Zu introduces Soul 6

I have a pair of Soul 6 arriving on Wednesday. I have Druid 6 and Definition 4 to compare it to. I'll post comments in a week or so.

Phil

I'm writing tomorrow. I did a detailed comparison with Druid 6 over the weekend, and listened to Soul 6 on ten different topology amps.

The high efficiency is unrelated to fears of forward midrange. That's a nutty idea. There are other factors in a speaker that can result in that but if a neutral 100db speaker sounds forward, you have problems upstream from the speaker.

Writing this up tomorrow.

Phil

When Druid 6 succeeded Druid 5, some people found the leap in vividness, obvious in the latter speaker, disorienting relative to the relaxed, gear-and-material-tolerant Druid 5 and 4 before it. The jump in quickness and transparency rewarded quality recordings and upstream gear, but no longer smoothed over some sins in source material and the gear chain. For a while, Zu sold both Druids 5 & 6 side by side to ease the transition and accommodate preferences. Druid 6 was clearly the better speaker, while Druid 5 was the more forgiving one.

Soul Supreme is essentially a Druid 5 re-engineered into a compact form factor and so Soul 6 is at least as startling an advance in musical vividity over Soul Supreme as was the case between the two Druids referenced. And just as with Druids 5 & 6, where the latter's cabinet engineering was key to the differences between the two, so it is with these two Souls.

Up front, before I get into details, some quick notes about the sound of Soul 6. It has the snap, slap and quickness of a membrane speaker but with the punch and dynamic shove of dynamic Zu. Zu rates Soul 6 for +/-3db response, 38Hz - 28kHz. Believe it. On music with 35Hz content, rolloff is not detectable, and with known 32Hz content, its presence is solid. Spatial projection in width, depth and height is massive when warranted, all the more impressive when you are listening while looking at small floorstanders in front of you, where the driver centerpoint is about 27" above the floor. The scale of sound doesn't make sense while you're looking. But there it is. Tonally, Soul 6 is musically authentic top-to-bottom. You hear the full pipe of the human body in a singer, not just the throat. Bowed instruments sound loaded with real texture. You get a vivid presentation of the material resonances of wood and brass winds & horns. Drums thwack and snap, kickdrums slam, cymbals crash and shimmer at levels of realism few speakers can match. And at 100db/w/m sensitivity, those impressions are easily made with 8 to 20w of amplification, though if you throw a big amp's output into it, Soul 6 can take it. I have done my listening with a variety of custom tube amps ranging from 6w-18w per channel: PX25 SET, EL156 and F2a single-ended pentode, 300B and 2a3 triode push-pull, Williamson-circuit triode-wired EL34 push-pull, Quad II push-pull tetrode. And for good measure I lashed a pair of M2tech Crosby Class D amps as bridged monoblocks for 180w+ into the Soul 6's 8 ohms load.

There are some misconceptions floating around online about Soul 6. Among them:

1/ Soul 6 lacks bass. Wrong. Some people who already own subwoofers give them up after buying Soul 6. If you aren't getting proper bass response from this speaker, you haven't set the Griewe Gap correctly. Read the instructions on Zu's web site.

2/ Soul 6 is too "forward sounding." Not once it's burned in. This is why Zu now requires 4 weeks on their punishing burn rig before shipping. If a customer wants them shipped sooner, they waive the 60 days eval period and it's a final sale. It can still backslide a bit when shipped in cold weather, so when you get them, use them -- hard. If you want, when you're out just put the driver covers on and stream something withering and loud. If burn-in effects backslid from low temps shipping, you can get them settled in in a couple of weeks.

3/ The sound is "down there," this floorstander being only 32" tall. Again, a burn-in issue. It took just four days for the vertical acoustic focal point to rise to the level of my Definition 4 speakers. The coaxial driver behaves very close to a point source, with vertical and horizontal dispersion the same.

4/ Soul 6 is a ported speaker. Incorrect. No Zu speaker in their line is ported. The long teardrop openings along the edges of the floor-facing baseplate allow the Griewe driver-to-room acoustic impedance matching scheme to "see" the room and work, and they do not behave as ports.

5/ Soul 6 doesn't have a supertweeter. It does, right there in the center of the driver where some other Zu speakers sport a phase plug.

