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| Pulse-code Modulation (PCM) is the
most common form of a digital signal; it is simple
and compressed. In the digital audio context, the
digital ideal is to reproduce sounds as close to
the original source as possible or keep them digital
at all times. Something to remember is digital information
is lost in transfer due to misreadings and poor
algorithms, but can be restored with error correction
software and hardware interpolation grids. This
information in the stream is lost every time there
is a conversion from analog to digital and even
though the amount of loss is predictable, the predictions
can be varied and hence influences the resultant
signal. |
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| When playback of the digital signal
occurs, the original waveform is usually encoded
and then decoded and decompressed. This decompression
should exactly mirror the original compression process.
However, this is hard to guarantee, which is why
the iDome solution, which keeps the signal digital
right through the entire amplification process,
preserves the original integrity all the way. |
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Furthermore, any upper harmonics which have been discarded
through inefficient analog to digital conversion can never be
restored completely. Only the human brain has the processing
power to adequately process and complete the sequences correctly,
so when the digital stream is eventually converted to analog
via the speakers (all speakers are analog, since it is physically
impossible to hear digital pulses of light), the missing sequences
are filled in the same way as the human eye can predict quite
accurately the flight of an object and extrapolate its path.
Similarly the human ear will very accurately fill in the harmonics
and predict the fundamental frequency of a tone upon a signal's
re-conversion into analog via the amplifier/loudspeaker. Electronic
conversion is far from human brain standards and several such
conversions within an amplifier do not bode well for crystal
clarity, which is why purely digital signal processing is so
much more efficient. |
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The generally accepted frequency response of human hearing
is from 20Hz - 20kHz. According to Nyquist, the maximum bandwidth
that can be represented by a digital signal is less than half
that of the sample rate. This means one requires a minimum sample
rate of 40kHz. In real life situations, a slightly higher sample
rate is needed to make up for distortions, filters and interference.
But, the Shannon equation for reconstructing the original data
fully requires infinite samples. Fortunately the abit iDome,
with its pure digital frequency modulation, bypasses these problems,
and by keeping the digital source from the MP3 or DVD in its
digital format all the way through the amplification process,
it preserves audio fidelity and maintains total audio integrity. |
