Company Address: c/o Itone Audio, 3412 Eric Ct., El Sobrante, Cal. 94803.
Every loudspeaker system involves some important compromises with musical
realism. If there is some way to get superior performance in every area from
a single speaker system, no manufacturer has yet found it, and the laws of
physics indicate that it is likely no manufacturer ever will. One has to
be careful in making such statements, though. I was attending a Summer CES
with a professor of physics from the University of Chicago. He listened very
patiently to a speaker manufacturer tout his product, then identified himself
and explained why the concept couldn't work. Without pausing for a moment,
the manufacturer replied, "This speaker is so good, it can defy the
laws of physics!" The laws of physics, however, are gentler than the
laws of economics, which normally impose very severe limits on cabinet and
driver size in all but the most expensive speaker systems. These, in turn,
normally impose yet more severe limits on power-handling capability and deep
bass response.
VMPS is a small speaker company which seems determined to prove that, while no speaker designer can break the laws of physics, a really dedicated designer can break the laws of economics. Their Super Tower/R and Tower II loudspeakers cost from $878 to $2,058 per pair, depending on your choice of the smaller or larger model, your choice of tweeter, and whether you buy a kit or an assembled unit.
Even the top of this price range is far lower than what a pair of most good subwoofers costs, and the VMPS Towers prove that a good, high-end speaker can be affordable and still deliver both wide dynamic range and all the deep bass power any audiophile could desire.
Right at the outset, I should note that most speakers under $2,000 a pair simply don't provide any real deep bass response. They usually start to cut out at frequencies from 80 Hz down to 40 Hz. While this may lead to good frequency response claims in brochures, real bass power is not being delivered to the listening room, and what bass power there is comes at the cost of serious distortion and impedance problems.
Size alone is not the only problem, although larger enclosures and drivers present manufacturers with major cost, transport, and room decor-compatibility difficulties. Most full-range systems with crossovers are lossy in the deep bass, while too many others exhibit serious phase shift and driver polarity inversion. Small woofers require long excursions to move a lot of air and rarely achieve any savings in mass because about 75% of the system mass consists of the voice-coil and former assembly, rather than cone area.
It is difficult for a designer to match the driver's impedance to the air in a room without the use of some sort of loading, either with a slot or duct or a large folded horn. The only practical alternative to a large enclosure size is equalization, and active equalization has usually led to serious increases in distortion and to overdriving the woofer at peak power. For a good readable summary of the engineering issues involved, see Handbook for Sound Engineers--The New Audio Cyclopedia, Glen Ballou, editor (Howard W. Sams & Co., Indianapolis, Ind.). Most manufacturers, usually for economic reasons, use drivers with limited bandwidth and limited power-handling capability within that bandwidth. Such speakers tend to overload. This is particularly true in the bass. While cost considerations limit most systems to just two or three drivers, it becomes extremely difficult for a single driver to handle both the deep and middle bass, and even more difficult to find a single driver that can handle the entire bass. Crossover design presents equal challenges, with some designs having control problems such that the resulting system is extremely sensitive to amplifier damping.
The solution most high-end speaker manufacturers use is either to deliberately sacrifice low- and mid-bass response for superior upper bass and midrange response. The other common solution is to raise the price of the loudspeaker and reach a reasonable compromise between bass power and extension and what is practical to mass-produce. VMPS, in contrast, has accepted the cost of making relatively small numbers of large enclosures with proprietary 12- and 15-inch woofers and built-in subwoofers.
Even the smaller system in the VMPS Tower line, the Tower II, uses a 12 inch, mass- and slot-loaded passive radiator as a subwoofer; a 12-inch, high-compliance, low-mass woofer; a 12-inch mid-bass coupler; a 5-inch midrange; a dome tweeter, and a top firing tweeter to improve dispersion. All of this is housed in a cabinet which measures 43 x 15 x 16 inches and weighs 95 pounds. The version of the Tower II under review also had the optional ribbon tweeter and higher performance dome tweeter and costs $1,328 per pair, assembled. This is not cheap, but the Tower II provides at least three times the cabinet volume of virtually all the speakers in its price range, not to mention the presence of several more drivers.
