VAF Research Signature i91 MKIII Bookshelf Speakers review

VAF Research has been designing and hand-building loudspeakers in Adelaide since 1978, giving the company a long and continuous history in Australian hi-fi. Its range spans everything from accessible standmounts to serious high-end floorstanders, and the Signature i91 has held a particularly enduring place within it.

First introduced around 1999, this large standmount has been tinkered with over the years, benefitting from iterative upgrades all in the pursuit of the best-possible sound.

I certainly went into this review with high expectations as my previous experience with VAF’s more affordable DC-2S standmounts (AHF #543) revealed the company is capable of delivering impressive imaging and musical engagement. Given the Signature i91 MkIII on review here is a far more substantial proposition in both price and size, I was already filled with excitement before I’d even unboxed them.

EQUIPMENT

This MkIII version was introduced around 2021. VAF doesn’t necessarily market it as an entirely new speaker, but rather a refined continuation of a well-established formula.

It’s certainly retained its physical presence. This is a substantial standmount speaker in every sense. Standing 440mm tall, 220mm wide and 360mm deep, and weighing 15kg apiece, the Signature i91 MkIII is considerably larger and more solidly built than the average bookshelf design. As a result, each speaker arrives in its own carton, and getting the 15kg cabinets safely onto suitably heavy-duty stands is best treated as a two-person task.

The weight is not solely the result of MDF panels measuring up to 36mm thick, but also VAF’s substantial internal bracing. VAF adds the Signature i91 MkIII uses precisely mitred joints, substantial internal cross-bracing and its own Hypersoft damping material, all intended to suppress internal reflections and standing waves. The combination, says the company, “ensures maximum attenuation of any internal standing waves”.

The pair supplied for review wear VAF’s handsome Feature Eucaplypt timber veneer, priced at $5,158. I cannot say for certain whether it was the finish itself, but unboxing them produced an unexpected first: I noticed the smell of a pair of speakers! It was a pleasant, warm timber aroma — an oddly specific detail, perhaps, but one that immediately reinforced the sense that these were carefully finished objects rather than boxes from a production line.

The surfaces are equally enjoyable to touch, smooth as anything, with an attractive sheen that brings the grain to life. Alternative finishes include Black Oak, American Cherry, Tasmanian Blackwood and Australian Jarrah; having experienced the Feature Eucaplypt, I am now rather curious how those smell, too!

Once they were out of their individual boxes and on some stands, it was pleasing to see the i91 MkIII marry a good aroma with stunning looks. They adopt a similar visual aesthetic as the more cost-friendly DC-2S, which in turn proves they are unmistakably a VAF design. And if you weren’t too sure on first look, just take a glance at the bottom-right corner and you’ll see the company’s logo taking pride of place.

At the centre of the i91 MkIII is a 170mm coaxial driver, manufactured especially for VAF by SEAS in Norway. SEAS — short for Scandinavian Electro Acoustic Systems — has been producing loudspeaker drive units since 1950, and its engineers developed one of the earliest soft-dome tweeters in 1968. The company was also heavily involved in the production of the Dynaco A-25, released in 1969 and which went on to become one of the best-selling loudspeakers in history.

The driver in the Signature i91 MkIII combines a polypropylene woofer with a Sonomex soft-dome tweeter mounted at the cone’s centre — the same coaxial driver features in the smaller, more affordable Signature i90 too — while the crossover uses hand-wound copper inductors.

Such a configuration allows VAF to achieve its goal of time alignment, since the tweeter and woofer share the same acoustic centre, meaning their output arrives together more consistently than in a conventional multi-driver array. VAF says this has further benefits, including broadening the general listening area, as opposed to delivering sound to a ‘sweet spot’. Indeed, VAF’s Head of Sales, Mike Ziersch says “With coaxial drivers, pretty much everywhere is the sweet spot!”

The i91 MkIII uses dual front-firing bass-reflex ports, positioned above and below the coaxial driver, meaning they’re a little more forgiving when it comes to placement than rear-ported designs. It doesn’t mean you can or should immediately place them up against a wall of course, as the cabinet’s proximity to room boundaries will still have an effect on bass and tonal balance, but you at least get a little more wriggle room.

Around the back, a substantial full-height terminal plate projects from the cabinet rather than sitting flush with it. It accommodates two pairs of gold-plated binding posts for bi-wiring or bi-amping; the review pair arrived bi-wired. Conventional single-wire connection remains possible — the terminals accept bare wire, spade, and banana plugs — but the arrangement gives owners scope to experiment with cable routing or separate amplification for the tweeter and woofer sections.

