The structure of SACD is similar to DVD, with single and double playing surfaces and single and double information layers. At present, most SA CD disks on the market adopt single-sided and double-layer structure. One layer is a 0.6mm substrate, which stores the signals in the traditional CD format of 16bits and is compatible with CD, and the other layer is a high-density translucent layer of the 0.6mm substrate, which stores the signals in SACD format, and then the two substrates are bonded together like DVD discs. This kind of CD can be played on ordinary CD player or SACD player. Of course, their sound quality is different.
The technical index of SACD is far superior to that of CD, but it is similar to that of DVD-Audio. The core technology of SACD is DSD (Direct Stream Digital), which is essentially different from the multi-bit recording principle of CD and DVD-Audio.
Technical points of drainage services department
The technology of DSD is simply to sample the signal at 2.8224MHz and output the signal stream of 1bit after multi-stage δ-σ modulation.
Multi-stage (e.g. 7th order) delta-sigma modulator uses negative feedback to compare the signal with the last sampled waveform (differential operation). If it is greater than, output "1", if it is less than, output "0". The adder accumulates waveforms in the sampling period to form the next comparison waveform. δ and σ are the meanings of difference and sum, respectively. It can be seen that 1 bit signal stream is a relative value, while the quantized value recorded by traditional PCM is an absolute value.
It is a schematic diagram of 1 bit data flow after sine wave is modulated by multi-order Δ-σ. The figure shows that in the positive half cycle, the greater the amplitude, the more "1" appears; In the negative half cycle, the greater the amplitude, the more "0" appears. This picture reminds us of the sound waves transmitted by the loudspeaker in the air: in the first half of the week, the paper basin is pushed out to compress the air in front of the loudspeaker and increase the air density. The greater the amplitude, the greater the density; In the negative half cycle, the paper basin is pulled back, which reduces the air density. The greater the amplitude, the lower the density. It can be seen that the 1bit signal stream actually reflects the sound density formed in the air after the original analog signal acts on the speaker! At present, some companies have been developing digital power amplifiers and digital speakers, hoping to provide 1 bit binary data directly to digital speakers after being amplified by digital power amplifiers. Digital loudspeaker is not only a simple low-pass filter, but also a transducer that converts electric energy into acoustic energy, which not only simplifies the structure, but also improves the playback performance. I believe that in the near future, we will see the practical application of this digital device.
Compared with the traditional PCM signal, the modulation process of 1bit signal stream is simpler, with high precision, low cost and simpler demodulation process. Theoretically, the audio analog signal can be successfully restored only by an RC integrating circuit at the playback end. At the same time, some inherent distortions of PCM are fundamentally eliminated, and audio signals are highly restored. The sampling frequency of DSD system is 2.8224MHz, which is 64 times that of traditional CD (44. 1kHz), and the total information capacity is 4 times that of traditional CD. Theoretically, the frequency response range can be extended to 0Hz-400kHz, which greatly exceeds the limit of traditional CD 20k Hz. And the oversampling frequency of 64 times that of CD can make the quantization noise in the auditory range completely distributed outside the auditory range of human ears. Moreover, the so-called "noise shaping circuit" is developed in DSD technology, which can further transfer the noise in the audible frequency band (0 ~ 20kHz) to the super audio frequency range above 20kHz, thus making the signal-to-noise ratio of SACD as high as 120dB.
Compared with DVD-Audio, SACD and DVD-Audio have different principles and circuits, but the sound quality is much better than that of traditional CD. As far as technical indicators are concerned, SACD is comparable to DVD-Audio. Therefore, the dispute between the two has not yet been unified. But as far as the current situation is concerned, SACD has always maintained a leading position.
First of all, SACD is one step ahead of DVD-Audio in hardware supply. As early as two or three years ago, Sony had a flagship SCD- 1 that caused a sensation in the industry, followed by SCD-777SE, SCD-555, SCD-XB940, and even DVP-S9000ES and MANNT900. Philips' SACD 1000, Japan's famous Hi-Fi products' DP-100/DC-1splitter, and others, such as Japan's Joan, Aiwa and First Audio, are too numerous to mention. So far, the DVD-Audio lineup has only a few varieties of Panasonic, Shengli, Tianlong and other companies. Recently, however, DVD audio is catching up.
Secondly, SACD was the first country to provide software. Up to now, more than 300 kinds of SACD records have been published, and nearly 100 kinds can be seen in China. On the one hand, Sony and Philips rely on their own record companies to continuously publish SACD records to show their support. On the other hand, we persuaded Telarc, DMP, Nassau, DI GITAL and other fever record companies to join SACD Chen Ying, and constantly introduced SACD software, which left a deep impression on consumers. However, DVD-Audio was unlucky, and the anti-piracy password was cracked in the cradle by computer hackers, which greatly delayed the launch schedule of DVD-Audio records, which is also the main reason why many record companies suffering from piracy temporarily did not consider supporting the DVD-Audio camp.
Grade: SACD has positioned itself at the high-end level from the beginning. Sony's first flagship SCD- 1 is extremely feverish. Both the internal materials and the whole machine technology are designed in strict accordance with the specifications of Hi-end record player, and the low-end models to be launched in the future are also designed and manufactured in strict accordance with the concept of heavy and stable materials. It is welcomed by most hi-fi enthusiasts. In the struggle with SACD, DVD-Audio camp has always regarded DVD-Audio as a cheap and effective function, which is attached to popular DVD players for publicity, giving people the feeling that it is a staple food. In addition, DVD-Audio has many functions, but it is not exclusive. The body is slim and the material is ordinary, which is not good-looking in the eyes of audio enthusiasts, thus losing to SACD in terms of grade.
