Why subwoofer

The sensitivity of a subwoofer is how much power the sub needs to produce a given volume. And this sensitivity is expressed as a sound pressure level SPL number. The impedance refers to the electrical resistance of the sub and is represented in ohms. When matched with a good amp and head unit, a quality subwoofer will provide the following benefits for your car audio system:. Subwoofers expand the bass response to reveal sounds in your music that your speakers alone cannot reproduce. The majority of car stereo speakers start dropping off at around 50Hz.

But a quality subwoofer will reproduce low frequencies down to 20Hz or lower. Quality subwoofers have the speed and transient response to reproduce bass clearly, so even the fastest bass lines are clear and precise. Lower-quality subwoofers may not be able to handle the rapid starts and stops in vocals and instrumentals that are found in many genres of music. And, as a result, these lesser subs will have unclear acoustic sound. Subwoofers lower distortion by reducing the acoustic demands on your other speakers.

When a full-range speaker reproduces low-frequency bass, the large cone and diaphragm in the speaker can create distortion.

While subwoofers are all but required for home theater, the role subs play in music systems is almost as crucial. So even if you have a pair of bookshelf or tower speakers with 5-inch or smaller woofers and are perfectly satisfied with the bass, you literally don't know what you're missing.

Adding a sub to larger speakers also makes sense -- in fact, all but the most humongous speakers benefit from adding a sub. Here's the best part: Adding a sub isn't just about more bass.

With a great sub the system's dynamics rock harder, and soundstage depth and spaciousness improve. A well-matched sub will dramatically enhance the overall sound of your system, and adding the right sub will make a bigger difference than upgrading electronics.

That was certainly the case with enthusiast Jeff K. After consulting with the folks at Zu Audio he took the plunge and bought their Undertone Mk. II subwoofer. I've heard Jeff's system before so I was eager to hear how the sub changed the sound. The dynamics are more compelling, the soundstage widens, and the stereo imaging becomes more accurate. Even if you prefer spinning folk records and watching dialogue-driven indie dramas, a subwoofer helps produce a more vibrant, all-encompassing sound.

Honestly, you can place your subwoofer anywhere. But since all rooms are constructed differently, the results are going to vary. We get it. Not everyone has a dedicated home theater or listening room with the flexibility to place your subwoofer anywhere. Along with placement, acoustic treatment is another factor to consider if you want to get the most out of a subwoofer.

It calibrates each speaker to create a more harmonious home theater experience. Placement can also be determined by whether you've opted for a down-firing or front-firing subwoofer. While there's no discernible difference between how each option sounds, there are certain factors you need to evaluate depending on the space you're looking to fill, specifically whether you're placing the sub in a home or an apartment.

Shop Subs Now. While it is relatively easy to generate high levels of bass over very small bandwidths and that's what most cheap subwoofers tend to do , designing something that can generate a high output over a broad bandwidth, with very low distortion, and remain a sensible size, is pretty tricky.

Creating low-frequency sound at studio replay levels requires the movement of a lot of air. This requires a powerful amplifier, a very large bass driver or several smaller ones , and a lot of diaphragm displacement. An easy way of achieving high efficiency is to place the driver in what's called a 'band-pass cabinet'.

This is essentially a resonant, tuned box, with the driver hidden inside and the sound escaping through one or more ports. You see these quite commonly on cheap home theatre systems and in car 'boom boxes. This is great for film explosions and crashes, but is not much use if you want to hear which notes the bassist is playing, so it is best avoided for serious monitoring duties.

The majority of subwoofers employ some form of 'reflex' design, which combines practical efficiency with useably wide bandwidth, and in convenient sized enclosures. The design principles are thoroughly understood, with the front of the driver radiating directly and its rear contributing via the enclosed cabinet volume through one or more ports. Not all reflex designs are born equal, but most studio-quality subs will be of this kind of design.

A rather less common alternative is the 'closed box' design. The cabinet is sealed, and only the front side of the driver contributes sound to the room. Efficiency is relatively low, and significant demands are placed on the amp and driver the latter needs to be able to cope with unusually large excursions.

However, this approach has considerable benefits in terms of its phase response, timing and distortion. Another close variation on this theme is the 'transmission line' approach, which aims to combine the best elements of both sealed and reflex cabinets.

These two types tend to be the most expensive, but also the easiest to align and integrate, and with the most accurate sound. Don't be fooled by the size of the subwoofer. Bigger doesn't necessarily mean better, or even greater low frequency extension, although it does usually equate with louder; that business about needing to move a lot of air, again. The physical and electrical alignment of a subwoofer is a much misunderstood process, but to get it wrong is to destroy the accuracy of the monitoring system as a whole.

Firstly, it is vital that the subwoofer and satellite speakers are all in the same phase as each other — by which I mean their electrical polarity and time alignment. If this is not the case, the crossover region will have an obvious bulge or dip in level.

Potentially, there are a lot of sources of phase shifts that can mess up the crossover region. The subwoofer and the satellite speakers have their own mechanical phase responses to take into account, plus the electrical phase characteristics of the crossover filters themselves. There is also the time delay caused by having speakers located at different distances from the listener, and some cabinet designs introduce further acoustic delays, which often vary dramatically with frequency and in some cases can exceed 40ms — a whole video frame!

If there is a phase control on your subwoofer, as on the PMC TLE1 pictured here, you will find that small phase adjustments can often make surprisingly large differences to the smoothness of the crossover region, especially if the subwoofer and satellites are from different manufacturers. A lot of the better specified subwoofers include a phase-adjustment facility either switched or continuously variable , which can help to correct for the mechanical and electrical phase differences between the satellites and the subwoofer.

Unfortunately, though, not all designs are equally effective and, more importantly, phase correction is not the same as delay compensation. If the subwoofer is located nearer to, or farther from, the listener than the satellites, some delay compensation will be required to achieve the correct time alignment.

Though some bass-management or surround sound monitoring systems incorporate this function, not all do so. When it comes to placing a subwoofer, there are several things to consider. Although a high-quality subwoofer should not output the higher frequencies that allow its position to be determined by listening, that doesn't mean it can be put down just anywhere.

Firstly, the subwoofer's location in the room — especially its proximity to walls — will have a significant effect on its frequency and time-domain responses. In a typical room, there will be a few 'best' places amongst many more that are unacceptable. Secondly, unless delay compensation is available, the sub should ideally be located at the same distance from the listener as the satellite speakers.

It makes sense to place a single subwoofer in front of the listener, rather than behind, and directly facing the listening position too. It should be well away from corners, but you should also avoid placing it at the centre of the room width, in order to minimise excitation of standing waves. The closer the subwoofer is placed to the wall, the greater the bass boost will become.