When we talk about sealed vs ported boxes, you may hear the terms bass-reflex vs acoustic suspension. What do these terms mean and which one is better? We answer this in detail in this speaker enclosure article.
Firstly, let’s explain these terms.
Acoustic suspension (sealed enclosure) is a method of speaker cabinet design that has the speaker drivers mounted in a sealed box or cabinet.
Bass reflex (ported, vented enclosure) is a type of speaker enclosure that uses a port or vent cut into the cabinet with a section of tubing or pipe affixed to the port.
but to make VERY deep bass in a very small cabinet.
Bass reflex boxes are more efficient around the tuning frequency and allow the bass to be extended a bit more than acoustic suspension sealed boxes. On the other hand, the acoustic suspension design offers deep bass in a very small cabinet, reduced bass distortion, a low resonance frequency, and reduces the pressure on the back of the speaker.
Before we continue, it is important to note that a bass reflex box will not match up to the deep bass offered by a good acoustic suspension box unless it’s very big or tuned very low. However, if large or tuned low, the system will probably overload and lose control of the speaker very easily, resulting in very high distortion.
Before we help you to decide which one is suitable for your needs, let’s see the design and performance characteristics that differentiate these enclosures, the limits of your listening room, and other potential factors.
Benefits of Acoustic Suspension
Acoustic suspension systems or sealed boxes reduce bass distortion. Normally, bass distortion is caused by stiff motor suspensions in conventional loudspeakers systems.
Benefits of Bass Reflex
The port affixed to bass-reflex boxes enables the sound from the rear side of the diaphragm to increase the efficiency of the system at low frequencies. Typically, sealed boxes won’t be as efficient.
Design and Build Quality
Acoustic Suspension: Acoustic suspension, known as a sealed speaker cabinet, is typically small, but if you are not interested in getting “tight” and focused sound, you can find a large cabinet.
These enclosures are filled with sound damping materials such as fiberglass to improve audio quality.
Bass Reflex: On the other hand, a bass reflex enclosure, also called the ported cabinet, is typically large and, and as the name suggests, it has at least one vent or port.
Unlike an acoustic suspension, these enclosures come with a thin layer of sound damping materials on their internal walls.
This process of damping the sound arguably takes more time than filling an enclosure with sturdy damping materials.
Due to the difficulty of designing bass-reflex cabinets, they are often a little more expensive than their sealed counterparts. Of course, this applies if you are comparing enclosures of equal value.
However, when choosing between bass reflex and acoustic suspension, you most likely want to think of many other aspects than just the design difficulty and cost.
Acoustic Suspension: Acoustic suspension boxes are much easier to build and has some tolerance to errors.
If you have a little bigger or smaller than you intended, you will likely get your desired sound quality despite the mistake.
However, please note that too big acoustic suspension enclosures are less efficient. Designers often make them small deliberately.
Bass Reflex: Bass reflex, on the other hand, is challenging to build and have little tolerance to errors.
A slight deviation from the approved size of the cabinet, port, or location of the vent can significantly impact the overall sound quality.
So, when choosing one, you must consider whether the duct has been tuned with the suitable woofer and box size as required. Alternatively, you can buy your ported enclosure from a reliable and experienced brand.
The Efficiency of Bass Reflex and Acoustic Suspension Boxes
You will agree that bass reflex and acoustic suspension are efficient, depending on your requirements.
For example, in a small room where you need quality sound, an acoustic suspension can be more beneficial to you than a ported cabinet due to the size.
Here are some of the significant factors you need to consider when thinking about your enclosure’s overall performance:
Some enclosures are more prone to distortion than others. Let’s see which one between bass reflex and acoustic suspension is better distortion wise:
- Its better speaker damping reduces distortion (+1)
- At low frequencies, more excursions can cause more distortion (-1)
- Less excursion at resonate frequency equals less distortion (+1)
- Impact of port reduced below resonate frequency, more excursion increases distortion(-1)
- Port can increase distortion. However, with advanced software design tools and port shapes available, this shouldn’t matter (+0)
Every speaker has the unique ability to produce a specific range of frequencies much better than others. However, that doesn’t stop the frequency response from dropping off from time to time. Lowers frequencies roll off noticeably, and we call that bass roll-off.
The roll-off can start at 50Hz, but you will still have some bass at 40Hz. However, it won’t be as loud as it was initially. In some cases, even higher frequencies can experience this.
Acoustic Suspension: Acoustic suspension subwoofers are best known for providing a gentler bass roll-off than bass reflex subs.
Bass Reflex: So, a bass reflex sub can be loud enough, but it rolls-off faster, meaning if you cherish the deep, rocking, and thundering bass, you should consider having one with a large woofer. This way, you capture the low frequencies despite the bass roll-off.
Timing can differentiate between the best and the worst experience when enjoying music. Many people feel good when they get the low notes they sent to the sub as closely as feasible to the ones coming from the speakers.
Acoustic suspension subwoofers work like many other speakers. When you get into a room that is approximately 2,500 cubic feet or more, your bass demand will likely increase significantly. So, one acoustic suspension speaker will not address your sound needs well.
On the other hand, the air that the woofer moves may sync closely with your other loudspeakers. However, the ones from the event can be slightly behind.
You need to keep the resonance low enough to prevent the human ear from noticing the difference. If you do that, you can solve the timing issue and have better quality sound in a larger room.
Acoustic suspension can also play quality bass. With higher amp power, it can perform much better.
Nonetheless, the sealed speaker begins to roll-off at 12dB/Octave, which is much lower than its rival. However, as we have seen, it provides a gentler bass roll-off than bass reflex.
Bass extension refers to the ability of an audio system to play the lowest notes. Bass reflex is the best for lower frequencies due to the influence of the port or ports. However, the quality can begin to suffer when the bass roll-off starts at 24dB/octave.
In other words, the acoustic suspension will have a much better response somewhere down the line than the bass reflex.
Acoustic Suspension vs. Bass Reflex- What are the Key Differences?
We have seen many differences between these enclosures. Let’s summarize the key points:
- More accurate sound
- Smaller enclosure size
- Requires more power to produce louder bass
- Produce louder sound
- Soundless accurate
- Large enclosure size
- It doesn’t require many amplifiers power to produce quality sound
Depending on which of the above features best suits your needs, bass-reflex can be better than acoustic suspension, and vice-versa, it all depends on your own requirements.