VMPS Tower 11/R loudspeaker
The Tower II/Rs (the R designation for the ribbon supertweeter optionmore on that anon) arrived on a Thursday. On Saturday Brian Cheney (President of VMPS and designer of their loudspeakers) arrived with soldering iron, glue gun, power drill, and obvious enthusiasm for the project at hand. The VMPSes, like their larger stablemates, have very flexible, user-accessible adjustments: separate mid-, tweeter, and super-tweeter level controls, and user-adjustable bass damping. Brian spent two days ensuring that everything was copacetic before surrendering his loudspeakers to this critic's clutches. It promised to be an interesting weekend.
It was, but before getting to that part of the story, a more detailed description of the Tower II/R is in order. Two 12" woofers are employed; one has a free-air resonance of 22Hz with a natural (acoustical) low-pass rolloff around 200Hz. The second active woofer has a free-air resonance of 60Hz and, with a lighter magnet and lower moving mass, responds up to the 600Hz woofer/mid crossover point. It is designed to be the "faster" or transient woofer. Reflex loading of the bass is by means of a mass-loaded 12" passive radiator facing downward at the bottom of the cabinet, firing into a slot which vents out the front.
At 600Hz, the 12" upper woofer crosses over to a 5" midrange driver. All three cone drivers in the system are polypropylene and manufactured by VMPS. At 4.5kHz a soft-domed tweeter takes over, augmented at the extreme high frequencies (above 15kHz) by a leaf-ribbon tweeter (footnote 1). An additional supertweeter (a piezo) is wired in series with the "ribbon" and mounted on top of the enclosure, firing toward the ceiling. Crossovers are quasi-second-order at 600Hz, and first-order (6dB/octave) elsewhere, with the exception of the high-pass on the super tweeter (2nd-order12dB/octave). (A quasi-second-order network is a series network providing first-order rolloff at and near the crossover frequency, steepening to second-order about an octave above and below that frequency in either direction, thus preserving good phase characteristics through the crossover region.) The physical layout of the drivers is rather unconventional: the three upper-range units are spread horizontally across the top of the baffle, super-tweeter on the inside (in the preferred setupthe systems are mirror-imaged), tweeter in the middle, and midrange to the outside and slightly lower than the tweeters.
The pricing and available options of the Tower II/R require some explanation. The basic Tower II has a piezo supertweeter (not a ribbon/leaf) and sells for $1198/pair. (It is also available in kit form with an assembled cabinet for $878/pair). The ribbon/leaf tweeter option adds $130/pair for a total of $1328/pair. Additional options included in the review units were a better soft-dome tweeter (a Morel) at $45/pair, all WonderCaps in the crossover at $152/pair, and Powerline II internal wiring at $50/pair. Grand total: $1575/pair (the price shown in the "Specifications" sidebar).
Since I had requested all of the tweaks and upgrades in the review pair of Tower IIs, Brian Cheney arrived prepared to do battle with the interior of the loudspeakers; several of the WonderCaps remained to be installed. Next, the mass-loading of the passive radiator was adjusted; the system is "tuned" by the user by adding or deleting mass in the form of Mortite rope putty. That effort, combined with the adjustment of the mid, tweeter, and super-tweeter level controls, took an hour or so. Brian made all the adjustments; I must say I found his choice of level settings to be on the mark, and never felt the need to fiddle with them after he left. The bass loading was another matterI did do some limited experimentation later, on my own, with this adjustment in an effort to tighten up the low end somewhat. But more on this later.
I used the VMPSes with several amplifiers. They were not particularly amplifier-sensitive, but of the three which saw the most service in the systemthe Aragon 4004, Motif MS-100, and PS Audio 200C (not the latest version)the PS Audio was the best match, its taut, lean low end being particularly well-suited to the warm balance of the Tower II. The VMPS was, however, a relatively easy load to drive, though its sensitivity appeared somewhat lower than specified. My efficiency measurements were strictly relative, not absolute, but the Tower II measured about 2dB less sensitive than the Synthesis LM-300, rated at 91dB/W/m. If all of the level controls of the VMPS were cranked up to maximum, there would be about 4dB more output above about 600Hz. This would increase the apparent sensitivity of the loudspeaker, but I wouldn't want to listen to it that way.
I have mixed feelings about the use of level controls on a loudspeaker. They do give the listener a degree of control to improve the overall balance in his or her own environment, but they also make it possible to mess up the balance, and are sources of potential trouble. Still, many listeners can make good use of the flexibility provided by these controls, especially in a complex, multi-way loudspeaker. And as long as the controls are within a few notches of the center position (mine were set between 11 and 12 o'clock), you'll be within tweaking distance of a good overall balance.
