Spiral acoustics Tornado

Quite a long time has passed since the moment when I made this acoustics. Time passes, and I notice negative phenomena associated with my work to one degree or another. I decided to share with you my column design. Searches in acoustics were aimed only at practical results.

And so, after much experimentation, I created one structure, which I gave the name Tornado. Here is one sketch from my official papers from the German patent office. The construction of the column is clearly shown here. The design of the column at the bottom is open, that is, it has direct contact with the room.

Vibration board

This element has mechanical mobility, because attached with silicone to the column case. During the operation of the head, the board should vibrate and naturally something should happen. And strangely enough, some “miracles” occur, the board practically does not vibrate and somehow this has a positive effect on the sound quality. According to acoustic measurements by the “Sinus – Burst” method, the sine no longer has a “cut off head” – the upper part of the amplitude, and distortions K2 + K3 fall sharply in measurements from the best indicator for PI 5% to 1.3% in this case, with good geometry sinus.

It turns out that no one considered the work of forces in a physical concept in such a simple mechanism as a speaker. And in it, active and reactive forces work according to Newton’s law (Actio = Reactio) and they perform different work. Active forces go to the production of the movement of the diffuser, and the reactive forces make a complex path of their movement coming into the mass of the speaker.

When forces come to some mechanism or mass, they “look” for where they can realize their energy, or rather a weak point. But, in a well-built structure, such a place is difficult to find and there is nothing left to do but go back. Returning back already with losses, the reactive forces begin to interfere with the active forces, i.e. generate distortion, which creates problems for us in sound, and on acoustic measurements we see a sine without a head.

The vibrating board (V-board) creates antiphase motion for the reactive forces generated by the head. Moving in antiphase, the B-board actively eliminates reactive forces, thereby conserving the energy of the speaker as a whole.

As it turned out, everything is interconnected in acoustics: Q_ms-> Q_es-> Q_ts-> V_as, even in laboratories this is confirmed. But in the laboratory they experimented with changes in only one quantity Q_es, affect Q_ms somehow actively failed, but it turned out that influencing Q_ms you can get almost any result you want. Of course, you need to influence Q_ms by acting only on reactive forces and thereby increasing the efficiency of the system as a whole. So I am experimenting with the head where V_as= 204 liters, managed to realize it in the resonator V = 40 liters at Q_ts= 0.7, this is really an unusual indicator V = V_as/5.

Resonator

To make a resonator that can “sing”, let’s face it, is not an easy task. The fact that the work of the resonator depends on its geometric dimensions was found by Helmholtz and this served as the basis for the theory. The vibrating board design, or boards, is completely unfamiliar to theory. As practice has shown, such a resonator does not require an accurate calculation of its dimensions, and has a higher performance, which means more energy.

This effect is realized in practice as the construction of speakers without preliminary calculation, and with a small-sized resonator.

The resonator for a Tornado is usually two times smaller in size than for a FI with the same head, perhaps this indicator can be more, with different heads I did it differently.

In such a resonator, one already has to monitor the conservation of energy and the use of cotton wool or other material as a sound absorber is no longer permissible – such a resonator simply stops working and the bass disappears. Analyze this moment yourself, for example, I do not understand any design where the energy is extinguished inside the resonator … One can only guess what sound is given by a column with cotton wool inside.

When building a resonator with an B-plate, the only criterion is the adjustment of the interaction of two volumes: a resonator and two spiral propeller channels. This can only be done by measuring the TSP parameter. This is the most important point and only this requires skills in working with acoustic measurements.

Everything can wait, measuring the frequency response and a bunch of other acoustic measurements, but this measurement, which is made electrically, is the main one in the construction of acoustics and must be mastered and preferably understood. I am adjusting the cross-section of the channels in the propeller to the specific TSP graph. The most efficient and low-distortion graph will be the B4 graph, a graph with two equal impedance amplitudes.

Test hole

This is the name of the hole, or channel, through which the resonator is connected to space. In the design, the FI is a pipe channel, and it is located inside the resonator, located on the front or back of the column case. In a Tornado, the role of a control hole is played by two spiral channels, they are usually located in the lower or in the final part of the structure. That is, the spiral channels are not located inside the resonator, but on the side opposite to the speaker, this is a direct-flow structure in terms of the arrangement of the elements.

Spiral channels are obtained with a special device – a propeller in the round part of the column, each channel has a spiral turn equal to 180 ° at an angle of inclination or a pitch angle of 30 °. In these channels, a sound wave, the speed of which is 343.3 m / s, receives a turbulent motion, where forces are created against its spiral-translational motion. It’s a familiar tornado effect, and that’s the name I gave my design.

As it turned out later from practice, the effect of turbulence is quite productive for the air resistance to the resonator. The cross section of one spiral channel is approximately the same as that of the FI channel for a given head, but there are two of them in Tornado, which means that the Tornado design has a communication channel that is twice as large in cross section. Even that speaks to how turbulence works. Such spiral holes work directly with the wave, unfolding it in phase, but they no longer work as an additional emitter.

The propeller is built on the principle of least loss, its diameter should be the same size as the speaker used, or larger. The spiral holes must bend around the largest possible diameter for a given propeller design.

And that’s not all that spiral holes can do. So, by changing the design of the propeller, you can get a “linear” impedance, which is simply necessary in midrange speakers, like …