How many subwoofers are enough

Usually, the bigger the size of the subwoofer, the richer the bass produced. If the subwoofer meets all the other requirements and space is not an issue, it is advisable to go for the biggest one you can find. However, do not underestimate the power of getting multiple smaller subs. With the right power, enclosure, and placement, smaller subwoofers can be pretty powerful as well. One large subwoofer is good, but even better is having multiple subwoofers, which can be very beneficial to your audio experience.

A single subwoofer packs a powerful bass, but the evenly distributed, well-defined, and tight sounds produced by multiple subwoofers enhance your listening experience, particularly for a sound system that covers an ample space or in various rooms. With a single sub, the sound is localized to only one spot, but with multiple subs, there is a wider listening area.

Think of a single subwoofer as a standing fan that blows in only one direction and multiple subwoofers as a central airflow system that reaches everyone and everywhere; which would you prefer? Multiple subwoofers have more power and radiating area, which means they have less low-frequency distortion and better dynamics than a single subwoofer. The load is split between each subwoofer, meaning they work less to give a specific output and remain comfortably within linear operating range. With a single subwoofer, you are hardpressed to find the perfect location for the best sound production.

However, multiple subwoofers give you more room to experiment with the positioning. Apart from the quality of sound produced, the visual quality of the subwoofer to the decor of the room might also be necessary.

Multiple smaller units of subs placed in strategic positions look more aesthetically balanced than a single bulky sub. Sound waves can reflect from room surfaces reading to resonance. Some frequencies will become louder due to constructive interference of the bouncing waves, while others can become lesser due to destructive interference. Multiple subwoofers do not add more bass to the audio; instead, they distribute them evenly around the room.

As you add the third or fourth sub to the first one, you might begin to notice the sound improvements. However, after the fourth one, the law of diminishing returns sets in, and you will hear little to no difference in the sound produced.

Increasing your sub from one or two to three or four will give optimal performance, but anything after four is overkill.

The first thing to understand is the basic concept of a subwoofer system. What it is trying to do, and how does it work? Obviously, the fundamental idea is to reproduce low frequencies. In most cases, this is roughly the bottom two octaves, from 20Hz to 80Hz. However, here lies the first major issue we need to take onboard: having a special box that generates low frequencies doesn't guarantee good bass in the listening room — in fact, far from it!

The room's own acoustic properties are of paramount importance. If you put the world's best subwoofer in an acoustically poor room, you'll get very poor bass performance! I have frequently come across monitoring systems where the owner has added a subwoofer in the hope of curing a weak or lumpy bass response, only to discover the situation either doesn't improve or actually gets worse! If the room has nasty standing-wave problems — and almost all home studios do — it's vital that these acoustical problems are sorted out first, before you spend money or time on a subwoofer.

You can often improve a room's acoustics dramatically for minimal cost with some basic DIY. And with a treated room you may well find that your existing speakers actually deliver much more and better bass than you thought! Another useful benefit of a subwoofer is the additional power handling accorded to the system as a whole. The acoustic energy in music is highest at low frequencies and tails off with increasing frequency.

So employing a dedicated box to handle much of the power-hungry bass takes that burden from the satellites, with useful benefits in overall power handling and clarity. Most stereo systems have two main speakers, yet we have only one subwoofer. Why not two subwoofers as well? In some situations there can be advantages to having two or more subwoofers, but in general one is usually sufficient. The reason for this is connected to the fact that, for frequencies below about Hz, our sense of hearing measures the phase difference between a sound arriving at each ear, whereas above this frequency it uses mainly level differences.

Out of doors, our ability to determine a sound's direction remains quite accurate down to remarkably low frequencies, but this ability collapses when listening indoors. Sources generating low-frequency sounds below about Hz tend to do so more or less omnidirectionally the sound wave travels from the source in all directions because the wavelength of sound is usually larger than the object itself.

When a low-frequency sound is generated within an enclosed space, the spherical sound waves created will reflect off the boundary surfaces of the room to arrive back at the ears with a multiplicity of phase variances, due to path-length differences.

This confusion of signals makes it impossible for the ear and brain to extract a reliable phase difference, so normal directional acuity fails. So in theory, since you can't tell where the low frequencies are coming from in a room, one subwoofer will be entirely sufficient. The harmonics of the bass notes will be reproduced by the satellite speakers — which typically start to take over above about 90Hz — and these will provide plenty of directional information through phase and level differences, in the usual way.

