Meridian Audio Speaker - Manual (Page 8)

Because you are nearer to the left
speaker, the sound takes less time to
travel from the speaker to your ears –
and you are further from the right
speaker, so the sound takes longer to
arrive. Meridian’s approach to “bal-
ance”, using the power of DSP, auto-
matically adjusts these subtle time
delays, so wherever you decide to sit,
signals will arrive at the right time, as
well as at the right level.
In addition, our processors can provide
decoding using Trifield and Ambisonic
technologies, which literally recreate a
solid image of the original environment
in your listening room – producing an
incredibly lifelike surround-sound experi-
ence, and even rotate the soundstage to
suit where you are sitting.
Meridian’s DSP loudspeakers utilise 48-
bit internal fixed-point resolution. This is
a long way beyond what anyone can
actually hear, but when you perform
DSP operations, additional bits are creat-
ed and it is vital that these are pre-
served.
Furthermore, whenever digital signals
are processed, they have to be dithered
correctly.
Dither is a special form of noise that is
added to a digital signal whenever oper-
ations are performed on it. It smooths
out imperfections and significantly
improves the sound of a system. In fact,
a properly optimized dither signal can
make the resolution of a digital system
effectively infinite (See sidebar, “What is
Dither?”).
DSP technology is also used to provide
additional features, such as tone con-
trols and, because the loudspeaker
knows the sound pressure level it is pro-
ducing, loudness controls can be imple-
mented more naturally than ever
before.
The same principles can provide dynam-
ic bass extension in smaller speakers,
where low frequencies are boosted
more at low levels. The system com-
putes cone movement, frequency and
level, and as a result can provide bass
protection, shutting down if there is a
risk of parameters being exceeded. The
voice coil temperature is also calculated,
permitting precision thermal protection.
And finally, allowance can be calculated
for different locations of the loudspeak-
er in a room, such as boundary com-
pensation when it is placed near a wall.
Digital signal processing also comes into
play when you use a system at different
levels. Our ears are less sensitive to bass
and treble when we listen quietly: DSP
can compensate for this according to
carefully-research psychoacoustic princi-
ples.
“Human-sized” speakers
Meridian’s speakers look, as well as
sound, distinctive, and of course both
these factors are related. It has been
shown that loudspeakers that are as
close to human-like as possible produce
the best imaging – mirroring, in a sense,
the position of human sense organs.
The “head” of a Meridian DSP loud-
speaker (such as that of the DSP8000
shown above) produces the vast majori-
ty of sound from 200 Hz up, which is
where stereo and surround localization
takes place.
page 8 Meridian Loudspeakers: The DSP Path The Meridian Papers - 1
What is dither?
Why do we need it?
➤ …Dither is not only required when a
signal is converted between the analogue
and digital domains: it is also needed any
time a digital signal processing (DSP)
operation is carried out, such as decoding
a surround bitstream from a DVD, apply-
ing a DSP preset, or passing through a
digital tone control.
The more highly optimised the dither sig-
nal, the higher the resolution – the further
you can hear below the noise, and the
more detail you can hear.
In a properly dithered system, the resolu-
tion is effectively infinite.