SMART Devices 2X150VT Hybrid Amplifier

By Sue Kraft

Absolute Sound Magazine, October 2002

SMART Theatre Systems has long been in the business of making sound products, but unless you've been involved in the commercial cinema industry during the last 25 years, you may not be familiar with it. Also known as Smart Devices, Inc., the company was founded by president Norm Schneider in the late 1970s as a manufacturer of audio equipment and related accessories designed exclusively for professional movie theaters. Its journey into the land of the home-theater and high-end audio market began last year with the launch of several pieces of consumer gear, including the CS 3X Jr add-on processor and a monstrous 180-pound subwoofer powered by a 600 watt amp. One of its latest offerings is the 2XI50VT, a real bang-for the buck two-channel hybrid tube/MOSFET power amplifier. (There is also a non-tube version available, the 2X150.)

According to Smart, the predecessor of the 2XI50VT was the TA242, a rackmount amplifier manufactured from 1987-1993 for professional cinema use, which becomes a bit puzzling when the literature states: "You may recognize this amplifier as one of the dominant premium performers of the 1970s and 80s." Except for its sort of retro Art Deco finish and tube peeking out of a window in the front panel, the 2XI50VT is a dead ringer for the Hafler DH-200, a popular amplifier from that period. Norm Schneider admits the resemblance is no accident. "We liked the classic design of the Hafler so much we stole it," he says cheerfully. "And you can quote me on that." So does this mean the chassis is a replica of the Hafler DH-200, and the remainder of the circuitry a modified version of one of its pro amplifiers? Whatever the heritage of the 2XI50VT, the bottom line here is performance. The proof is in the pudding, as they say. And in this case, the Smart pudding is sweet.

At 23 pounds, the 2X150VT is a lightweight as far as amplifiers go, but still has a build quality that is surprisingly rugged for its modest $2,250 price tag. A stainless steel top cover and steel chassis base are flanked on each side by hefty two-inch deep heatsinks. The front panel tube is backlit via a blue LED, as is an illuminated on/off rocker switch on the lower right side. A row of LED power-level indicators for each channel are on the lower left side. The back panel includes a socket for a detachable IEC cord, a ground "lift" switch, and a mono bridge-switch to convert the unit from stereo mode to a 500-watt mono amp. There is also a main power and two speaker fuses, as well as two floating (non-grounded) gold-plated RCA jacks adjacent to level control knobs for each input. Because the five-way binding posts are quite close to each other, Smart recommends using 10 AWG or smaller speaker wires. Although it was a snug fit, I was able to get my 4 AWG cables to work, but banana plugs were a necessity for this size wire.

A look inside the 2X150VT reveals a design that looks simple but well thought out. (Smart has long held a license on this modified Peter Hochstein-patented design.) Surrounded by amplifier modules on the sides is a large toroidal transformer (made in-house by Smart) that occupies the center front half of the chassis. Behind it are two large (22,000 microfarad) power supply capacitors topped by a circuit board. The input stage uses a single, dual -triode Sovtek 6922 tube, which handles both channels, while the output consists of three pairs of performance- matched MOSFET devices. Of particular note in this circuit design is the implementation of a higher rail voltage of 75VDC for the driver board versus a lower output rail voltage of 65VDC. According to Smart, the difference here helps to isolate high-current supplies from driver supplies, resulting in cleaner and more stable power.

Also worth mentioning is a special warranty service that may be unique to Smart (at least I am not aware of any other audio manufacturer to make this offer.) Three years after purchase, Smart will replace the input tube and thoroughly check out each amplifier, making any adjustments necessary, at no cost to the buyer. Return shipping is even covered on their dime. Six years after purchase, the same service is again offered, but at that time, a small fee will be charged.

Upon first listen, the 2XI50VT reveals a decidedly rich, warm, smooth disposition;you might call the sound "tube-like" in nature, although some of the modern tube gear seems to remind me more of solid state. The sound was also a tad soft, but still quite dynamic. Conservatively rated at 150Wpc (into 8 ohms), the 2X150VT never broke a sweat driving my 14?ohm Coincident Total Eclipse speakers, and maintained its sonic integrity at all volume levels. The bottom end was extended and well controlled. As I've found with a few HDCD discs, there was almost too much bass on Brian Culbertson's "Just Another Day" (Nice & Slow, Atlantic, 83444), but the 2X150VT did an effective job of keeping the bottom octaves reigned in and solidly planted. I wouldn't characterize the transients as being sharp or lightning fast, but they still had enough snap to provide a palpable sense of life and excitement. Piano was rendered with pleasing naturalness, and cymbals had a consonant delicacy.