VAF quotes a 45Hz–18kHz frequency range for the i91 MkIII, that low-end figure no doubt being a byproduct of the generous cabinet volume and twin ports. It suggests the i91 MkIII can cover most music with convincing bass weight without immediately requiring a subwoofer, although listeners wanting the lowest rumbles or home-cinema ambitions may still want a dedicated sub.

It is worth distinguishing the standard i91 MkIII from the externally similar i91 MkIII SE. Both share the same cabinet and coaxial layout, but the SE is effectively a more comprehensively upgraded variant. It employs VAF’s newer high-excursion magnesium-alloy woofer and magnesium-alloy tweeter. Its crossover is necessarily redesigned around those different driver materials and also uses higher-specification Solen and SCR capacitors in critical signal paths. Internally, the SE receives van den Hul 12AWG silver-coated copper cable — the same wiring used in VAF’s flagship Signature Series floorstanders — whereas the standard i91 uses high-quality 12AWG OFC copper.

On paper, the SE promises greater bass impact and more midrange and treble detail, while the company describes the regular model as the more delicate and relaxed of the two, with excellent imaging and soundstaging. In fact, VAF goes as far to say the regular Signature i91 provides a “level of accuracy and performance not seen in any other loudspeaker at their size or price”.

The i91 MkIII is rated at a relatively accommodating 90dB sensitivity and a nominal 6-ohm impedance, making the process of selecting partnering equipment relatively simple. For this review, it was partnered with Marantz’s Model 50 integrated amplifier, with 70W-per-channel output into 8 ohms, rising to 100W into 4 ohms.

LISTENING SESSIONS

For my listening, I placed the VAF Signature i91 MkIII approximately 25cm from the wall behind them (measured to the rear terminal plate). And, since the company’s coaxial-driver arrangement is intended to maintain time alignment across a broad listening area rather than concentrate performance into a narrower sweet spot, I left them firing straight into the room, rather than being toed in towards a listening position.

I had an absolute blast spending time with the VAF Signature i91 MKIII. Alongside familiar favourites, the speakers had me flicking through old playlists and uncovering forgotten classics — always a good sign. Rather than feeling like they demanded “audiophile” recordings to impress, the i91 MkIII made me want to keep listening to anything and everything, from high-energy dance tracks to slow and sultry ballads. Fortunately they lapped everything up that I could throw at them.

One such rediscovery was Alt-J’s debut album An Awesome Wave. I admit I was never completely sold on the group when they hit the scene way back in 2012, which was a little annoying at first because my friends could not get enough of them. Whenever one of them was the designated driver for a day out, Alt-J was almost inevitably playing. The band eventually did grow on me however, and ‘Taro’ is now one of my favourite tracks.

When played through the VAF i91 MKIIIs, ‘Taro’ was delivered with exceptional cleanliness and organisation. The track’s shifting, irregular rhythmic patterns remained easy to follow, with each instrumental element afforded enough space to make sense of the arrangement as a whole.

The speakers had no trouble separating the higher frequencies from the low bass line, preventing a tangled mess, which gave the song a controlled and open presentation.

Music was streamed from Tidal Connect to Marantz’s CD 50n network CD player, before being passed to the Model 50 integrated amplifier. However, most of my song choices came from my expansive Apple Music playlists (I’m still holding out hope for an Apple Music Connect feature one day). The main one I used for this review comprised thousands of songs that were once on my Spotify account but that were eventually migrated over to Apple’s service some 10 years ago. After I left Alt-J, I came to the Cs and Chris Rea — on went ‘The Road to Hell Pt. 2’.

Rea’s crooning vocals and instantly recognisable melody allowed the i91 MKIII to show off its more restrained strengths. The opening melody carried a lovely warmth, while the overall presentation was detailed, clean and natural. What impressed me most however was the fact the speakers never once seemed to overdo it. They didn’t once feel as though they were trying a “hey, look at me” performance, rather they simply revealed the track with relaxed confidence.

While it may be that, on paper at least, the standard i91 MKIII is less bass-capable than its SE counterpart, I nevertheless wanted to really test the low-end capabilities because, with my initial playthroughs, it seemed plausible that the speakers might benefit from a subwoofer to add more low-end authority.

Billie Eilish’s ‘bad guy’ quickly challenged that assumption. The i91 MKIII immediately used the large enclosure and ability to get down towards 45 Hz extension to its advantage, delivering the track’s pulsating bass line with depth and energy. There was ample drive and punch for a properly zealous listen, yet Billie Eilish’s vocal remained crystal clear and precisely placed above the heavy bass foundation.

