Setting up a subwoofer in a car
Content
The subwoofer is a good addition to the car's sound system. But it is worth considering that buying an expensive subwoofer does not guarantee high-quality sound, because this device needs to be properly tuned. To connect and set up a subwoofer properly, you must not only have good hearing, but also a deep knowledge of car audio theory.
Of course, before setting up a subwoofer in a car, it is best to seek help from specialists, and for those motorists who want to do it themselves, this article will be useful.
Where to start setting up a subwoofer?
Subwoofer tuning begins from the moment the box is made. By changing the characteristics of the box (volume, length of the port), you can achieve different sounds. At the same time, you need to know in advance which audio files will be mainly played in the car, as well as which amplifier will be connected to the audio system. When the subwoofer is already supplied in a manufacturer's case, then the flexibility of setting is, of course, limited, although with the necessary knowledge it is quite possible to achieve the desired sound quality.
One of the important factors affecting the sound quality is the amplifier, we advise you to read the article "How to choose an amplifier".
LPF (lowpassfilter) filter setting
First you need to set up a low-pass filter (LPF). Every subwoofer today has a built-in LPF filter. The filter allows you to select the threshold at which it begins to block high frequencies, allowing the subwoofer signal to blend naturally with other speakers.
Installing a filter, like setting up an active subwoofer, consists of a lot of experimentation - there is simply no definite correct “formula”.
The subwoofer is designed to reproduce low frequencies, it cannot sing, this is the task of the speakers. Thanks to the LPF low frequency filter, we can make the subwoofer play bass current. You need to make sure that the filter value is not set too high and the subwoofer does not overlap the woofers of your full range speakers. This can lead to over-emphasis on one frequency range (say, around 120 Hz) and a fuzzy speaker system. On the other hand, if you set the filter too low, there may be too much difference between the subwoofer signal and the speaker signal.
The subwoofer's playback range is typically 60 to 120. Try setting the LPF filter at 80 Hz first, and then test the sound. If you don't like it, adjust the switch until the speakers sound the way you want.
On the radio itself, the filter must be turned off.
Subsonic tuning
Next, you need to activate the infrasonic filter, which is called "subsonic". The subsonic blocks the ultra-low frequencies that naturally occur in some songs. You cannot hear these frequencies because they exist below the threshold of human hearing.
But if they are not clipped, the subwoofer will use extra power to play them. By blocking infra-low frequencies, the device will be able to more effectively reproduce precisely those frequencies that are within the audible range. Moreover, in this case, failure of the subwoofer coil due to the accelerated movement of the diffuser is excluded.
What is Bassboost for?
Many amps also include a Bassboost switch that can increase the power of the subwoofer by setting it to a specific frequency. Some motorists use the switch to make the sound more “rich”, although it is usually used to evenly distribute the bass. If you set the switch to the maximum value, then the subwoofer may burn out, however, turning off Bassboost completely is also not worth it, because in this case, the bass may not be heard at all.
Adjusting the Input Sensitivity (GAIN)
Some motorists do not understand how to properly set the input sensitivity. Input sensitivity indicates how much signal can be applied to the input in order to obtain the rated output power. It must be adjusted to normalize the input signal voltage.
It is very important to set the input sensitivity correctly, as this will help to avoid signal distortion, poor sound quality, or damage to the speakers.
To adjust the "GAIN", you need
- a digital voltmeter that can measure AC voltage values;
- a test CD or file containing a 0 dB sine wave (very important not to use an attenuated test signal);
- instructions for the subwoofer, which indicates the permissible output voltage.
First you need to disconnect the speaker wires from the subwoofer. Next, you need to make sure that the bass, equalizers and other parameters are turned off on the head unit in order to get a clear sound. In this case, the input sensitivity level should be as low as possible.
Make sure a digital voltmeter can read AC voltage and connect it to the speaker terminals on your speakers (you can secure it with a screwdriver). After that, you will have to turn the sensitivity “twist” until the voltmeter shows the required voltage value, which was indicated in the specifications.
Next, the recorded audio file with a sinusoid must be fed to the subwoofer from time to time by changing the volume of the audio system until interference occurs. In the event of interference, the volume must be restored to its previous value. The same goes for adjusting the sensitivity. An oscilloscope can be used to obtain the most accurate data.
Acoustic phase
Most subwoofers have a switch on the back called "Phase" that can be set to 0 or 180 degrees. From an electrical standpoint, this is the second easiest thing to do after an on/off switch.
If you set the power switch to one side, then two conductors will carry the signal from the output to the rest of the electronics in one direction. It is enough to flip the switch and the two conductors change position. This means that the shape of the sound will be reversed (which is what the engineers mean when they talk about reversing the phase, or switching it 180 degrees).
But what does a regular listener get as a result of phase tuning?
The fact is that with the help of manipulations with the phase switch, you can achieve the highest perception of the middle and upper bass while listening. It is thanks to the phase shifter that you can achieve all the bass for which you paid.
In addition, the phase adjustment of the monoblock helps to achieve exactly the front sound. It often happens that the sound is unevenly distributed throughout the cabin (music is heard only from the trunk).
Delays
Subwoofers tend to have small delays, and they are directly proportional to the size of the distance. For example, speakers from the American manufacturer Audissey deliberately set a longer distance to prevent this delay.
It is worth noting that manual tuning of the amplifier for a subwoofer is possible only if there is an external processor or an integrated processor. A sign that the subwoofer is causing delays is lingering bass, which sometimes ruins the sound. The purpose of the delay setting is to achieve simultaneous playback of the subwoofer and front speakers (the sound should not be allowed to lag even for a couple of seconds).
Why is it important to dock subwoofers and midbass correctly?
If the subwoofer is poorly docked with the midbass, then the sound will be of poor quality and inferior. This is especially noticeable at low frequencies, when some kind of nonsense is obtained instead of pure bass. Sometimes such deplorable options are possible, when the sound from the subwoofer will generally play independently.
In fact, this applies to all types of music, and not just, say, classical or rock music, where the playing of "live" musical instruments is observed.
For example, in tracks that belong to the EDM genre, which is so popular among young people, the brightest basses are located exactly at the junction with the midbass. If you dock them incorrectly, then low-frequency loud bass will at best be not so impressive, and at worst will be barely audible.
Since it is necessary to tune the amplifier to the same frequency, it is recommended to use an audio spectrum analyzer to obtain the most accurate data.
How to understand that you have set up the subwoofer correctly?
If the subwoofer is connected correctly, then people in the car simply cannot hear it, because it should not interfere with the main signal.
If you listen to music at a low volume, it may seem that there is not enough bass. The lack of bass at low volumes is a sure sign that the subwoofer has been connected correctly.
Of course, there should be no noise, distortion or delay in the audio signal, and it does not matter what type of design is used.
The percentage of bass in each track must be different, that is, the playback must completely match the original track recorded by the producer.
The next article we recommend reading is titled "How a Subwoofer Box Affects Sound".
Video how to set up a subwoofer
Conclusion
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