6/ Soul 6 has a crossover. It does not. There is no electrical dividing network between the amp and the main driver. The supertweeter is on a simple high-pass filter with its roll-in corresponding to the natural roll-off of the Zu FRD.

Some shoppers and reviewers have trouble understanding Zu speakers in general and Soul 6 in particular. The gains in transparency, sonic scale and sheer aliveness delivered by both the newest Zu driver and the talk-killing okoume ply & stiff, light skeletal structure make plain flaws, or errors-in-engineering-judgment, in source material, as well as imperfections upstream of the speakers in some systems. If you think Soul 6 is "too forward" after complete burn-in, the recording you're listening to may be the source of your irritation. Especially if you are coming from a traditional crossover speaker with also a somewhat recessed midrange, the clarity and neutrality of Soul 6 can be initially disorienting. Depending what speaker you are migrating from, you may prefer a differently-voiced phono cartridge than what you're using. You might prefer a different filter choice on your DAC if that option is present. EQ customizations in Roon may have to be reconsidered and reset.

The Omen series of Zu speakers, along with Soul Supreme, natively have discernibly more of what people call "warmth" built in. This, and the 12 ohms and 16 ohms loads makes them pretty much "any amp" speakers. You can keep to your preferences, but very few amps will not sound good on those speakers, including the revival of 1970s Japanese receivers via Ebay and pawnshops. Soul 6 requires more consideration in matching to amps. Its uncompromising transparency, detail portrayal and snap rule out any amp with a rough top end or slow and bloated bass. If an amp is inarticulate and prone to congestion or losing threads in complex music, there is nothing in Soul 6 to cover for it. This does not mean you need an expensive amp for Soul 6. You just need an amp that is musically-convincing, clean and pleasing to you. Questions about using Soul 6 with low power amps come up in my message box here. Sure, you can wire a 2w/ch 45 tube amp if you're willing to listen within its dynamic requirements or your room is small. I prefer the 8-25w range to really enjoy the dynamic elasticity and explosive potential in a Zu speaker. And no, Zu speakers aren't strictly for tube amps. There are lots of Zu owners rocking solid state, though high-damping amps of any kind often can sound inelastic and forced. Good Class D can be great. The speaker is very well controlled with modest-damping-factor amps. Just understand, that depending what you are migrating from, and the extent of your audiophile proclivities, dropping Soul 6 into an existing system may well drive one or more changes to the gear chain upstream.

But, take some time to work with Soul 6 and you'll experience the quickest, most responsive, Zu speaker to date, along with all the normal Zu traits in tone and musical authenticity you expect. Now these notes are for us hifi geeks here. There's another constituency for this speaker: plain music lovers who want to buy a speaker they can easily place in an apartment, get some affordable electronics and source(s), love that it's compact and looks great in all the combinations of finishes and colors Zu offers. That constituency is as interior design driven or style-conscious as they are concerned for good sound. And they love the mid-century (the last one) clean simplicity of Soul 6.

One question that often comes up regards the comparison between Soul 6 and Druid 6. When Sean Casey first told me about Soul 6, he said "This is the best speaker we've ever made." I asked, "Really; you think it's better than Druid 6? Hard to believe." His answer was to say, "OK, that I'll have to think harder about."

Soul 6 does some things a little better than Druid 6. It's somewhat but discernibly quicker on transients and other dynamic shifts. It's 1 db less efficient than Druid 6 but its speed makes it seem a tad more explosive. Its supertweeter is rated out to 28kHz whereas the Radian 850 in Druid 6 is really great to 18kHz and struggles to get to 20kHz. So there are some true phase-improving low ultrasonic effects, which are subtle and not because you're hearing the extra 10kHz of content directly. There's a little more slap and snap to bass and percussion in Soul 6 than Druid 6. BUT, Druid 6 is as a whole the better speaker. The more expensive Druid has fuller and denser tone than Soul 6, particularly vocals and strings. It conveys electric guitar more compellingly, a keynote for me. Druid 6 bass response is slightly deeper. It can dip just below 30 Hz. The Radian 850 gives Druid 6 more harmonic grace than the Soul 6 supertweeter. And as fabulously as okoume + Zu engineering slashed cabinet talk in Soul 6 over prior Souls, the complex, proprietary multi-materials, hand-laid Druid 6 cabinet ply has even less. Druid 6 sounds more planted, grounded and that may be in part because of its greater mass and thick aluminum plinth. In a correspondence with Zu I summed up Soul 6 as having "the agility of a hummingbird and the presence of a wooly mammoth." They used that in some marketing language. Well, Druid 6 adds to that menagerie some of the added sonority of a blue whale.

