of discipline in most SET bass was easily discernible, but it was a small enough error to be OK,; euphonic even. In Druid 5, it was a bit more noticeable still, but the Druid 5 FRD was quicker, and the floor-plinth-gap was much less fussy than with original Druid. WIth either 845 SET or 300B PSET, the lower bass limit of Druid 5 left bass performance with SET on balance, in equilibrium.

Druid 6 bass extension provides no cover. There's a guy on What's Best Forum that wants to fight me over this, claiming that I just need a better SET amp that isn't saturating the OPT core. But he's missing the point. Not only can I hear some compromises in even slightly-rising harmonic bass-region distortion in the best SET amps, an equal problem is the very low damping factor in SET topology. You can use very good SET amps for deep bass performance with Definition because the powered subwoofer is not not controlled by the SET amp. The bass character is derived from the SET power amp output signal, but the subwoofer is dynamically controlled by the solid-state Class D sub-bass power amp.

In Druid 6 all driver control not acoustically managed by the Griewe scheme or by the driver itself is left to the amplifier / FRD interface. And for this, SET is in my view suboptimal for Druid 6, whereas it is quite good with Druid 5. Now, if your tolerance for, or you have a preference for, euphonically rich bass, no one can say you are prohibited from enjoying it. And you may feel that the rest of SET benefits are worth accepting the deep bass compromise revealed with Druid 6. But I am noting for myself. SET bass is too distracting to be authentic and I cannot find a way to make it right. What does work very well is triode push-pull (I have had extensive hours with both 2a3 and 300B push-pull) and single-ended pentode/tetrode amplification. Does triode push-pull or SEP duplicate everything exceptional about SET? Not quite. But SET doesn't duplicate everything exceptional about good SEP either. I have had 20 years of continuous SET amplification in my systems, along with a couple of SEP amp in rotation during that time. So, it's not a matter of commitment to SET. It's a matter of commitment to objective, authentic sound. I will land on something not SET for Druid 6, and for different reasons (my solar installation RFI) on Definition 4 too. I'm not having any real difficulty finding successors.

If you read the amps survey I publish here later, the whole matter should be clearer.

Phil
Not sure about getting to RMAF this year. That show has an uncanny habit of overlapping professional obligations that, of necessity, eclipse it on my calendar. But maybe.

Phil
So far, so good. With the caveat that it's great specifically with the KR 300B Balloon Glass, same as was true in my Audion Golden Dream 300B PSET. Which isn't inexpensive. But the KR is the only 300B that gets bass right and everything else is objective and tone-dense; nothing sloppy anywhere in the frequency range. The Sophia carbon plate is pretty good. The Takatsuki is thoroughly disappointing; dynamically dead, old school rounded sound. Very well-made; just not musically credible by comparison, unless you like that over-smoothed sound.

I have no love for the Electro Harmonix 300B, but the EH 2a3 Gold Grid is quite good, especially for its moderate cost. The KR 2a3 is as good as their 300B, but the EH is an excellent 2a3 step-down in cost that gives up disproportionately much less in SQ relative to the KR equivalent. There is no equivalent value step-down in 300B, IMO. Shuguang also makes a large-glass 2a3 that is more dynamic and boisterous than the EH 2a3 Gold Grid. I give the EH an edge in refinement; the Shuguang gets the nod on energy and projection in 2a3.

I have had a series of amps made to explore circuits as alternatives to my longtime Audion SET amps. The builder is the same, the circuits are a mix of vintage designs cloned, and the builder's originated circuits, with some of my own specifications added. One thing I have to note off the bat is that I am getting more spatial depth from Xiao Nan's amps than *any* I've had through my home, ever. I haven't yet pinpointed why. I've always run monoblocks. But his amps (common element is his transformer winding technique) are either better preserving spatial information than any other amps I've heard on my systems (and when you add up all the amps people have brought over the years which which to listen to Zu, it's quite a range) or he has managed to add a spectacularly effective and musically-convincing distortion in precise measure to whatever he builds, irrespective of circuit. I'll say it's the former.

