Regardless of the amplifier or speaker, the objective parameter that has the greatest impact on sound quality is the amplitude-frequency response, which is usually called the frequency response. There are two main requirements for frequency response. One is that the frequency range is wide enough, the low frequency is lower, and the high frequency is higher. Second, the amplitude change in the frequency range should be as small as possible, that is, as uniform as possible. Otherwise, it will directly affect the tone balance of the entire frequency band. In fact, many of the subjective sound quality arguments, such as brightness, harshness, and turbidity, are all related to frequency response.
As far as the frequency range of the speaker is concerned, it is now easy to achieve a high frequency above 20 kHz, which basically covers the upper limit of the auditory frequency of the human ear. The difficulty is low frequency playback. For Hi-Fi playback requirements, it should reach the lower limit of the human ear hearing 20Hz, and should have a sufficiently high sound pressure level.
Otherwise, due to the low sensitivity of the human ear to low frequencies, it is unable to perceive. Unfortunately, at present, most home Hi-Fi speakers can not meet the above requirements, and as far as CD records are concerned, for the vast majority of people, including many audiophiles, have not listened through the speakers in the family. Have heard the sound of 20Hz. If you use ordinary bookshelf speakers, let alone, I am afraid that even listening to 40Hz sound is not possible.
The best solution to extend the low frequency on the existing stereo playback system is undoubtedly to add one (of course, two) subwoofers. Because it has the advantages of the well-known "two-wire" connection, "bi-amp" drive and "pre-stage electronic crossover", it not only extends the low frequency, but also reduces the distortion of the original system and improves its dynamic .
However, pure audio enthusiasts often do not like this. They believe that the subwoofer is a "home theater" thing, and "Hi-Fi" is a car running on two roads. This is not the case. Let ’s think about it. When you enjoy a concert on DVD, do n’t you want it to be Hi-Fi?
Think again, the sound included in the soundtrack of a DVD movie is far broader than music in terms of frequency and intensity range. The various sounds that the human ear can hear in nature and the artificial sounds that nature does not exist are almost all possible and have appeared on DVDs. Therefore, as long as your requirements for sound reproduction are the requirements of the Hi-Fi sound system. It can be said that the home theater system in the true Hi-Fi sense should be able to meet the playback requirements of the Hi-Fi audio system. On the contrary, this is not necessarily the case.
Some audiophiles also believe that Hi-Fi systems should not use subwoofers, and even think that large speakers with low replay frequency should not be used in small rooms. Otherwise, the overall sound quality will be affected. It should be said that this is based on certain facts. But it should also be noted that this is not exactly the case.
In fact, after using the ultra-low sound box, the overall sound quality actually declines for two reasons. First, the sound conditions in the room are inappropriate. For example, low-frequency standing waves are not effectively suppressed, and the low-frequency reverberation time is too long. The second is the poor quality of the subwoofer used. Therefore, in order to hear good bass, you must first have a good ultra-low sound box, otherwise it is "no rice cooking." Then comes the coordination of the room. Well coordinated and mutually beneficial. Poor coordination can only be counterproductive. So, how can you choose a good subwoofer?
For the purchase of speakers, some audiophiles believe that the performance cannot explain the sound quality, and the performance data is too professional, and it is difficult for the general reader to grasp. Therefore, the purchase of speakers should be based on listening, "receiving goods by ear". Unless there is no data to see, this argument makes little sense. It is even more misleading to recommend it to general readers.
We think that there should be no "primary" or "priority" between subjective listening price and objective performance test. In other words, before buying a subwoofer, first "watch" and then "listen". First collect and understand the price, appearance and performance specifications of similar products, and then select 2-3 "target" products from them for key audition. This is also the most reasonable procedure for purchasing other audio products, which can achieve the effect of "multiple effects with half the effort".
Before deciding to buy a subwoofer, you need to make a point. It is quite difficult to replay a speaker to 20Hz Hi-Fi and have a sufficient sound pressure level (up and down 100dB). Although the bass of many high-end speakers sounds satisfactory, strictly speaking, it does not yet meet the above basic requirements for Hi-Fi playback. In other words, for the Hi-Fi playback of the bass, most people are still difficult to get it in one step, as expected. But this does not mean that we have done nothing about it. This is because many speakers we are actually using have the possibility of further expanding low frequencies and reducing distortion to improve sound quality. In general, the frequency band to be improved is 60Hz-100Hz for bookshelf speakers, 40Hz-60Hz for medium-sized floor-standing speakers, and frequency bands below 40Hz for large speakers.
For a subwoofer, we have three requirements for its frequency response. First, the replay frequency should be as low as possible. Second, the frequency response should be as uniform as possible. The third is that the sound pressure level within the range of playback frequency is as high as possible. But it is very difficult to comprehensively meet the requirements of Hi-Fi playback from these three aspects. Even if these requirements are met, the volume of the speaker is large and the price is expensive, which is not acceptable to most enthusiasts. Therefore, many subwoofers with different performances, forms and price grades have appeared on the market to meet users with different needs.
Although, in the selection, we must first choose the subwoofer with high and even output sound pressure level in the low frequency band that needs to be expanded according to the existing system and actual needs. It is important to note that only speakers with a high and uniform sound pressure level can achieve low playback distortion, which is the key to ensuring the sound quality of the system.
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