How to make a subwoofer for your own home?

Subwoofers are speakers that are specifically designed to work with extremely low frequencies. The first subwoofer amplifier was developed in 1970 by Ken Kreisler. Modern devices practically do not differ from it. They function as typical power amplifiers. The only difference is that they bring more energy to the speakers, create a strong movement of low-frequency sound for large volumes. Building your own subwoofer amplifier is a useful way to save money on audio equipment, so it’s best to know how to make a subwoofer for your home.

Basic system concept

The first thing to understand is the basic concept of a subwoofer. The basic idea is to reproduce low frequencies, about two octaves from 20 Hz to 80 Hz. From here comes the first prerequisite - the presence of a special enclosure that will generate low frequencies and guarantee good bass.

The second condition is the room’s own acoustic properties. If you place the best subwoofer in the world in an acoustically bad room - there will be no bass! If problems with acoustics are identified in the room, it is important that they be fixed before making a subwoofer with your own hands.

Another useful advantage of the subwoofer is the additional power control provided to the system as a whole. The acoustic energy in music is the highest at low frequencies, and decreases with increasing frequency. Thus, the use of a home-made housing for working with most dizzying bass is possible only with the use of special audio systems.

Create a custom subwoofer

Before making a home-made subwoofer with their own hands, amateurs ask themselves the question: “One or two subwoofers?”

Most stereo systems have two main speakers, but there is only one subwoofer. Some devices may have two (or more) subwoofers, but one is usually sufficient. The reason for this is due to the fact that for frequencies below 700 Hz, a person’s hearing measures the phase difference between the sound entering each ear. Sources generating low-frequency sounds (below about 100 Hz) tend to do this omnidirectionally when the sound wave moves from the source in all directions, and the sound wavelength is usually longer than the object itself.

Before you make a subwoofer with your own hands in the car, you need to purchase:

1. Old computer power source.
2. Car amplifier.
3. Speaker terminal.
4. Sandpaper, primer and paint.
5. Cords for connection.

First you need to draw up a case diagram, calculate its volume and port size, with the possibility of useful expansion up to 32 Hz. Before making a home subwoofer with your own hands, choose the design of the box, usually a cubic case with a side of 35 cm is enough.

Device manufacture:

1. To carry out the housing, you can use the 18 mm fiberboard panel, having previously cut all the details according to the drawing.
2. The port will need to be made after the hull is manufactured. Before you make a speaker (subwoofer) yourself, you need to decide on the shape of the ports. They can be of different shapes: round, square and rectangular. For this type of device, the use of a 110 mm rectangular gutter is sufficient.
3. Then you need to glue the body structure with wood glue and leave it on the clamps, preferably at night.
4. Install the port using sealant, glue and silicone.
5. Reinforce the free end to prevent vibration.
6. Finish the case, polishing, priming, painting. Before making a do-it-yourself subwoofer out of ordinary materials, it is best to apply a primer layer several times, leaving it overnight, then treat it with fine sandpaper until the finish becomes smooth to the touch. This will give a beautiful glossy finish after several layers of spray paint.
7. Internal isolation and noise reduction device. Add silicone wool to the body space and secure it to the walls with a silicone gun. This should make the cabinet less booming, because standing waves and resonance will be limited, and the bass will be sharper and deeper.
8. Before you make an active subwoofer with your own hands, you need to solve the issue of a built-in power source.
9. You need to connect a 500 W power supply from an old PC with all 12 V wires and ground with a 2000 W Lanzar Heritage universal car amplifier.
10. Then connect the green wire on the power supply using the grounding wires on the amplifier, and if the amplifier has REM, connect it to 12 V. Everything, after that the device should work.

Speaker Bass Control

Bass control is the process of removing the bass element of a signal supplied to each satellite speaker and routing it to one or more subwoofers. In fact, this is no different from a conventional crossover except that the bass driver is in a separate housing and a control tool is needed to combine low-frequency sounds.

Before you make a subwoofer for your computer with your own hands for a simple stereo system, you need to think through a bass management system. It is usually built into the subwoofer and can be active or passive (most systems are active).

There are various connection schemes, but most of the line signals from the controller or preamplifier first go to the subwoofer, and after filtering the signals, they go to the speakers. Some systems work the other way around, first connecting the signal to the speakers, and then to the subwoofer.

Systems designed for home use often work with speaker level signals. For surround sound systems, bass control is usually performed in the surround controller, rather than in the subwoofer.

Types of woofer enclosures

It is relatively easy to create high levels of low frequencies at the very low bandwidth that most low-cost subwoofers have. Before you make a subwoofer with your own hands, which should generate high performance in a wide bandwidth and low distortion in reasonable sizes, you need to study the perception zone well.

Creating low-frequency sound at studio playback levels requires the movement of large amounts of air. This requires a powerful amplifier, a very large bass driver (or several smaller ones) and a multi-level aperture. An easy way to achieve high performance is to place the source of bass in the so-called “strip cabinet”. This is, in fact, a resonant body and sound passing through one or more ports.

Most subwoofers use a form of “resonance” that combines practical efficiency with the bandwidth of large enclosures. A less common alternative is the “closed box” design. The cabinet is sealed, and only the front of the speaker transmits sound to the room. This approach has significant advantages in terms of its phase response, time, and distortion. Experts believe that you should not get carried away with the size of the subwoofer, as more is not necessarily the best.

Electrical equalization

For many novice users, this is a very obscure process. To make a mistake in it is to destroy the accuracy of the sound monitoring system as a whole. Before making a subwoofer with your own hands, it is very important to understand the geometry of the movement of sound waves. Therefore, satellite speakers must be placed in the same phase with each other in electrical polarity and timing. If this is not the case, the graphic region of the sound will have an apparent level of bulge or fall.