Soul 6 gets far closer to Druid 6 at $6000 vs. $11,500, than the price difference suggests. I had a 1st-time Zu listener visit over the weekend. He was very excited about Soul 6 but is not strictly price driven. He wanted to hear Druid 6 too. It took only seconds for him to say, "I think Druid is worth the extra cash; it sounds even more natural than the Soul." And yes, I agreed. That said, if I had one hifi system only, and didn't have room for Druids and Definitions, I could build it around Soul 6 and listen all day long for years ahead. Soul 6 is an outstanding and landmark speaker that can satisfy the broadest swath of buyer interests of any speaker Zu makes today. It fits anywhere, it costs enough to be great but not so much as to be unreachable, and it works equally well on any genre of music that's produced at least reasonably well.

One last thing I have to point out. Zu's cabinetry is impeccable and their finishes look and feel fantastic, especially the mirror gloss, for anyone who can splurge on that. But even the base finishing is beyond reproach. They are shipped with outstanding protection, unpack easily, and at just 39 lbs each and 32" tall, setup is a one-person job. If you can do it, sooner or later add Zu B3 speaker cables. Once you hear and own Soul 6, if you want to shade them for smoothness over spotlighted detail, do your cable loom in Zu Mission. If you want to fully leverage the speaker's hear-through clarity to the utmost, build your cable loom in Zu Event II. Or mix Mission and Event to taste and budget.

My listening for these notes includes vinyl, ripped CDs, CDs, Bluray Audio, SACD, movies from Bluray, Netflix, AppleTV, and music streaming via Auralic streamers and Bricasti DACs.

Note: When you buy any Zu speaker that is Griewe based, download the updated instructions from Zu to guide you through setting the Griewe Gap between the bottom of the speaker and the floor. Getting it right affects more than just bass, but bass response is your first clue you're in the zone.

I must have missed something. If so, I'll add it in the comments.

Phil

Amps:

• Williamson. This is a classic push-pull circuit that debuted in 1947. If you have owned a vintage or modern push-pull EL34, KT66, 6L6 amp, you know the realm. My pair are wired for triode output operation. 18w.
• Quad II. I have both made-in-UK by pre-Asian-owned Acoustical Manufacturing Ltd, and Xiao Nan's top clone updated via his proprietary transformers. 12-15w, depending how measured.
• 300B and 2a3 push-pull triodes: Lots of variety in how this genre sounds, both in transformers and circuit execution, as well as in what power tubes you choose. Mine are quick, modern, rich and smooth. 18w and 13w respectively.
• The F2a amp is a modern clone of the old Klangfilm 204 studio/theater single-ended pentode amp, in this case minus one voltage amplification stage and with better transformers. Shindo also makes a couple of F2a amps. Mine are fast, linear, revealing. 10w.
• The EL156 single-ended amp isn't a clone of a vintage circuit. It's a Xiao Nan design leveraging a vintage tube not well known in the US. It was introduced in Germany during the '50s tube wars to compete with the KT88 and 6550. It, along with the F2a, are among the Deutsche Post 10,000 hours tubes. It was and remains one of the best, most linear power tubes ever made. Clean and strong. 18w.
• PX25 SET. This is a Xiao Nan simple circuit, with AC filament so it has a little hum still to be tuned out. 6.5w. If you've owned or heard a modern single-ended triode amp, you know the realm.

Analog: On both of my systems, each is equipped with a Luxman PD444 direct drive turntable. This is one of the 1970s Japanese legends. The 444 accommodates two tonearms. One has a Stax UA70 long arm and a Thorens TA-110 standard length. The Stax has an Ortofon SPU -A Gold; the Thorens a vintage Denon DL103M or DL305. The other Luxman has Victor (Japan) UA-7045 10.5" tonearm and a Victor UA-7025 std length. The 7045 carries an Ortofon SPU Meister Silver; the 7025 a Zu103. I sometimes trade out one of the long arms for a Thomas Schick carrying an Ortofon SPU Meister Silver with a Ruby cantilever. There are a handful of other cartridges that see less time in grooves.

