How to choose the right subwoofer?

Classic home subwoofer

We localize the squeak of a mosquito in a dark room perfectly, our hearing allows us to very accurately determine the location of this annoying sound source. This is because it gives out a frequency of several kilohertz, and the wavelength is a fraction of a millimetre. By the time delay with which this sound reaches our ears, we clearly determine the coordinates of the bloodsucker. But if the mosquito sounded at lower frequencies with a wavelength of tens of centimeters, then the delay could not be determined. Hunting by ear would become impossible. However, such a "low-frequency" mosquito, theoretically, should be the size of a whole cow!

It is the large dimensions of the emitter necessary for reproducing low frequencies, and the inability to localize it, that led to the appearance of a subwoofer in the modern audio complex - a special low-frequency speaker system.

What lineup do we sound in?

Subwoofers are used in two versions. If as part of a stereo complex, then this configuration is called triphonic. In addition to the subwoofer, it also includes a pair of satellites - mid-high-frequency speakers. Such a solution is much more compact than its classic counterpart - two full-size speaker systems (each of which has its own built-in subwoofer). Usually, a more “musical”, accurate and high-quality subwoofer is selected for it.

When choosing a subwoofer for a home theater, power comes first - it must match the rest of the set. At the same time, one should not forget that it is very easy to “grow up” to almost any triphonic over time to a full-fledged home theater. Or vice versa: by using only a part of the home theater set, you can get quite a decent triphonic.

Subwoofer (pictured left) as part of a classic triphonic

Where does the signal come from?

Depending on the answer to this question, we use an active or passive subwoofer. An active subwoofer is distinguished by the presence of a built-in amplifier, and for it to work it is enough to receive only a linear input signal. Naturally, such a sub is more expensive and its purchase does not make sense if, say, the kit already has a power amplifier.

If the subwoofer is purchased separately, you should take care of its compatibility with the rest of the complex. The most unfortunate option will lead to the fact that the active subwoofer will have to be turned on with a separate button, and each time its volume should be adjusted separately from other equipment, which is very inconvenient. This option should be considered unacceptable.

To avoid this, firstly, the device must have an automatic switch-on system when a signal appears at the line input. Or, for example, the amplifier must have a block of switched power outlets, to one of which we connect the sub. In this case, when it is turned on, the amplifier itself supplies power to it. Secondly, if the sound system does not have a volume-controlled line output, an active subwoofer can be connected to the power outputs of the amplifier. But then for this the so-called high-level input must be provided in the subwoofer.

Where does the subwoofer live?

Flat subwoofer with two drivers can put, put, hang

In fact, this is perhaps the most important and interesting question. Due to the characteristics of hearing discussed at the beginning, the subwoofer can be installed anywhere. In fact, the listener cannot determine the location of the subwoofer, while the surround effect created by the satellites at medium and high frequencies remains unchanged.

On the other hand, when the subwoofer is operating indoors, the so-called interference pattern is formed, and the nature of the reproduction of low frequencies seriously depends on the mutual placement of the subwoofer and the listener. Moreover, the listener cannot be transplanted somewhere into a corner - it remains to move the subwoofer. The place of the best sound for a subwoofer is determined exclusively experimentally. And with the point "in the middle, between the speakers" it almost never coincides. Get ready for the fact that the sub will “play” best somewhere under the sofa, in the corner, near the battery, and so on. Therefore, rather than a standard cubic-rectangular enclosure, it may be better to opt for a flat subwoofer or some alternative design that works well in that particular location – although sound often has to be sacrificed for the sake of design. It is worth paying attention to instances in which the emitter is directed downwards - in combination, the sub is able to “work” as a table, cabinet, stool ...

Please note that in the case of a passive subwoofer, you will still have to lay a cable from the amplifier to it - this can be a real problem. An active subwoofer is more democratic in this sense: it can often be equipped with a remote sound signal transmitter. And although it still has to be connected by a power cable to the nearest outlet, this task, usually, is noticeably easier.

Dimensions matter

For high-quality reproduction of low frequencies, the size of the emitter must be comparable with the wavelength. In this case, it is equal to 30 – 50 cm, so judge for yourself. If there is space and the interior allows, you should choose a larger subwoofer. Other things being equal, it will sound better. In addition, you should pay attention to the presence of a phase inverter in the case. A phase inverter allows you to achieve greater returns with equal power, but more musical models are still made in closed cases. To compensate for the vibrations of a powerful subwoofer speaker, subwoofers are made with two or even more radiators. Such models are often more compact and sound cleaner. Usually, they have built-in amplifiers, and they are more expensive.

Subwoofer with slotted bass reflex and radiator, downward

Setting for the best

The smaller the set of equipment is initially focused on connecting an active subwoofer to it, the more customization options it should have. It is worth paying attention to the presence of its own signal level regulator, as well as a variety of frequency response (amplitude-frequency response). All this allows you to correctly "stitch" the sound of the subwoofer and the rest of the acoustics, so that they exactly complement each other, leaving no voids in the sound picture on the one hand and not "fitting" into the sound of each other on the other.

When positioning a subwoofer, it is very useful to apply phase control. On most models, it is presented in the form of a switch "0 – 180". Roughly speaking, there are two options - phase or antiphase. For more precise tuning, it is useful to have smooth adjustment over the entire range. In fairness, it should be noted that a quality subwoofer setup is an entertaining business and requires a certain amount of experience. But when it is completed, a real, powerful and full-bodied sound appears.

In this connection - a special hello to your neighbors!

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