This review page is supported in part by the sponsor whose ad is displayed above

Reviewers: Marja & Henk
Sources: CEC TL5100, Audio Note tube DAC, Philips DVP 5500S SACD/DVD player, Metronome CD3 Signature [in for review]
Preamp/integrated: TacT RCS 2.0 room control system; modified Audio Note Meishu with AVVT, JJ or KR Audio 300B output tubes
Speakers: Avantgarde Acoustic Duo internally wired with silver; Avantgarde Acoustic Solo in HT 2.0 setting; Audio Note AN/Jsp silver-wired; Tannoy Glenair [in for review]
Cables: Audio Note AN/Vx interconnects; Siltech Paris interconnects; Gizmo silver interconnect; Qunex 75 reference interconnect; Crystal Cable CrystalConnect Reference interconnect, CrystalDigit S/PDIF RCA/RCA and RCA/BNC, Y-cable, Crystal Cable Piccolo iPod to XLR, CrystalPower Reference AC-Eur/IEC; CrystalSpeak Reference, Audio Note AN-L, Gizmo silver LS cable; Virtual Dynamics Revelation power cords [in for review]
Power line conditioning: Omtec PowerControllers
Equipment racks: Solid Tech Radius
Sundry accessories: IAR carbon CD damper; Denson demagnetizer CD; Nespa #1; TacT RCS calibrated microphone and software; Exact Audio Copy software; Compaq server w/Windows Server 2003 and XP; wood, brass and aluminum cones and pyramids; Xitel surround processor; Manley Skipjack
Room treatment: complete set of Acoustic System Resonators; Gizmo's Harley Davidson cap
Review Component Retails: In euros - Basic 200; Silver 375; Gold and Special Gold 925; Platinum 1,695. Contact for exact pricing because of fluctuations in the material's market price.

At many shows we visited over the last couple of years, we have seen them - wooden blocks approximately 2 x 2 inches with a shiny hemispheric cup mounted on 'em. Think miniature Tibetan or Japanese singing bowl. Looking closer, the wooden blocks sport an Acoustic System and Made in France branding. They are supposed to enhance the acoustic qualities of the rooms they're placed in. Almost all rooms we spotted them in sounded really good. Coincidence?


It wasn't until the Paris show at the end of last year that we had a chance to get close and personal with these Acoustic System resonators. At that remarkable show, the man behind Acoustic System, Franck Tchang, was present and had his own room. The room itself had an odd shape with an asymmetrically placed large entrance and lots of glass windows. The audio system was placed left of the door so there was no even distribution. The whole system was way off center. Franck Tchang deliberately set his equipment up in that odd way. Yet the sound of the dCS front-end, Karan amplification and Franck's own loudspeakers was musical, airy and full of detail. Behind the equipment rack and on various places to the side and rear walls -- even on the glass -- the resonators perked up their shiny little heads.
Franck played all kind of music, most of it guitar based. When we sat down and confirmed that we liked the music, he turned it up and sat next to us. During the third or fourth track, Franck suddenly got up and did something on the right side wall. Instantly, we were sucked into the soundstage, almost being on the edge of the stage listening as though to a monitor feed. What the heck? Franck then placed -- as we now realized -- the resonator back into its original position and we found ourselves back in our original sonic seat perspective. Removing and replacing other resonators altered the apparent acoustic seating or room every time. It became obvious that we had to learn more about these resonators and Franck Tchang. So we made an appointment to visit Franck in his studio in Paris (another good reason to drive down to Paris - as though we needed excuses for that).


Our human hearing is quite extraordinary in how it functions. In a small room, early reflections from walls, floor and ceiling arrive at the listener very closely behind the direct sound which -- in this case -- emanates from the loudspeakers. In a bigger room, the early reflections arrive later. The propagation time is longer. These early reflections are important cues for us yet they do not hinder us from determining the original sound's origin. This is referred to as the precedent effect. As the amount of reflections increases, the listener perceives them spaced more closely until they fully merge. Once merged, these acoustic reflections form one reverberant field that completely envelops the listener. It is this enveloping sound that communicates to us the sense of surrounding space. Yet the reverberant field gives us listeners more than just spatial information. It provides additional timing cues and data on timbre or sound color.


With this information on direct and reflected sounds and how they influence our perception, let's bring Franck Tchang into the picture – or to be more specific, his patent for the acoustic resonators. One can learn a lot from the French patent bureau. By means of a silver tripod, the resonant cup is secured atop its wooden block and placed within the vicinity of a sound source (read, loudspeaker). Sound waves from the loudspeaker excite the cup and it starts to oscillate/vibrate. Depending on size and material density of the cup, it will respond to a specific range of frequency similar to a tuning fork. The listener responds to this action as sensing a widened soundscape and enhanced sound density.


