When I received the Soul VI, I was struck by how beautiful they look vs the pictures I'd seen online. The dark Okoumé is a splendid match for my room's colour palette, size just right to be unobtrusive yet substantial. The peculiar shape of larger base and narrower cover creates a sense of stability and the coaxial drivers on top suggest light-house beacons.
The combination of wooden cab, black cones and silver trim makes for a perfect balance of modernity and classic timelessness. My wife approved as well so a big success. I won't go into detail about the Soul VI's design choices because this article is no formal review and Srajan covered these topics already in his writeup. The most significant characteristics relevant to my room integration exercise however are worthy of discussion.
First, the Soul VI is based on a full-range driver with a whizzer cone in whose throat sits a compression super tweeter high-passed at ~10kHz on a single-pole filter. There is no filter on the widebander. Second, the Soul VI uses a set of four finger-shaped downfiring vents to extend response to 38Hz. This demands careful tuning of the floor gap where material, carpet, taste (bass tightness vs reach and power) plus room response intersect.
The cabinet is made as a braced assembly of 12mm Okoumé Ply. This makes the enclosure inert enough that when combined with the Zu-Griewe bass management, it aims to make the Soul VI easy to install. Still, best results in any given room are achieved only after some dedication to speaker placement optimization. Luckily Zu provide a thorough systematic guide to what for the newcomer could otherwise be potentially confusing. They call their technique the Zu Mono and Mirror Method.
My initial positioning had the Soul VI at roughly 40cm from the front wall 2.5m apart, centred on the room's central axis so 1m from each side wall then toed in 30° to form a classical equilateral triangle. This can be a good starting point because if we don't get a cohesive sound field with solid centre fill, something is wrong with our system or room. In my case I was surprised by how good things were already at this point so I let a few days go by to familiarize myself with the presentation. Baseline established, I went back to ZMMM and followed its guidelines. The first step is for the bass and identifies with just one speaker playing, no toe-in or tilt, approximate wall distances. This is done by first placing our head close to the speaker at listening height, finding the spot where bass response is best balanced, then move to the listening chair for confirmation, exploiting the reciprocity of bass between the two. After a few iterations I ended up increasing the front-wall distance to 60cm. The second step aims at the midrange and involves, still in mono, mostly toe-in and potentially some minor adjustments of the XY position. The variables at play are colour and density changes in the midrange from recessed to intimate, from darker to more open. This led to less toe-in of ~20°. The last step focuses on the treble and what happens as we angle the driver to fire more or less directly at our ears. Again toe-in factors plus tilt. The latter also affects the floor distance so gap height. If we find that the best treble tilts the Soul VI up significantly, Zu recommend experimenting with risers to increase the elevation of the treble beam without disrupting bass response. After some nudging of the various angles, I reverted back to what I achieved previously, happy that no risers were needed since I actually sit quite low in my couch.
The next step was to mirror the second speaker's position and listen in stereo not mono. Compared to my initial equilateral triangle, this presentation now was indeed more open, with a larger deeper soundstage, treble somewhat more subdued and diffused, bass tighter and cleaner likely due to increased front-wall distance. Now I went back to the Zu Griewe tuning to check if I could get more oomph in the low bass without getting woolly. As I started to get familiar with the Soul VI character, I noticed how responsive, fast and alive they are, providing nice toe-tapping drive which I didn't want to compromise with slower-sounding bass. The reaction of the Soul VI to height changes was surprisingly noticeable, so much so that after starting with spacer coins, I returned to Zu's recommendation of paper sheets to have more adjustment finesse. The best compromise I achieved has a 12mm gap at the front and 5mm at the back. With this process completed which took less time than randomly winging it, I directed my attention mainly at tonal balance so some finishing touches to fine-tune the soundstage. As I mostly listen to acoustic music played in real venues so not studio productions, I value ambient recovery and expansive staging very much. The balance between a denser solid centre image which can feel claustrophobic and a more diffuse but larger soundscape which can produce fuzzier images and a side-lobed flat presentation lacking cohesiveness was a challenge. With the Soul VI, I got best results by bringing them out even further at 80cm, closer so 2.3m and with reduced 15° toe-in. The following observations reflect this final layout.
Zu Audio strongly recommend plenty of burn-in to stabilize both their mechanical and electrical elements. My pair came with several weeks of factory calisthenics but Sean indicated that this period was to be considered just a beginning. To be honest, I had no apparent signs of constriction or stiffness from the go but after a month of 4-6 hours of daily use including the TV, I was under the impression that the sound had become more fleshed out, rich and full especially at very low volumes. This capability of delivering satisfaction even at quiet levels is relevant to me as I can afford the luxury of concert SPL only occasionally. Hence my enjoyment would be seriously limited by a speaker that sounds dull or dead at low volumes. The Soul VI keeps most of its signature even at late-night levels and for me that's a definite feature. The two words that kept popping in my listening notes were engaging and pleasing. This sound comes across as rich, smooth, slightly dark, with a degree of warmth which to my tastes is just right to invite a spontaneous relaxed acceptance of the musical flow without causing excessive coloration or detail obfuscation. The upper midrange and treble present in a corporeal, smooth, slightly thick fashion. That prevented any sort of offensive bite to disrupt the positive attitude the Soul VI inspired. These won't invoke attention to detail or an intellectual approach to sonic analysis. Rather their allure is the holistic combination of energy, rhythmic liveliness and harmonic richness, with a strong centre of gravity in the upper bass to upper midrange region. Stringed instruments, especially the more masculine cello or double bass, and vocals both female and male convey with credible weight lightly on the denser side.