Right now, the custom 300B / 2a3 dual mode p-p triode pair are my favorites, running a quad of KR 300B balloon glass. I am using those on Definition 4, 20w with the 300B; 15w with 2a3. On Druid 6, I tip back and forth between the F2a SE-Tetrode Klangfilm KLV204 Clone, and the 2a3 push-pull (different from the dual mode amps). But next week I have three (and final) heavyweight contenders arriving: LS50 / GU50 Parallel Single Ended Pentode, Telefunken V69 Clone (F2a p-p for 25w full Class A), and EL-156 Single Ended Pentode. So no final assessments quite yet.

As for the practical matters: both triode push-pull and single-ended pentode/tetrode are immune to my solar RFI environment, for which SET amps have proven perfect antennas. And both push-pull triode and single-ended pentode/tetrode solve the bass quality / discipline problem otherwise heard with SET on Druid 6's extended bass response. More coming.

Phil
I'm really interested to see what you land on.  My wife and I are installing 1000 square feet of panels this fall and 400 of them will be over our listening room.  I can't tell you how thankful I am for all the information that you are sharing.  My wife will be pretty happy if I can land on a set of Monos that are half the price (with KR glass) of the Audions we were planning on.  

Are you running your system directly off of a dedicated power wall?  
I have a semi-dedicated line for my main, Definitions 4 system. There are only a few other low-use sockets on the circuit. I have two Tesla Powerwalls supplementing my solar, and they are set up to power everything but HVAC for backup. To get the energy consortium subsidies on the Powerwall(s) you have somewhat narrowed implementation options for the first two years. They limit how much you can reserve for backup. They want to maximize the batteries' contribution to avoidance of domestic peak load consumption from the grid. And because the batteries' energy is returned through an inverter to your AC line, I haven't found a major sonic advantage in hifi. Maybe it pulls the quietest, best-sounding, wee-hours power earlier into the evening but it's not big, like when I have run audio gear off ganged motorcycle batteries in my past. Basically, if AC is coming out of the wall, it's coming via something grungy and noisy.

I have my power amps on dedicated Bob Hovland balanced power isolation transformers. They make more difference than powering AC from Tesla Powerwall, or not.

My original intent was to have Xiao Nan build several amp circuits on affordable economics to land on a direction that I'd then find established market equivalents for. Now I am not so sure I'll need anything more than what Xiao Nan can build. The two matched pairs of KR300B cost more than the tubeless amps. And that's the thing: a lot of people would feel better about paying four, six, eight, ten thousand dollar for amps, and then balk at buying $2400 worth of KR power tubes + NOS rectifier, input and driver valves. But most of those amps, with stock Shuguang, JJ, TJ or Sophia tubes will not sound as true as Xiao Nan's amps with crème de la crème glass. And the KR 300B and 2a3 are quite long-lasting, too.

Phil
Phil, after a 100A fuse, I split the power (from before the feed to the rest of the chapel) to take a dedicated 18mm SWA cbl up to my audio room, and then daisy chain a bespoke consumer unit and 8kVA Westwick 8K balanced pwr transformer, running six Oyaides dedicated lines to six Furutech duplexes.

Other than some hum from my Definitions 4 spkrs' subs amps (present from before I installed balanced), my sound is hefty, solid, airy, textured, that "after midnight" sound 24/7.

Phil, it's a shame you can't hear my 70W Nats 211s here, you might change yr mind on the concept of using them on Zus.
Hi Phil. Awesome write up, many many thanks.  I’m really looking forward to your upcoming findings with the amps and Zu’s. Really appreciate all the info you put out there. I’ve actually been reading your posts for a long time, even on other forums. Like that killer advice you gave about using a 6922 adapter with the Havana DAC. But I stay off the forums because they can be a... contentious place, to put it mildly. Anyway, thanks for all your work and experimentation. 
Phil, have you ever tried Whammerdyne amps with Zu’s? I’m interested in those cause they look so cool and weird. They’ve been on my radar since I’d seen some show reports of them with Druids. 