VMPS specifies that the Tower II has a-3 dB point of 22 Hz, a bandwidth up to 30 kHz, and harmonic distortion of only 0.7% at 1 watt in a free-field or anechoic environment. The Tower II is relatively efficient and produces 95 dB SPL at 1 meter for 1 watt, but it can take power up to 300 watts. The manufacturer claims it can deliver 126 dB SPL with 5% harmonic distortion, and I found it could deliver well over 110 dB SPL without any audible sign of breakup. (Audio does not pay me enough to audition speakers at higher SPLs!) A quasi-second-order filter is used to preserve good phase response, and the drivers are compensated for time delay.
The Super Tower/R is a larger version of the Tower II, offering even more deep bass and power-handling capability. The larger array of midrange and high-frequency drivers expands the apparent image and soundstage. A pair costs $2,058 assembled, with the ribbon tweeter and high-performance dome tweeter, and uses a 15-inch mass- and slot-loaded passive radiator firing down toward the base of the cabinet. It uses a 15-inch low-bass driver, a 12-inch mid-bass driver, two 5-inch cones, two 1-inch soft dome tweeters, a ribbon supertweeter, and a top-firing tweeter. Its cabinet is 49 x 17 x 21 1/2 inches and weighs 166 pounds.
VMPS specifies that the Super Tower/R has a-3 dB point of 20 Hz and a bandwidth up to 40 kHz, with harmonic distortion of less than 0.5% at 1 watt from 22 Hz to 40 kHz in a free-field or anechoic environment. The speaker is relatively efficient, producing 96 dB SPL at 1 meter for 1 watt, and it can take power up to 350 watts. Once again, a quasi-second-order filter is used to preserve good phase response, and the drivers are compensated for time delay.
In both models, the low-frequency and midrange speakers use polypropylene cones. The cabinets are very heavy and are solidly reinforced and damped. Mirror-imaged, the drivers are placed to produce an apparent point source. Both models provide a full range of treble and midrange adjustments, which, for once, seemed to produce best performance at the nominal flat setting. The bass can be tuned to produce the best response for a given room and system by mass-loading the passive radiator to trim its O. Experimentation in this area is absolutely essential. A Tower that has been carelessly set up, without the proper loading, will either lose deep bass power or will sound far too boomy. The overall construction is very good, although there are some obvious hand built touches. Good-quality components are used throughout the crossovers.
I have gone into unusual length in describing the VMPS Tower II and Super Tower/R because they are so radically different from most speakers in their price range and are much closer to the large high-end monitors in terms of size and complexity. Quite frankly, the economics of these speakers amazes me; I really don't see how VMPS can deliver so much for the price.
Once again, however, it is the sound that counts, and the VMPS Towers seem to live up to their specifications. I used third-octave pink-noise and warble-tone generators, and despite the fact that no one can make truly accurate real-room measurements of low end response with such techniques, the bass I did measure was extraordinarily extended and flat. Subjectively, it is possible to get a very good idea of bass quality by listening to bass and baritone voice, complex and full organ music, a grand piano like the Bosendorfer, and bass viol, cello, and percussion. In each case, both VMPS speakers had extraordinarily good resolution of both the deep bass and the mid- and upper bass.
I should hasten to add that good bass does not mean a steady diet of cannons and bass drums. It also does not mean boom or exaggeration. It means being able to hear the full impact of the organ, without any smear of its lower tones, and being able to feel the lowest notes while understanding the mid- and upper bass as music.
Virtually all speakers either give up a great deal of detail, emphasizing part of the bass register at the expense of other notes, or fail to deliver the notes you feel more than hear. This tends to make organ music seem dull and lacking in variety and has similar effects with virtually all bass instruments. The Towers-along with a few much more expensive speakers and subwoofers like the Infinity IRS, larger Duntechs, and ENTECs--really do give you all the music.