Sound quality: Due to SACD's own positioning and the technical simplicity and advantages of 1 bit quantized DSD direct data stream, most experienced audio enthusiasts feel that SACD is slightly superior in sound quality after hearing it with their own ears. So many friends in the audio industry think that if a home theater is compatible with Hi-Fi, DVD-Audio should be the first choice. However, SACD is your ideal choice for friends who mainly play high-fidelity music, especially those who pursue true and pure sound quality and timbre.
Introduction to xrcd
Xrcd adopts K2 interface developed by Japanese JVC company, including mastering equipment, manufacturing technology, hardware and theory. By inventing this technology, the original master clock system is used to control the time base of each link in optical disc production, which greatly reduces the jitter distortion coefficient of optical disc production and the group difference coefficient of glass master mold, and correspondingly improves the plate-making accuracy, thus greatly ensuring the fidelity in optical disc production.
Xrcd can be said to be a perfect 16 bit, and it can present the highest sound effect of cd on any record player without any additional equipment. On the same sound system, xrcd is obviously superior to the original cd in transparency, smooth extension of high frequency, three-dimensional sense and smooth texture of beads. What a transparent voice, clean background, musical instruments and voices without any anger and burr. This is the first time to listen to XRCD. The original CD is like a mist between the listener and the player. Xrcd is like a gust of wind blowing away the light smoke, and everything is clear in front of you.
Xrcd2 is an upgraded version of Xrcd.
Introduction to xrcd2
Xrcd2 has taken a big step towards the goal of perfect digital audio. It is a representative technical achievement of JVC's deliberate pursuit of reproducing the original sound for many years. Xrcd2 is a recording product developed after in-depth study of related equipment and theories in the process of master art processing and industrial processing. She provides xrcd series to listeners who are looking for high-quality sound quality in a better version. At the same time, like other products in the xrcd family, it does not need to use a special decoder and a special cd player.
The usual optical disc processing procedure is to arrange the master disc and send it to the processing factory for tabletting with U-matic 1630 tape or PMCD or DDP tape. From then on, performers, producers, directors and sound engineers can only pray that the products-CDs-will not change much with their carefully created works. There is no sound judgment benchmark between the recording studio and the production and processing factory. Even if the digital series is correct, it may not guarantee the highest sound quality reproduction. In addition, the production process of CD is composed of a variety of equipment and technologies, so its sound quality is also affected by various equipment conditions. This means that in order to faithfully reproduce the sound recorded on the original master, we must seriously pursue every small link from the tuning of the CD master to the production and processing. Therefore, it can not only meet the simple and high index of the existing detection data. Therefore, we should not only rely on simple test data, but also use long-term auditory experience to judge the best equipment with the best auditory effect. This effort even includes various test combinations from installation connection mode, AC power supply system, clock accuracy, recording format, handover system to CD material, and the result is xrcd2. So far, she has described the original sound more clearly than any CD, thus successfully providing a CD with better sound quality.
The processing of xrcd2 starts from the processing of the host. The analog signal is first made by a special mixer, and then converted into a digital signal by a 20-bit K2 A/D converter made by JVC Company. Then this 20-bit digital signal is output from the SDIF-2 interface through the newly developed digital K2 and recorded on the magneto-optical disk (MO). In this process, digital K2 is used to block the influence of digital part on analog part, thus realizing high-purity analog-to-digital conversion. In addition, in the processing procedure of xrcd2, a magneto-optical disc with stability and recording capacity greater than 20 bits is used as an audio recording carrier to be sent to the production procedure.
I got a 20-bit PCM-9000 magneto-optical disc from JVC Yokohama Factory, and played it again through the number K2. In this playback stage, the "Gita" noise parasitic in the digital signal is eliminated. Next, K2 super encoder converts the 20-bit signal into a 20-bit dominant 16-bit signal, which is encoded by EFM and sent to K2 laser. Here, the EFM signal is played back before being sent to the laser disc recorder. In the final stage, the residual transient "Gita" noise in the data stream is removed.
Through the above process from the master to the production process, the highest sound quality of the original master is transmitted to the CD. Fully take care of the details of the original sound, so as to reproduce the delicate performance of the performer, and reproduce this sound without distortion during recording, so that the audience can fully understand the performance intentions of the performer, producer, director and sound engineer. This is xrcd2.
Xrcd technology has been well received by the industry, and the latest version of xrcd2 products has strengthened the advantages of xrcd series in faithfully reproducing the original sound. In order to maintain the advantages of xrcd brand, JVC company has strict requirements on the quality selection of master tapes, and various processes such as master tape reproduction, master tape production and tabletting. In addition, due to technical secrecy and other reasons, JVC strictly stipulates that it can only be processed and produced in its local designated production studios and designated factories. Because of these characteristics, even if illegal copying is carried out in such a strict way as digital to digital engraving master, the advantages of xrcd will not be obvious without using xrcd technology in processing. So xrcd is also called "cd that can't be pirated".
What is HDCD?
HDCD is the abbreviation of high definition compatible number. It adopts a new recording technology. When the analog audio signal on the master tape is sent to the HDCD encoder, it will be encoded into a digital signal, the resolution of which exceeds the traditional CD standard of 44. 1KHz and 16bit, and the generated signal will exceed the capacity of ordinary CD.
High compatibility and high resolution HDCD