Mario Murace, Chief Designer of Chario Loudspeakers, was kind enough to consent to an exclusive interview with the Ultra High-End Audio and Home Theater Forum. My thanks go to Hiram Toro of Koetsu USA, distributor of Chario Loudspeakers in the US, for facilitating the interview.
Thank you for agreeing to be interviewed for the Ultra High-End Audio and Home Theater Forum. I dare say many of our members are not familiar with Chario Loudspeakers. Would you tell us a little about your company?
I would also like to thank you for giving me the opportunity to present our firm to your kind readers. At the same time please apologize for my limited English and my attempt surely substandard attempt to address this technical discussion into your vernacular.
It does not surprise me that you or for that matter most of the American market is not well acquainted with our brand. Often best-sellers are at hand in every bookshop, but if you are in search of meaningful writing you have to go through dusty shelves. After all it this path the one a true journalist has to follow to give readers knowledge of events.
My partner Carlo Vicenzetto (Sales Manager) and I (R&D Lab) founded Chario Loudspeakers in 1975. Since then we have travelled a long way and now we are proudly marketing our products in over 36 countries. After a hiatus of several years we have returned to America, thanks to the support of Hiram Toro and Koetsu USA.
Please find at the following address some relevant news about our achievements through the years: Chario History
Would you describe your loudspeaker design philosophy and tell us what aspects of design you deem most critical?
Over thirty years of research into Acoustics and mostly in Psychoacoustics has convinced me about two things:
* There is no design philosophy better than any other, there are only equations….
* There are no critical topics to be addressed, all of them are equally critical….
I would guess my answer is surprising to you, but please take into consideration the following two thoughts:
* Audio is a world community of enthusiast in search of techniques of true reproduced sound
* Psychophysics tells us that none of them are perceptually compatible one to each other (see HRTF’s)
These are statistics-based concepts, so the inferred conclusion is:
* Each person has its own belief of what is correct sound reproduction
You, your colleagues and I do believe there is a real thing we call High Definition Audio worthy of our love and attention. But each one of us is moved toward our beliefs based on our physical/mental/cultural formation, so that Bertrand Russell’s statement is welcome:” Because there is more than one religion, only one could be true or they are all false “. Hence, we have to ask ourselves which one is right… surely I’m not the holder of truth because there is still a lot to be discovered in our discipline.
What is Psychoacoustics? It’s a very hard discipline residing in between Mathematics and Cognitive Perception, aiming at harnessing the knowledge the ultimate transfer function of an acoustical event to sound perception. The fundamental hypothesis is that there is a brain capable to understand mechanical vibrations and then turning them into sensations, evoked emotions and perceptions. From the Systems Theory we adopt the property that a sound does exist until the brain processed a vibration, and because sound is an element belonging to Subjective Domain, we are forced to accept the inconvenient truth that:
* Sound doesn’t exist in Nature, but in our mind only.
So, if you and I were seated on a sofa talking about the pleasantness of one large diameter-woofer dipole bass reproduction vs. small-diameter multi-woofer monopole vertical array and there is no speaker system playing in the room…from a crude math standpoint we were talking about nothing because there isn’t any causal event to be processed. But, again if there were an acoustical source…we still were talking about a fuzzy concept of sound because our own Transfer Functions are dissimilar.
Then, why so much research into perception, especially about Loudspeaker Quality Assessment? Simply because manufacturers need to know a general shared trend to comply with it in order to successfully sell their loudspeaker systems.
Regarding the scientific community there are a lot of points of views in contrast to one and other. For instance, the use of one mono subwoofer instead of four stereo subwoofers for multi-channel LFE. These choices are both right (is it possible?) but from a perceptual standpoint they are addressing different topics:
* The first is addressing coherent power response Sub+Sat
* The second is concerned primarily with IACC @ very low frequencies (20-100 Hz).
So, if we arrange a double blind psychoacoustic experiment to ascertain the consistency of the above topic approaches by means of a listening test with one forced choice between two systems with a total of n panelists, what do you think the results will be? Will we find a 100% preference for 1 mono or 100% preference for 4 stereo? Unfortunately none of them….Actually we shall find x for mono and n-x for stereo! We call that “The researcher’s regret” that makes perception variables extremely hard to handle…and to understand.
