First, linearity. Let me be very clear, lest you get the wrong impression: In frequency response, the Pi Monitor is much different than a Lowther of yore. Indeed, the Voxativ-designed-and-manufactured AC-4D driver (which is what I’m using in the Pi Monitor at the moment) is a far cry from something like a vintage Lowther cone. The Voxativ’s neodymium magnetic engine is considerably stronger and more uniform in its strength, its ultra-lightweight wood diaphragm considerably stiffer and more linear in response, and its ingeniously designed AST cabinets (see my interview with Voxativ’s owner and chief engineer Holger Adler below for more on AST) far more invisible than the Lowther’s Alnico magnet, twin paper cone, and DIY enclosure. Indeed, for a horn-loaded loudspeaker, the Pi Monitor is quite respectably flat throughout most of its range.
You might expect the Pi’s whizzer tweeter (see the interview with Holger Adler for details on this device) to roll off from the mid-treble on out, but it doesn’t. It is quite linear and extended. Where the speaker has its chief audible issue is in the upper mids—from about 1kHz to 4kHz. The Pi Monitor is not elevated by much in this area, which in itself wouldn’t make it very different than many multiway loudspeakers; however, the Pi Monitor is a horn-loaded loudspeaker, and there’s the rub.
The trouble with horns is that they amplify everything—from dynamics to noise to nonlinearities. As a result, this slight irregularity in frequency response is turned (by the horn) into a touch of “cupped-hands” coloration on some program material. While you won’t hear this trace of shoutiness on the majority of acoustic instruments, you may notice it on some vocals. Chet Baker on Chet Baker Sings, for example, sounds just a bit like he’s warbling into a megaphone on certain notes within his (limited) range.
Now you might think this frequency/horn glitch would be a disqualifying flaw. But it isn’t. The problem simply isn’t large enough or pervasive enough to matter that much. (And I’ve discovered that it vanishes almost completely with Voxativ’s own 805 integrated amp, which has been voiced expressly for the 9.87.) Compared to what I’ve heard from every other horn speaker, this is a smooth, neutral driver in a superior horn enclosure. Moreover, the Voxativ’s smidgeon of cupped-hands coloration in the upper mids is more than counterbalanced (as already noted) by the terrific dynamic energy and astonishingly high resolution of detail the speaker brings to every kind of acoustic music. The 9.87 makes instrumentalists (including Chet Baker, whom the Voxativ—and the Voxativ alone—tells me was recorded by a separate mic on vocals) sound so alive and present, so “there,” that I’m perfectly willing to forgive it its slight touch of, uh, horniness.
You may have noticed that I keep talking about how well the 9.87 performs with acoustic music. This isn’t to say that it won’t rock—just that it won’t rock like, oh, a Magico M3/M6 mated up with a pair of JL Audio Gothams or Magico Q/M subs. Why? Because the Pi-Bass’ two 12" dipole drivers can’t move air like Gotham’s direct-firing twin 13.5" cones or the Q Sub’s twin 15-inchers do. The slight reduction in slam on Fender bass and rock drumkit notwithstanding, the Pi-Bass modules are models of woofer/subwoofer excellence—very deep-reaching (down into the 20Hz range), very low in distortion, very linear, very detailed, and, best of all, when properly adjusted, nearly seamless matches to the Pi Monitors. They fill in the low end (from 120Hz down, which is where I cross over) almost as if the Pi Monitors themselves are doing the heavy lifting. As a result, when you hook up the Pi’s to these critters, you won’t give up midband resolution to subwoofer-masking the way you do with most other subs.
Sonically, this past year has been good to me. In it, I’ve heard the finest planar loudspeaker (the Maggie 30.7), the finest dynamic loudspeakers (the Magico M3 and M6), and one of the finest omnidirectional loudspeakers (the MBL 101 E MK. II) it’s been my pleasure to audition. The Voxativ 9.87 (which is “pi” squared, in case you’ve been wondering—a whimsical way of describing the improvement that adding the Pi-Bass modules makes to the Pi Monitors) is far and away the best folded-horn single-driver loudspeaker I’ve ever heard. For those of you who listen primarily to acoustic music, who like their dynamics untrammeled, and who want their detail, both musical and recording, as high as that of an electrostat without any electrostatic-like loss of color or body, it comes with my top recommendation. If you’re also a fan of SETs or relatively low-powered tube or solid-state amplifiers, the Voxativ 9.87 becomes a veritable one and only top recommendation. Which, come to think of it, is precisely what it is for the right kind of listener—a reference product.
Specs & Pricing
Type: Single-driver horn-loaded loudspeaker with dedicated, powered (250W) subwoofer
Frequency response: 20Hz–20kHz
Driver: Voxativ AC-PiNd or others
Sensitivity: 98dB–110dB/1W/1m maximum (driver dependent)
Recommended amplifier power: 50W
Dimensions: 16" x 47" x 16"
Weight: 150 lbs.
Price: $39,900–$69,990 depending on driver ($49,990 as reviewed)
JV’s Reference System
Loudspeakers: Magico M Project, Magico M3, Avantgarde Acoustics Zero 1, MartinLogan CLX, MBL 101 E MK. II, Magnepan 1.7 and 30.7
Subwoofers: JL Audio Gotham (pair), Magico QSub 15 (pair)
Linestage preamplifiers: Soulution 725, Constellation Altair II, Siltech SAGA System C1, Air Tight ATE-2001 Reference
Phonostage preamplifiers: Walker Proscenium V, Soulution 755, Constellation Perseus, Audio Consulting Silver Rock Toroidal
Power amplifiers: Soulution 711, Constellation Hercules II Stereo, Air Tight 3211, Air Tight ATM-2001, Zanden Audio Systems Model 9600, Siltech SAGA System V1/P1, Odyssey Audio Stratos, Voxativ Integrated 805
Analog sources: Acoustic Signature Invictus Jr./T-9000 tonearm, Walker Audio Proscenium Black Diamond Mk V, TW Acustic Black Knight/TW Raven 10.5, AMG Viella 12
Tape deck: United Home Audio Ultimate 1 OPS
Phono cartridges: Clearaudio Goldfinger Statement, Air Tight Opus 1, Ortofon MC Anna, Ortofon MC A90
Digital sources: MSB Reference DAC, Berkeley Alpha DAC 2
Cables and interconnects: Crystal Cable Absolute Dream, Synergistic Research Galileo UEF, Ansuz Acoustics Diamond
Power cords: Crystal Cable Absolute Dream, Synergistic Research Galileo UEF, Ansuz Acoustics Diamond
Power conditioners: AudioQuest Niagara 5000 (two), Synergistic Research Galileo UEF, Technical Brain
Support systems: Critical Mass Systems MAXXUM and QXK equipment racks and amp stands
Room treatments: Stein Music H2 Harmonizer system, Synergistic Research UEF Acoustic Panels/Atmosphere XL4/UEF Acoustic Dot system, Synergistic Research ART system, Shakti Hallographs (6), Zanden Audio Acoustic panels, A/V Room Services Metu acoustic panels and traps, ASC Tube Traps
Accessories: Symposium Isis and Ultra equipment platforms, Symposium Rollerblocks and Fat Padz, Walker Prologue Reference equipment and amp stands, Walker Valid Points and Resonance Control discs, Clearaudio Double Matrix Professional Sonic record cleaner, Synergistic Research RED Quantum fuses, HiFi-Tuning silver/gold fuses