Last Updated on October 19, 2021 by Norvan Martin
If you are checking out subwoofers, there are two main factors or tradeoffs to consider – bass production and sound quality.
The fact is, in most cases, if a subwoofer can produce a tremendous amount of bass, the sound quality won’t be great. This is why there are essentially two types of subwoofers being marketed today:
SQ or sound quality subwoofers are designed to accurately reproduce sound with clarity and fidelity at the expose of producing a massive bass output. SPL or Sound Pressure Level subwoofers are designed to produce thundering and earth-shaking bass but at the expense of sound quality in terms of accuracy.
Let’s get into more details. What is the difference between SQ (Sound Quality) Subwoofers and SPL (Sound Pressure Levels) Subwoofers? Which is better? Which should you choose as a music lover or audiophile?
What are SPL Subwoofers?
SPL stands for Sound Pressure Level and is the pressure level of a sound, measured in decibels (dB). Basically, it is a measure of how loud your speakers and subwoofers are. SPL subwoofers generate a lot of sound pressure which produces a tremendous amount of bass.
However, this is at the expense of sound quality. To find out more, we have an entire article on SQL subwoofers where we discuss details on what is an SQL subwoofer, what they are used for, and more.
Determining your system’s sound pressure level is vital for people interested in producing powerful high-pitched audio.
If this is you, you need speakers and subs with the ability to move as much air as possible.
What are SQ Subwoofers?
SQ stands for Sound Quality, and it is all about using audio systems that create the perfect sound.
By this, we mean these subwoofers are excellent at producing sound with clarity and fidelity. This way, you will be able to hear every single frequency of the song clearly.
For SQ subs or speakers to give you accurate and tight bass, they should be able to eliminate overbearing frequencies and ensure superb tonal accuracy and excellent staging. Of course, this is the dream of every passionate audiophile.
Ported vs Sealed Enclosures
The purpose of SPL and SQ determines the type of enclosures that are suitable for each of them.
The cabinets also have unique pros and cons that they ultimately pass onto the speaker system. SPL uses ported enclosures, and SQ requires sealed enclosures. There are many differences between ported vs sealed enclosures.
SPL: Ported Enclosures
Ported enclosures are the best for SPL setups, and for good reason. As we have seen, sound pressure level is more about filling your room with bass than creating the perfect sound.
These speakers perform best in ported cabinets (also known as bass reflex enclosures) since they are designed to produce booming sound.
Ported enclosures have one or more ports that allow the free flow of air, which leads to greater output. These enclosures allow the lower bass response to roll off at not less than 24Db/octave.
Since the front sound waves and the rear sound waves couple, SPL speakers significantly increase output around the tuning frequency. This is good news for those who have turned to SPL to get more bass. That is the reason they are mostly used in rap and hip-hop genres.
Key Points Why Ported Enclosures Best for SPL
- Reduce distortion
- Create high-sound pressure
- Free-flowing air creates the desired sound effect
Key Points Why Ported Enclosures Less Favorable for SPL
- Harder to design
- Are large
- Can cause poor overall sound quality
SQ: Sealed Enclosures
Sealed enclosures are the best for all types of SQ audio equipment. SQ is more about creating the perfect sound than filling the room with sound.
This makes sealed enclosures, also known as acoustic suspension enclosures, the most suitable.
The air inside these enclosures helps in controlling the cone’s movement. Since the cabinets lack vents, their lower bass response rolls off at 12dB/octave.
When appropriately built, sealed enclosures produce highly accurate sound. They can have a smooth bass response and hard-hitting sound. Unlike ported enclosures, they are typically small in size. Large sealed cabinets can behave and sound like an infinite baffle.
Key Points Why Sealed Enclosures Best for SQ
- Accurate sound quality
- Excellent transient response
Key Points Why Sealed Enclosures Not the Best for SQ
- Sealed air restricts one movement, limiting the frequency
Though these two types of enclosures have some cons, they serve their purpose. Ported boxes are the best at creating loud, booming bass, which most SPL lovers seek.
Sealed enclosures help SQ speakers create high bass and play crisply, which is the users’ goal.
How can I Measure SPL and SQ, and Why Does that Matter?
The ability to measure whether any audio system meets your requirements is essential. It allows you to assess the performance objectively and take the best action.
However, to some audiophiles, there is much more to this than getting objective feedback. Perhaps, that is the reason you need to know which of these best meets your unique needs.
You can use a sound pressure level meter to measure the SPL in decibels (dB). This means SPL is objective, and you can accurately determine whether your speakers are pushing the required amount of air and creating enough pressure.
So, you can ascertain whether you have achieved your goal.
Many people are working hard to create the perfect sound. However, they may not achieve this goal since sound quality is subjective.
You have no proven scientific way to ascertain whether you are getting tonal accuracy and balanced proper sound staging.
Remember, many factors can affect your sound quality. Here are some that specifically impact sound staging:
Since SQ is subjective, you should rely on your judgment to determine whether the sound staging is proper.
If poor placement creates artificial sound, you are likely to assume wrongly that your SQ system is ineffective. For example, placing your subwoofer behind the couch may improve bass, but placing your sub under the coach will not.
You can solve this by adding other SQ speakers. Passionate audiophiles will do more than this and ensure their speakers are positioned to provide optimum performance.
However, beginners who rely on any device to determine how to improve sound quality are highly likely to make the wrong decision.
A room’s interior can also influence your sound staging. Different surfaces have varied responses to sound waves. For example, glass walls reflect sound, causing it to bounce around and negatively affect the sound quality. Other surfaces such as upholstery absorb sound waves.
So, if you are using sound staging as one of the parameters for determining your SQ speaker’s efficiency, you may likewise get it wrong.
So, between SPL and SQ systems, which one is perfect? From the above explanation, SPL can help you to fill your room with bass at the expense of clarity and fidelity.
At the same time, SQ promises to give you perfect sound but fails to provide you with an objective method of assessing its efficiency. So, we can’t talk about perfection here.
SQ and SPL subwoofers; which is better in car-audio systems?
SPL car audio systems are based on what is known as a “Burp-Box,” which is a Sub-Woofer Box designed to achieve the maximum possible dB rating but often sounding terrible for music! They are meant to produce a frequency “Burp” that ranges from 50 to 80 Hz in most circumstances,
SQ car audio systems are designed to provide a balanced sound without being too Treble or Bass-heavy, and they normally take a lot longer to set up to have everything sounding exactly right! SQ Sub-Woofer boxes are normally tuned lower than “Burp-Boxes,” sacrificing total SPL output, but that isn’t necessary here because we don’t drive about playing one frequency “Burps.”
If you want to choose either SQ or SPL audio equipment, remember that neither of them is better than the other. It is really about preference.
These terms are somehow controversial in the music industry today, but understanding how they differ can mean a whole world of difference.
Nevertheless, understanding how to take advantage of the small details can mean a significant difference. The choice ultimately comes down to your preference.
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.