What is a subwoofer?

Audio equipment

What is a subwoofer?

For those of us who like to listen to recorded music and movie soundtracks, high-performance speakers are the window to an immersive audio experience. People with normal hearing can perceive up to 10 octaves of frequencies, from approximately 20 Hz to 20 kHz. But most so-called “full range” speakers can’t really reproduce that full range. They do well with the mid and high frequencies, which require less power and air movement to reproduce, but they often fall short on the lower frequencies, better known as “the bass.”

Why speakers have problems with low frequencies

The lower the frequency, the larger the speaker driver must be and the more amplification power it requires to play at reasonable levels. Many of the larger floorstanding speakers can go down to 30Hz, while smaller bookshelf speakers can’t go below 50Hz or even lower. And at the bottom of their range, the output of these speakers starts to dip, robbing you of what an artist or director intended you to hear (or feel). Don’t worry, we’re getting to the subwoofer.

Even though your speakers can reproduce sound up to 30 Hz, there is often a lot of sound information below that frequency, especially in movie soundtracks and many musical genres. For example, the bass of EDM synths can easily reach down to 20 Hz, and Saint-Saens’ Symphony No. 3 includes organ tones down to 16 Hz. Additionally, explosions and mood-altering effects in many movies can easily reach 20Hz or less.

Furthermore, these super low frequencies have to be higher than the rest of the sound spectrum to sound balanced due to the way the human auditory system works: we are less sensitive to low frequencies than to medium and high frequencies. However, full range speakers start to lose power at the lower end of their range.

Most importantly, effortless, accurate bass increases the impact of music and movies. Who doesn’t love chest-pounding bass lines and seat-shaking explosions? Most speakers simply cannot deliver the maximum satisfaction that only comes with massive low frequency output. So how do you get that amazingly deep and powerful audio experience? With a subwoofer.

The subwoofer solution

What is a subwoofer? It is a speaker specifically designed to reproduce only low frequencies (also called bass). Additionally, most consumer subwoofers are powered, meaning they have their own internal power amplifier. This allows the main amplifier to focus on the main speakers, which require less power than a subwoofer.

Adding one (or two) of these specialized speakers is perhaps the most transformative upgrade you can make to your home audio system. By adding one or more subwoofers, they fill the gap from the bottom of the main speakers’ frequency range down to 20 Hz and even lower, below the threshold of human hearing. When bass feels like this, movies and music are more exciting and immersive.

Frequencies this low are felt rather than heard, delivering a palpable audio experience that cannot be replicated by any other speaker channel. Also known as “infrasonic bass,” low frequencies below 20 Hz can be impressive at times and disconcerting at others. When purchasing a subwoofer, you should ensure that it can achieve a frequency close to or below 20 Hz (like all SVS models) to get the most out of your audio experiences.

A subwoofer and speakers should form a smooth, cohesive audio experience from the highest treble to the deepest bass. The high end of a subwoofer’s range (50-130 Hz) typically overlaps the low end of the main speakers, increasing the output at the bottom of their range and allowing the speakers to focus more on what they are comfortable with: the medium and high frequencies.

Many cheaper subwoofers do not have the amplification power or driver control to maintain the same transient response as a loudspeaker, or they overdrive certain frequencies to compensate for the lack of output in the lower octaves. Both problems cause imprecise or even annoying bass that can detract from the quality of the overall sound. Properly designed subwoofers produce the right amount of bass output at the right frequencies and at just the right time for a harmonious listening experience. The result is perfect reproduction of the entire audible spectrum. It is common for users and reviewers to comment that their speakers have never sounded better after adding a subwoofer.

To reproduce the lower two octaves, a subwoofer’s driver cone is typically 10 to 18 inches in diameter, which is larger than the woofer or woofers in most main speakers, since they must move much more. air. The driver cone is attached to a powerful set of motors driven by strong magnets that move the cone with precise control. It is essential to keep in mind that not all transducers are the same. The most popular size is 12 inches, and the performance difference between the worst and the best 12-inch subwoofers is colossal. For this reason, you should focus less on the size of a transducer and more on what it can do.

Can the subwoofer driver move enough air to create massive output in the lower frequencies? Can it stop and start in unison with the main speakers and play musical notes or sound effects that leave your sense of disbelief in suspense? Is it accurate, fast and faithful to the original content? If you meet all these conditions, you are listening to a top-class subwoofer. Lastly, does it pair perfectly with the main speakers? A subwoofer powers the entire room by moving air, creating the sensation that the bass is coming from all the speakers, not just where the subwoofer is located. If you are interested in knowing how subwoofer drivers affect performance, we have an article about it here.