Phono preamps are Nagra BPA, Parks Audio Puffin, Soundsmith MCP-2 Mk II, M2tech Joplin II phono ADC fed into DAC.

The Definition 4 system uses a Luxman TVC for linestate control. The Druid 6 system has a Melody HiFi Pure Black 101 6sn7 linestage in the preamp role, stuffed with unobtainium 1944 production Sylvania metal-base chrome domes.

The Bricasti DACs are M21 Platinum and M1LE-Gold.

Phil

rhythmnsound,

I owned quad ESL-57 and then stacked ESL-57 40 years ago. Loved them. WIth the right tube amplification and absent deep bass cravings, that is a compelling combination that spoils you for many modern alternatives, within SPL and dynamic limits.

I got into Zu 18 years ago after a multi-decades search for something that would deliver the immediacy of Quad ESL, crossoverless lack of choke points, and with the dynamic shove of an efficient dynamic speaker. From 1980 to 2004 that wasn't available, so I settled on reasonably-efficient 2-way systems. I also ran those Quad ESLs on a precursor to Atmasphere -- Julius Futterman hand-built OTL monoblocks, so we're roughly on the same page if time is offset by many years.

I have listened to many Devore-based systems. The central problem with Devore is poor integration of the behaviors between drivers. Particularly, the woofer behaviors are laggard, so in every Devore speaker I've heard, one hears disparate driver behaviors accentuated by bloated bass that just throws off any chance of coherency. I hear the crossover choke points over unified tone and time/dynamic behaviors, and the differences in tweeter and midrange dynamic behoaviors.

The Marantz 8b can sound old school and slow with certain tubes. If you are aiming for that quick, articulate, acrobatic Quad ESL sound from that amp with a dynamic (Zu) speaker, stuff it with the STR-450 EL34 tube Mesa Boogie sells (NOS last production Siemens/Germany). They are hypertested, reliable, crisp, clean, fast and toneful.

Once you do that, amp attributes accrue to Zu speakers. If you can't do Druid 6, Soul 6 is Zu's most lightning-quick, agile, acrobatic, responsive.speaker, and when you get the Griewe floor Gap adjusted, it's good for easily recognizable 32 Hz tones with an expansive, point-source dispersive soundstage

Point is, if you appreciate the agility of stacked vintage Quad ESL-57s, Soul 6 or Druid 6, or for that matter any Zu speaker is the closest dynamic equivalent for practical use in domestic spaces, and it will blow away the Quad on dynamic elasticity, tonal realism and convincing bass.

Phil

rhythmnsound,

I’ll add that I’m a 50+years guitar player and both acoustic and electric guitar sounds are critical to my impression of authenticity.

All the Zu speakers do electric guitar via specific guitar amps unusually authentically. Soul Supreme will do that do. Soul Supreme is more amp-friendly for a wider-variety of amps due to its 16 ohms impedance and beautiful Radian 850 supertweeter that rolls off beyond 18kHz. The Soul 6 hides nothing but also reveals everything you crave. It’s quicker, punchier and delivers more harmonic air. But it won’t cover for trouble cascading from upstream in your gearchain -- nor from a terrible recording.

But if Quad ESL is your measure of sound, Soul 6 is the most unified, articulate, electrostatic-quick dynamic speaker I know of, except it delivers more tone.

Phil

@aberyclark The ODS requires the plinth because the Radian 850 used as the supertweeter makes the speaker more top-heavy than standard OD, but the upgrade is well worth it. Much more harmonic grace with the Radian 850.

@rhythmnsound If you buy Soul 6, they ship after 4 weeks in Zu's intense-abuse burn rig. It's not just the driver but also the internal wiring harness that needs it. In fact, the concentric-supertweeter FRD is so transparent it makes the need for burn-in of the dielectrics more obvious. I mention this because if you buy during cold weather shipping, that will cause some backsliding on the benefits of burn-in. If that happens, you may notice some initial stridency in a band bounded roughly by about 600 Hz - 1500 Hz. It is not the same sound as horn shout but is in the realm, and of course the supertweeter has nothing to do with it. The other thing if burn-in backslides is that the speaker will throw a low soundstage initially. I just pushed them hard for a couple of weeks. Every time we went out for a few hours I put the protective driver discs on, turned on ESPN and cranked up the volume on their bombast. In the first four days, the vertical focal point of the soundstage notched up until by the fourth day it was projecting to the same vertical point as my Definition 4s on the same music and movies. That narrow midband stridency faded day by day until it was gone after about 2 weeks. Settled in, Soul 6 is remarkable not for any horn colorations but for its objectivity, transparency, cat-like agility and sheer rhino force even with modest-power amps. The supertweeter is only a factor above 10kHz.