The Smart was never cold, thin, bright, or hard, as some solid-state amplifiers in this price range can be. The soundstage was impressively spacious and three-dimensional on Eva Cassidy's Live at Blues Alley (Blix Street Records G2-100461) and vocals liquid smooth and lush. I did notice a slight lack of air and resolution of inner detail, but also missing was any trace of grain or harshness, making numerous extended listening sessions pleasant and non-fatiguing. And despite minor detail limitations, the 2XI50VT still had plenty of high-end energy and gusto to keep both my toes and fingers tapping!

The only other noticeable shortcoming of this other- wise proficient performer was a blending together or homogenizing of images. I found it somewhat difficult to follow the musical lines of individual instruments on Dave Grusin's TKO. [Migration GRD 9592). Here is where I found a little tweaking with aftermarket power cords to be helpful. Of the exotic AC cords I had on hand, at least the ones that didn't cost more than the amp itself, the TG Audio SLVR added some focus and definition. The difference was immediately noticeable, from top to bottom, all through the frequency range. I wouldn't go so far as to call the improvement a transformation to the stellar clarity and focus of my reference Tenor amps, but it was definitely worth the effort of investigating.

My SACD collection consists of fewer than a dozen titles, and the vast majority of my listening was with the Sony DVP?NS900V as a transport only, with the Bel Canto DACL The Sony as a stand-alone player on SACD (an external DAC cannot be used with the Sony during SACD playback) afforded an even more dramatic improvement in focus and imaging, but the sound wasn't as full or lush as on regular CD with the Bel Canto DACL Transients were sharper and depth of soundstage remarkable on Rebecca Pidgeon's The Raven [Chesky SACD2051, but the gains in depth came at the expense of a narrowed soundstage. I've heard some extraordinary sound on SACD, but in this particular case, I preferred the Red Book CD.

I enjoyed the warm and engaging nature of this Smart amp. It suffered a few minor shortcomings, but I found its overall performance was as solid as its build quality. Some may find the 2X150VT a little too forgiving, but careful system matching could very well make for truly excellent sound. And who can argue about the price?

SPECIFICATIONS Description: Hybrid tube/MOSFET stereo power amplifier Output power: 150 watts into 8 ohms; 240 watts into 4 ohms (both channels driven) Input impedance: 50k/ohms Dimensions: 6 x 10 x 16 inches Weight: 21 lbs.
ASSOCIATED EQUIPMENT Sony DVP-NS900V SACD/DVD player, Bel Canto DAC1, van den Hui P-1 passive and BAT VK-3i preamps, Tenor 75w OTL monoblock amplifiers, Coincident Total Eclipse speakers, Harmonic Technology Pro Silway 11 interconnects, Wireworld Gold Starlight digital cable, Dunlavy LCR speaker cable, TG Audio SLVR power cord, and PS Audio Ultimate Outlet.

MANUFACTURER INFORMATION Smart Theatre Systems, Inc.
5945 Peachtree Corners East Norcross, Georgia 30071
Phone: 1-800-45-SMART; (770) 449-6698 www.smart-cinema.com
Price: $2,250

Manufacturer's comments

Sue Kraft mentions the amp's ability to drive her 14-ohm Coincident speakers. This amp is rated to drive 4 ohm loads, and in reality will drive much lower impedances well, which means that speakers with low impedance dips should not be a challenge. We have driven 2-ohm loads easily, although at sustained high power at such low impedances, the speaker fuses may blow. A switch on the back allows the amplifier to be run as a monoblock with power over 500 watts into 8 ohms.

The amp comes with a unique 14 AWG 100% shielded power cord. In some cases, substituting a premium type cable may make a difference, as the reviewer found.

Smart has an in-house toroidal transformer manufacturing capability. We can tailor each transformer to each application and fine-tune it quickly and easily. The 2XI50VT power transformer is wrapped with a magnetic shield to reduce induced noise and helps to maintain the very good signal-to-noise ratio. This allows us to make a power-house amplifier in a small package.

Each amplifier is tested to ensure that it exceeds the published specs. An individual Certificate of Performance is included [with each amp] to prove the characteristics of that single amplifier. For example, our literature states the 2XI50VT THD is 0.9. In almost every case, the actual distortion is 0. 15, or less. Also we conservatively rate the amplifier at 150 watts per channel, but most measure closer to 200 watts per channel with both channels driven.

Norm Schneider Smart Theatre Systems