From the patent it becomes clear that beside the density of the basic alloy used, the dimensions of the cup are of importance. Its height and diameter determine the sort and amount of the perceived effect. To recap, the Acoustic System resonators get excited by acoustic waves in the room. They sympathetically resonate at specific frequencies and thus add their output to the sonic event. This adds new direct sound sources to those represented by the loudspeakers and their early reflections. Since the cups' resonant frequencies are quite high, these secondary sound sources operate exclusively in the overtone range. Additionally and importantly, they arrive at the ear later than the sound waves which activate them, mixed in with the early reflections of the speakers yet being perceived not as a reflections but direct sound from discrete sources.


At a live concert, the direct sound comes from the stage and the remainder of the venue is responsible for the reverberant field . When the music is recorded, the emphasis is on the direct sound. The spatial information captured -- in the best case -- is that of the actual venue. In a typical studio recording, all spatial information is artificial, however. When playing back such recordings in the home, the direct sound plus spatial information is transduced by the loudspeakers. We're talking 2-channel here. Very few multi-channel recordings contain authentic spatial information rather than effects. This mix of information is then radiated directly at the listener and -- via walls, floor and ceiling -- as reflected sound. To repeat, recorded reflected sound becomes direct sound during playback. Mixed emotional responses result from that confusion.


With resonators adding their overtones and acting as extra sources of delayed direct sounds located at strategic locations in the room, the listener's brain is tricked. It is tricked to experience the room rather differently than without the resonators. These tiny cups with their high pitch trigger our attention in a subtle way. It seems that in place of the resonator, there is something more. More space?

Our date with Franck Tchang arrived and we drove the less than 500 kilometers from Rotterdam to the city of lights and went to his studio located in a very lively neighborhood and in a typical Parisian house. Behind a double door in the street, there's a court and in its right-hand corner is a door with a sign "Acoustic System". There a smiling Franck Tchang opens up and leads us into his office. Taking a seat at a long Chinese table, Franck then starts talking, first a little about himself by way of introduction. He comes from a family of jewelers. He is passionate about music and the guitar in particular. He is an avid guitarist and plays acoustic and electric versions. Then our conversation quickly veers to the subject of resonators.


Franck puts one little cup on the table while we are talking. We immediately notice how Franck's voice is changing. It becomes clearer and more articulate yet Franck doesn't change his voice. It's the influence of the resonator responsible for this perceived change. When an additional resonator cup gets placed on the table, the effect of the first resonator is enhanced. When even more resonators are added to the cluster, it gets too much. His voice becomes unintelligible. One less and we're back on track. A whole stack of blue boxes awaits us to take home and experiment with - a complete set of 9 resonators. On a piece of paper, we get instructions on where to start putting the various resonator types. From these basics, we can then experiment with changing locations and types to achieve the best results.


Before listening in Franck's treated room, we visit his workshop. Here all the woodwork and metallurgy is performed. After removal from the mold, all cups are hand-polished, then turned. An employee, a master drummer by night, thereafter tunes each cup by ear. If it isn't tunable to perfection, the cup is rejected and molten down again. Franck's experience in metal work and metallurgy is fully exploited to prepare the correct balance of the alloys' ingredients. Each hemispherical cup with a diameter of 17mm is made of a specific one. Be it copper and silver or silver and gold, the detailed mix is proprietary.


Then we enter the listening room. The same set as already encountered at the Paris show greets us in the modestly sized room. It is approximately 4.5 meters long and 3 meters wide. Behind the audio rack, two high double-glazed windows overlook a small courtyard. Between the two windows is a brick wall. On this piece of wall, three resonators are visible. More resonators are attached to the sidewalls and behind the listening position.


We listen to a number of guitar-based pieces, naturally, from Robben Ford and Steve Ray Vaughn to the flamenco of Robert Wolf. At one point, Eric Clapton's Unplugged was playing. Franck left the room and a few moments later, we saw him in the back of the courtyard doing something. What he did we did not know at the time. The result of his action was uncanny, however. In utter amazement, we looked at each other and noticed that Eric Clapton no longer occupied his spot on stage. He'd moved forward. When Franck reappeared, he admitted that he'd removed a resonator outside the room in the courtyard. So a resonator behind at least two panes of glass still influences the perceived sound.