Perhaps we Westerners keep on committing this mistake of considering an everlasting dichotomy of real events:
A or B…White or Black…Hard or Easy…Up or Down…like physicists did at the turn of 20th century, facing the paradox “Light is discrete or wave?” I guess that if they could have asked Easterners who would have answered: “Both”…
<both> is the only acceptable point of view in Psychoacoustics
In conclusion, all these words only serve to justify my answer: there is no design aspects (parameters & variables) worth of more attention with respect to others; I pursue a reasonable compromise among them. They all together work side by side to build up our own perception but there are million of sound perception as many as people in the world. I still do not have enough knowledge for an absolute choice criterion. At present time I only rely on numbers.
You appear to place great emphasis on cabinet construction, employing separate cabinets for the low and high frequencies on several models and very thick front baffles on others. What are your design goals for your cabinets?
There are misinformed manufacturers and misinformed audiophiles. The first believe that speaker cabinets should resemble musical instruments behavior, with ear-tuned resonances, vibrating baffles and lute-shaped boxes. Most of them are simply as I said misinformed and lacking academic training, the rest are just “clever” businessmen in search an uninformed market. Impulse response of any speaker system should be unitary if we want the original signal to pass through without any distortion (time & frequency). All resonances should be dumped, but there is a trade off between cost, size, ease of manufacturing and performance, not to mention mechanical inertia of any accelerated mass. In Audio Engineering the key word is always compromise.
What is a “bi-dimensional hyper-exponential hourglass vent design” and what are its advantages?
Because any speaker cabinet volume is small compared to open air, the in-box pressure generated by a woofer is extremely high (140-160dB SPL). This acoustic pressure generates a force at the entrance of the vent that accelerates the air mass inside the pipe (bass reflex duct). Of course air particles move back & forth at high rate and when velocity amplitude exceeds 37 m/s (82.7 mph) the motion within the pipe is whirling adding turbulence. The solution is simply to increase the vent diameter, but math forces us to make the pipe longer…acting as an organ pipe! A good solution is to turn on to a variable section duct, with larger throat and mouth and narrower central body: just an hourglass. Like low frequency horn speakers, theory tells us that the horn should be infinite to avoid any energy reflection due to impedance variation. Of course it’s not possible (a compromise) so there are different strategies (hyper-exponential equation) to flare the final part of the duct in order to make a gradual cross-sectional expansion up to the infinite volume of open air.
But a real hourglass would call for a very difficult woodworking. Luckily, the wavelength to duct ratio is so high that there is no need to make a 3D hourglass, it suffices to have a two dimension profile squeezing the hourglass along its symmetry axis and you’ll get two parallel surfaces, i.e. a bi-dimensional vent).
Tell us about your unique crossover configurations. For example, your Solitaire speaker is a five-way design with cross-over points which are very close together (530Hz/650Hz/800Hz/900HZ/1,500Hz). That is a very unusual design.
It’s a complex topic…..there is no way to summarize the whole subject within a few pages of a web interview. Let me only introduce the concept:
“A multi-channel stereophony center speaker is fed via a monophonic signal that reaches both the listener’s ears. This simple process is useful for source of localization, but during the performance of a High Definition Audio System it’s necessary for the ear-brain mechanism to rely upon added information to make the virtual stage credible. In order to define a complete set of psychoacoustic quantities for quality assessment the listener has to be aware of another subjective quantity named Spatialization.
Briefly, for home reproduction we have to cope with two psychoacoustic quantities: Localization and Spatialization. One is the opposite of the other. I am accustomed to use Heisenberg Indetermination Principle to point out the uncertainty of these two quantities whose correlation coefficient is null
or negative. It simply means that:
* when localization is 1 then spatialization is 0 (listening to music in an anechoic room)
* when spatialization is 1 then localization is 0 (reading a sermon in a large gothic cathedral)
High Resolution Audio calls for both qualities to fool the ears and making the audiophile believe what he is listening to. The Solitaire theory is based on Overlapping Points, a previous unconventional crossover configuration aimed to make the transition from adjacent drivers seamless so avoiding the timbre change due to radiation impedance variation because of different driver radiating surfaces. If you are interested to know more this is the link:
As stated on the brochure, Solitaire is not a specific design but rather a set of theories into a design. What I mean is the hypotheses on which it is based upon are necessary and sufficient to make any alignment you want. Anybody can make experiments and gather information about auditory perception. Of course, we have our own equations. But skilled people can find good models to work too.
On several models you use very large dome tweeters. Are these tweeters proprietary to your company and what benefits do you feel they impart?
