The theory of HiFi sound system and power amplifier has profound knowledge. If you want to study them thoroughly, it is not a simple matter. If you want them to exert the best results, then we need to explore more mysteries. To stimulate their potential performance. Then we will answer some questions about traditional HiFi speakers and amplifiers.
Traditional speakers refer to boxes that use dynamic speaker units. They generally have the following problems:
1. The midrange has a sense of shroud, which is a reflection of the compression and the effect of the cabinet caused by the back-EMF of the moving coil horn.
2. The treble is not transparent enough, lacks a sense of air, and even has high frequency retraction. Some high frequencies appear sharp. This is the characteristic of the dome (anti-dome) unit.
3. The overall timbre is either hard or meat, and there are few that are just right. This is a poor match between the amplifier and the speaker.
4. Poor clarity of mid- and high-frequency, mostly due to unsatisfactory power division of the latter stage.
It can be said that currently available traditional stereos have a certain room for improvement. Don't be superstitious about high-priced foreign goods, so do they.
If I say that the traditional dome tweeter has essential flaws, it will inevitably attract many users. But the fact is that even Dana, which is known as the highest quality of the tweeter, and some products that use beryllium metal diaphragms are still not ideal. There are two main reasons.
One is that no matter how light, thin and hard the diaphragm is, or it must be linked with the voice coil and other components, the driving quality is not light, which limits the improvement of transient characteristics.
The second is the propagation characteristics of the dome, making it less equidistant than mid-bass. Although the balance is adjusted at 1m, the actual use is generally more than two meters. At this time, the high frequency will be obviously lacking, especially the super-high part is not transparent enough, it is difficult to create that ethereal sense of aura.
The flat unit shows advantages. By the way, simply analyze several types of treble: although the aluminum ribbon treble is flat, the quality is still large, and the internal stress resonance of the aluminum foil has a metallic smell; the horn type treble is subjected to multiple reflection diffraction, although the efficiency is improved, but the super Treble, as the saying goes, the light board is hairless, the sound is bright and thorny, not moist, and it is accompanied by special cavity sound staining. The outstanding unit should belong to the electrostatic unit. (Ultra high here refers to 16KHZ-25KHZ, which is a more practical frequency band, and higher ultrasonic waves are suspected of commercial hype.)
Don't misinterpret the intent of modern digital sound sources
The new-generation digital audio source SACD, DVD-A and other frequency response limits have been greatly increased (above 50KHZ), so people blindly catch up in the playback link and get a 100KHZ tweeter, as if humans have degenerated into Batman. You can all enjoy ultrasound. In fact, a normal young person can hear 16KHZ pure tone is quite good ear power, the overall physiological feeling of 25KHZ music overtones may have reached the limit of ordinary people. Those with higher hearing should be Superman. (Currently, recording microphones have limited bandwidth, and may not record higher ultrasound). Therefore, I think that the playback limit can be guaranteed to reach 30KHZ well, which is both practical and marginal.
I have done two recording comparisons; 16BIT / 44KHZ, 24BIT / 96KHZ all recorded tape music (the highest frequency is 12KHZ). The former (it can be seen that at 20KHZ is only two mining points, relative to analog signal distortion is inevitable) is hard, both digital. The latter is equivalent to the original tape. This shows that the most important thing for high bit rate and high frequency is to improve the sound quality of the audible sound segment, but the widening of the frequency domain is too biased. CD decoding uses upsampling and other measures to achieve the same result.
The key to high-fidelity speakers still depends on the controlled transient indicators. The transient response is good, and the frequency response is high. The high frequency response is not necessarily good (there may be a high resonance frequency, and various distortions will still be not small). Therefore, everyone must have a clear understanding of super high.
Printed circuit boards which are used in medical industry.
The manufacturing method of the multi-layer board is generally performed by the inner layer pattern, and then formed into a single-sided or double-sided substrate by printing etching, and is incorporated into a specified layer, and then heated, pressed and bonded, as for the subsequent drilling. The hole is the same as the plated through hole method of the double panel.
The equipment and processes required for multi-layer boards are more complex and high-end. When designing the size of multi-layer boards, it is often necessary to consider more factors, especially the size of the equipment, whether it can allow such large size.
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