Advanced Ribbon Technologies
METRO
Ribbon Hybrid Loudspeaker System

The Advanced Ribbon Technologies' Metro loudspeaker system is a floor standing ribbon hybrid loudspeaker designed for small to mid-sized listening rooms. The Metro loudspeaker defines a technological leap in ribbon loudspeaker design: it is the first ribbon loudspeaker in history that combines the incredible dynamics of an enormously powerful motor moving a nearly massless diaphragm with wide, even dispersion pattern in both the horizontal and vertical domains.

Historically, all ribbon, electrostatic and planer magnetic loudspeakers suffered from extremely limited vertical dispersion, leading to a very small listening "sweet spot" within which one had to remain in order for the loudspeaker to sound its best. Over time this became known as the head in a vice effect. Advanced Ribbon Technologies has overcome this limitation, and the Metro loudspeaker exhibits both a large listening "sweet spot" in the seated position and an enormous listening "Sweet Field™" that completely fills the room. In fact, the Metros sound wonderful almost anywhere in the room and because they do not suffer from floor and ceiling reflections like their coned and domed cousins, the sound field remains homogeneous regardless of room size. This technology is patent pending.

The .A.R.T. .7 ribbon driver used in the Metro incorporates over sixteen pounds of magnetic material – more than most fifteen inch woofers. All of the magnetic strength is concentrated into a narrow gap to drive the ribbon diaphragm 20 square inches in surface area that is less than two thousandths of an inch thick. Because the motor is so strong, the .A.R.T. .7 ribbon has unrivaled speed and dynamic capability and communicates subtlety and detail with remarkable clarity.

A 7" woofer made by SEAS of Norway takes care of the Metro's low end. The woofer's motor was developed using the Klippel analyzer which measures tiny variations in magnetic field strength relative to cone excursion, and through Klippel optimization and the incorporation of multiple Faraday rings, the woofer has nearly three quarters of an inch of peak-to-peak linear excursion. This allow the Metro’s bass section to move more air than many 10" woofers, yet with the exceptional speed of a much smaller, lighter cone. The cabinet volume and port tuning is computer optimized, extending the Metro’s low end 39 Hz. Because of this perfect balance of cabinet volume and tuning, the Metro can perform at extremely high volume levels without a hint of fatigue or threat of overexcursion.

Crossover design is the single most important element of any loudspeaker system. The .A.R.T. Metro’s crossover is a symmetric third order network at 361 Hz. The high slope gets the woofer out quickly while allowing the ribbon to operate at its maximum bandwidth, yet the integration is seamless and there is no hint of a transition region. This very sophisticated network employs 14 passive elements and over 20 individual components, yet the ribbon itself it coupled to the binding posts through only a single reactive element.

If the crossover design is a loudspeaker’s brain, the quality of the crossover components employed are its heart. The Metro is built with only the highest quality crossover components, including precision wound tension-free air core inductors, custom made military grade power resistors, and polypropylene film and film-foil capacitors, some as large as 200uF. All crossover components are hand matched to ±0.5% tolerance. The networks are assembled by hand using point-to-point wiring, crimped connections and silver solder. Solder is never used as a connector and there is no wimpy PCB. The crossover network as well as many of its components are made by hand in our own facilities.

Sound quality is stunning. In fact, upon first hearing the Metro's, the most common reaction is "Wow!" The clarity is riveting, the level of annunciation is unrivaled, and the sound stage is absolutely huge. In fact, when one is not immediately in front of one of the loudspeakers, it doesn't seem like the music is coming from the speaker at all. One has to experience it to comprehend how complete the illusion can be.

The Metro's voicing is remarkably linear, and if it errs at all it is that it tends to be a touch forgiving in the midrange and has a bit of extra womp at the bottom end. A little emphasis at the bottom really strengthens the entire presentation, and by balancing it precisely with the rest of the spectrum the loudspeaker sounds solid without being the least bit heavy.

Vocal reproduction is amazing, particularly female vocalists which are carried entirely by the ribbon. Because there is no crossover transition, there is no region where voices change character as the drivers change radiation pattern and speed. The best words to describe it would be harmonic continuity. To view the Metro's measured performance, click here.

The Advanced Ribbon Technologies Metro Ribbon Hybrid Loudspeaker System is one of those rare loudspeakers that has it all; extraordinary clarity, exceptional dynamics, unprecedented speed, and a natural intrinsic musicality that makes it a joy to listen to for years to come. Hand made with pride in the heart of New York's Adirondack Park, the largest protected wilderness in the contiguous United States.

Advanced Ribbon Technologies Metro loudspeaker system ....$6,900 per pair (fully assembled in Anthracite/Chrome)

Those highly skilled in woodworking can also order the Metro sans cabinets, build and assemble the loudspeaker them self. This is the Metro Loudspeaker Kit, $4,600 per pair, available though www.NorthCreekMusic.com. The kit includes .A.R.T. and SEAS drivers, fully assembled crossovers, and everything else required to build the finished loudspeaker system except the wood. Cabinet plans are available through this link.