Equally important, the Tower speakers achieve a flat transition of energy from the deep bass into the upper midrange. They demonstrate that the real advantage of deep bass power lies in its ability to communicate all the natural warmth of ordinary music, not in its ability to reproduce sound spectaculars. If you like solo piano music, string quintets. small modern-jazz groups, and some of the older music for oboe and woodwinds, you will be just as impressed with the Towers' bass as will someone who is into power rock. It is amazing to hear how important realistic bass extension and power are for enjoying the midrange in very ordinary music, and how much of the impact and warmth of music most small speakers give up.
The Towers offer special advantages in reproducing the power of music such as 19th-century symphonic spectaculars and grand opera. Most speakers condition us into listening to such music at far lower volumes than are heard in a live performance. The Towers have the combination of power-handling capability and low distortion that encourages live listening levels. These are also the levels that expand and open up the soundstage and allow you to hear all the music. Lower levels distinctly alter the apparent tonal balance and dynamics of instruments because of the ear's lower sensitivity to bass and treble (the Fletcher-Munson effect). It was a real pleasure to find affordable speakers that provide this gain without pain.
I do have to say that it was my daughter who really put the Towers through their paces in terms of sheer power and bass energy. She ran through her collection of British rock records at normal volume and then sank into the depths of heavy metal at volumes I regard as being as unpleasant as the music. She even hooked her bass guitar up to my stereo system, and the Towers survived at least as well as the house did. The end result was that her friends who play rock came to hear the Towers and then their friends came. The general reaction was that the Towers were the first realistic rock speakers they had ever heard. I, thank the muses, will never know, from my own live concert experience, if they are realistic. I will, however, certify that these VMPS speakers provide very realistic reproduction of big band jazz-which is as close to live heavy metal as I ever intend to get.
As for the upper octaves and the soundstage, both Towers provided very good performance, although several high-end speakers with similar price tags are superior. The sound stage was wide and open, and imaging was good. Depth was also good, although not truly outstanding. The overall coherence of the upper octaves was good, and the treble was sweet and extended, balancing the extension and power of the bass. With proper adjustment and attention to the mass damping of the passive radiator, both Towers were very coherent speakers.
Anyone who has heard the Quad ESL-63s, Thiels, and Vandersteen speakers at their best would probably agree that it is possible to provide a still more open and coherent sound stage, slight improvements in the realism of timbre, and more sweetness and apparent air. There is a trade-off between the bass and power of the VMPS and the upper-octave and soundstage performance of some other top high-end speakers.
As for the differences between the Tower II and the Super Tower/R, I lacked the courage to explore their relative dynamic limits. The larger Super Tower/Rs do produce a more open soundstage and a notably smoother midrange and upper midrange. They also sound slightly more dynamic, even at humane listening levels, and there is more "feel" and emotional impact from the deep bass. The two are, however, very similar in overall sound character and performance.
To sum up, the VMPS Tower II is worth a trip to a dealer simply to rediscover bass and to hear what you will be missing in most other speakers in its price range. It is the only speaker even close to its cost that is capable of true deep and powerful bass response down to 25 Hz. Overall, these systems may not produce quite the air, detail, and smoothness of the very best competition in the same price range, but such compromises are limited. I feel that the Tower Il is an unquestionable "best buy" for lovers of deep bass and sheer power. It will be of particular interest to fans of organ, rock, big band, and full orchestral music, as well as grand opera.
The Super Tower/R is a bigger, smoother, and better integrated version of the Tower II, with a larger array of drivers, and it offers a more open soundstage and more depth. While it lacks the openness and air of some competitors in its price range, the overall integration is excellent. I know of no rival, in terms of the ability to offer deep bass and sheer musical power, at anything like the price.
-Anthony H. Cordesman
(Audio magazine, Jun. 1989)
Also see:
VMPS FF-3 Speaker (Auricle, March 1997)
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