Misunderstandings and common problems in the use of home theater subwoofers

       Misunderstandings and common problems in the use of home theater subwoofers

1. In a home theater system, it doesn’t affect much without a subwoofer, right?

There are some relevant proverbs circulating in the circle of home theater players: "The subwoofer is the soul of the theater, and one shot can cover up all the ugliness..." These are all affirmations of the role of the subwoofer. It can be said that a home theater lacking a subwoofer, The overall sense of atmosphere, shock, etc. will be greatly reduced, and there will be no immersive movie-watching experience at all. In addition, technically speaking, the subwoofer is not dispensable. In at least a "5.1" home theater system, in addition to making up for the low frequency of other channels, it is still the ".1", an independent channel.

2. What exactly is a good low frequency?

Explosive large dynamic bass, comfortable massage feeling (shaking the sofa, shaking trouser legs, blowing leg hair, numb scalp...); clear, clean, powerful, punching to the flesh; fast, vigorous. Never sloppy, rumbling, and dizzy.

The old snail here has to say that some people regard this continuous booming sound as a sense of low frequency volume, which is a big mistake. In short, the easiest way to evaluate what is a good low frequency is to let your body feel it. , The sound that can make you watch movies heartily is a good sound, and the sound that makes you feel uncomfortable is not good.

3. What's the point of double cannons, doubling the loudness?

According to the equal loudness curve, if the sound pressure level increases by 10dB, the ear will feel that the loudness has doubled; and if the output power of the power amplifier is doubled, the sound pressure level will increase by 3dB. That is to say, if the sound pressure of a single cannon is 100dB, if you add another same cannon with the same power output, the sound pressure level will reach 103dB. Does not double the loudness. The biggest significance of dual cannons in a home theater system is to reduce standing wave interference (it cannot eliminate standing waves), make the low frequency distribution more even and flat, and obtain more sound sweet spots.

4. Which port on the subwoofer should be connected to the power amplifier?

People often ask this question, should I plug in red or white, the sockets should be divided into left and right, should I have two subwoofer cables or one point two Y plugs, etc. It is actually very simple. First of all, you have to distinguish between input and output. English is " The words "in" and "out" should be plugged into the input interface at this time, so don't make a mistake.

Then, if your subwoofer comes with a low tube system and it is very powerful, you can consider wiring input (corresponding to the English "line in", usually a white lotus head). After the signal enters the subwoofer, it will be processed twice by the subwoofer ;And if your subwoofer does not have a low tube or is not adjustable, or the quality is not good, it is recommended to use the low-frequency effect interface (corresponding to the English "LFE in", usually a red lotus head), so that the low-frequency signal can be directly amplified , not adjusted by the internal processor of the subwoofer, but directly passed. Generally speaking, the old snail recommends that you use the LFE interface first.

In addition, some high-end guns have both Canon head (XLR) and Lotus head (RCA). It is also recommended that you give priority to using the Canon head to balance the input, so as to reduce interference, especially for long-distance transmission, the advantages are more obvious.

5. What is dynamic?

Dynamic range (English: dynamic range) is the ratio of the maximum value to the minimum value of the variable signal. It can also be expressed in base 10 logarithm (decibel) or base 2 logarithm.

For the audio signal, this is also a very important parameter, which is equivalent to the contrast ratio of the projector. It determines whether the black level of the picture can be completely subsided, and whether it can present "colorful colors" in the same frame. Black" can also show dazzling white.

So this friend's understanding of dynamics is wrong. A large dynamic range is a good thing, and it won't make the sound unpleasant. In addition, using two AV power amplifiers of different brands and different models, it is not appropriate to copy the parameters, because different power amplifiers have different design concepts, different sound processors, and different reference systems. It is definitely wrong to copy the settings to produce sound effects. , Even taking a step back, two power amplifiers of the same brand and model may be different, so you must not copy them, and you must not be lazy in debugging.

6. The subwoofer can be placed anywhere, right? For example, stuffing it into the corner of the wall does not take up space.

There are three possible reasons for thinking this way. First, because the subwoofer is not directional like other channels, so everyone may be led into a misunderstanding, thinking that it is true, you can place it casually; the second is that it may be considered from the perspective of efficiency. , because placing the speaker against the wall can enhance the low-frequency efficiency, especially in the corner, it will produce an effect similar to that of a horn, and the energy is easier to strengthen. This method is suitable for use when the subwoofer is relatively small or the power is small, but such a harm It is also obvious that the sound source in the corner will excite all room modes, that is to say, the standing wave will be strengthened, and the balance of the frequency response may be greatly damaged. If you are not an expert, please operate with caution.

There is another possibility, that is, I really don’t understand it at all, and I think it can be played casually (I have also seen the cute new installation method of placing the surround speakers next to the front speakers...)

In fact, this is all a wrong approach. Friends who have experience in home theater debugging know that if the subwoofer is adjusted, your theater debugging work will be more than half successful. Finding the gun position is an extremely energy-intensive and labor-intensive process. Physical work, you can make a good sound by throwing it anywhere? For novices, the possibility is about the same as buying a lottery ticket, but don’t be discouraged. We can summarize some rules through a lot of previous experiments. For example, usually the subwoofer is placed on the The midpoint or one-third of the side wall (if it is a double cannon, it is recommended to place it in a symmetrical position), usually good results can be obtained.

In short, the environment and size of each audio-visual room are different, and everyone needs to find the best placement in the process of exploration. In the absence of acoustic testing equipment and heavy subwoofers, the easiest way is the "crawling method". : First put the subwoofer at the listening position, with the muzzle facing the curtain, play the most familiar low-frequency test clip or test sound, then crawl all over the floor, listen to all the places where the subwoofer can be placed, and finally choose a location with good sound , put the subwoofer here.