The basic principle. "According to the laws of classical mechanics, in addition to volume, mass and the material properties it consists of, each object in the universe exhibits a whole spectrum of natural frequencies which is completely dependent on these parameters. The first frequency is called the main or fundamental above which its harmonics occur. Based on that, we conclude that
"Regarding the mechanical parameters of materials, here we distinguish two, namely the Young's modulus and the damping or internal loss factor. For them, the following are true:
"Naturally all of the above also applies to acoustics. By creating a large acoustic chamber, the first and subsequent natural frequencies can reach significant values to badly distort the sound of a speaker. To damp parasitic resonances at these frequencies, it is necessary to significantly strengthen the inside enclosure with various stiffening ribs and partitions. The latter eat up internal volume which is most necessary for the operation of large woofers. Ultimately, the dimensions necessary for such cabinets reach incredible values.
"From all of the above, we can conclude that by creating a loudspeaker of deliberately compact dimensions with properly selected geometry and materials, such issues can be completely avoided. The natural resonant frequencies of the compact loudspeaker enclosure are located much higher and for their full damping it is sufficient to simply design with the right materials and shape.
"At 385x200x297mm, the enclosure of the Binom-1 is very compact. It is made of bent plywood panels under constant tension. To increase stiffness thus raise the resonant frequencies, the insides are compressed with a stainless steel brace which doubles as driver mount and torques up tension by pressing onto the massive 4mm curved aluminium plate on the back. To further enhance this constant tension, the box is pulled together from the outside by a 2mm thick layer of real piano lacquer. This construction moves the resonant frequencies into a fully damped bandwidth due to the internal material loss factor. Thus the entire internal enclosure volume loads a single driver.
"If we look at the results of a modal analysis of our cabinet, it shows how its natural frequencies are set in a zone where sufficient internal material loss damps them. Thus unwanted parasitic resonances are almost completely destroyed. The remaining minor oscillations are in a clearly 'green' zone to not affect the sound of the system." In short, without any filler material or partitions, the constantly tensioned Binon cabinet is exceptionally well self damped to reduce box talk to the barest minimum and let the driver speak for itself. The Binom-1 isn't just a pretty face but brainy by what goes on inside. Even the shiny lacquer has a structural not just cosmetic function.
On the ported question. "Yes, to do it as successfully as the Binom-1, a driver with special parameters is needed. A detailed analysis of this issue is very difficult. I will confine myself to one formula. Sound is created by moving the driver's diaphragm through the voice coil. The modulus of force that occurs as a result of the interaction between conductor, current and magnetic field can be described by the law of ampere where F = BILsinα, i.e. B = the value of magnetic induction Tl, I = current strength in the conductor, L = length of conductor with current and α = the angle at which the conductor is located.
The following conclusions can be drawn from this equation:
"For even greater simplicity, we take the values of the variables I, L, sinα equal to one. Thus, the force F depends only on the value of induction B in the magnetic gap. The bigger the induction, the bigger the force F. At the main resonant frequency, the driver diaphragm moves in anti-phase to the main signal. At this frequency, the loudspeaker becomes an alternator. Its current counteracts the main current for so-called self damping or breaking. The magnitude of this counteraction is directly proportional to the value F to increase with increasing magnetic induction B. From this follows that the greater the magnetic induction, the greater the sensitivity at medium and high frequencies and the lower at low frequencies. With bass-reflex designs, the effect increases because the diaphragm, with increasing frequency, works in anti-phase two or more times. The use of a closed box or bass-reflex design for such drivers is unacceptable.
"This situation can be saved only by the enormous length of a back-loaded (not necessarily) horn which, to the best of its size, is usually curved twice. It is the resonances arising at the bends of the horn areas which amplify the signal at low frequencies. Now in the bass response, several peaks appear, usually at 60, 120 and 240Hz. These resonances are secondary to the main signal and, I believe, have nothing to do with good sound. Among audiophiles, this effect is called 'horn sound'. All or almost all existing classic broadband loudspeakers have large magnetic systems. Manufacturers boast of giant magnetic-induction values in their air gaps. Thus the terms broadband and back-loaded horn became synonymous.
"In the Binom-1, I deliberately did not select the maximum possible but optimal values of B and L. These provide a linear conversion of electrical energy into sound across the entire frequency range. The phase inverter system or port is tuned about 10Hz below the self resonance of the driver. This allows us to dissolve these frequencies, thus reduce the influence of the opposing current i.e. the self-damping which increases the low-end response."
