Tips for choosing, buying and installing a subwoofer: In this second part of our background on subwoofers, we will give you a number of tips for the purchase and placement of this loudspeaker that provides the low tones.
Tips for choosing, buying and installing a subwoofer
The first step in the context of choosing, buying and installing a subwoofer is to choose a subwoofer that suits your setup. Sometimes it is not that difficult. If you build a surround setup based on speakers from a reputable manufacturer that also focuses on home cinema, then chances are that a suitable subwoofer is available. In theory, it should fit perfectly with the speakers you choose …
But with a manufacturer that is more focused on stereo, you will often have to look elsewhere for a subwoofer. That in itself is not a problem. You can safely combine a subwoofer from one brand with speakers from another. With the other surround speakers, it is best to stay within the brand and even within the speaker family, because then you have good timbre matching (read: the speakers are tuned similarly).
Really good subwoofers are hard to make, which also explains why some speaker manufacturers prefer not to venture into it. That is why there are also certain specialized brands that have a huge reputation in the field of subwoofers. These are often lesser known North American brands, because you have a greater tradition of home cinema installations there. SVS and the British REL are fine examples, as are Velodyne and Sunfire. There are still some. Mainstream brands that have developed good reputations in the field of subs are for example Bowers & Wilkins, Dali, ELAC, KEF, Klipsch, Monitor Audio, PSB and – if you want to appeal to your piggy bank – Paradigm and Wilson Audio.
Whichever brand you choose, choose a model where you can adjust sufficiently. What you need is an auto power mode, a crossover frequency control (with which you determine the upper limit of frequencies that the sub plays), a volume control and a phase knob. If you want to add a subwoofer to a stereo setup, a music mode and a cinch or XLR input are useful. After all, you will have to use a pre-out output with a stereo amplifier without a dedicated sub output.
In practice, you will have to choose a sub with dimensions that (may) fit in your living room. But size shouldn’t be the determining factor. Our rule of thumb: the bigger the better. And also: the more solid, the better. A dancing sub is funny – but not good. Be warned: a subwoofer is often a heavy thing for this reason.
How much power?
Do not focus on wattages. You may never actually use that 1,000 watts and the figures you read are a bit like the official consumption figures for cars. At the same time, a sub must have some power ( see our background piece on subwoofers ), especially if your space is a bit larger.
Deeper is better
The frequency range specified by a manufacturer is only an indication. Unless it specifies at which frequencies the response falls below -3 dB, for example. That is a bit more concrete. The rule of thumb here is that a larger woofer will often produce a deeper bass – although smaller subwoofers can still play lower thanks to bass reflexes.
Control is important for music playback
In movies, a tight bass is better than a slow or woolly bass. But with music it is simply crucial because otherwise any sense of speed and rhythm can disappear from songs. This is the secret of more expensive subwoofers: a tight, controlled reproduction, which is reflected in a short impulse response. The impulse response indicates how long a loudspeaker ‘vibrates’ when it plays a sound.
Buying and installing a subwoofer – Choose the right crossover
You have to choose the point at which the subwoofer stops working and the other speakers take over. Too high, and you will hear certain sounds noticeably coming from your subwoofer. That undermines the stereo or surround image. Too low, and you have a ‘gap’ between what your speakers can reproduce and when your subwoofer starts.
The crossover point is best determined by your AV receiver, with a stereo amplifier you have to look at the frequency range of your stereo speakers. A rule of thumb: let the sub take over everything around 80 Hz, even if those floorstanders can be even lower. Ideally, you will work with an amplifier that has a high-pass filter that ensures that those lower frequencies are no longer sent to your stereo speakers. If there is no setting to do this, you should experiment with the crossover. You may have to lower the crossover on the sub to prevent a certain low frequency coming from the stereo speakers from counteracting the same frequency from the sub – paradoxically, so that you experience just less bass.
With bookshelf speakers you may have to adjust the subwoofer higher than 80 Hz, because the small speakers cannot be that low. It is certainly advisable to place the sub at the front of the room.
Placement of the subwoofer
The placement of a sub is extremely important. It is often advised to place the sub in the front of the room, not at a corner and not against a wall. That’s not bad advice, but not always feasible. Sometimes the subwoofer has to be at the back of the room. Do not set the crossover too high. If you have a small sub and you want excessive bass, you can of course place the device in the corner. This is still possible for films, but it is not recommended for music.
Buying and installing a subwoofer – Do not install the subwoofer
You never put a regular subwoofer in a cupboard. It’s very tempting to hide that ugly thing, but you just create an extra enclosure around your subwoofer. One that was not acoustically designed and can therefore only deteriorate the sound. If tucking the sub away is a necessity, check out other options. Like subs that are built into the wall, which works surprisingly well. You also have models that fit under seats, although these are also compromise devices.
Easy to measure
With measuring systems you can solve many problems in the room. But you may not have the time or money for that. But you can already get started with a simple app on your tablet or smartphone. Before your inner audiophile starts to take off, it’s a rudimentary solution. But a pronounced room mode can be detected in an app such as RHA Audio, as in the screenshot with this article. We played a sweep test tone through the receiver (where successive frequencies are played at the same volume, possibly through a number of apps) and then quickly see that there is a noticeable peak around 50 Hz. If you listen carefully, you will also notice this. Based on this measurement, you can experiment with a different placement of the subwoofer or with the equalizer on the receiver. Are you ready for a more advanced approach.
More information of buying and installing a subwoofer
More tips and advice for purchasing, using and setting up your audio and video products can be found in our tips and advice section . Also read What is a subwoofer and why do you need it and how to place them.