Audio Alto AA 5 K speakers detailed info

Many of you asked me to write more about Audio Alto AA 5 K high efficient modular speakers. Here is complete official info… 
The concept of high quality loudspeakers that achieve a higher or high intensity sound pressure while providing linear frequency range between the lowest and highest audio frequencies (20-20000 Hz) is linked to the size of the speaker units, size of boxes and thus indirectly also the weight. Such systems are therefore generally large, cumbersome, and (very) heavy. If this desired parameters would include also features like high efficiency and low distortion, in most cases we encounter parameters that are usually mutually exclusive and it is (very) difficult to find balance between them (especially if designers do not want to use too many compromises ).
The objectives of the development model for the AA 5 K overcome some mechanical and functional deficiencies of modern speaker systems as well as overcoming as many electric and acoustic parameters which are conventional speaker systems on the market offer.
Speaker System AA 5 K design achieves a flexibility of setup, which may be e.g. vertical, horizontal, or, for example, form a cube. Individual units of the speaker system AA 5 K are equal in size and therefore the user can arbitrarily combine (install) them together and thereby fulfill the space he/she have available, as well as she/he can chose the preferred appearance. The figure below shows some possible configurations.
The medium-tweeter unit both in terms of room size and the position of the listener can be placed on top of the bass and bass/medium units or, for example in between the bass and the bass/medium units. With this setup we can adjust the optimal height for the listener position.

Vertical beaming

Each of the units of the speaker system AA 5 K is equipped with feet (spikes) that are vertically adjustable. Unit (s) can thus not only adapt to uneven floor space but each individual unit can be tilted for example in the direction of the listener and thus achieve an optimal beam of sound pressure (i.e. vertical dispersion).

Dimensions and weight
The selected design of the individual units of the speaker system AA 5 K also enables a very important feature of the system – due to the modularity and (small) size of each unit, each unit more compact and far from set, which allows for less vibration and resonance of the box. The dimensions of the units are (H x W x D) 308 x 308 x 500mm. The size of the business of the speaker is 8 units (H x W x D) 1320 x 308 x 500mm (2 x 4 units), the size of the 6 units is (H x W x D) 990 x 308 x 500mm (2 x 3 units).
With such a design is achieved yet another practical aspect of the speaker system – the user, despite the large mass (each unit is heavy 25kg) is capable to move and optimally set the system without additional aid (one or more assistants).
Speaker grills
Each system unit could be covered with a speaker grill. The grill is fastened with four neodymium magnets and is easily removable. Aesthetic advantage of such a method of attachment is that on the face aren’t visible any holes or attachments.
Electric and acoustic properties
System AA 5 K is a passive loudspeaker with an impedance of 4 Ohms. Model 6 (6 units) has a nominal power of 200W and 400W of music power, model 8 but the 300W and 600W of music power. 
Low frequency units
Bass units are the same in both models by the manufacturer of professional Beyma units, each with a diameter of 250mm with a declared capacity of 400 / 800W AES, sensitivity of 96dB / 1m 2,83V. Large power drivers enable exceptional response and dynamics as well as a large sound pressure. A large sound pressure at low and low/mid frequencies is also achieved with minimal movement of the membranes and thus also with extremely low harmonic distortion. Below is a view of factory measurement distortion versus frequency.
Medium and high frequency units
For medium-high and high frequencies AA 5 K uses a professional AMT (Air Motion Transformer) unit witch brings the highest sonorous quality of the most demanding audiophile to the world of live music.
In this type of transducers, invented by the German physicist Oskar Heil, the generation of the sound takes place in a very different way than habitual in ribbon tweeters. In figure one; we can see that in this device, the diaphragm is formed by longitudinal folds, like in an accordion. In the straight face of each one of these folds, there is a printed conductive copper thread.
The advantage in this type of device consist in the small and very controlled movement of each fold, accelerating the surrounding air inside each fold, which produces an almost perfect acoustical output, both in amplitude and in phase in all the radiating area of the transducer ( ). 
The result is extremely accurate sound with outstanding dynamics and very low distortion. Using Horn is in the AA 5 K reaches the phase alignment of the subwoofer and mainly very constant and wide horizontal radiation angle. The following figures shows the measurements of distortion versus frequency as radiation (horizontal, vertical), response time (Waterfall) and see multi-tone image and the associated distortion compared to other (i.e. compression) units.

Frequency response 
The figures below shows the AA 5 K frequency response measured in (typical untreated) living room. The measurement is spatially averaged. The measures of the room are (H x W x D) 2.5 x 4.5 x 8m. In the frequency response are visible the some reinforcements and attenuations due to reflections, resonances and room standing waves.
The result of the design and development of speaker system by AA 5 K is a system that easily adapts to the needs and taste of the user. 
It allows the user to assemble, disassemble and during setup to easily move the speaker system in the room, irrespective of a large weight, alone (without additional assistants), the user can, thanks to specially designed spikes, depending on distance from the speakers and the size of the room, adjust the height of the mid/treble unit and with this optimize the acoustic beam, the specially designed addition to the spikes (base with fleece) under the basic unit allows, without major problems to move the already assembled speaker.
In addition to the above-mentioned (mechanical) properties and AA 5 KG also provides superior electrical and acoustic parameters, which are:
use professional units for low (10 inch 400W / 800W AES) and high frequency, the use of Air Motion Transformer for medium and high frequencies, maximum linear frequency range 30-20.000Hz,  very low distortion (sound pressure 95-100dB) for frequencies 30-20.000Hz, the2nd harmonic  frequency is below -50dB, the 3rd harmonic frequency is below -65dB, mechanical phase aligned units, high sensitivity of 95dB / 2,83V / 1m, which allows the use of low power amplifiers the Xover design allows excellent bass driving capability with amplifier having higher output impedance (lower Dumping factor), maximal sound pressure is greater than 116dB, minimum and maximum impedance between 3.7 Ohm and 7.4 Ohm (45Hz-20.000Hz), maximum linear electric and acoustic phase (from 1.000Hz to 100 Hz + -24 deg., from 1.000Hz on + -0 deg.), switchable setting for medium-high tones (from 1.200Hz to 20.000Hz) -2dB, 0dB, + 2dB, constant and wide horizontal dispersion medium at mid/high and high frequencies.
Note *: measures performed by driver manufacturer Beyma