See it at CEDIA Denver
September 3-7, 2008

Like the floor standing Metro, the .A.R.T. 0.7 and 1.1 In-Wall Ribbon represents an entirely new level in planer transducer performance.

The .A.R.T. 0.7 ribbon is constructed on the same frame and diaphragm as the Metro ribbon, with over 16 pounds of magnets driving 1.5 grams of aluminum. Yet because of its in-wall housing its frequency range is extends from 140Hz to beyond 20kHz, a window of over 7 octaves.

The .A.R.T. 1.1 is built on a massive welded steel frame harnessing over 30 pounds of magnetic material. The 1" by 45" (25mm x 1.1m) diaphragm has more radiating surface than most 10" woofers, yet weighs less than 2gm. Its increased surface area directly results in increased bandwidth, in this case the 1.1 performs from 100Hz to beyond 20kHz, nearly 8 octaves.

Both the 0.7 and 1.1 are incredibly fast and move enormous amounts of air without distortion.

One of the most unusual – and prized – characteristics of a long ribbon transducer is that their perceived loudness level decreases very little with increasing distance. What this means to the home theater installer is that one can accomplish a uniform multi-channel sound field over an extremely large listening area –typically ten to twelve times the square footage that one can achieve with conventional loudspeaker technology – without any complicated set up procedures or frequency response massaging. Of this the .A.R.T. 0.7 and 1.1 In-Wall Ribbon transducers take full advantage.

Long ribbon transducers also do not suffer from floor or ceiling reflections that can dramatically alter the sound quality of even the best traditional loudspeaker systems. Because floor and ceiling reflections are purely local phenomenon on a micro scale, their effect in typical media rooms is that the left and right loudspeakers may sound completely different even though they measure – and sound – identical in the manufacturer’s lab. Because .A.R.T. transducers are immune to this type of reflection, they left and right loudspeakers sound the same. This and our unique Sweet Field™ technology translates directly to better imaging and a rock solid sound field.

The .A.R.T. 0.7 and 1.1 In-Wall Ribbons are designed for new construction home theaters and are built into an integral cabinets housing both the high pass crossover network and the damped transmission line which absorbs the ribbon's rear wave. The cabinet is designed for framing-standard 16" on-center mounting and wall penetration is 3 3/8" (8.6cm), so it fits comfortably inside a standard 2x4 wall. Cabinet height is 32" for the 0.7 and 48" (122cm) for the 1.1.

Both the 0.7 and 1.1's ultra-wide bandwidth allows one to cross over to their subwoofer of choice, and because the crossover frequency is so low there is complete freedom of subwoofer placement.

For more information on Advanced Ribbon Technologies' In-Wall and In-Pillar Ribbons, click this link.

.A.R.T. 0.7 and 1.1 In-Wall Ribbon loudspeaker modules ….pricing available upon request, available only to CEDIA-trained dealers, please contact North Creek Music Systems, Inc., info@NorthCreekMusic.com. North Creek Music Systems, Inc., is a proud CEIDA member.

Designer’s Comments on the Metro

It’s not often that a professional designer in any field gets to do something really cool.

Developing the new Advanced Ribbon Technologies' Sweet Field™ ribbons and then designing the Metros has been this kind of adventure. Every aspect of their development – coming up with the ribbon frame from scratch, developing a method to machine the diaphragms, building a precision corrugator, finding a way around the vertical dispersion limitation – all of it has been a wellspring of creative energy.

The .A.R.T. ribbon drivers came about as an evolutionary step beyond the technology I was working with at Apogee Acoustics in the early 1990’s. Everyone who has heard a pair of Apogee’s, set up properly and with compatible electronics, can recall the remarkable speed and agility of a true ribbon driver. About two years after leaving Apogee, I visited the factory had a discussion with two of their engineers about ideas I had for improving the ribbon tweeters. Apogee was bought out a few months later, and to the best of my knowledge none of these ideas ever found their way into production. I never shared them with anyone else, but for over a decade I kept a "ribbon pad" going with new ideas, drawings, and a formula or two. A few years later, while developing the crossover update for the Apogee Stage, I decided it was time to build the new ribbon, determine if my ideas were indeed improvements, and see where it went from there.

The new ribbon driver showed some promise, particularly higher efficiency and more extension at the extreme top end. But the main limitation of the design was still its limited vertical dispersion and an extremely narrow "sweet spot". I knew that for the new ribbon to be a revolutionary step (not just an evolutionary one), the vertical dispersion issue had to be resolved.

It took several years, and a lot of failed and partially successful attempts, but by the spring of 2006 I had come up with a new type of diaphragm design that could be configured to create both a larger "sweet spot" at the seated listening position and a huge uniform sound field throughout the listening room, and the "Sweet Field™" was born. No other planer loudspeaker ever built has this kind of radiation pattern, and it was really surprising to hear how the sound field when one is standing and walking about in the listening room. Even outside the room, in the hallway or around a corner, the sound field is so consistent that it really seems like a live performance is occurring. The illusion borders on magical.

