August 2008

VMPS 626Jr Loudspeaker
Sheer madness!
Review By Dick Olsher
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  Is there anyone out there who isn't familiar with VMPS Audio and its maverick designer Brian Cheney? Established over 30 years ago, VMPS has in the interim established a fine reputation for quality, value, and innovation. The company's longevity in the ultra-competitive loudspeaker business underscores the soundness of its design and manufacturing philosophy. So, all of you high-end audio newbies, pay close attention to Brian's honest, and I might add accurate, take on the current high-end scene: "We do not price our products to mislead the consumer, who naturally assumes price and quality are related. No automobile selling at Ferrari prices would dare offer VW performance, but that is precisely what is happening in many instances with today's audiophile speaker systems. We find such pricing practices a shame and a scandal, the cause of endless confusion and grief for music lovers who want the best but do not have six figures to invest in sound equipment."

The 626Jr is a case in point. It sports a fairly compact (1.8 ft³) rear-ported enclosure that is intended to be stand-mounted. An 18 to 24 inch high baffled stand is recommended. What I found most shocking is just how much sound quality these speakers deliver at an asking price of only $1,175/pr. It all starts with a sophisticated driver complement, that you're unlikely to encounter at even a $5000 price point. First, the bare facts. It is a three-way design featuring a 6.5" woven carbon fiber cone woofer with a hefty 40-ounce magnet and a 4-layer 1.5-inch diameter voice coil, a planar magnetic midrange, and a spiral-trace tweeter. The 626Jr is manufactured in the USA, but the 1-inch thick MDF cabinet is fabricated in China by Mark Shifter's Sound Art woodshop. The cabinet is well damped internally with five "Black Hole" damping sheets. Too often high-end speaker projects degenerate into an expensive wood working exercise, leaving far too little room in the budget for quality drivers. The 626Jr demonstrates that even at this price point, there's room for well-engineered quality drivers.

The detachable grilles incorporate patent-pending constant-directivity waveguides (CDWG) for the midrange and tweeter, consisting of a highly damped 20.66-inch wide diffraction slot (only 0.375-inch deep to prevent horn loading of the tweeter) which provides 180-degree dispersion and a wide sweet spot at the expense of some treble rolloff (more about that later). VMPS suggests that you audition the speakers with both waveguides on, one on and one off, and both off to see which gives the best tonal balance in your room. Note: when experimenting with the waveguides, the grille covering the woofer should be removed. It pops off from the inside by pushing on the cloth. In addition, level controls are provided on the rear baffle for the midrange (left pot) and treble (right pot). The suggested starting settings are "noon" for the midrange and "1 o'clock" for the treble.

Technical Details
Crossovers are said to be series first order at 220 Hz and 7 kHz, with all of the drivers connected in phase. All filter components are trimmed to exact tolerance, at better than 0.1 percent. The range from 220 Hz to 7 kHz, which includes the critical midrange and presence region, is entrusted to a push-pull, 2.5" x 7," planar with a neodymium motor. This is a Bruce Thigpen design, which was originally licensed to Sonigistix/Level 9 Sound some years ago and manufactured for a while in Canada. The panel was incorporated into a computer speaker and marketed under the Monsoon brand name, and went on to achieve a cult following among PC multimedia enthusiasts. Brian explains that unfortunately a mechanical design flaw made the driver unreliable and the company had shut down several years back. However, VMPS not only had the foresight to accumulate a large inventory, but the patience to rebuild each panel for improved reliability and frequency response. The story does not end here. Apparently, Eastech bought out Sonigistix and has resumed panel production in China, but Brian does not know if the panel's mechanical problem has been solved. But rest assured that the panels used in the 626Jr are totally reliable.

The spiral trace tweeter used here does not have a conventional voice coil. Instead, it uses an etched Mylar diaphragm which sits in the fringing flux (stray field) of the pole piece and top plate of a conventional tweeter motor with a 10 oz magnet. It's the familiar spiral trace unit originally designed for and used in the large Genesis speakers and dubbed the "Emit R" by Infinity. It is presently made in Taiwan by Pen Shien Industrial. Brian points out that the moving mass of the planar mid panel is less than 1 gram compared with the 15 gram to 40 gram of an average cone midrange or midwoofer. Moving mass of the spiral planar tweeter is 80 mg, compared to a soft domes' 1 to 1.5g. Brian feels that the reduction in moving mass is responsible for the perceived speed enhancement of these drivers.

Brian explains that the key to the CDWG technology is the insight that for a planar panel most of the output comes from the center of the transducer, or within about 12mm either side of the central vertical axis. This is the area responsible for about 75% of the speaker's radiation over its operating range. Thus, he says: "It should therefore be possible to reduce the width of the panel by suitable means to a value which would enhance its directivity while reducing its sensitivity only slightly, 1 to 2 dB of SPL. This must be done without reflecting a lot of energy back into the diaphragm causing frequency response peaks/notches and coloring the sound unacceptably. In other words, one might suspend a disco ball in front of a speaker and improve its directivity, and in so doing destroy whatever good sound qualities the system already possesses."

