Functional Quality
People
have used audio equipment to play music for a hundred years. Some peculiar voice states (emotional states of sound) of audio
equipment still linger after the technological development of various periods. Gradually, this sound state is inadvertently
regarded as a necessity for audio equipment. However, when we examine the development history of the ever-evolving recording
and playback technology, we can find the formation track of this seemingly normal but unreasonable phenomenon, and repair
the deficiencies left over from the past.
The development of music signal sources from LP records to audio CDs has
made a leap in technical indicators. However, there has been a regression in the naturalness of the sound. We can realize
that this is an unreasonable phenomenon by comparing their technical indicators. Frequency response, phase characteristics,
dynamic range, linearity, resolution, signal-to-noise ratio, each has a fully improved audio CD. Compared to LP records, it
should be able to express sounds more accurately. However, it is inferior to LP records in terms of naturalness of sound and
accuracy of emotional expression of music. Electronic equipment is used in various fields, and their performance and quality
are closely related to technical indicators. But when it comes to audio equipment, the relationship is so completely different.
People's attention to this unreasonable phenomenon has promoted the development of audio CD technology. Advances in digital
filters, data error correction, D/A quantization, etc. have improved the sound quality of audio CD playback. And it drives
the quality of other audio equipment to improve. However, the problem of the correctness of data read by the player caused
by the structural quality of the CD still exists. CD playback still needs to rely on a strong micro-dynamic filter to suppress
its irritable voice, so it is difficult to break through the sound quality. XRCD directly uses the master disc to make CD
discs. The fundamental problem of the quality of the disc structure is thus improved. This is a positive step towards the
improvement of CD sound quality. However, other audio equipment has begun to expose their fundamental flaws, and once again
hinder the further improvement of sound quality.
The bottleneck that affects the sound quality of the audio system
is moving back and forth between the signal source and the signal processing. The special aspect of the sound system gradually
emerged with this movement. When we examine the characteristics of the sound state transitions of the music signal source
changes at various stages, we can find that they have such a relationship: some unique sound states of audio equipment are
gradually becoming stronger as the frequency domain of the sound source gradually widens. This is precisely in the continuous
expansion of the frequency domain of the audio source, the real-time nature of the frequency spectrum must compete for the
sound quality of a dominant audio system. When an audio CD wants to show its wide full-range spectrum, the real-time nature
of the spectrum is even more difficult to compromise, and strive to control the sound quality of the audio system. (For the
real-time performance of the spectrum, please refer to the particularity of the audio system)
With the expansion of the frequency domain of the audio source, the tone will be improved. However, the destruction
of the real-time nature of the frequency spectrum also distorts the sound state of the played sound (the emotional state of
the sound). In the early signal source changes, the frequency domain has not been greatly widened, and the real-time problem
of the frequency spectrum has not seriously changed the sound state. At this time, the timbre benefit is greater than the
sound state defect, and people have recognized the sound quality gains with considerable benefits. Moreover, this distortion
of voice was inevitable at the time. In the past, to correct this sound state distortion, it still needs to rely on the integral
effect of the filter or micro-dynamic filtering to complete. Such a processing method can cause a deep negative change in
tone, which is undoubtedly difficult for the market to accept. Yes, the extension of the frequency domain is the main body
of every sound source improvement. If, on the other hand, the filter is used to delete this most valuable income, audio enthusiasts
will certainly not accept it. The sound state distortion of audio equipment is accumulated in this environment, and gradually
becomes stronger as the frequency domain of the sound source continues to expand. Until the appearance of audio CD, the entire
sound spectrum was presented without phase distortion. The real-time problem of the frequency spectrum will inevitably become
a stumbling block and hinder the functional quality of the audio system from improving with the improvement of the signal
source.
The peculiar sound state of audio equipment is overwhelmed on this rugged road. It can no longer withstand
the strict requirements of the excellent electrical characteristics of audio CDs. Modern digital recording technology can
record on-site information in the full frequency domain without phase distortion. This information is encoded in a way that
distributes the magnitudes in time series. At this moment, the real-time extent of the playback device processing these values
also completely controls the exact quality of the equipment's functions.
There have been many opinions and methods
on how to identify the exact quality of audio equipment. The audio industry has also set up many technical indicators to deal
with this matter. However, a large number of facts have proved that we still cannot accurately assess the exact quality of
audio equipment based on these current indicators.
It is not difficult to find that for various types of music, their
electrical signals have different frequency domain widths. If the quality assessment of a audio system needs to be related
to the extent to which it can accurately play music types, on the basis of many current technical indicators, it would be
more appropriate for us to identify the actual working quality of the audio system by combining the following methods: The
bandwidth of the real-time processing signal determines the quality of its functional attributes.
The evaluation method
is to use the "same delay time" to assess the bandwidth that the analog circuit can load. The audio system needs
to process broadband electrical signals. In this process, it can process the width of the frequency band in real time, reflecting
the exact quality of its playback function. Its meaning is equivalent to that the quality of a computer is related to the
width of the number of digits it can handle at the same time.
Created by Chen
Date: Sep-2014
Last revision date: Sep-2021