Some questions about traditional HiFi speakers and amplifiers

The theories of HiFi sound systems and amplifiers are very profound. It is not easy to study them thoroughly. In order to make them work best, we need to explore more of their mysteries to stimulate their potential performance. So 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 mid-range has a more or less enveloping feeling, which is a reflection of the compression caused by the back electromotive force of the dynamic speaker and the effect of the cabinet. Some audiophiles think this is called high mid-frequency density.

2. The treble is not transparent enough, lacks airiness, and even has high-frequency retraction. Some high frequencies appear sharp. This is a manifestation of the characteristics of the dome (reverse dome) unit.

3. The overall tone is either hard or soft, rarely just right. This is because the amplifier and speakers are not well matched.

4. The clarity of mid- and high-frequency is poor, which is mostly caused by unsatisfactory power division in the later stage.

It can be said that the traditional audio equipment currently on the market has room for improvement. Don’t be superstitious about high-priced foreign products, as they are the same.

If I say that traditional dome tweeters have fundamental flaws, it will certainly arouse the disgust of many users. But the fact is that even Dynaudio, which is known as the best tweeter, and some products using beryllium metal diaphragms are still not ideal. There are two main reasons for this.

First, no matter how light, thin, and hard their diaphragms are, they still have to work in conjunction with components such as the voice coil, and the driving mass is not light, which limits the improvement of transient characteristics.

Second, the propagation characteristics of the dome make it attenuate more than the mid-bass at equal distances. 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 ultra-high part is not transparent enough, making it difficult to create that kind of ethereal and ethereal aura.

Planar units have advantages. Let's briefly analyze several types of tweeters: although the aluminum ribbon tweeter is flat, it is still heavy, and the internal stress resonance of the aluminum foil itself has a metallic taste; the horn tweeter is reflected and diffracted many times, which improves efficiency but loses the super-high sound. As the saying goes, a smooth board has no hair, the sound is bright and sharp, not moist, and accompanied by special cavity sound coloration. The electrostatic unit should be outstanding. (The super-high here refers to 16KHZ-25KHZ, which is a more practical frequency band. Higher ultrasonic waves are suspected of commercial hype.)

Don't misinterpret the original meaning of modern digital audio sources

The upper limit of the frequency response of the new generation of digital audio sources such as SACD and DVD-A has been greatly increased (above 50KHZ), so people are blindly chasing in the playback process and making 100KHZ high-pitched heads, as if humans have degenerated into Batman. Everyone can enjoy ultrasonic waves. In fact, a normal young person can hear 16KHZ pure sound, which is considered to be quite good hearing. The overall physiological perception of 25KHZ music overtones is probably the limit of ordinary people. People with higher hearing should be superhuman. (Currently, the bandwidth of recording microphones is limited, and higher ultrasonic waves may not be recorded). Therefore, I think that the upper limit of playback can be guaranteed to reach 30KHZ, which is both practical and has margin.

I have compared two recordings; 16BIT/44KHZ and 24BIT/96KHZ both recorded tape music (the highest frequency is 12KHZ). The former (it can be seen that there are only 2 sampling points at 20KHZ, so distortion is inevitable compared to analog signals) is relatively hard, which is a digital flavor. The latter is equivalent to playing the original tape. This shows that the most important thing about high bit rate and high sampling frequency is to improve the sound quality of the audible sound segment, and it is biased to pay too much attention to the widening of its frequency domain. CD decoding uses measures such as up-sampling and interpolation to achieve the same effect.

The key to high-fidelity speakers is to look at the controlled transient indicators. Good transients mean high frequency response, but high frequency response does not necessarily mean good transients (it may be that the resonant frequency is high, and various distortions will still be significant). Therefore, everyone should have a clear understanding of ultra-high.