Once so popular in tuning installations, today’s subwoofer are sometimes questioned reluctantly to incorporate them due to their size. It is understandable, in order to reproduce the most serious frequencies of the audible spectrum usually have a large diameter, require a speaker for which one must look for a location, and need their own amplification. It is logical that some fans will consider their installation.
The question is, to what extent is it worth a subwoofer? Are there boxes that optimize their size with respect to their performance? Does it take up so much amplification? And above all, is the subwoofer necessary for maximum fidelity and fuller enjoyment of audio in the car?
Is the subwoofer necessary?
The first thing you need to know is if you need the subwoofer on a car audio equipment. And the answer is that normally … yes.
The main reason, and one that differs greatly from the cabin of a car than would be the audition in a saloon, is that the bass speakers are not in a solid wooden cabinet, but are installed in the doors of the vehicle. And car doors are not what we could call precisely solid …
Due to the certain flexibility of the sheet (as rigid as it seems a priori) as well as the weakness of the panels, the doors of a vehicle undulate and radiate when the loudspeakers emit the most severe frequencies; Muddying and spoiling the clarity of reproduction.
For demanding installations, this makes it very necessary to apply a high-pass filtering from the source or the processor and to reject the most severe frequencies (thus to stop reproducing them), in order to obtain a cleaner general reproduction at moderate and high volumes.
It is true that the soundproofing of the doors is a key step to improve its absorption and rigidity, which will reduce resonances and reduce that limit of the frequency range affected. But the problem will not disappear completely at the most severe frequencies, so a certain step-high filtering will still be necessary if we are to maximize quality and dynamic range at moderate and high volumes.
Another reason why a subwoofer is necessary in a car audio equipment of a certain level, is due to the engine noise and rolling of the vehicle, whose spectrum is mainly distributed in the bass and subwoofer range. That is to say, the noise inherent in the operation of a car masks and messes up the serious part of the music, which makes it necessary to have a greater sound power in the bass frequencies to maintain a flatter response that can overcome the noise of the vehicle when we are on going.
Therefore, if the step-high filtering of the previous paragraph adds the rolling noise, we have conditions that make virtually disappear the most serious part of the spectrum and its details.
Not least, another reason why we can consider a subwoofer is because of the great fun, enjoyment and transmission of fast-paced sensations that only a faithful and deep response on subwoofer gets to convey.
Acoustic boxes, why?
So far we have seen sound justifications for which we are interested in adding a subwoofer to the equipment. The skeptic’s next question to the subwoofers is: “Is the box really necessary?” And again, the answer is yes.
If you install the subwoofer on the vehicle doors or simply in the rear tray without reinforcing, its behavior would be chaotic due to the low frequencies and high power it emits. The great inertia of your excursion and the acoustic resonances of the doors or the tray, together with the interference of the sound emission from the rear side of the speaker, would produce a simply disastrous sound, not to mention that in addition the physical integrity of these structures Would be called into question.
Instead when we install a subwoofer in a robust box, on the one hand we cancel the vibration and resonance of the surface of which is anchored, and on the other hand we practically eliminate the emission of sound from the back side of the speaker.
Popular Types of Speakers
When choosing an enclosure for a subwoofer, we find a variety of possibilities, each with advantages and disadvantages compared to others. Let’s give a few brushstrokes about the most commonly used types and their characteristics.
Sealed Box: precise and detailed subwoofer
A sealed box is an airtight enclosure in which the subwoofer is installed, where the air inside the box behaves like a spring that helps control the excursion limits of the subwoofer, and in which, thanks to its construction, the emission Sound from the rear side of the speaker is completely canceled.
It is suitable for musical styles that require a rigorous and precise bass. Well built and dimensioned according to the characteristics of the concrete subwoofer, it will provide a flat and detailed response, a deep extension and a high power input although with a low performance that will require an oversized amplification. Personally it is with the type of box with which more satisfactions I have had, since I like the precision and the detail that its sound offers.