And have you ever tried Linear Tube Audio amps? I have the LTA Ultralinear and it’s pretty good but I slightly prefer the sound of the LTA MZ2 with the Druid VI’s. But it’s only 1 watt. So I’m getting that itch to buy another amp again. The Klangfilm and 2A3 push pull you mentioned look very interesting.
The Whammerdyne amps use 2A3s don't they? In most rooms that won't be enough power. Nice sounding amp though. The Druids are about the same efficiency as my speakers, and I have a smaller listening area, in which 45 Watts/channel is barely enough.
It looks like all the Whammerdyne amps use 2A3’s. Wattage isn’t an issue for me though because I’ve never played loud enough to clip an amp. The amp currently in my system now is the First Watt SIT 2. 10 watts into 8 ohms and actually only 8 watts into 4 or 16... I swap in my LTA MZ2 sometimes and use it as an integrated amp and that only puts out 1 watt and I’m fine. Also have a 45 amp that only puts out 1 watt. Dynamics and slam and transient attack are still pretty good with the Druids, even at a lower volume. I haven’t found many speakers that can do that. And I really do mean low volume. For years, I didn’t know what volume I was listening at and out of curiosity, I downloaded an SPL app on my phone. I mostly listen at 50 to 60 dB. “Rocking out” is about 70 dB for me. 
Which Whammerdyne? Would you spend the cash for the Parallel Single Ended model? I'm guessing not.

I haven't heard the Whammerdyne. And I have only an academic interest in it because a 2a3 SET amp just doesn't have enough shove, even for 101db/w/m Zu. They quote 4.6w of "peak power." Whatever that is. Remember those distant days of the RMS standard? That 4.6w of "peak power" is probably more like 1.5w of RMS power. You may not have clipped your Firstwatt SIT2, but you'll clip that Whammerdyne. Even a single piano note can drive exceedingly-fleeting transient clipping in more powerful amps, which can be subtly degrading. Plus the amp is built with 4/8 ohms terminals. Are you using with Druid? If so expect less at 16 ohms.

These amps are touted as the "finest 2a3 amps on earth." Which is a mindless claim, because who's heard all of them? No one. There are *many* good things about Whammerdyne's design principles and execution. Build quality is beyond reproach. But the power level is impractically meager unless you just don't care about dynamic realism. Maybe you don't.

Also note that the Whammerdyne amps are direct coupled. In principle that's a good thing, ensuring it sounds fast, transparent, clear. In practice, it can make a large percentage of recordings you actually want to live with and listen to somewhere between less listenable to unlistenable. I have a couple of d-c amps in my mix. I use them selectively.

If you are really only listening at 50-60 db, maybe you'll be happy with a 2a3 amp. I can't really say. Given the noise floor of even a reasonably quiet domestic environment, you are listening to a very limited dynamic range at that level. I don't recommend 2a3 (nor 45) SET for practical hifi. You don't need a lot of power for Zu, but 2a3 Push-Pull or PSET is preferable for that tube for all-purpose amplification. If you have multiple amps which you use selectively, then sure. There will be times when a 1.5w - 2w SET seems just right. Not enough times for me, though. If it works for you, Whammerdyne should be worth an audition.

Phil
Thanks for the input Phil. I actually do have a bunch of amps that I swap around and a few specialized ones and after reading your reply, I thought about it and I realize I already have too many low power amps. At least 4 one watt amps, don’t really need more than that... 

At first I couldn’t believe my listening level was so low but I measured it with an SPL app on my phone. Then used that same app to measure different things and they all came out in the range that they should have. For kicks, I went to a local rock show last night and the app measured it around 100 to 110 dB with peaks at 120. So any thought that my SPL app was measuring on the low side was abolished. 

Credit to the Druids that they still sound good at 60 dB. The dynamic range may be compromised but I’m listening at nearfield, 7 feet, so that should help. I’ve tried other speakers at 60 dB and they do sound lifeless, though. 

So now I’m really interested in your feedback regarding the 2A3 push pulls and the Klangfilm clones. Can’t wait 😁
So now I’m really interested in your feedback regarding the 2A3 push
pulls and the Klangfilm clones. Can’t wait 😁

I'm in the same boat.  Can't wait to hear what you have to say about the Tube Fantasy gear moving forward.  I have till RMAF till I get my new Druids, but I'm losing my mind trying to figure out what direction I'm going with my tubes.  