Yes, our tweeters are a proprietary design. They share large diameters because I use very low crossover frequency (1000-1400 Hz). The thermal overload requires a large voice coil for heat dissipation. Lower crossover frequencies make the transition from drivers smooth because the two directivity factors are similar. This implies that energy distribution in theory is even with no suck out, no lobbing errors, and therefore the probability to convey correlated reflection to the ear and spectral density increases. This is the basilar hypothesis that triggers the Haas effect in order to concentrate attention to the first wave-front arrival, hence greatly reducing the conflicting information to which rooms contribute with delayed resonances.
Do you feel a more limited horizontal dispersion of the tweeter is a benefit and, if so, why?
I suggest we refer back to my discussion on Solitaire. Tweeter polar radiation and its diffusion around crossover frequencies are strictly linked to localization (high directivity) and spatialization (high dispersion). The same follows for the polynomials used in crossover networks. Bessel and Butterworth low order allow overlapping drivers and cause acoustic interference, while Chebychev and Linkwitz-Riley high order do the opposite. Neither of them is a beneficial! Pro & Cons are always present and these are wrong ways of categorizing acoustic events.
As a researcher I shouldn’t embrace any, and practically I do so. Two way speakers with large tweeters show a power drop out over 6-7 kHz, but linear power transfer around 1 kHz. Both are necessary. My choice is not the best choice; it is simply the one that in my opinion yields reasonable convergence of conflicting variables. But it’s only an opinion. In audio the number of variables is higher than the available equations, so you have to create many of these equations. Why should some values be more important than others if our understanding of the human auditory system is so limited?
For many of your speakers, you place the tweeter on the bottom of the array with the mid-range and the bass drivers above it. That is non-traditional to say the least. Would you tell us the advantages of that arrangement?
The reason can be found within the WMT proprietary principle based on Overlapping Points. As I stated previously to take under consideration all the possible variables it is useful to address the double nature of each physical event. Sorry I keep repeating this point of view but anyway it’s necessary.
If we assume localization and spatialization to be necessary quantities from a psychoacoustics point of view we are forced to find out a solution to take care of both. One possible path is to add de-correlated information to the brain, extracting new signals from that available at speaker terminals. But this sounds as Entropy Principle violation, because we are not able to create more information than that available on the recording! Of course, the trick is not to work on the electrical domain but in the acoustical domain, splitting the overall signal among different drivers with a special alignment capable of randomizing energy throughout the room, exploiting the multiple reflections. On axis first arrival transient must be kept unchanged. Vertical three way design allows for a solution. Further up-side-down inversion gives the system increased entropy from all directions but the front axis. It’s only a strategy to handle the many psychoacoustic variables that come into play. It’s not the best, because no one knows the best, it’s simply a viable solution suggested by math.
You manufacture a very broad line of speakers, some thirteen different lines according to my count, with multiple speakers within each line. Why is such a broad range necessary?
Yes, we recognized it recently. During the many years we had line groupings to allow the dealer mix and match to approach different segments of the audio market. After the current global crisis markets have changed, and we are restructuring our line-up and running production.
In closing, is there anything else you would like to tell us about your company or products?
I suppose you may have sensed our unconventional perspectives in this interview. Our scientific point of view may sound sterile for those who have an emotional connection to reproduced music. I fully understand why that perception may arise. But actually as much as I am an engineer I am an audiophile (phile=lover), and I know how different these two human dimensions are. Science and love are two sides of a coin so you can’t see both sides at the same time. I heard a joke sometime ago that there was this man so strong that when he squeezed a quarter, Washington’s face would be poke out through a Capitol’s window. This is the impossible path we face.
We Italians use the phrase “to put one foot in two shoes” which for American it could be more or less translated to “political correctness” or to say things could be accepted by everybody without offending anyone. But I soon realize it’s not really possible and my words inevitably become curt and blunt when I keep my mind on the path of reality. Many people are particularly proud of their achievements, and they think their point of view is the best, whereas Russell wouldn’t agree. Furthermore Karl Popper jokingly upholds the thought that “when a hypothesis is working it is the right moment to falsely validate it”. I took these two masters as a foundation for Chario’s design ideology. We have yet to arrive to the absolute truth, and I’m personally convinced that it will never happen in my time. Doubt is my friend when I talk about acoustic events, because there are infinite answers as much as shades of meaning for the word “s-o-u-n-d”. Still, we do persevere… Thank you.
Thank you again for joining us.