Bass Reflex Box: vigorous and deep bass
The bass reflex boxes, instead of being totally airtight, have a duct (called a port) that communicates the volume of air inside the box with the outside, behaving like a resonant element that takes advantage of the emission of the face Rear of the speaker inside to emit it to the outside and in phase with the frontal emission. The objective is to reinforce the response of the front face of the speaker and optimize its performance, so that you get more sound pressure than you would get from a sealed box For the same amplification power. Bass reflex boxes require a precise calculation of their volume and the tuning of the port, so that they can offer a lower bass than sealed boxes, but on the contrary are much larger sizes.
Some people prefer Bass Reflex sound for rock, heavy metal or any powerful and rhythmic style, although for others their sound may be overly resounding.
Box Step Band: maximum footprint
Bandpass boxes are a special type of bass reflex box designed for maximum performance and impact in a particular frequency band. The loudspeaker is normally mounted inside a double acoustic chamber (one sealed and another bass reflex) so that the sound is emitted by the part of the port. Taking advantage of this acoustic strategy, the sound it emits is especially reinforced and powerful in a narrow frequency range.
Being highly efficient boxes in that narrow range of frequencies, they tend to be resonant or resounding. Its aggressive sound fits some users who love rap, reggae or hard rock.
Free-Air and Infinity Baffle Enclosures
A free-air system consists of a speaker installed on a surface that simply separates the emission from the front face of the speaker from the rear, so it could not be considered a box itself. An acoustically similar variant would be the infinite baffle box, which consists of installing the speaker in an extremely large sealed box , so that the spring effect of the air inside the box is minimal.
In a vehicle these types of enclosures are presented when we install the subwoofer in the rear tray of the vehicle, with its front face emitting towards the passenger compartment and the rear to the interior of the trunk.
These types of systems save space and have a rather flat response, but require subwoofers that are prepared to work in this way and a very good solidity of the panel or tray where they are installed. The absence of a box makes them very attractive to install, but on the contrary will admit less power than the other types of boxes, since there is no additional acoustic control of the excursion, as it happens in other enclosures.
The importance of box calculation
As we have seen, we not only have to define the type of box that interests us, but a correct design of its dimensions according to the specifications of the concrete subwoofer, is paramount. A good calculation and a good construction of the box can make the difference between enjoyment and disaster.
The calculation of boxes is a whole world, with its conceptual bases behind and its design formulas. As a help, there are software programs such as WinISD, Bassbox or Unibox, which will serve as a tool for calculation and simulation of the response before building or purchasing the box.
We have already seen that the enclosure is crucial part of a subwoofer and that can not be overlooked. And another needs associated with the addition of a subwoofer is its own amplification.
And because they are speakers that emit at frequencies where the ear is less sensitive, they need to be large and move with great excursion to emit those low frequencies with the necessary amplitude. This implies that they require remarkable amplification.
In this sense, we find two types of subwoofer: passive subwoofer , ie speakers that do not include amplification and require that they be provided by an external amplifier installed in the vehicle; And active subwoofers , which include amplification embedded in the box itself, which makes them attractive to more practical users.
Choose the type that we choose, luckily today the amplification of a subwoofer can be extremely efficient and discreet, thanks to the performance and excellent size / power ratio of the class D amplifiers that the market offers today, suitable for the Subwoofer amplification for both efficiency, quality and control capability of the speaker.
So, subwoofer yes or no?
In my opinion it is worthwhile to enjoy a subwoofer sharp and deep also in the car.These sounds are part of the real world, they are in nature and in instruments and to a greater or lesser extent all recordings have musical components that are situated in this part of the spectrum. If we do not reproduce them with clarity and detail, we will be losing part of the sensations of the original recording.
Many people like to feel a serious very powerful that stands out above the rest; I personally am more supportive of only completing the answer for a realistic and realistic reproduction to the deepest deep end. But even for this alone, we will need a great acoustic power in the subwoofer frequencies, free of resonances and that surpasses the noise of rolling, that only making a hole in our trunk to one of these “passengers”, we will be able to obtain.
What do you think, would you incorporate a subwoofer into your lives?