The subwoofer and satellite speakers have their own mechanical phase responses, as well as the electrical phase characteristics of the crossover filters themselves. There is also a time delay caused by the presence of speakers located at different distances from the listener. Many of the advanced subwoofers include a phase adjustment device (either switchable or stepless), which can help eliminate mechanical and electrical phase differences between the satellites and the subwoofer.

If the subwoofer is closer to the listener than the speakers, some delay compensation will be required to achieve proper time alignment. Although some bass monitoring systems or surround sound systems include this feature, not all listeners use it.

Home Sound Tips

Ideally, the subwoofer and sound system should be aligned using proper acoustic measurement equipment. When it comes to placing a subwoofer, there are several important points to consider:

1. Before you make a subwoofer with your own hands (photos are placed in this article), you need to choose its position in the room. Of particular importance is its proximity to the walls, significantly affecting the frequency and time response. If there is no delay compensation, the subposition should be at the same distance from the listener as the satellite speakers.
2. You must place a separate subwoofer in front of the listener, not the back. It should be away from corners, should not be placed in the center of a wide room to minimize the excitation of sound waves. The closer the subwoofer is to the wall, the greater the bass boost.
3. Some models are designed to be installed near a wall, and small changes in distance from the wall can make a big difference in the balance of deep bass, so the user should not be afraid to experiment.
4. In order for the subwoofer to work correctly and not be localized, the crossover between the satellite and the subwoofer must be set below 90 Hz, which means that the satellite should ideally have up to 70 Hz or so. Anything above this begins to invade the midrange, and the subwoofer becomes localized.

Proper sound system connection

Before making a do-it-yourself subwoofer for your home, you need to check the rated output power. After manufacturing the device, you need to check the calculated and actual power. It will depend on the supply voltage and speaker impedance.

Verification Procedure:

1. Set the subwoofer to the listening position with an approximate filter and volume setting of 85 Hz and a volume that seems correct.
2. Play a collection of music tracks with well-recorded bass lines in different keys.
3. Create your own test track using the sound generator or keyboard, playing each note with uniform speed settings.
4. Empirically, listening in each potentially practical place of the subwoofer, find a position in which a consistent and natural bass sound is created, where the sound is well balanced, and all the bass notes are fairly uniform.
5. Optimize the subwoofer level and the flow around the filter and phase / delay. These controls are usually interactive, so you need to experiment with their settings and choose the best combination.
6. If the deepest and highest bass notes seem correct, but everything goes wrong in the crossover area, then you need to adjust the crossover frequency up or down to find a smooth transition.
7. If possible, adjust the phase control.

In this case, you must be careful: adding a subwoofer will inevitably lead to some deep basses annoying the neighbors. Generating very low bass can also create standing waves in the room, and this will cause various parts of the building to rumble and resonate.

Home Cinema Function

Subwoofers are usually easy to connect, given that only two cords are commonly used. One for power and one for audio input. There are several ways to connect a subwoofer to an amplifier, receiver, or processor (also known as a home theater receiver).

The preferred way to connect the subwoofer is through the receiver output (designated as SUB OUT or SUBWOOFER) using the LFE cable (acronym for low-frequency effects). Almost all home theater receivers (or processors) and some stereo receivers have this type of output.

The LFE port is a special output for subwoofers only. The user will see it as SUBWOOFER, not as LFE. You just need to connect the LFE jack (or subwoofer output) on the receiver / amplifier to the Line In or LFE In jack on the subwoofer. Usually this is only one cable with RCA connectors on both ends.

RCA stereo amplifiers

Sometimes you may find that the receiver does not have an LFE subwoofer output. Or it may happen that there will be no LFE input on it. Instead, the subwoofer can have left and right (R and L) stereo RCA jacks. If RCA cables are used in the Line In of the subwoofer, the RCA cable is connected and the port R or L is selected on the subwoofer. In the case when the receiver has both RCA connectors for output, it is necessary to turn on both. This process is similar to connecting basic stereo speakers.

Before you make a subwoofer with your own hands, you need to clarify the channels. If it has two sets of spring clips for speaker output, then this means that other speakers are connected to the subwoofer, and then to the receiver to pass through the audio signal.

When it has only one set of spring clips, the subwoofer will have to use the same receiver connections as the speakers. The best way to achieve this is to use reliable clamps, as opposed to overlapping bare wires, which can be dangerously in contact with each other when connected.

Stereo sound optimization

Subwoofers are used in most home theater systems and can dramatically improve the sound of stereo systems. They can provide the basis for sound, so adding sub is not just adding deep bass. Rather, they can improve the overall sound of the system.

Connecting a subwoofer to a two-channel system differs from the methods used in home theaters. AV receivers have a bass control function for directing low frequencies to the sub, and mid and high frequencies to the speakers. The subwoofer is connected to the receiver using one connecting cable.

Stereo receivers, preamps, and built-in amplifiers rarely have subwoofer output jacks or offer bass control options. Therefore, instead of using these connections, you can use subwoofer speaker levels, as well as “high-level” inputs.

Sub without amplifier

Most subwoofers are designed to work without an amplifier. They have a high-level input (sometimes called a speaker level input) that connects to the speakers. All you need to do is launch another pair of speakers from the amplifier output to the high-level input on the subwoofer.

This connection works the same as the subwoofer preamp output. It takes voltage from the amplifier as a signal. And sends it to the subwoofer. It does not lead to power consumption on the amplifier to which it is connected, and is a common signal with the main speakers, and not the power of the amplifier. And since there is no power, all impedances remain unchanged.

The most prestigious REL subwoofers are made in England. They are the "gold standard" of the industry, their value exceeds $ 9,000! Music lovers do not have to spend such money at all, since creating a subwoofer in the age of the Internet has become much easier.