A quality subwoofer is an indispensable component of a high-fidelity sound system. If you want true full-range sound, you could spend many thousands of dollars on speaker systems and never get there, while adding the right subwoofer solves the problem affordably. And in the world of subwoofers, the most affordable models tend to be in the 8-inch driver category.
While 8-inch subwoofers are on the smaller side, especially sealed models, you'd be surprised at how much punch they are able to pack into a compact. In this article, we're examining some of the best 8-inch subwoofers for you to consider.
Subwoofer Designs: Sealed, Dual-Opposed, Ported & Passive Radiator
Although there are more than four types of subwoofers, the following designs are the most common among consumer models.
Sealed: This is the simplest type of subwoofer design. It is, in essence, just a driver in a sealed box with an amplifier to power it. But looks can be deceiving, modern sealed subwoofers use DSP programming to tailor the response and output of the driver, and how it interacts with the amplifier, so as to maximize the output as well as the fidelity that can be achieved with this type.
Sealed subwoofers are compact and comparatively affordable. However, ported models at similar price points, although larger, tend to offer more output near the port tuning frequency.
Dual-opposed: This type of subwoofer design places two of the same driver at opposite ends of the cabinet. the result is what's called "force cancellation" where the momentum of each of the subwoofer drivers cancels out the other. As a consequence, dual-opposed subwoofer designs are notably free of any vibration imparted by the driver.
With a dual opposed design, you can have a very small enclosure with a comparatively large amount of driver surface area. The result is higher output than you would get from a single driver in a similarly sized cabinet. The only catch is you need a lot of power to overcome the pressure differential in such a small enclosure, so you're paying for a beefier amp as well as two active drivers. This is a relatively uncommon type of design, but it is very effective and likely represents the best way to make an extremely compact subwoofer that still offers high performance.
Ported: A ported sub uses one or more tuned ports to increase output near the tuning frequency. Although this requires a larger cabinet for a given driver size, from a cost-benefit perspective the extra output is typically considered to be worth the compromise, at least in installations where there is room to spare. Ported subwoofers are the most common variety, so there's a ton of different models to choose from. The main thing to know about corded subwoofers is that they usually roll off very steeply below the port tuning frequency, unlike sealed subs that have a more gradual rolloff.
Passive Radiator: Passive radiators are extremely similar to a tuned port. The passive radiator is a driver within the same cabinet as the active driver, but lacking any motor structure. Instead, the diaphragm of the passive radiator is tuned by how much it weighs, as well as its size relative to the main driver. The comparative disadvantage of a passive radiator is higher cost than a tuned port, while the advantages that they are immune to the port distortion sounds that can be an issue with some ported designs.
Frequency Response Specs
Although response specs can be a useful guide, that is only the case if it's an apple-to-apple comparison. But with subwoofers, it's hard to really compare the response spec because it is not tied to the output level. It is often the case that a sub will start to have trouble—running out of power or out of cone excursion—primarily with the lowest notes. So if you can find independent third-party measurements that can help verify the specs, that adds confidence.
Now, if you are dealing with accurate specs, in terms of Hz, you'll find some 8" subs only go down to the 30s while others claim response into the 20s. For a small sub to reach below 30 Hz requires a fair bit of power, so you'll see a correlation between wattage and low-frequency extension. But here's something to keep in mind: A lot of music only has bass down to 35 Hz or so (of course there are bass-heavy genres where this is totally not the case). But movies far more frequently task subs with digging deep.
Product Overview – Best 8-Inch Subwoofers
With so many subwoofers on the market, it might seem like you need audiophile-level knowledge to make a proper choice. Don't worry; we've done the work for you. We'll be reviewing the following 8-inch subwoofers: