Ported speakers, also known as bass reflex systems are a type of speaker enclosure that uses a port or vent cut into the cabinet to equalize pressure between the inside and outside of the speaker.
As the diaphragm moves, the port causes an increase in the internal pressure of the speaker cabinet. This pressure is then funneled through the port. This makes the speaker waves more powerful and makes the speaker far more efficient overall.
There are two types of ported speakers. These are rear-ported and front-ported speakers. Each of them is unique. If you want to buy ported speakers, you need to know their differences and similarities to make the best choice.
The Differences Between Rear Ported and Front Ported Speakers
The first easily noticeable but noteworthy difference is the location of the ports. Rear speakers have a port on the rare panel. Front ported speakers have a port on the front baffle near the drivers.
How is the difference in a port location significant?
1. Space Requirements
The main reason many smaller bass-reflex speakers use rear ports is the lack of adequate space to accommodate them on the front baffle. The enclosures that house tweeters with large mounting plates for rigidity, for example, often have rear ports for this reason.
Also, speakers with the bracing mounted inside the enclosure in the front location where the port should ordinarily also have rear ports.
The only element that is often found in this part is the speaker wire terminals. The fact that the terminals are usually relatively small also makes it possible to see better why the rear panels of small speakers can be the best place to put the ports.
From a performance point of view, there can be no difference between rear-ported speakers and front-ported speakers. But this can only be true if you are careful about the wall proximity of your ported enclosures.
2. Speaker Placement
When positioning your rear-ported speakers, you need to be much more careful if you want to prevent time smearing, the chief enemy of quality sound.
Take an example, if your home theater room is small, then you may have your couch against the wall. How do you place a 7.1 speaker system in this case? Speaker placement with your couch against the wall or with a lot of obstacles in the room for example are very important considerations when choosing rear or front ported speakers.
The human brain is incredibly sensitive to the arrival time of sound to each of our ears. If you flush the speaker against any wall or any solid surface, the flow of air in and out of the rear port will be restricted, which will then limit bass response.
The perfect solution is to leave about 6 inches between the speaker’s rear panel and the wall or solid object behind. That will create adequate room for the port and the woofer cone to work together seamlessly to give you the performance that you desire.
This does not mean that front-ported speakers are immune from time smearing. They are only a little safer.
When you are mounting any ported speaker, remember that all walls and solid objects reflect sound. This is why in-wall speakers with enclosures are always front ported.
To prevent the subsequent negative impact, you should ensure your front-ported speakers are away from the wall, mainly if they are in a corner.
Do ported speakers sound better?
Ported enclosures can dramatically decrease your power requirements because they increase the bass output of a speaker by around 3 dB compared to a sealed enclosure. To match a 3 dB output boost through amplification, the power applied to the speaker needs to be doubled.
Choosing the Right Sized Ported Speakers
Front ported speakers can transmit midrange frequencies that are reflected within the box. The speaker can also generate “wind noise” if the speaker is undersized and there is turbulence around the opening of the port.
Rear ported enclosures can also experience the same effect. However, they can mask “wind noise” to some considerable degree. As we have said, you must avoid placing it directly against a wall or a solid object. Otherwise, the audio problems may persist and then worsen.
Note: If your ported speakers are large, and you place them in the right position, you are highly likely to manage these sound problems with ease.
How do Ported Speakers Work?
The port causes the volume of air inside a speaker cabinet to react with the volume of air on the outside. If you change the port you change the response of the cabinet, and certainly putting a rear ported cabinet near a wall will change the way the port works, thus changing the response.
The Similarities Between Rear Ported and Front Ported Speakers
Other than the location of the ports and the strict wall positioning requirements, ported speakers are mostly the same.
In terms of performance, the lower bass response enclosure rolls off at 24db/octave. This means they are faster than sealed speakers.
Rear ported, and front-ported speakers are efficient since the cone has great freedom of motion.
The fact that much air flows freely through the ports also improves the quality of the boom. Here are other common benefits of both rear-ported and front-ported speakers:
- Reduction of cone excursion and distortion
- Extra “bump” due to the free flow of air
- Enhanced performance around vent tuning
Like anything else on the planet, rear-ported speakers and front-ported speakers also have a few disadvantages. Here are the main problems:
- Possibility of the total loss of cone control that can lead to high distortion
- Unpleasant sound coloration due to midrange sound effect
How to Position Ported Speakers for the Best Experience
You can minimize the problems associated with either front-ported or rear-ported speakers by positioning them for great sound. Here is how you can use to place your speakers are required.
Ensure that the speakers form an equilateral triangle with the place where you will be positioned when listening
Get approximately 8-feet separation for flooring speakers or 4-feet separation for bookshelf speakers
The tweeters should be about the same height as the listeners’ ears
Angle your speakers to point your head directly
Minimize sound reflection by removing any objects that may be standing between your ears and the speaker
Keep the turntables on a different surface other than your ported speakers
If you make the adjustments and realize that the song has ‘locked” into place, then you have successfully found the right spot.
The process of achieving excellent sound in the speakers involves some degree of trial-and-error, so you can rely on your creativity to enhance your experience.
How Far Away From The Wall Should Rear Ported Speakers Be?
Rear ported speakers should be at least 2-3 feet away from the nearest wall (especially if your speaker is in a corner). Many speakers have rear-facing bass ports. Positioning a rear bass port too close to the wall will reflect sound waves, resulting in time smearing.
So there you go, our quick guide to rear ported vs front ported speakers. Despite the differences between rear-ported and front-ported speakers, you can be happy with any of them if you follow the recommended practices. Keep in mind that they handle bass a little differently. Moreover, excellent construction and design and the size of the speaker can minimize the problems.
Norvan Martin is the founder of BoomSpeaker.com. He is a professional Electronics Engineer and is passionate about home theater systems and AV electronics. BoomSpeaker was created as an online hub to share his knowledge and experiences as it relates to home theaters and home audio electronics.