Quad ESLs certainly have somewhat more finesse on delicate details than any dynamic speaker, but Soul 6 gets very close and in turn the Quad cannot even remotely match the Zu's frequency extensions top and bottom, nor its dynamic elasticity and ability to project acoustic force. Soul 6 also doesn't have the Quad's single-seat beaming. You have much more flexibility for placement and the prime listening window gives you seating latitude for communal listening.

@snapsc I haven't heard an open-baffle speaker that has quite the objectivity and tone equal to the crossoverless Soul 6. The partial dipole nature of dynamic open baffles helps with live-like spaciousness along with placement complications in many rooms. The Zu has that similar spatial projection without the room placement problems, plus bass is very well controlled. Where Soul 6 and good open baffles are similarly spirited is in the openness, agility and jump factor heard from both.

Phil

@kingofgix  Soul VI will take you further in terms of leveraging ongoing evolution of your system and I don't see any reason you can't mate it with your existing system, the W4S DAC probably being the component you'll eventually come to upgrade. But Soul Supreme is definitely the more forgiving of upstream compromises (including source material), of the two speakers. Its Radian 850 supertweeter is harmonically graceful but does not equal the extended frequency response of the Soul VI tweeter. Also, if you run the Soul Supreme at its native 16 ohms impedance, eschewing parallel loading resistors, your Hegel's output will be reduced roughly in half but a lot of solid state amps sound a little cleaner and smoother into 16 ohms than into 8 ohms. It's not major but can be noticable.

One option you have is to buy Soul 6, taking advantage of Zu's 60 days return policy, and if you feel you need to back off on vividness a bit, you can order Soul Supreme if you come to that conclusion about Soul 6.

Phil

@kingofgix The Yggdrasil is a good DAC at its price. But if you are planning to spring for that I suggest you consider the mhdt Pagoda Balanced instead. I had a chance to directly compare both R2R DACs for three months. Both have organic, natural sound. The mhdt was better dynamically and does a noticeably better job of remaining uncongested in any combination of musical complexity and dynamic surge. The Yggdrasil's one slight advantage was in rendering deep bass, but on full orchestral works or even "stadium" rock, it smears events and loses instrument threads during crescendos while the Pagoda kept its composure and conveyed the weave intact. You also get some latitude to tune the Pagoda via choice of the output buffer tubes.

The comparison was made using tube adaptors to enable use of 6922 tube types in the 5670 sockets. That's key. The Pagoda retains its uncongested advantage with certain 5670 tubes but is dynamically burstier and more explosive, plus throws a larger soundstage, with a good 6922-type installed.

Then there is the matter of whether to spring for a Pagoda or Pagoda Balanced. If you don't have a balanced system, the single-ended Pagoda is fine and saves some cash over Pagoda Balanced or Yggdrasil. Theoretically, there is no reason to use a Pagoda Balanced in a single-ended system since via single-ended outputs you are only using half the circuit. But, having had both Pagoda Balanced and single-ended Pagoda (two systems), I found that Pagoda Balanced in a single-ended system sounds discernibly better via XLR>RCA adapters than via its own single-ended outputs or a Pagoda. So, given the price similarity, if you are prepared to buy an Yggdrasil, I suggest a Pagoda Balanced and a pair of balanced output adapters instead, along with 5670>6922 socket adapters and a nice pair of NOS 6922 or CCa tubes. If sticking with 5670 tube types, Raytheon 2c51 or Bendix 6385 come closest to what can be obtained using 6922 types.

