Focal UTOPIA BERYLLIUM Série Manuel Utilisateur page 8

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The recent introduction of multi-channel audio systems has considerably influenced the
common quality and performances criteria of subwoofers. The energy stored up in a
frequency range spreading from 20 to 120Hz is so high that it requires the use of new
technical means. The high efficiency digital amplification named BASH
answer to these new requirements.
®
Focal-JMlab uses the BASH amplification technology, a patented invention of the society Indigo,
under licence. This technology ensures an outstanding energy efficiency, allowing a very high output
power, without being damaged by heat losses. This technology is presented as an hybrid high-end
system which combines both the advantages of the D class and the AB class, the former renown for
its high energy efficiency and the latter reckoned to be more musical.
AB class
The AB class analog amplification technology, well-known until then for its good qualities, is widely
used, and more particularly in self-powered sealed subwoofers: actually it has an energy efficiency of
about 65% and considerable acoustical performances. However, when used with a music program
signal, the typical efficiency appears to be seriously affected and is reduced to a smaller level, between
10 and 30%, according to the type of music you want to reproduce. Today, a multi-track digital
mix found on DVD features soundtracks which are filled with a considerable amount of bass. In
order to reproduce these soundtracks as faithfully as possible, a high amplification power is inevitably
required. AB amplification technology is then rapidly pushed to its limit. With regard to its weight,
price and size, the AB class amplifier is then not suitable anymore.
D class
The D class turns out to be the first solution to tackle this problem. This so-called digital
amplification technology uses a high frequency PWM system which allows the transistors to deliver
their best performances. This process defines variable bandwidths directly proportional to the
power and frequency of the output signal. Thanks to this technology, the energy efficiency increases
considerably and gets up to 90% at continuous peak power and 60% with a music program signal!
Although there is one important restriction: the sound quality proves to be too poor, since it is
deteriorated by intermodulation distortions and ringing effects.
BASH ®
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The BASH technology we decided on for the production of the Sub Utopia Be is a pertinent
implementation of the previously mentioned amplification methods, making the most of both the
AB class and D class amplification technologies. Actually, the small energy efficiency of the AB class
strongly depends upon the fact that the supply voltage of the amplifier remains stable. Losses are
only the result of the multiplication of input voltage by different leaking currents. The key idea of
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the BASH technology is based on a continually variable supply voltage which tends to zero when
there is no input signal and reaches its highest level when the amplification power requires. As this
supply voltage is continually variable but always lower than that of an AB class amplifier, there is
necessarily less losses. To meet these requirements, the amplification device benefits from a AB
class structure while the variable power supply uses a high speed D class unit in order to constantly
supply the amplifier with the appropriate power. This new structure allows the amplifier to keep
the advantages of the AB class in terms of sound rendition while reaching the energy efficiency level
of the D class which gets up here to 85% and between 50 and 60% with a music program signal.
The losses reduction offers here another advantage: it allows to conceive very compact but powerful
amplifier units since there is less calories to dissipate. The Sub Utopia Be device then delivers a
1000Wrms output power.
®
Using a BASH amplification system, powering a 40cm subwoofer equipped with a W cone driver
on the Sub Utopia Be now allows to obtain an uncommon 128dB pressure level within the lowest
part of the spectrum.
Your Focal-JMlab product was developed and manufactured with high-quality
materials and components which can be recycled and/or re-used. This symbol
indicates that electrical and electronic equipment must be disposed of separately from
normal garbage at the end of its operational lifetime.Please dispose of this product by
bringing it to your local collection point or recycling centre for such equipment. This
will help to protect the environment in which we all live.
BASH
User manual Sub Utopia Be line
® is the real
The very high efficiency of the BASH
conceive high-power, compact and light amplification systems.
The AB class amplification technology uses a stable supply voltage. Losses
are directly proportional to this high supply voltage. The BASH
uses a "by request" fluctuating supply voltage. As the power input of the
amplifier is seldom implicated, this voltage remains quite low on average or
even very low at low level.
The energy efficiency of an amplifier is usually about 65% but only at its
nominal power. On a 75W RMS device, the efficiency drops to 35% for a
20W output power. Comparatively, the BASH
maximum energy efficiency of 85% from 20 Watts on.
Bash
of D class.
®
amplifier
® technology makes it possible to
®
® Technology Amplifier have sound quality of AB class and efficiency
® technology
system reaches its