We are going through a system transformation right now as we are going from 2 homes to one.  I had Soul Supremes at one home which I sold 3 months ago and Omen Mk II in our mountain home.  We are currently just running a 1976 Marantz on the Omens to get us by while we wait for our new Druid Mk VIs.  We are building the new system around the Druids, and I had been planning on running Audion Golden Night 300Bs till I saw what Phil's experience was with the Mk VIs and his solar panel issue.  I've been checking this thread a couple times a day to see if Phil has showered us with any more wisdom regarding his amp experiments.  As of right now, and solely based on Phil's findings so far, I'm going to be leaning towards a 2a3 PP.  If Phil is willing to walk away from his beloved Golden Dreams I'm definitely paying attention to what he is moving to.  I'm very lucky that Phil has been sharing as much info as he has been regarding his new direction with the Druids.  I'd love to bring in tons of amps and audition them, but that isn't in the cards for us.  We live in a pretty remote mountain town and shipping large packages is a nightmare.      

        
Haha, yeah, I agree on wanting to see what Phil discovers next. Although he doesn’t know me at all, I’ve been reading his experiences on forums for years. And I’ve been buying from Zu for a long time (over a decade) and have spoken to Sean and Gerrit a bunch of times and I know that their preferences are very similar to mine and that they frequently use Phil’s input as well... And at this point, I have about 11 pairs of Zu’s and over a dozen amps and I have yet to find anything that does everything I want.

That’s not to say I haven’t had good sound. I’ve had a lot of magical moments with my gear. But in different aspects and I’m tired of buying so much gear and making sideways shifts. I’m hoping to make a system that satisfies all my preferences. 

For example, when I got my Druid Mk IV’s in 2008, it was my first foray into audiophilia. So many things amazed me about them. The tone density and how natural everything sounded. And dynamic. I remember listening to Tool’s 10,000 Days and being surprised when the lightning kicked in. It literally startled me, how realistic it sounded and the speed of the attack... Years later, I was astounded by my Druid Mk V’s with my Devialet 120. The clarity and transparency and lack of distortion made me feel like I took some earplugs out or something. Shortly after that, I got a pair of Omen Bookshelf Mk II’s and just on a whim, connected them to my Exogal Comet/Ion. That amp literally transformed those speakers. Dynamics and transient speed became insane. Better than anything I’ve heard. Listen to songs like Rammstein’s Feuer Frei and the initial slam of the drums and guitars at the beginning of the song literally made me jump, I wasn’t expecting that. And yet when I tried my Exogal set on the Druid V’s, it wasn’t the same. Weird, because those are better speakers. 

Sorry for the long post but the point is that I’ve had a lot of magical moments with my Zu’s but I’m hoping to find an endgame amp that pushes all my buttons. It may not exist, but I figure it’s time to start asking people that have the same speakers and similar preferences. Took long enough, haha.
Phil- would you recommend people do Druid VI with Submission subs or simply wait until Sean's next Definition for a medium-sized room?


GloriousUnicorns, it would be nice to think one amp can do it all, but I suspect that may be in vain.

In my 800 sq ft rooms, I've run 3 lots of amps, Hovland Radia SS, 35W Audion Black Shadow 845 SETs, and currently 80W Nat Audio  SE2SE 211 SETs.

They all sound different, and compelling in their ways. My preference is for the beefy Nat 211s, takes the Zu Defs 4 tone density to another level.
Some catchup:

Our brainless administration's dumb trade war with China has slowed shipping of my last couple of custom amps. I expected them earlier this month but now it will be sometime in June. Shortly after I get them I will complete my amps survey. It's coming.

Correction: Audion Black Shadow monoblocks have been various rated for 24w and currently 25w, never 35w.

The Zu Submission is an excellent subwoofer but I only occasionally recommend separate subs, and would not generally use them in a "medium size room" with Druid 6, over going to Definition 4 or its coming successor.