Fat Freddy’s Drop’s ‘Shiverman’ took the VAF Signature i91 MKIII further still, revealing another level of low-end capability. The speakers were able to dig deep into the track’s dub-influenced bass without losing their sense of control or cohesion. Rather than merely producing more bass, they retained the separation and rhythmic poise that made earlier tracks so convincing, allowing the groove to feel weighty, immersive and genuinely physical.

The i91 MkIII’s strengths were not confined to close, focused listening at enthusiastic volume either. I moved my seating position back to around five metres, and even when reducing the Marantz Model 50’s output, London Grammar remained strikingly clear and communicative. On ‘Stay Awake’, in particular, the speakers preserved the delicate texture of Hannah Reid’s voice, while the track’s dynamic shifts retained their impact without requiring high playback levels. Of course, increasing the volume only had a positive effect, but I was pleased to find the Signature i91 MkIII had little trouble firing into a large space.

CONCLUSION

For all their talents, what I ultimately took away from this review was the knowledge that the i91 MkIII has an uncanny ability to make music feel inviting. The speakers keep every element of a track easy to follow without stripping away its warmth, character or sense of fun. They can deliver proper low-end impact, too, without allowing bass to obscure everything above it. They are truly wonderful speakers to listen to, to look at — and, apparently, to smell. I can also readily imagine them being a pleasure to live with.

LABORATORY TEST REPORT

Readers interested in a full technical appraisal of the performance of the VAF Signature I-91 Mk III Loudspeakers should continue on and read the LABORATORY TEST REPORT published on this page. Readers should note that the results mentioned in the report, tabulated in performance charts and/or displayed using graphs and/or photographs should be construed as applying only to the specific sample tested.

Newport Test Labs measured the in-room frequency response of VAF Signature I-91 Mk III Loudspeakers using wideband pink noise as the test stimulus, with the measuring microphone at a distance of one metre from the tweeter, on the tweeter axis.

The result of this test is shown in Graph 1 (above), and you can see that the response extends from 44Hz to 20kHz ±3.5dB. This is an excellent result under any circumstances, but made even more impressive because the speaker was tested on a stand, remote from all wall boundaries. If the speakers are positioned on a bookshelf or on stands close to a wall, the already impressively extended (for the driver diameter and cabinet size) bass response would be extended downwards even further.

The low-frequency performance of the single co-axial driver in the VAF Signature I-91 MkIII is shown in Graph 2 (below), where Newport Test Labs has used a well-known nearfield measurement technique that replicates the response that would be obtained if the driver were to be measured in an anechoic chamber.

You can see that the response of the bass/midrange cone starts rolling off at 70Hz, but is extraordinarily flat above this frequency, right out to the graphing limit of 500Hz, essentially being within ±1.5dB between these two frequencies.

Although the output of the cone starts rolling off at 70Hz, you can see the outputs from the two front-firing bass reflex ports (the red and blue traces on the graph) both peak at 58Hz and provide appreciable energy from 35Hz to 90Hz, essentially extending response downwards and reinforcing the bass response.

It’s notable that despite being located at opposite ends of the front baffle, the outputs from the ports are almost completely identical, so VAF has obviously taken considerable care with the internal design of the enclosure to deliver this result. There is evidence of a slight port resonance at around 260Hz, but it’s very slight and has minimal effect on the overall frequency response of the system.

The overall impedance of the VAF Signature I-91 MkIII is comfortably in ‘nominally 8-ohm’ territory, with Graph 3 (below) showing that the impedance (red trace) drops below 8-ohms only between 120Hz and 500Hz, and then only to a minima of 6.9-ohms at 200Hz.

The slight glitch on the impedance trace at around 260Hz is additional evidence of the slight resonance mentioned previously. The phase angle (orange trace) is very well controlled to within ±30-degrees right across the audio band, which is excellent. Newport Test Labs’ individual measurements of the low- and high-frequency sections of the crossover (the blue and green traces) show that the electrical crossover point is at 2.4kHz.

The efficiency of the VAF Signature I-91 MkIII, as measured by Newport Test Labs, was rather lower than average for all hi-fi loudspeakers (which is 87dBSPL), but about spot-on for the average of two-way designs in small-to-medium sized cabinets, with the lab reporting sensitivity of 85.5dBSPL at one metre, for an input of 2.83Veq.