With the grilles removed (the recommended mode of operation), the multi-driver front panel of the Tower II/Rs presented a rather busy visage. Combined with the slightly somber walnut veneer, this appearance will not be universally admired; I found the II/Rs' styling slightly inelegant. I mention this to alert those for whom it matters, especially those who must consider the WAF (Wife Acceptance Factor, not Women's Armed Forces).
VMPS has gained a reputation as a producer of big-bass high-dB reproducers, and I approached my auditioning of even one of their "smaller" models with trepidation. Would I have my internal organs rearranged (a career change as a medical curiosity was not in my plans) or, at best, be severely pummeled about the head and shoulders? Not to worry. VMPS's reputation is vindicated with respect to low-end extension and power, but the Tower II/R also had qualities which make it suitable for use at typical domestic levels and with program material which doesn't necessarily loosen the plaster.
But it is the bass response of the Tower II/R which demands the most discussion; it is likely to be the loudspeaker's most controversial characteristic. A loudspeaker with the bass extension and power of the VMPS will be more room-sensitive than normal. Most loudspeakers depend on room reinforcement for adequate low-end response, and if a loudspeaker itself rolls off in this region, the inevitable bass peaks and dips caused by the room will be less troublesome. My room has an emphasis in the 5060Hz area. Nearly all rooms have a problem somewhere between 50100Hz; the higher in frequency, the more noxious. Extended low-frequency response will tend to excite room modes you didn't know you had, which is precisely why many audiophile loudspeakers steer away from it. But VMPS has plunged ahead; if its Tower II/R sacrifices some "speed" for extension (and I believe that it does), and is thus more room-sensitive than most, that tradeoff is one VMPS is willing to make. I have heard superior low-end transient response in my listening room, but have not yet heard greater power and bass range at anywhere near the price.
If that sounds like faint praise, it isn't meant to be. But it is meant to alert you to the fact that the Tower II/Rs do not have a "typical" audiophile bassa lean low end which varies from well-balanced to rather thin, depending on the room, associated equipment, connecting cables, or (particularly) program material. The VMPS can, on the other handand depending to some degree on those same factorssound full, deep, and solid, or rich, warm, and overripe. I did experiment some with mass loading of the VMPS woofer system, adding about 30 grams to the passive radiator of each system (plus placing each speaker on Tiptoes, which VMPS states is equivalent to adding another 30 grams). Brian Cheney had loaded each system with about 60 grams, and preferred the balance without Tiptoes. Increasing the mass loading and Tiptoeing the cabinets did tighten up the bass somewhat, but the change was not dramatic. Repositioning the loudspeakers and/or listener had a more significant effect.
I ultimately settled on the original long-wall loudspeaker placement, with the listener a bit further from the rear wall than during the initial auditioning and consequently about two feet closer to the loudspeakers. But I still encountered the same problem Dick Olsher had in his review of the VMPS subwoofer in Vol.8 No.4 (not surprising; the Tower II/R has the same bass system): I never found a truly satisfying compromise between extension and tautness. Even with the Tiptoes and the 90-gram mass loading per system, the sound of the VMPSes' low end would be better described as a bit full and expansive rather than tight and punchy.
But the same might be said for many loudspeakers attempting to reach below 30Hzeven some costing several times as much. A small percentage of program material did appear over-endowed in the low-frequency end through the VMPS, but by no means the majority. Well-recorded plucked double bass was reproduced with a good balance of snap, resonance, and detail; Essential Pentangle, Vol. II (Transatlantic TRACD 606), a somewhat variable CD remastering with several superb cuts, makes extensive use of it. So does Serendipity (Reference Recordings RR-20CD). On these recordings and others, this instrument, while not as tautly rendered as I have heard it, was nevertheless presented with a realistic weight up through the midbass, which gave it a natural sense of size and scale.
Percussive bass was often striking through the VMPSes. The deep, reverberant quality of the body of the drum predominated over the sound of the struck drumhead or skin, but the results more often than not were very effective. The Big Drum in KODO sounded like the 700-pound behemoth it is. Well-recorded kick-drum and orchestral bass drum, while again never exceptionally tight through these loudspeakers, could definitely raise goosebumps and even, on occasion, roll down your socks. On the negative side, the infamous Telarc bass drum, never in my experience overly taut, came over on the Tower IIs as very deep but sometimes rather fat and overripe. But a Telarc bass drum is not a Telarc bass drum is not a Telarc bass drum; it has substantial variations from recording session to recording session, from orchestra to orchestra, and the VMPSes preserved the differences, never homogenizing them into a generic sound.