We all have speakers in our home, whether that’s big sound systems for the TV or stereo speakers for enhanced music listening. If you’ve ever looked carefully at such speakers, you may have noticed holes in the front or rear. So, what are they for?
Speakers have holes to allow the lower frequencies that often get trapped in the back to be enhanced. When your speaker is working, the vibrations inside compress air in the front and back, which can become unbalanced. Bass reflex systems have these holes, so the bass sounds are not lost.
This article will discuss how speakers in enclosures produce sound and what the holes are used for. We’ll also go over the sound quality of such speakers and whether or not they might be right for you.
Why Do Speakers Sound Better in a Box?
The vast majority of speakers come in an enclosure, also known as a cabinet designed to enhance sound quality. It is essential for a speaker to be in a box to ensure that the sound it produces does not get canceled. To understand this better, you must know how audio waves travel.
When you play music, the sound you hear is a kind of energy, which translates from vibrations within your speaker. Also known as sound waves, they are moved, or pushed, back and forth, creating pressure waves that we hear as sound.
As your device sends electronic waves into the speaker, the transducer converts this energy into sound waves. A coil inside the speaker begins to move, which, in turn, moves the cone at the front of the speaker. This is the vibration that causes air to be pushed and compressed.
When a speaker pushes air out into a room, it also compresses the air inside, reducing it into the speaker itself as a vacuum. Without the enclosure, this vacuum would cancel out the pressure created at the front, nullifying any sound made. This is referred to as ‘out of phase.’
Out of Phase
Out of phase pressures can cancel each other, hence no sound. However, a box ensures pressures from both the front and back sides do not meet. The box helps produce bass sound but at the loss of a higher amplifier to compensate for the pressure in the box.
The pressure in the box holds the speaker back. However, if the speaker has a port/hole, the pressure is led there through a vent or tube, and the sound comes out at a particular frequency.
The enclosure allows the back of the woofer to be protected from the front of the woofer. That way, the back waves will not meet the front waves and cancel each other. The holes on the box will help distribute the sound at specific frequencies, influencing the sound quality.
Changing the Size of the Box
The quality of sound you get from your speaker is also determined by your box design. You can get an increased output without using a big speaker by ensuring your speaker enclosure is 20% more than the recommended size. You’ll also need to adjust the size of your port accordingly.
Why Do Speakers Have Holes?
As mentioned above, when your speaker is making sound, it is vibrating within, causing pressure to build up. When we talk about your speaker being ‘out of phase,’ we’re mostly discussing lower frequencies that are ‘trapped’ at the back of the speaker cone inside the enclosure.
Speaker holes relieve the pressure coming from inside the box and enhance those lower frequencies. These holes must be appropriately punched to ensure the sound comes out at a specific frequency.
The tubes are connected to the back of the speaker cone and are primarily used to increase the output, help to eliminate distortion, and improve the overall bass response of the sound.
The bigger the speaker, the bigger the hole typically is. Well-designed speakers with holes will push pressure that creates bass sound for the speaker and allow the woofer to work more smoothly. This is more noticeable in larger speakers, as the sound produced in this case is much louder, and it’s easier to pick up on discrepancies in the music.
Sound Quality of the Speaker Holes
Such speakers are known as Bass Reflex Speakers, and they are designed to ensure that the speaker’s back waves and front waves cannot meet. Instead, the lower frequencies are routed to the holes, giving you a sound with added bass.
Unfortunately, the bass that you hear from the holes is not always the best. The bass that these speakers produce sounds great only at specific frequencies. For that reason, many people don’t like ported speakers all that much.
Some say that ported speakers make “chuffing” or raspy sounds, which many people dislike. That does not mean ported speakers are not good — there are good ones on the market, like Bud Fried’s IMF line, which uses a front hole known as a transmission line.
A transmission line speaker uses a long tunnel, making the bass sounds from the woofer travel further before they reach your ears. This helps to ensure the sound is completely in phase.
How Big Should the Holes Be?
As discussed earlier, the quality of sounds coming out of the holes depends on the size and shape of the port/vent. At specific frequencies, certain sounds are projected based on the Helmholtz resonance, of which the port system resonates according to the:
- Duct’s effective length and cross-sectional area
- Enclosure’s internal volume
- Sound speed in air
Modern technology enables speaker designers to determine the port’s best diameter and the length of its tube. With the help of current computer software, designers can decide how big a vent and how long the port’s pipe should be compared to the speaker’s cabinet size. Even with thorough calculations, designers must continue to test their prototypes to ensure that the speaker box will produce excellent sounds.
Should You Get Ported Speakers?
There’s nothing wrong with getting ported speakers. While not everyone loves them, that does not mean they don’t sound great, and nobody wants them. There are many excellent ported speakers out there, and they are suitable for many different settings.
For example, ported speakers are great for live performances. Manufacturers providing speakers for settings such as this often take porting solutions into consideration. Porting can give users increased bass response and efficiency to make up for resonance issues.
Bass reflex speakers have better bass responses compared to sealed box speakers of a similar size. However, the issues that bass reflex speakers have tend to cause the resonant frequencies to become louder. Plus, the resonance extends to several seconds, causing a ‘boomy‘ effect.
Earlier, we mentioned that ported speakers tend to make “chuffing” noises. Chuffing is caused by large movements of air inside the speaker holes. When the holes have an inadequate surface area, they cause an unpleasant sound when the volume is higher.
While there are advantages of using holes on speakers, a poor design can, unfortunately, affect speaker performance. Ported speakers are usually not suitable for settings where neutrality or highly accurate sounds are required, such as in recording studios. Even so, many bass reflex systems around the world today can overcome these challenges.
You might already have ported speakers at home, which are speakers with holes. In normal speakers, it’s not uncommon for the enclosure to trap and suppress the bass energy. The holes in ported speakers allow for the low frequency sounds to be increased, giving your music much more bass.
The size of the vent and its pipe is vital to the speaker’s sound quality. Well-designed ported speakers can produce good sounds. However, some people dislike the chuffing and effects that the speakers tend to make.