Sonic Impressions
Aside from the slight reduction in midrange sensitivity, VMPS states on their website that the waveguides induce a 6dB/octave treble rolloff on-axis above 10kHz because they effectively spread the same amount of energy over a much wider solid angle.

But my own in-room measurements, with the waveguide on (red curve) and the pots set at 12 o'clock for the midrange and 1 o'clock for the treble, showed that the midrange driver starts rolling off at about 4 kHz resulting in a major presence region suckout. The extreme treble did not look all that bad, because the tweeter starts filling in around 7 kHz. Listening tests confirmed that the tonal balance with the waveguides was way too laid back. And trying to raise the midrange level failed to fill in the suckout, and made the overall balance far too midrange heavy.

The good news, however, was that without the waveguide (green curve) the 626Jr measured quite flat at the listening seat - at least above 300 Hz. Not surprisingly, the resultant tonal balance was quite neutral from the lower midrange through the treble. It was an easy decision to put the waveguides aside and complete the evaluation without them. Granted, without the waveguides the sweet spot was very tight. But I discovered that it could be considerably improved by using an extreme toe-in position, such that the midrange driver axes intersected about two feet in front of the listening seat. As an added bonus, soundstaging was also enhanced in the process. Not only did the width dimension expand, as a fairly obvious consequence of the toe-in, but the depth perspective increased as well.

The only useful stands on hand were the Reference 3A Solid stands. These allow for height adjustment but are not baffled (as per VMPS recommended setup) so as to effectively extend the speaker's front baffle. I suspect that stand-mounting these speakers on an open-air type stand slights the upper-bass. While there was plenty of midbass to be had, I would have liked a bit more of a big tone balance which is driven by a robust upper bass and lower midrange. For me, it's all about tonal balance. It's the foundation for a realistic musical experience. Mess it up and you're left with a caricature of a live performance.

Even with less than ideal stands, the 626Jr acquitted itself reasonably well when asked to reproduce large-scale orchestral works. Given a power amp that can sink at least 100 wpc into an 8 Ohm load, there was little power compression in evidence when the music shifted gears from soft to loud - a performance level that without a doubt highlights the quality of the 6.5" woofer. I don't know of any minimonitor that can embrace orchestral music as cleanly and without trepidation as well as the 626Jr does. Of course, the 626Jr's imaging wasn't quite minimonitor like, but nonetheless was sufficiently precise to favorably impress. Bass extension in my room reached into the 30s, and bass lines were reasonably well defined. A slight sibilance was evident early on, which turned out to be a function of the treble pot setting. In my room, settings between 12 and 1 o'clock sounded quite natural. I was a bit apprehensive at the start of the vinyl playback session, as I am with any bass reflex design, due to the possibility of severe cone pumping and the resultant Doppler distortion due to turntable/arm subsonics. Well, in this case I need not have worried. Box tuning is around 39 Hz, which helps, and certainly at no time did I observe any cone pumping.

The star attraction was clearly the midrange. Textures were consistently sweet sounding with plenty of finely nuanced low-detail, and very good transient attack. Harmonic colors were fabulously variegated. Violin overtones were reproduced with persuasive levels of sheen, while massed strings sang with the sort of harmonic purity I would expect from far more expensive speakers. Female vocals also benefited from a pure upper midrange and presence region.

Conclusion
Sheer madness! The VMPS 626Jr represents an insane level of sound quality at its asking price. It all starts with a cast of excellent drivers, remarkably well integrated using a first-order series crossover. Throw in a decent cabinet and you end up with a speaker than competes with speakers costing even three times as much. The old adage about good engineering does not cost any more than bad engineering applies here in spades. That push-pull ribbon midrange is something special indeed. My suggestion is to snap up a pair while you can.

Specifications
Type: Three-way planar/dynamic hybrid
Sensitivity: 88dB/1W/1m
Frequency Response: 37Hz to 20kHz (+/-3dB)
Nominal Impedance: 8 Ohms (4.6 Ohm minimum)
Internal Wiring: Bass - 14 gauge Analysis Plus oval 
Mid/Treble - 18 and 20 gauge Teflon silverplate
Dimensions: 24 x 10.5 x 13 (HxWxD in inches)
Weight: 46 lbs.
Finish: satin black or oak 
Price: $1175/pr plus shipping

Company Information
Itone Audio/VMPS
3429 Morningside Drive 
El Sobrante, California

E-mail: VMPSaudio@aol.com
Website: www.vmpsaudio.com