Electronic Fans News [Author / Pan Chang]: Due to historical reasons, the CD format has low standards. Therefore, the CD and the "master tape" (the so-called master tape is the original file when recording, generally files above 24bit / 96KHz) In contrast, the difference in hearing is relatively large. Therefore, in recent years, a variety of "master tape" players have appeared in the market, with a wide range of brands, eight technologies immortalized, propaganda, and dazzling; because there is no industry standard, which is good and bad, I believe most of the "fans" are more Hard to tell.
Here, Pan Chang, an audio expert, has disclosed his valuable experience to the process of engineers developing players, and hopes to help you choose products.
Basic skills required for design
To make a good product, we must first understand this product, I believe this is the most basic condition. After designing a product, how can I know if it meets the design requirements? As a simple example, if a conductor stands on the podium and compares the live scene he heard with the recording played back through the speaker, this assessment is relatively relevant, because the sound system is always a "simulated scene" The system needs to be compared with the real site to know how much reduction can be achieved. It is difficult for ordinary fans to have this condition without this music training. Therefore, the evaluation standard is relatively low and it is easily affected by objective factors. Of course, you do n’t have to be a conductor yourself, but if you can often go to the concert hall to listen to music, you can also make up for this shortcoming, but be reminded that the seats in the concert hall have a great impact on the sense of hearing. This can be simply categorized as: music-savvy, or a team of music-savvy experts.
The general system architecture of the digital player
Most electronic products are divided into software / hardware, at least for digital players. The field of digital players is relatively wide, from hardware to software, from digital to analog, spanning multiple fields, and these fields are not easy to combine. To make such a product, the time required is to Yearly calculations are not accomplished by simply investing a lot of work. Speaking of which, many engineers who make mobile phones may disdain, saying that mobile phones are more complicated than a simple player? Indeed, the software and hardware system of the mobile phone is much more complicated, but the requirements and the player are indeed much worse. No part of the mobile phone will require a dynamic range of 120dB, nor will it require -110dB THD + N, designed by the author. Experience and the parameters of various manufacturers, the highest requirements of mobile phones are only -96dB THD + N. Compared with the requirements of audio, the difference may be as much as 10 times. These parameters are all tested and improved by various methods. What comes out is not that there is any formula that can be calculated or there is a reference model.
For a system to be perfect, the depth of the combination of software and hardware is very high, so you need to plan well, you must be proficient in hardware and software, indispensable, our friends developed USB decoders and found that different drivers have a great impact on the sound, Different circuit designs have a great influence on the sound, and there are even many phenomena that have not yet been supported by theoretical models. Therefore, the entire product design must be very proficient, otherwise the required parameters cannot be achieved.
Why are imported audio products so expensive, there are many customers? Why is it so difficult for domestic brands to go abroad? Designing a product, technology is an aspect, but audio products require more time and experience. For example, with so many models of op amps, how to match them? why? There can be thousands of combinations of operational amplifiers alone, and it is not necessarily a device with good performance that must produce good sound. So this is one of the main reasons that audio products are more difficult to develop. It is best to develop as a hobby. At the same time, a good sound is comparable to a luxury product. A pair of speakers can easily have 6 digits. Designers without this consumption ability often find it difficult to design products aimed at this consumer group, so it is necessary to understand the true market and value of this genuine product. . Therefore, it is best to design such products with money and leisure, otherwise it is difficult to do well.
The developing countries are still struggling to survive in "food and clothing", while the developed countries basically have enough food and clothing, while paying attention to the value of copyright and other spiritual civilizations. No matter what kind of product, most of the research in developed countries pursues excellence, and the land in China is still mostly "cottage" for the time being. "Can sound" and "good voice" are not a concept, it takes time and enough accumulation, so it is basically difficult for a young company to meet the requirements of "good voice", because we also come over in this way, there will be details below Discussion.
How sensitive is the human ear
The experimental results of the physics laboratory of Taiwan University show that the frequency accepted by most human ears is 20Hz-20000Hz, and the experimental results show that the sensitivity of the human ear is very high, the human ear has the strongest acceptable sound and the weakest The sound-to-noise ratio reaches an astonishing 1012 (this data is personally reserved, I remember it was 118dB before). If this data is converted to a bit rate, it is 240 (118dB according to the data in the memory, it is 220). This means that 16bit is far from meeting the requirements of the human ear, which has higher requirements.
Here is a practical example. A mother and a newborn baby sleep separately in a windowed room on the side of a busy street. The tumultuous traffic does not wake the mother, but the hum of a baby with much less noise than the window Can wake up the mother. This example shows that the complexity of the human body is not simply a few parameters that can be described. The professor who proposed this example pointed out that because the brain has a strong filtering function for information, this is caused. At the same time, the brain will "adjust" the received information, enlarge what is needed, and filter out what is not needed, so it can be achieved The function of extracting weak information in a complex environment. So a well-trained recording studio can easily point out the problem and reach a height that the instrument cannot.
In addition, how much time does the human ear's hearing memory have? Scientific statistics show that 6 seconds. This parameter will be referenced in How to evaluate below.
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