Then Franck invited us for lunch which we accepted with pleasure. We both had developed a headache and a walk would do us good. Over a delicious Vietnamese lunch with steamed fish and various vegetables, Franck told us more about his fascination with music and how he hit upon the idea of his novel resonators. He told us that he once had met a Japanese gentleman who had lined his room with violins and that the music in his room had sounded extraordinary. That started him thinking what he could do with his jeweler's background. He thought of a small resonator in the form of a cup. In order to enhance its excitation potential, he added four triangular wings to the cup. Instead of angling the wings at 90 degrees each, Franck used a wider angle, consequently the other two angles are smaller. This opens the possibility to vary the resonator's effect by turning the cup in the horizontal plane. To prevent influences due to mounting, wood entered the picture next. With his background in guitar playing, Franck favored maple as the wood for the mounting block - hard and soft maple. The interface between cup and base is a silver triangle. This adds a further tuning feature. Raising the triangle so that only the single stem links cup and base alters the resonator's effect. Fully inserted into the wooden block, all three points of the triangle make contact. Then there's yet a further tuning option. Insert a small ball bearing in the cup. It will dampen the resonator just a little.


Franck is also working on a professional level with his invention. Various companies already use his expertise and products for adjusting acoustically troubled rooms. The professional resonators are slightly different from the domestic ones. Instead of the wooden block, their cups use a fixed stem attached to a small, 0.4 inch hardwood cube.

Back at the Acoustic System headquarters, we performed some more experiments of adding, removing and tuning resonators while listening to music. Mentioning our headaches, Franck knew what caused them. Just before we arrived, he had added some extra resonators to his room, overdoing the acoustic information points. As with all good things, too much can go retrograde


Just before we left, Franck gave us three professional resonators to experiment with. He advised us to use them in the bedroom and let him know what the results would be. Now packed with 12 resonators, we went to our Paris hotel to evaluate our collected impression, aurally and psychoacoustically. Before we went out for dinner, we placed the professional resonators in the bedroom, two next to the headboard and one across the room in the middle of the other two. When we came back later, the room felt -- or more specifically, sounded -- different. We stay quite often in that very same hotel room and now it seemed as though the background din, the noise floor, was lower. The whooshing of the air conditioner, the drone of passing traffic... it all seemed pushed farther into the background. The resonators do not only add overtones to the environment, they also attenuate certain frequencies at least to human perception. Need we add that we slept like the proverbial babies and woke up more relaxed and refreshed than in a long time?


Back at home the experiments started in earnest. The first thing we did was mount the three professional resonators in the bedroom. The Paris experience was too good not to continue. Then we unpacked the 9 boxes filled with domestic resonators - one platinum, one basic, five silvers, two golds and one gold special were laid out on the table. Each type of resonator cup has its matching soft or hard maple wooden pedestal. From the basic drawing of our listening room where Franck Tchang had noted the type and location, we began


His advice had been to put the platinum resonator symmetrical between and behind the loudspeakers. We chose a place roughly 10 inches or 25 centimeters above the tweeters. The resultant effect was evident right away - image depth had increased. 12 inches or 30 centimeters above the floor right beneath the platinum resonator, we placed the basic version. Placing resonators is easy and reversible due the yellow 'blue tack' used. The sticky stuff also isolates the wooden block from the wall. The gold special resonator was placed 24 inches from the ceiling, still in the same vertical line as the other resonators.


Time to listen. The change was very obvious. Besides increasing stage depth, bass was much tighter and coupled better to the room. After a few CDs, we additionally concluded that not only was image height more defined but it had in fact increased.


Enthusiastic by this quick success, we started adding more resonators. We first stuck four silver resonators to the front wall, at the same height as the basic above the floor and at the same distance from the ceiling as the gold special. Our entire left wall is lined with bookshelves so instead of placing the resonators on the side wall close to the front wall, we choose the front wall itself for a start. Our listening room presently uses a long-wall setup. Adjacent to the right speaker, there is a glass bay with the living room table. We decided to put the resonators where a wall would be if the bay wasn't there.

When we sat down to listen to this configuration, it was apparent that another positive change had occurred. We were now about front row to the musicians, quite close but with an aural view deep into the soundstage. With three more resonators left, we got up and went to work to place the last ones. The left gold resonator we could fix to the sidewall above the bookshelves at the same height as all the other elevated resonators. The right gold resonator was easily fixed at a mirrored spot of the left gold resonator, only now on a cupboard. With one to go, it was time for the last intermediate listening session. We were amazed to be back at our original seats, yet farther back in this virtual venue. The venue had grown as it were. We were farther back, the side walls were further away yet the stage was just as wide as before.


When we placed the last silver resonator behind the listening couch and sat down again, the effect was almost scary. It was as if someone had moved the wall behind us backwards. With now all resonators in place -- a preliminary place to be sure -- the effects could not be missed. Franck advised us that even though the direct results are satisfying, it takes up to 48 hours before the resonators have settled in.


Even so, we already noted the following. Next to a more defined, articulated and deepened soundstage, the room seems to have expanded. Music and sound levels that at the same volume setting previously overloaded the room now work splendidly. The earlier compression effect when the room 'filled up' have been transcended.