Of course, a driver’s potential is only realized when its magnets are electrified, which is the job of the amplifier. Low frequencies require more power to reach the levels necessary to create a compelling and immersive experience. The lowest two octaves require a lot of power, more than most AV receivers and full-range amplifiers can deliver while driving the main speakers.

As with transducers, the design and output capacity of an amplifier are of utmost importance to the performance of a subwoofer. The amplifier must be capable of delivering massive amounts of current to unleash the full potential of the transducer, while maintaining accurate frequency response and transient speed. The amplifier built into a powered subwoofer is dedicated solely to low frequencies, typically providing several hundred or thousands of watts of power to the subwoofer’s motor and driver assembly.

Subwoofer DSP: the brains behind the Braun
In addition to an internal power amplifier, the best subwoofers (including all SVS models) include a DSP (digital signal processor), which offers several advantages. The best DSPs rely on sophisticated technologies to handle all the complex functions and the acoustic expertise of designers to program them so that they do everything necessary for impressive and accurate bass reproduction.

For example, a DSP allows designers to precisely tailor the frequency response of the subwoofer and ensure that the driver is always under control, even at extreme playback levels. The DSP also allows the subwoofer to take full advantage of the room gain in sealed cabinet subwoofers and provides users with precise control of many parameters such as phase, polarity and parametric equalization from a smartphone app or controls. of the rear panel. If you have a well-designed DSP, you can have it all.

How to Choose the Best Subwoofer for Your Home Theater or HiFi System
A subwoofer is an ecosystem of all the parts mentioned above, expertly integrated. More important than the size of the drivers, the power of the amplifier and the DSP is the ability of a subwoofer to deliver an incredibly immersive audio experience with all types of content. The sum of these parts and the way they interact to reproduce musical instruments, sound effects, bass lines, and other low-frequency materials define the acumen of a subwoofer.

When considering different options, it is important to understand the performance attributes that make one subwoofer better than another. To help you in your deliberations, here’s a quick summary of what you should listen to while you shop. If a subwoofer can do all of these things well, is within your budget, and fits your lifestyle considerations, chances are it’s the right subwoofer for you. For a more detailed overview of the topic, check out our blog post, 5 Things to Consider When Choosing a Subwoofer.

1 Capable of extreme low frequency extension
2 Produces low frequencies at sound pressure levels

3(SPL) higher without distortion
4 Millimeter precision in frequency response
5 Crisp transient speed (or the ability to stop and start in an instant)
6 Perfect match with full range speakers

One or more subwoofers really enhance the listening experience with almost any sound system. SVS offers a wide variety of models, from the compact and powerful SB-1000 sealed subwoofer, with its astonishing musicality and seemingly robust output, to the colossal and thrilling PB16-Ultra ported subwoofer, which serves as a sonic benchmark for many audio systems. reference home cinema.

How to connect a subwoofer
Since most subwoofers have their own power amplifier, they typically receive a line-level audio signal through an RCA interconnect cable. AVRs, preamplifiers/processors, and even some sound bars and small powered speakers provide one or more subwoofer outputs that send a line-level signal to a subwoofer. If your electronic system does not have a line-level subwoofer output, you can send full-range speaker-level amplified signals to a subwoofer if the subwoofer includes speaker-level inputs, as is the case in many cases. The subwoofer reduces the signal to line level and applies its own low-pass filter, allowing only the low frequencies to reach the internal amplifier.

One subwoofer to rule them all
Each SVS subwoofer adheres to the five performance attributes listed above and features world-class construction materials and technology throughout the driver, amplifier and cabinet. After adding an SVS subwoofer, many users comment that it is the most impactful system upgrade they have ever made. They hear and feel sounds they have never experienced before from content they have heard hundreds of times. Massive, subterranean bass, but also delicate and nuanced when needed, is a truly incomparable sensation, and SVS subwoofers deliver in spades.

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Simon Müller

Simon Müller is the driving force behind UMusic, embodying a lifelong passion for all things melodious. Born and raised in New York, his love for music took form at an early age and fueled his journey from an avid music enthusiast to the founder of a leading music-centered website. Simon's diverse musical tastes and intrinsic understanding of acoustic elements offer a unique perspective to the UMusic community. Sporting a dedicated commitment to aural enrichment and hearing health, his vision extends beyond just delivering news - he aspires to create a network of informed, appreciative music lovers. Spend a moment in Mueller's company, and you'd find his passion infectious – music isn’t simply his job, it’s his heartbeat.