Submission over-matches the acoustic scale of Druid, and most rooms have enough problems supporting deep bass as it is. Plus, the clutter! And the complications to maintaining coherence. The big advantage of Definition is having everything in a roughly one-square-foot footprint with bass coherence built in and just a pair of towers for stereo. Further, a pair of Druid 6 + a pair of Submissions becomes a $20,500 expenditure in basic finish. That's $3600 more than a pair of Definitions in basic finish, and the Druid + Submission still won't achieve the spatial and dynamic scale the Definitions will. Nor will Submissions make Druid 6 more intimate. Adding a pair of Submissions to Druid 6 pollutes what's most pure about Druid yet fails to achieve Definition's scale and balance.

I think Druid 6 + Submission is an interesting exercise, but ultimately a hifi curio someone might do just because they can. The configuration doesn't make sense to me. You would have four towers of clutter to get less spatial scale above the Submission's range, than a pair of Definitions. Given the economics, I think Druids -- any version -- should be enjoyed sans subwoofers, therefore at their most orthosonic. Definitions are the better way to get 16 Hz bass underpinning domestically, for the scant percentage of your recorded music that has it. Now if one has a love for complicating what was simple, blurring what was focussed, exaggerating what was objective, and / or has an unusually-accommodating room, I suppose go for it. But if you have a really large room, you'd go to Definitions in Zu's line anyway. Better to add true supertweeters to Druids, or buy better amplification.

Phil
Spirit,
I should’ve been more specific. I know there’s no amp that can do everything. However, there are a lot of “audiophile” aspects I don’t really care about, like soundstaging, ultra deep bass, etc. So I want to find an amp that perfectly suits me and can do all the things I look for. Like great tone, speed, dynamics and attack. That’s why thus far, I have so many amps and I switch between them depending on my mood. 

Phil,
Thanks for the update. Sorry if I was coming off as nagging or impatient about what’s up with the amps, just excited about it, haha... I agree with you that I feel like the Druid VI’s do not need the Zu subs. But I did hear the VI’s with the Dominance subwoofers and it was actually pretty badass. The Dominance subwoofers are similar to the Submission. Large sealed cab but the Dominance use the LAB 15 driver while the Submission use the LAB 12. But sound quality is about the same, if I understood Sean correctly. The Dominance subs added a nice layer of dimension to the Druids. 
No doubt that Druids + Submissions will make the initial impression of being altogether badass. Living with that over time and a full spectrum of music can be another matter. But it depends what drives your perception of convincing musicality. Or maybe that doesn't even matter. Some people simply go for an emotional response irrespective of whether what's inciting it is musically convincing. Put another way, I am not advising that Druid 6 + stereo subs is better than a pair of Definitions, but you can certainly find someone who will!

Phil
GloriousUnicorns, we all have different requirements/preferences when it comes to amps, and spkrs.

I actually now look at the whole amps/spkrs/room package as a concept.

I've always listened in large rooms, this one and my previous one being 800 ft*2 (current volume 5500 ft*3, last one 10500 ft*3).

So for me I needed more power in my tube amps than my previous 25W Audion Black Shadow 845s provided. Got this w my current 80W Nat SE2SE 211s.

Both were preferable to the Hovland tube pre/SS pwr I ran previously.

My Nats have really enhanced the tone density Zu presentation, energising my room even at lower volume levels, maybe with a slight trade off in treble energy and speed.

It's a compromise that is very easy to live with.
Spirit, that sounds pretty awesome but the Nats are out of my price range. Good to hear that they work well at lower levels too. I’ll keep them on my radar. Maybe a lower model or a used one might pop up. 

Phil, well said. That’s a good point. Thanks. 
My opinion --- Tektone is number one in High End speakers
  number 2   is Zu audio. number 3- is Triton by GoldenEar Technology.
All other brands need to move to garage or flee market . Period
Take my feedback as one opinion only please. I would argue that the "best" amp for Zu Druid 6s is completely dependent on your preferences for what you’re looking for from a high-efficiency speaker, what room and room characteristics you have, and what tubes choices you have. Of course the quality of both the design and the parts and build of the amp matter too, but I would argue that when speaking of a particular amp brand and model, all 3 of these other factors play a giant role in whether you’re going to prefer any of the amps mentioned here over any others on the Zus.

