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AXD1

DEVIALET AXD®
Expert Pro Active X-over Design Technology

Why did we develop AXD®?
At Devialet, we were the first to develop an exclusive technology capable of adapting our amplifier
performance to the characteristics of the loudspeaker it is connected to, in real time and withoutadditional hardware. This technology is called SAM® (Speaker Active Matching) and is based on amathematical model deducted from measurements made on each loudspeaker, so Expert Pro cantailor the sound signal to fit their precise requirements. For the first time, SAM® made it possibleto achieve perfect temporal alignment between the recorded signal and acoustic pressure from yourloudspeakers.
Today, more than 1000
800 speaker models are SAM®-ready but we wanted to push the technology
further and offer a solution to the most demanding audiophiles, capable of maximizing theperformance of ultra high-end loudspeakers. That is why we partnered with some of the world’s
leading speaker manufacturers, to design the shortest analog signal path between an audio sourceand speaker drivers while limiting analog sections to a minimum. The result of this quest for
perfection is AXD®, the ultimate conduit between Expert Pro and some of the finest loudspeakers
ever built.

What is AXD®?
AXD® (Active X-over Design) combines the endless possibilities of Devialet Expert Pro DSP (DigitalSignal Processor) with the crossover networks of some carefully selected high-end speakers, tocreate a complete, perfectly optimized setup. AXD® is the only technology capable of extracting thebest performance out of these extreme audio systems delivering sound in its purest form.
AXD® is:— an active crossover (X-over) design for the speakers, performed in the digital domain, using
DSP-based crossover filters already available inside Expert Pro systems. Each speaker active
profile is a faithful implementation of the formulas provided by their creators and designers, 		
and then validated and signed by them, with no exception.
— the shortest analog signal path in the history of audio, with even less distortion and noise,defining a new level of transparency, precision and therefore faithfulness.
— the future of extreme high-end audio systems, giving loudspeaker designers whole new
possibilities only available in the digital domain.

2How does AXD® work ?
Modern multi-way high-end speakers are difficult to design and to drive, with drivers of different
characteristics and massive passive crossover filters which have to be designed with many
constraints such as counter electromotive force on drivers (woofers can load other drivers),
sensitivity driver leveling, etc.
Here is an example of a classic high-end setup, with passive crossover filters.

Classic High-End set-up3Every input signal has to go through a number of analog devices before being transformed intomusic by the drivers. On average, the length of analog electronic circuitry in a classic setup is 55-110cm, excluding interconnect and speaker cables. Along this distance, according to the number of in
between components in the signal path, the signal loses integrity, and distortion appears.
In Expert Pro systems, the analog path has been reduced to a minimum, achieving a huge
improvement in sound quality associated with signal processing capabilities such as our exclusive
SAM® technology:

Expert Pro set-up

The number of analog devices the signal has to go through before being transformed into music has
been drastically reduced, so the total analog path of the audio signal is already the shortest in theworld. In this setup, the full range signal is sent to the speakers, and the frequencies repartition ishandled by the passive crossovers.
Another solution is to place the crossover filters before the amplifiers, and to amplify each driverwith a different amplifier. This is called active crossover filtering.

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Active crossover filtering has long been regarded as an ideal solution for crossover filters for thefollowing reasons:Accuracy:—— Active crossovers are an easy way to vary or fine tune each frequency band to the specificdrivers used, the frequency response is then independent of the dynamic changes in a driver’s
electrical characteristics.
—— It provides a better isolation of each driver from signals handled by other drivers, thus
reducing intermodulation distortion.
Efficiency:—— The power amplifiers are directly connected to the speaker drivers, thereby maximizing
amplifier damping control of the speaker voice coil, reducing consequences of dynamicchanges in driver electrical characteristics, all of which are likely to improve the transient
response of the system.
—— It reduces power amplifier output requirements. With no energy being lost in passivecomponents, less powerful and more accurate amplifiers can be used, especially for tweetersand mid-range drivers, which potentially increases quality.
To achieve active filtering, Devialet developed an easy-to-use technology. Together with thespeaker manufacturers, we developed a dedicated R&D tool and invested resources to make sure
it is easy to create the most accurate active profile for each speaker.

5Expert Pro AXD® set-upIn a AXD® setup, the crossover filtering is done in the digital domain, inside the Expert Pro DSP,
so each amplifier output can be directly connected to its corresponding driver.
The result is a more dynamic, open, detailed and natural sound.
At the same time the system is elegant and easy to use, just a set of dedicated configuration files
and the connection of Expert Pro to the speakers. In several minutes you can enjoy the original
sound from the speaker designer.

6What are the benefits of AXD® ?
Three key advantages of AXD® to remember:—— AXD® provides superior possibilities to the loudspeaker designer, compared to passive crossover
constraints.

—— AXD® enables higher precision and purity: no tolerance spread on component values, no distortion
nor noise induced by the passive components of the passive crossover (inductance non-linear distortion,
thermal distortion and resistors noise,...). The shortest analog signal path in the history of audio. Less iseven more.

—— AXD® maximises the efficiency and linearity of the amplification system: 100 % of the power
delivered by the amplifier is used by the speaker driver. The amplifier does not have to deliver extra
useless power dissipated as heat by the passive crossover. The overall distortion level is further reduced,
the dynamics enhanced.

Passive X-over:—— Analog domain—— Filter network composed of resistors,

Active X-over Design AXD®:

capacitors and coils—— Digital domain—— DSP-based digital filters—— No tolerance issues (100% reproductible—— Loss of efficiency (can only lose energy)

from one DSP to another)-> more distortion from the amplifier—— No thermal distortion (digital—— Tolerance issues (variance betweencomputation)

analogue components)—— More overall power (more Expert Pro—— Thermal distortion issues (analogueunits)components)—— Shortest signal path in the history—— Aging of analog components—— Imperfect L/R matchingof audio (straight wire between Class Atransistors and Speaker Driver’s coil)—— Software upgradable—— Multiple structure—— More phase-accurate oriented—— No aging issues of analog components—— Non linear corrections, upon request

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AXD® crossover filters response
VS passive filters response8

Two examples below to illustrate the above:
Devialet AXD® — Vivid Giya G1 Spirit

2x 250W

2x 250W

2x 1000W

2x 1000W

Devialet AXD® — YG Acoustics Sonja 2.2

2x 1000W

2x 1000W

2x 1000W

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