Speaker woofers and subwoofers are different pieces of equipment required for an immersive audio experience. Although they are comparable in some ways, they are vastly different in others.
Woofers and subwoofers work by moving back and forth to create pressure waves that our ears can detect. The biggest difference is the amount of air pushed by each and the frequencies each is suited for.
Woofers are mainly found on multiway speakers (2-way, 3-way…) and typically reproduce frequencies of 80 Hz to 5 kHz (5000 Hz) which are mid-range and bass frequencies. Meanwhile, subwoofers come in dedicated enclosures and mainly reproduce sub-bass frequencies (typically, 20 to 80 Hz).
But before we look at each component in more detail, it’s crucial to understand the frequency range reproduced by each.
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Woofers and subwoofers frequency range
Human beings are limited and on hear frequencies ranging between 20 Hz and 20 kHz (20,000). Woofers and subwoofers reproduce the lower frequency band (Usually, 5000 Hz down to 18 Hz).
Woofers can best handle the following frequencies;
- Upper midrange
- Lower Midrange
Subwoofers, on the other hand, can handle the following;
- Some Bass
What this means is that a subwoofer is a specialized woofer dedicated to sub-bass frequencies. On the other hand, woofers can reproduce a wider frequency range.
Upper Mid-range frequencies
These frequencies range from 2 kHz to 4 kHz and are mainly handled by woofers.
Most Woofers can play frequencies of up to 5 kHz but are crossed below this frequency for a smoother response.
Upper mids are where most dialogue information lies and are responsible for audio life, especially in movies.
Mids range from 500 Hz to 2 kHz and are also reproduced by woofers. This is where most instrumentals and vocals signals lie in a soundtrack.
Low Mid-range frequencies
Also played by woofers, low mids range from 250 Hz to 500 Hz. These frequencies convey low harmonic and some warm bass information.
Bass frequencies range from 60 Hz to 250 Hz and are played by a combination of woofers and subwoofers.
There is more thumping at this frequency band.
Some larger woofers in full-range speakers can play these frequencies with no problem but it is usually recommended to add a subwoofer and cross it over at around 100 Hz to prevent localization (More on this later).
These frequencies range from 20 Hz to 60 Hz and are also known as the low-frequency effects or LFEs.
LFEs are mainly felt than they are heard and are usually played by dedicated subwoofers.
Speaker Woofers explained
Woofers are speaker drivers used in the reproduction of mid-range, mid-bass, and bass frequencies (60 Hz to 5 kHz).
They are made of a voice coil attached to a diaphragm (cone) and moves back and forth in response to the electrical audio signals and in the process the cone movements to create sound pressure. The size of these woofers can range from 4” to 8”.
Woofers can, therefore, be found on speakers of different sizes ranging from small satellite speakers to full-range 4-way speakers.
Full-range speakers have 3 woofers and a tweeter for wider frequency response. These woofers can handle most of the lower frequencies from upper mids down to the bass frequencies but may not be smooth at the lowest frequencies.
Some 3-way speakers have 2 woofers but these woofers may not be able to handle the lowest frequencies as well as the woofers on full-range speakers can.
Monitors/bookshelf speakers only have one woofer usually about 5 inches in size and will need a powerful sub that can handle the bass frequencies better than the woofers can. The same case applies to satellite speakers that need subs with wider frequency response.
An external amplifier usually powers woofers on smaller passive speakers (not always the case). Larger speakers may be powered by built-in amplifiers capable of supplying power (watts) to the more powerful woofers. These speakers are known as active or powered speakers.
However, you should note that there is a difference between powered and active speakers which comes down to whether the crossover is active or passive.
Active crossovers filter signals before transmitting them to dedicated amps for each driver. In passive crossovers, the signals are amplified before being sent to the crossover circuit.
Subwoofers are specialized woofers housed in separate enclosures. This is because the best location for the other speakers is not often best for the sub-bass response.
