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Subwoofer

The bass range has always attracted musicians and music lovers with its peculiarity: it is not so much heard as felt by the whole body. Household shelf acoustics are not able to reproduce all the low-frequency splendor, subwoofers were invented for this purpose. Today they can be found everywhere: in home audio systems and cinemas, cars, and concert venues. This article will tell you everything you need to know about subwoofers.

Why do I need a subwoofer?

If the characteristics of the speaker system are not enough to get deep rich bass, a subwoofer comes to the rescue. It allows you to turn ordinary shelf and floor acoustics with small speakers into a full-fledged speaker system. The sub is especially critical for those who like music rich in the bass dance electronics and rock and roll. For similar reasons, subwoofers like to be installed in cars, getting a disco on wheels. But classical and jazz lovers do not stay away: for them, a natural dynamic bass is also of great importance.
In-home theaters, there is nowhere without a subwoofer at all. The lion’s share of the wow effect from the movie falls on various explosions, bass drops, and music with a pronounced low-frequency component.

It is very easy to find out if the existing speaker system can cope with low frequencies. It is enough to listen to a recording of a sine wave running along the entire audible spectrum on it. Most often, something is heard on household speakers without a sub, starting from 50-80 Hz. The subwoofer will extend this value to 20-30 Hz.

As a result, the subwoofer allows:

  • Fully reveal the musical composition.
  • Play bass without distortion at high volume.
  • Do not overload the amplifier.
  • Get a better sound.

The bass speaker in a separate case solves a lot of difficulties and allows you to get a fast elastic bass with little blood.

How does the subwoofer work?

It is technically impossible to make a speaker that reproduces all frequencies at the same time. For the speakers to reproduce as many frequencies as possible, they are made multi-band: a small speaker (tweeter) responsible for the high, and a large speaker (woofer) for medium and low. Sometimes the tweeter is placed right in the middle of the woofer, this type of construction is called a coaxial speaker. However, this is not enough to play sub-bass, so the audio system is supplemented with a subwoofer the etymology of this term is now obvious.

Also, an individual case is needed for the subwoofer, and that’s why. The frequency of 50 Hz corresponds to a wavelength of 7 meters, 20 Hz 17 meters. Only a fairly large object can produce a wave of this length. For example, a double bass string is 42 inches (106 cm) long, a modern bass guitar string is 34 inches (86 cm). To reliably reproduce the sound of these strings, the diameter of the speaker must be identical in size. Of course, it is difficult to imagine such a thing in household speakers.

Listeners note that with the increase in the size of the diffuser, the detail and dynamics on fast parts are somewhat lost, since a large membrane needs time to oscillate, but at the same time the bass itself sounds more natural.

Thanks to the subwoofer, it became possible to make small speakers, accompanying them with just one bass speaker in a separate case. Such a system became known as tectonic, it is designated as 2.1. In all systems of form 5.1, 7.1, 9.1, etc., the same digit “1” after the dot is the subwoofer.

There are several types of sub-construction:

A closed box. Such subwoofers are considered “the most musical”, they have a rather delicate and restrained bass, gently expanding the range of the home audio system. Suitable for lovers of classical music, jazz, calm rock, thoughtful electronics, and ambient.

A box with a phase inverter. The phase inverter is a hole with a pipe, the dimensions of which are designed so as to enter into resonance with the speaker at a certain frequency. This increases the efficiency of the device and further expands its frequency range. Such subs are distinguished by the most aggressive sound, perfect for fans of dance electronics, rock, watching movies. In addition, this design allows you to get a dense low bass with a small speaker size, so it is also the most common type of subs.

Passive radiator

To simplify it, this is a phase inverter with a diffuser instead of a hole. It is a cross between a closed box and a phase inverter a musical and at the same time fast bass, gives excellent results with a small speaker and in a small volume of the case, often found in high-end acoustics.

Bandpass

In this case, the box is divided into two chambers, and a speaker is mounted in the partition. Its main property is a natural low-pass filter, which determined its popularity in the past, but the advantage has lost relevance with the advent of active filters.

Horn subwoofer

These are needed for concert venues and large halls: the horn allows you to shoot a bass wave at a distance of up to several tens of meters. Very powerful, bulky, and expensive devices.

