You decide to make a subwoofer yourself. You already have a woofer, or you looked for a suitable one in the store. Where to begin? Here we will consider not the electronic circuit, but only the reproducing part, i.e. the subwoofer itself: a case with a dynamic head.
In addition to good speakers for high-quality bass reproduction, the correct
calculation of the volume of the
speaker box and knowledge of some of the subtleties of its manufacture are important. Homemade subwoofer should have an optimal box size. Whether it is a system in the car or a home-made
subwoofer for the home, a good case is the most important component that affects the sound quality.
Let's remember what
sound is all about
. This is a wave. Our ear is capable of catching vibrations with a frequency in the range from several tens to about 20 thousand Hertz (oscillations per second). This wave range is considered to be sound, in fact it is a little wider. What we don’t hear because of the very low frequency is infrasound, and the higher frequency, also not audible by us, is ultrasound (animals, for example, dogs hear it).
Sound waves propagate only in an environment with sufficient density. We hear sound because we are in such an environment (air).
The subwoofer reproduces the
lowest frequencies up to several hundred hertz. The sound wave is created by the movement of the plane of the diffuser (the moving diaphragm of the speaker). Her movement is transmitted into the air, and the sound that we hear appears. It turns out something similar to a pump.
The main task of the subwoofer enclosure is to obtain high-quality sound. A speaker without a box is not capable of this, because for a high-quality sound wave to occur, we need only one phase of it, and an open speaker gives us two at once: the positive and negative (front and rear sides of the diffuser membrane). It turns out the so-called acoustic
short circuit, which is very unpleasant for the ear. To separate the phase of sound from one another, the speaker box is used.
Homemade subwoofers have a variety of designs. The most common ones are with one speaker facing out, like on a regular speaker, but more complex devices are found.
As you know, in order to separate the phases of sound (as if to close one of them inside the subwoofer casing), its great rigidity is necessary so that the casing itself does not transmit vibrations to the air. Therefore, the quality of the material plays a big role. The stronger, harder, the better the result.
Remember that the most unfortunate option for any subwoofer is a symmetrical design. As a rule, the speaker is shifted away from the center. It is also not recommended to make a homemade subwoofer in the form of a cube, the sides should vary in size. All this is done to avoid resonance.
Homemade subwoofer should have a sufficient internal volume. If it is not enough, then the low-frequency sound noticeably weakens due to the strong pressure inside the box, which is created by the work of the membrane. If you need a homemade small volume subwoofer, then you need to take a woofer with a smaller diameter, because The recommended box volume directly depends on the size of its diffuser.
The table shows the recommended sizes.
| Diffuser | Body volume |
| 8 | 50-30 |
| 10 | 10-50 |
| 12 | 15-65 |
| fifteen | 30-105 |
| eighteen | 40-200 |
But it is better to consult the documentation for your speaker.