Phil

It has a supertweeter. The supertweeter is concentric in Soul 6, like in Cube. The largest advance is due to the completely redesigned cabinet. Okoume is both lighter and stiffer than the materials used in all prior Soul speakers. This allows an extensive revision to the internal bracing scheme, and a more complete implementation of the Griewe room acoustic impedance matching, for the Soul cabinet configuration. Okoume is also a primary driver on the cost difference over current Soul Supreme, including both the material and the increased labor to work it. Resonance control & energy management. in the entire system is better than Soul Supreme. I expect to like it.

Phil

Most systems have too much total gain, and this is independent of amplifier power. If you have separate preamp and power amp, the input sensitivity of the power amp and the output voltage of the preamp have to be considered to get useful range out of the volume control. You could have a 2w amp with an input sensitivity of 0.5v paired to a preamp with 10v out and find the system very annoying to use. On the other hand, you could have a 200/200w power amp with an input sensitivity of 3.5v combined with a preamp with 2.5v out and find that the preamp runs out of drive before the power amp can be driven to full power.

You can also find 12ax7 preamp circuits that have relatively low total gain. Many high efficiency speakers have low or only modest power handling. Zu speakers combine high efficiency with high power handling so large amplifiers aren't a problem, but they aren't necessary either.

There are other ways to solve this problem. One is to use a TVC or AVC for the linestage, so that you maintain the drive in the system without adding gain, or only a little (+6db). If for other reasons of your own you choose to combine a high gain preamp with a high gain power amp, you can use high quality attenuators between the two. Or you can choose a modest-gain active preamp (~10db - 12db) with a moderate-gain power amp (~22db) and have a usable system regardless of power level.

The cone of the Zu Soul 6 main driver is wood pulp (paper) based treated with nano materials. As Zu explains it, "...The driver’s cone is a paper pulp substrate, processed with a liquid solid matrix utilizing several nanoengineered materials. Some key components and compounds include: nanosphere ceramics, synthetic epoxy, cristobalite, plus the use of amorphous fumed silica and aircraft dope. The nano materials and application process reduce weight and increase strength and propagation velocity without incurring any sacrifices in damping..."

The nano materials and the carrier evolve as Zu drivers evolve. Like all Zu main drivers, the new Soul 6 driver (including the whizzer) covers the range of 35 Hz - 12kHz, with the range above 12kHz handled by a supertweeter on a high pass filter. In the Soul 6, the supertweeter is mounted concentrically in the center structure of the full range driver.

This is not a simple paper cone driver. It retains the tone and texture of paper, with the lightness, strength, stiffness of synthetic and metal cone materials that otherwise don't sound as good. The concentric driver behaves as a point source, and the okoume ply cabinet is as critical to the vivid, lifelike sound of Soul 6 as the latest main driver is.

Phil

Just an intermediate note here, prompted by Steve Guttenberg's evaluation on Youtube. There are some descriptive inaccuracies and setup errors, and one inadvertent error by Zu at the outset.

First, he has difficulty explaining the Soul 6 design. He refers to the supertweeter being "crossed over" and then tries to explain that the speaker doesn't have a crossover. If Steve simply and correctly noted that the supertweeter is on a high-pass filter, that whole word salad could have been avoided. He also refers to Soul 6 as a "bass reflex" design, mischaracterizing the Griewe driver-to-room acoustic impedance matching scheme.

It goes wrong in some vital ways from there, but Guttenberg does get the immediacy, speed, articulation, dynamic slam and tone factors. 

I am listening to a pair of Soul 6 right now. Steve says he couldn't get satisfactory bass from his pair at the more open end of his room, claiming roll-off at 57 Hz. Not me. Even before I got into making setup adjustments, just plopped on bare floor right out of the shipping cartons, Soul 6 showed solid 35Hz bass where present in music, and useful, audible response of 32Hz content in a relatively unbounded room, verified with 1/3rd octave visualization. Further tuning of the Griewe gap to the floor improved bass response and quality further. Why was real bass easy for me and elusive for him? Hard to tell through a procedurally-light video commentary.

Guttenberg then claims the speaker sounded best if he sat on the floor, complaining of tonal shelving at his seated height. So in an effort to fix that he and a buddy got the idea to tilt back the speaker, using long spikes on the front and the stub bolts on the back. Well, now the Griewe scheme can't work quite correctly and it influences the FRD well into the midrange.