The new diaphragm design exhibited an unexpected benefit: it had unprecedented dynamics. Historically, long ribbon drivers have an excursion limitation of about 6mm before tiny variations in their tension and magnetic field force them to twist, causing distortion. The .A.R.T. 0.7 ribbon can move nearly 25mm peak to peak, more than four times that of conventional ribbons, without exhibiting evidence of this type of break up.

The .A.R.T. ribbon’s unique diaphragm design is patent pending.

The SEAS woofer was selected because it has the most linear motor of any conventional woofer ever made, and carries the bass and lower midrange with remarkable clarity. It is also very fast, which is a must to integrate with the .A.R.T. .7 ribbon seamlessly. The only limitation is deep bass. The low end is limited to about 39Hz. For a loudspeaker that is only 10" wide and takes up barely a square foot of floor space, 39Hz is quite impressive, but those looking for the ultimate in low frequency extension will need a subwoofer.  

The Metros’ form actually started life on impulse. In the wood shop, machining the original prototype fascias, I could not get this picture of an old style round-top juke box out of my head, and the evolving prototype started to take on some of that shape. The purely rounded cabinet was sleek and with a good finish has interesting character. It did not however capture the spirit of the 1950’s Wurlitzer….. so narrowing the fascia and adding the edge panels, the visual prototype became somewhat multi-symbolic; the rounded top with bold side panels has a distinct New York City look, but the curved top keeps pulling the mind back to the Juke Box. We have tried to keep this spirit in the available finishes. The Metro Retro with Smooth Chrome edge panels hints to a ’57 Chevy and waitresses on roller skates; edge panels in Hammered Chrome are distinctly Art Deco.

As a dipole, the Metro’s can be picky about set up. The face of the loudspeaker needs to be at least 30" out from the wall, and some absorption or diffusion is suggested on the wall directly behind the loudspeaker. Diffusion of the rear wave output actually improves the soundstage by spreading the ambient field.

Also, the ribbon’s output varies considerably with altitude. This is because the mass of the ribbon diaphragm is actually less than the mass of the air surrounding it. To compensate for this, the ribbon has several different settings so one can fine tune its output based on altitude.

That said, the Metro’s sound quality is striking. Dynamics and dynamic contrasts are conveyed effortlessly. The soundstage is huge, but unlike larger planers the Metro sizes performers and instruments correctly and can focus precisely within the soundstage. The Advanced Ribbon Technologies’ Metro loudspeaker offers a combination of clarity, subtlety and speed that only a true ribbon driver driven though the best crossover components is capable of.

All Advanced Ribbon Technologies' and North Acoustics' loudspeaker systems are designed by George Short. George began building loudspeakers in his early teens in Rochester, NY. He built his first ribbon transducer in 1985 while an undergraduate at Virginia Tech, where he received a Bachelor's of Science in Physics in 1986. Following a two year independent study of electroacoustics and for the successful defense of his Master's Thesis, The Aperiodically Damped Loudspeaker System , he was awarded a Master's of Science in Applied Physics (Electoacoustics), also from Virginia Tech.

George began his professional career with Acoustic Research (AR), then the world's fifth largest loudspeaker manufacturer. His responsibilities included basic research in cabinet and cone construction, crossover design, and fundamental listening evaluation of drivers and crossover components.

In 1990 George joined the engineering team of Apogee Acoustics. Apogee was and remains history's only full range ribbon loudspeaker manufacturer, and considered among the most respected loudspeaker companies of their day. Throughout the 1990's, virtually every loudspeaker made by Apogee could be found among Stereophile Magazine's Recommended Components. George did both crossover and ribbon design for Apogee. 

In 1992, George founded North Creek Music Systems, a company dedicated to the advancement of the science of loudspeaker crossover component technology. North Creek was the first company to promote the use of military grade electronic components in crossover applications, developed several new technologies specific to high performance crossover manufacturing, was among the earliest distributors of Scan-Speak in the United States, and is quite possibly the only company in history to design a family of crossover components by ear specifically for high end audio applications. North Creek today supplies over one hundred loudspeaker manufactures world wide with some or all of their crossover component needs.

George founded North Acoustics in 2001, a company dedicated to employing the most advanced drivers, crossover components, cabinet technologies and manufacturing methods to design and produce the world's finest conventional loudspeaker systems. The North Acoustics' Spirit and Kitty Kat Near Wall Specific™ Loudspeakers offer exceptional performance in the most highly favored SAF environment.

Evolving from the North Acoustics family of finished loudspeakers and North Creek Music Systems' ability to manufacture delicate but complex instruments came the .A.R.T. ribbon transducers and systems.

"We believe that enduring quality is the most significant virtue of any product ™" - George E. Short III, 1992

Advanced Ribbon Technologies

www.NorthCreekMusic.com, Info@NorthCreekMusic.com