Subwoofers are used to augment the main speakers in a surround/stereo, for sound reinforcement in PA (Public Address) systems, and so on. They help reduce intermodulation and non-linear distortion on other speakers as they bottom down to their lowest playable frequencies.
Also, by easing the main speakers, they become more efficient, the risk of damage is reduced and in the process, more depth is added to the system.
Subs are often used to reproduce frequencies between 20 Hz and 80 Hz which are harder to localize. However, localization will come down to placement and the crossover point.
If you are limited by your room’s size and layout, you may need to place your sub(s) in between the main speakers and cross them at a higher frequency (100 to 120 Hz) to seamlessly blend them.
Consequently, with more room to play with, you can find the best location for the sub by using the “crawl method” widely covered on the net or use software such as REW for measurement-driven placement. You can then cross it at 80 Hz or lower to help it disappear into the room.
But not all subwoofers are built the same.
Subwoofer size vs cone excursion
Sub-woofers combine cones with larger diameters and more cone excursion to play the lowest frequencies.
A larger cone diameter is preferred since increasing the excursion past a certain point increases distortion due to flux modulation effects in the magnet circuit with increased output.
Typically, the cones range from 8″ to 21″ in diameter. The larger the cone surface area, the lower the sub can play as you will see in the table below.
|Cone diameter||The lowest frequency (Estimate)|
|8 inches (20 cm)||40 Hz|
|10 inches (25 cm)||32 Hz|
|12 inches (30 cm)||27 Hz|
|15 inches (38 cm)||21 Hz|
|18 inches (45 cm)||18 Hz|
The lowest frequency also depends on a myriad of other factors, especially your room’s bass response and placement. An EQ can be used to compensate for room response issues combined with proper placement.
However, the lowest playable frequency is not a guarantee of good bass performance. Different subwoofer types will be suited for different needs and spaces. For example, A boat sub may not be the best for a home theater.
Types of subwoofers
There are two main types of subs;
- Passive subs– Are powered by an external amplifier. This is usually a dedicated amp that outputs sustained power to the sub with low distortion. A receiver can also be used to a power a passive sub.
- Powered/Active subs use built-in amplifiers and should be placed close to a power outlet. But for a sub to be active it should have an active crossover circuit.
Subwoofers are highly inefficient only converting 1% of the power to acoustic energy (in the best case scenario). The rest is converted to heat.
To increase the bass output, a tuned port is added to the enclosure other than using a sealed enclosure. This makes a ported sub better suited for filling larger spaces with deep rumbles. But the Sealed vs ported subs (bass reflex) discussion is beyond the scope of this article.
Overall, efficiency can be improved through better design and construction of the enclosure and the bass driver.
Subwoofer Vs Woofer: Comparison table
|Size||Smaller. Typically range from 4 to 8 inches but can be as small as 2″ on smaller speakers.||Are larger in both diameter and excursion depth.|
Typically range from 8 to 18″.
|Frequency range||Can play frequencies from as low as 60 Hz to as high as 5 kHz.||Can handle frequencies of between 20 Hz and 200 Hz.|
|Power handling||Draw less power at reasonable sound levels.||Draw more power to move the larger drivers.|
|Enclosure design||Mostly use closed/sealed and passive radiating enclosures. May include tweeters in multiway enclosures.||Ported sub enclosures are more common due to their higher outputs. Sealed and passive radiator enclosures are also used.|
|Cost||Woofer drivers are cheaper when compared to sub drivers.|
|Sub-woofers are costlier.|
Can a Woofer be used as a Subwoofer?
A woofer cannot be used as a subwoofer since it is not capable of playing low enough to be considered one. Woofers are mostly used for mid-bass not sub-bass.
They are not capable of producing deep bass at will heavily distort as they bottom out. What’s more; they could eventually blow if the Xmax is exceeded and as they draw more power to play back the lowest frequencies.