I'll post complete comments on this speaker after I put them through some further violence to complete the break-in process Zu started. I think Zu erred by shipping Steve's Soul 6 pair too soon, and mine too. Their standard 2 weeks continuous burn-in turns out not to be sufficient for this new concentric driver, and stopping there leaves a narrow-band midrange stridency that gets wrung out by doubling the burn-in regimen on Zu's rack. A week in, the resulting glare is receding for me but it's taking extra effort to apply the necessary abuse. Hence Zu is going to require 4 weeks of break-in at the plant before delivering Soul 6. Druid 6 was very much the same way initially. Zu did 2 weeks of burn-in on their rig, then it took another nine months for my pair to fully stabilize. Zu shipped Steve's speakers too soon. Steve shot and posted his review too soon. Until the new-cone stridency is wrung out, the speaker will sound too forward on lots of modern recordings.

To a Druid or Definition listener, the Soul 6 acoustic focal plane will be perceived as lower than those speakers that have FRD output above ear level, but again as the speaker opens up during break-in, that focal plane drifts higher. On my couch, my ear height, seated, is about 39" off the floor. The Soul 6 floor to centerpoint of the concentric FRD is about 27". But after the first 3 days, TV and cinema dialog accurately attached to visuals on a 60" display mounted with vertical center at 44". The speaker scales well spatially and dynamically. Depth is not lacking. Right now I have the Souls 10 feet apart and the center still holds. Dispersion in all directions is better than for any single-driver Zu speaker to date.

But you have to get a complete break-in on them, respect the Griewe gap, and preferably not choose an overdamped amp. So far I've been listening to custom tube amps 10w - 18w (p-p triode, single-ended pentode), and 180w M2tech Crosby monoblocks (meting out the flogging). My experience is that all of the Zu concentric tweeter speakers demand more careful amp selection than the non-concentric tweeter models, even going back to the original Zu Cube. Soul 6 is no exception. More later.

Phil

The design is sound, and highly considered. Like anything, it just has to be used correctly. If it is, then what people like comes into play. -Phil

Incomprehensible. Always a riddle wrapped in a mystery inside an enigma. OK, Churchill said that, but it applies here.

Phil

Soul Supreme compacts Druid 5. Soul 6 compacts the sound of Druid 6. with the newer concentric driver. Druid 5 was a relaxed, easygoing, amp-tolerant speaker, more open and elastic than Druid 4. Druid 6 is strikingly more vivid, energetic, revealing and requires more thought about the gear train that comes before it, particularly the amplification. Soul Supreme and Soul 6 have a corresponding relationship.

One would expect a $6000 (Soul 6) speaker to both be more vivid and revealing than a $3800 (Soul Supreme now) one, and so it is. That difference is an opportunity but it also means that while both can work well in your room, Soul Supreme is less likely to prompt one or more changes in associated gear when plopped into an existing system.

Phil

 

 

Zu speakers don't need high power but they can benefit from it on some music if the amp doesn't give up too much qualitatively to deliver power. I usually listen to 10-18w single-ended pentode and push-pull triode or pentode amplification on both my Zu systems, but keep a pair of solid state monoblocks around (~270w into 6 ohm Def4; 90w into 16 ohm Druid6) for certain uncorked experiences. Of all the Zu speakers, the Soul Supreme will certainly be a different presentation than your Harbeth, but also the Zu closest to it. Soul Supreme is a 16 ohms speaker so your Hegel 390 will see its power reduced to ~125/125w, a considerable cut since the Harbeth is a 6 ohms speaker, raising your amp's potential output to about 375/375w into that load. Still more than you need for Zu but less overkill. You may find it sounds a little cleaner into the Soul Supreme's higher impedance.

The Soul 6 pair I am listening to are nearly settled enough for commentary, so I'll post more in a week or so.

Phil

I'm giving my pair of Soul 6 another week or 10 days to further settle in, then I will post complete comments, including some comparative notes relative to Soul Supreme, Druid 5, Druid 6 and Definition 4.

Phil

Yeah. Busy. I am having a small crowd in on Saturday so I can include a summary of external perceptions.

The speakers are fairly well settled in, but still not fully burned. Zu has come to the conclusion that the Soul 6 is so transparent it is revealing consequences of insufficient burn-in of the wiring harness. Pretty close now, especially on single-ended amps.

Phil