Do I Need a Subwoofer?

Your monitor system is arguably the most important tool in your studio. We base every decision in production, mixing, and mastering on what we hear through our monitors. In fact, we judge almost everything we listen to via our monitor system. The ideal monitor system for you depends on your tastes, production style, and budget, but for serious music creation and post-production, we need a monitor system with a frequency response that reaches below 30 Hz to above 18 kHz.

This specification is not extraordinary, and many modestly priced systems are adequate, but failing to meet these specs means that you're not hearing the full truth from your system. As professionals, our tools should exceed the quality of what our audience (and clients) uses.

If your system doesn’t meet these frequency response specs, or if you feel it’s time for an upgrade, you might wonder whether you need to add a subwoofer to your current system or upgrade to larger main monitors. In this article, we'll first discuss how to select the appropriate size monitors for your setup and then explore the benefits a subwoofer can provide.

For future reference, a system that includes a subwoofer to extend or enhance the performance of the main monitors is known as a "bass-managed" system. This differs from a dedicated LFE (Low-Frequency Effects) subwoofer in a theater setup, which is specifically designed to handle low-frequency effects such as explosions, earthquakes, and impacts.

How to Choose the Right Monitor Size

It’s important to choose monitors sized appropriately for your room. The size of the room and the geometry of our listening setup will determine the suitable size for your speaker cabinets.  We all know it's best practice to start with an equilateral triangle configuration, locating the listening position at one corner and each speaker at the other corners.

In a large room, the triangle can be large, giving us a wide range of speaker size options. In a smaller room, such as a bedroom, the physical size of the speaker cabinets is limited to fit the smaller triangle and limited floor space. 

For small rooms, the speakers should almost always be placed close to the front wall, with the listening position 35 to 70 inches (87 to 175 cm) from this wall. This arrangement, along with the size of the desk and other furniture in the room limits the size of the speaker cabinets. Large speakers simply won’t fit in this setup.

Conversely, small speakers are not suitable for larger rooms, where the monitors might be placed 10 feet (3 meters) from the listener. Manufacturers publish the recommended listening distance for each monitor system, but there is no general rule for what size drivers are appropriate for a specific room size. The speaker cabinets simply need to be able to physically fit into our room geometry.

Monitor Types

Once you’ve defined the listening setup, you can narrow down your choice down to near-field, mid-field, or large main monitor types. At this stage, your focus should be on selecting speakers that reproduce music in a way that sounds natural and accurate to you. While virtually all professional studio monitors are designed to be accurate, each model has its own sonic personality, so you may gravitate to one speaker over another.

For instance, you may find that you strongly prefer 2-way versus 3-way speakers or one tweeter type versus another. While virtually all professional studio monitors are designed to be accurate, each model will exhibit its own sonic personality.

Listen to different-sized speakers from the same brand and product line. For example, Kali offers the LP-6 and LP-8, both 2-way speakers; one with an 8-inch woofer and one with a 6-inch woofer. They also offer 3-way models, the IN-5 and IN-8, with 5-inch or 8-inch woofers, respectively.

There are pros and cons to each design. It turns out that although larger woofers can generate slightly higher SPLs, the low-frequency extension is nearly identical between models with 5-inch, 6-inch, and 8-inch woofers.  Despite this, many people have a strong preference for the sound produced by one design over another.

Ultimately, you should select a monitor that not only fits your space but also resonates with you sonically. Each type of speaker has its advantages and disadvantages, but the final decision should be based on what you hear and prefer.

Read the Specs

After selecting your preferred monitor, dig into the specifications to determine the low-frequency response. Manufacturers should list a -3 dB cut-off, as well as a -10 dB cutoff. A specification might read: -3 dB @ 50 Hz, -10 dB @ 40 Hz. This indicates that the speaker begins to taper off just above 50 Hz and sounds weak (half as loud) by 40 Hz. Many nearfiled studio monitors list their -3 dB point around 50 Hz, while high-end monitors for mastering may drop as low as 20 Hz or lower.

The frequency response and SPL ratings for Kali LP-6 and LP-8 show that the 8-inch woofer provides a couple of dB more output level and only a slight low-frequency extension. For serious work, both of the monitors should be supported with a subwoofer to reach down to at least 30 Hz. 

If the monitors you've chosen do not provide sufficient low-frequency response, consider adding a subwoofer to your setup. A subwoofer will take over reproducing the lower frequencies where the main speakers begin to fall off, and by doing so allow the main speakers to operate more efficiently. Subwoofers can help support larger as well as small speakers provided the subwoofer offers sufficient low-frequency extension and power relative to your main system. 

A subwoofer should not draw attention to itself. The sub extends the low-frequency performance of the speaker system so that the speakers and the subwoofer together yield a flat frequency response from around 20 Hz up to approximately 18 kHz. A single sub will suffice in a small production room, while a large room may benefit from two subwoofers.

Don’t worry—a single subwoofer won't disrupt your stereo image because your brain cannot locate the source of low-frequency information below about 80 Hz. While adding a second subwoofer can increase bass levels to complement larger main systems, integrating two subwoofers can be complex. Stay tuned, though we will tackle this topic in an upcoming article.

The Low Down

The bottom line for your monitor system is that it should achieve a flat response (±3dB) from at least 30 Hz up to nearly 20 kHz. If you find monitors that are the right size and have a sufficiently broad frequency response, you might not need an additional subwoofer. However, if your main system lacks power in low frequencies, adding a subwoofer should be considered. Properly integrating a subwoofer can be challenging, so be sure to read our upcoming article on how to choose and integrate a subwoofer into your system.

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