The sound of the subwoofer also depends on the material of its diffuser. Many people recognize that a paper diffuser sounds softer and more musical, metal, or synthetic more sharply and elastically. Composite, for example, Kevlar, is often used in cars due to reliability and resistance to external influences.

How to choose a subwoofer?

For home

The main rule is that the bigger the room, the bigger the subwoofer:
For a small bedroom, a speaker with a size of 8 inches and a power of 100-125 watts is enough.

Some music lovers prefer to install two subwoofers at once. This gives the following advantages:

In a room with one sub, dead spots may appear where there will be almost no bass. This is due to the interaction of the room with low frequencies there are areas where the waves collide in the opposite phase. This won’t happen with two subs.
In a large room, two small subs can give a clearer and more detailed bass than one large one, especially if you need to get the fastest and most responsive low frequencies.

A subwoofer installed somewhere to the side of the main speakers will interact differently with each of them, resulting in an offset stereo field. This is especially important in studio conditions, there are two subwoofers a standard story.

For cars

The car subwoofer is a real must-have for the music lover-motorist. You won’t get high-quality sound in the car without it. Subs for cars are mainly divided into active with a built-in amplifier, and passive.

For the studio

Today, most music is made in home studios and is reduced to near-field monitors. These monitors de facto do not reproduce low bass frequencies, so a subwoofer is needed to fully monitor them. The good thing here is that you can safely use studio monitors and subs from different manufacturers.

Where to put the subwoofer?

You need to put it on a chair or sofa in which the listener will sit, and walk around the room, determining by ear the position where the bass sounds the loudest, in detail and deeply. This will be the desired point.

It is also worth remembering:

It is better to put the sub next to the load-bearing wall it has more mass, reflections from it will give more bass. If, on the contrary, you need to get a more delicate bass, then it is better to place the sub in the back of the room.

If the subwoofer is equipped with a phase inverter, then it is desirable to place it no closer than 20-30 centimeters from the wall.
It is not necessary to put a sub next to a cabinet, sideboard, window, thin wall these surfaces will turn into a resonating membrane that will add dirt and droning to the sound.

 

Rack

A sub mounted on a stand will not transmit vibrations of its body to the room.

This will make the sound of the subwoofer itself better there will be less buzzing and droning.

Sound insulation. It is important to understand here that sound is like water, if there is a gap will flow. Every such leak needs to be eliminated. In most cases, it will be enough to fill the sockets and any holes in the room with acoustic foam and make a door threshold so that the door to the room closes tightly.

Bass traps

The principle of operation of bass traps is very simple: the heavier the better. Bass frequencies can only be crushed by a large mass, so bass traps are made of dense mineral wool (from 50 kg per cubic meter), and placed in the corners of the room because that’s where the bass accumulates.

Low-frequency resonators. These include Helmholtz resonators essentially boxes or vessels with a hole sharpened to absorb a certain frequency, as well as diaphragm absorbers that work with a wider frequency range.

How to set up a sub?

As a rule, a subwoofer has several basic settings:

Cutoff frequencies (crossover). It allows you to set the upper limit of the sound of the sub. To do this, you need to look into the characteristics of your audio system and find out its lower frequency. If, in addition, the amplifier of the audio system itself has a low-pass cutoff adjustment, then you can very accurately make friends with the subwoofer and speakers. On a computer, you can programmatically cut the bass from the speakers.

Phase shift adjustment. It is used when the sub is far from the speakers, and its sound is somewhat delayed in this case, the sound begins to sag due to the fact that the waves are not in resonance, but in the opposite phase, weakening each other. Adjusting the phase shift will solve this problem. Sometimes there is a toggle switch “phase rotation — needed if the sub “blows” in the direction of the speakers.

Volume level to adjust the amount of bass. It should approximately correspond to the volume level of the main speaker system. You can adjust it by ear, gradually increasing the volume of the sub until its sound begins to prevail, and then reduce it by one division.

Conclusion

The subwoofer opens up a whole dimension in music.

A properly tuned subwoofer adds depth to the music and expands its frequency range, but it does not distract call attention to itself and does not stand out from the overall picture.