I’ve got Zu Druid 6s and own 3 other pairs of Zus for reference (Soul Supreme, Unions and Cubes) and still own them all. I would have considered myself a Zu fanboy in some circles merely because I feel they offer a really high value and great high efficiency solution with a family sound that I enjoy a lot. To offset my fandom, I am currently having 2 custom sets of speakers made based off of some custom field coils and I am confident they will compete with Druid 6s if not beat them given early testing and comparisons with Druid 5s (yes, I believe Druid 6s are better than 5s). So I am confident that the Zus can be beaten for my preferences (having a similar sound to Zu with more musical detail and magic) in spite of my being a huge fan of the brand...I will know soon enough and confirm my own opinion there. Just want to state my biases from my own point of view.

You can read my previous posts regarding amp pairings with Zu speakers as I think I’m probably close to personally owning and trying roughly 20 different amp combos with them over the last 5 years or so. I still own many of the amps I’ve compared (I don’t seem to sell things as often as I should). One thing for sure is the Zus all do a phenomenal job reflecting the amp choices in front of them in the chain...and more so the further up the line you go with the Zus (the Druid 6s being the best at doing so of the 4 pairs I own).


Here’s my belabored point...

I’ve had my Druid 6s in 3 different listening rooms now since I’ve owned them. One was a smaller room with 9’ ceilings, the second in a medium sized room with vaulted ceilings, and the third a large room with 8’ ceilings. I’ve tried 7-8 of the same amps in each of the rooms with them. In every case, there were different strengths and weaknesses in the designs, albeit subtle in some cases, and my preferred "winning" amp changed. But the subtle differences are everything in this business.

In my current very wide listening space with the 8’ ceilings my preference pretty clearly floats to SET (PSET in the Audion case), with my Radu Tarta 45 having probably the most magic, followed closely by my Audion Golden Dreams. But the tubes used in these 2 SET amps make a TON of difference. With EML tubes in both, I didn’t prefer EITHER SET amp over the M60s in any of the 3 rooms. The Atma-Spheres are very very good (outstanding probably), but the SET amps eek out even more magic in this room, with these tubes (I’m using Gold Lion 300Bs in the Audions and NOS 45s in the Radu Tarta, so it’s not a matter of more expensive tubes).

I love Ralph and his Atma-Sphere amps and I can concur with their strengths. They are particularly strong when mated using great balanced cables to his MP-1 pre-amp which I own and have in my main system. My Atma-Sphere equipment is used, and both my pre and my amps have been upgraded by Ralph to his 3.3 versions, and the pre-amp has all available upgrades I’m aware of including the vcaps--my M60s do not have the vcaps. I’m sure the vcaps would make the M60s even better, but I don’t think it would change my opinion in this room. SET is beating them for emotional sound quality.

I consider the Prima Luna HP with KT150s a great push-pull amp, and while it also sounds phenomenal on the Druid 6s, I would put it just slightly behind the M60s in terms of my preferences.

I value front-to-back soundstage presence, sweet super-realistic vocal and tone, and string and piano percussive details and proper decay over the deepest bass control. So for me in this room, with these tube choices, the SETs still trump the higher-power Atmas and PrimaLuna push-pulls. I have the luxury of being VERY picky here, and as I stated, the results may differ for you in your room with your system and your preferences. I simply don’t think it can be cut and dry and universal for any amp recommendations here.

I don’t doubt Phil’s findings on some less expensive push pulls and maybe some day I will try one or two of those recommendations.
@parsons  The V-Caps are the most popular option with the M-60s. They do make the amps more involving- they just sound more real that way.
Ralph, thank you.  I'm probably going to get around to sending them in to you for those last upgrades.  As I said I really love them already and I know they've got more to give with the vcaps.  It goes without saying that your amps have endless power and should be in anyone's short list of great, emotional sounding amps, especially if you don't have the luxury of insanely efficient speakers.  There are also SET and SEP amps that have been in my system that I do NOT prefer even in my current dedicated space over the M60s.