During the next few days as the resonators settled in, we noticed changes every time we entered the room. Do you know the sensation of entering a modern concert hall? From a lively sounding hallway with normal sounding voices of fellow concertgoers, you enter a space that is instantly far more muffled and dampened. Voices become loud whispers and everything feels warm and comfortable. Of course the dimmed lighting and color scheme assist the visual effect but this is roughly what happened when the resonators were in the room.


We played music for many hours encountering new nuances in many recordings. Tiny details like fingers clicking on keyboards, strokes on strings or voices in the background became audible and were no longer buried in the room's noise floor. Listening since has become a far more relaxed occupation now that we no longer have to subconsciously filter out a certain noise level. This must be the same in the bedroom to explain why we sleep better.


After we had gotten a bit accustomed to the resonators in the house, it was time for further experiments. First we investigated the relationship between the listening room and adjacent bedroom with its resonators. The door between both rooms is always closed but there is an acoustic coupling via the door and an air coupling by the hole where the crank used to be. Removing the resonators from the bedroom made the sound in the listening room more compressed and flatter. Restoring the cups, this compression subsided. Putting a cork in the crank hole also altered the listening room's low-frequency response.


The acoustically awkward glass extension of the bay became the next subject of our endeavors. Franck told us that turning the cups horizontally changes the way the resonators behave. The pair of silver resonators on the right side of the front wall was initially aligned with the largest angle between the wings forward. Now we turned them counterclockwise by almost 90 degrees, with the smaller angle aimed at the middle of the room. The effect was phenomenal. The reflected sound from the glassy extension of the room seemed gone. It was as if a wall or screen had been inserted between the front and side wall further backwards. And evenly noticeable was the acoustic change perceived 'at the other side' of this fictitious wall. At the dining table, conversing voices had been quite harsh due to the proximity of the large windows overlooking downtown Rotterdam. With the turned resonators aiming their wider angled behinds at the table, we had a cozy-sounding eatery (further tests had Henk install an extra one permanently in his car).

More experiments were performed with the resonator on the back wall. First we took it off the wall and placed it on top of the TV between our 2.0HT setup with the Avantgarde Solos. A similar result as with the platinum resonator between the main speaker system was the outcome, not as strong but very noticeable. With the ease of the yellow tac, the resonator could swap places between pure audio use and A/V. In the audio setting, we spent time exploring the right height, angle, extension of the triangular support and even damping with a ball bearing. Every change altered the virtual place of the back wall and its consistency. We think that by now, we have found the best configuration for our use.


Raising the three resonators near the floor raised the imaginary stage or subsequently lowered it when placed closer to the floor again. The higher resonators determine the height of the stage and the width. It is no problem to have the resonators not 100% mirror-imaged.


After a lot of experiments and happy listening, we contacted Franck and shared our findings. He then came up with the following suggestion. Place a basic resonator -- the easiest is a professional version -- on a stick and place it in front of and in-between the two drivers of the Avantgarde subwoofer. Do this with both subwoofers. Make sure the resonators are 4 to 6 inches from the front of the subwoofer cabinet. Now cue some bass-rich music, sit back and wonder where the bass has gone. This really worked. Some music with lots of low frequency information became castrated. Turning up the volume made the woofers visibly work, with the cones moving lots of air but only harmonics reaching our ears in the listening seat. Or were our brains tricked again? The couch shook our delicate bottoms, our stomachs could easily feel the pounding bass yet we did not hear the low frequencies. Not that this use is advised but fun it was.


So what can we say about these little contraptions that when mentioned in audiophile surroundings cause a lot of eyebrow to wrinkle? Franckly, they work exactly as advertised. Maybe our homebrew explanation of how and why they work is not covering all bases but there is neither voodoo at work nor snake oil magic. It is pure Physics based on resonance distribution, partial cancellations and human perception.


When you go all the way and place 9 small gizmos on the wall of your listening space after you've spent quite a few dollars or euros on them, you are in for a few treats. First off, no one will object to the size or looks of these things. Acoustic System can provide them even lacquered in a custom paint to blend further with your decor. By acquiring a set, you go beyond dreaming of -- or saving for -- a dedicated music room. Is music not a social event that should be appreciated by you, your spouse and who knows who else? Or is it aural masturbation you are after in your own walled-off, sun-deprived listening room? How about starting with just a few resonators for the middle front wall? Once in the room, you can play around to find the optimum setting and placement. That's treat number two. Number three is the one it's all about. Music in an Acoustic System resonator treated room sounds truly musical and natural. No hint of HiFi with its analytical coolness. Don't forget this holds true for analogue as well as digital media. Though the usual hyenas on the forums will cackle with ridicule, serious music lovers would miss out a great deal if they mistook the small size and unconventional behavior of these unusual acoustic treatments for a joke. They're anything but a joke. They're the most eye-friendly effective room treatments we've come across yet and highly recommended.
Franck Tchang's email