So, although the bass itself is folded down to mono, the impression of stereo imaging is actually preserved perfectly satisfactorily. This theory is all well and good, but I often hear people comment that they can hear where a subwoofer is placed in the room. This isn't because of some special acoustic ability on their part, though —rather, it is because of the poor performance of some subwoofers!

Designs constructed at a low cost, employing inferior drivers, and those designed to favour efficiency above all else, tend to generate a lot of 'out of band' noise — lots of harmonic distortion and audible port noises, or other artifacts. These occupy the mid-frequency range, which not only makes their position easily detectable, but also obscures and masks the critical mid-range frequencies from the satellite speakers.

So adding a cheap subwoofer to quality satellites will actually tend to make the system less rather than more accurate. A good subwoofer needs to have a very linear driver which is expensive , an accurate and powerful amplifier which is expensive , and a well designed and built cabinet which is But cutting corners on any of these aspects is a false economy.

I've listened to and used a lot of different subwoofers, and the best are, for all the obvious reasons, produced by the same companies you associate with good monitor speakers. They are all relatively easy to set up because of the inherent close matching and the appropriate electrical alignment facilities.

Whereas many subs are large cuboid boxes, the TLE1 has the form factor of a computer tower case, which I find both aesthetically and practically appealing. When buying a sub, the key is to try it in your own listening environment, with your own satellite speakers — particularly if the subwoofer is from a different manufacturer. Some combinations will integrate far better than others, and only a home audition will reveal the success or failure of a particular combination.

The diagram shows a bass-management system. Each of the five main channels goes through a high-pass filter to remove the low-frequency element of the signal, before being passed on to the appropriate amplifier and speaker. Bass management is the process of removing the bass element of the signal fed to each satellite speaker, and routing it instead to one or more subwoofers.

In essence this is no different to a normal crossover — it's just that the bass driver happens to be housed in a separate enclosure, and there needs to be some sort of mixing facility included to combine the low-frequency contributions from at least two channels.

In the case of a simple 2. There are various approaches to wiring, but most route line-level signals from the controller or preamp to the subwoofer first, which filters the signals and outputs them for the satellites. Some systems work the other way around, connecting the signal to the satellite first, and then down to the subwoofer. Systems intended for domestic use often work with speaker-level signals. For 5. The diagram on the previous page shows such a system.

All five channels are also summed and passed through a low-pass filter to remove the mid- and high-frequency content. This signal is then combined with the dedicated LFE signal which is also low-pass-filtered and boosted in gain, according to the appropriate specifications , and routed to the subwoofer speaker. It is worth bearing in mind that, since each of the five channels in a 5.

As listening is always the final arbiter of what is right, having effective tools like this is critical in achieving the best possible quality. It is important to note that we left electronic EQ to the last step, not first. It was critical to deploy multiple subwoofers and SFM to smooth out the frequency response across all the seats. Only then can EQ effectively do its job as any changes it makes will equally apply to all seats. Without it, changing the response for one person could very well make it much worse for the other people in the room.

This is why an automatic room EQ by itself is rarely this effective. For example, if the room is not a rectangle, our rules of thumb for subwoofer placement no longer hold. Same occurs if the room construction is not symmetrical e. Even simpler things like soffits in our ceiling could make the placement non-optimal. While SFM can compensate for a lot of these variations, it cannot physically move the subwoofers to a better and more optimal location.

The answer to this problem is to use computer modeling to analyze the room and its acoustic impact and use that data to identify the best number and possible location of subwoofers. CFD is a method of analyzing fluids as they move using computer modeling. Since air is a type of "fluid," we can use this modeling technique to determine what happens when the subwoofers energize the room.

While CFD has been around for a long time and is a critical part of design in many industries from cars to airplanes, its application to audio for subwoofer optimization is rather unique. This work was pioneered by Keith Yates design group and represents the state of the art in room acoustics optimization today. The nice thing about modeling the room and subwoofers in a computer is that it is effort-free. We can let the computer run for days if needed to find the most optimal configuration for us.

In the case of our reference home theater over 30, potential combinations of subwoofer and location were simulated to identify the optimal solution we used. Imagine moving the heavy subwoofers in your room 30, times to find the best possibly location for them! Then consider that one of the subwoofers is actually on our ceiling and you see that what the computer is doing simply is not practical any other way.

The simulation is cool in other ways in that it not only generates the results we want, but provides highly educational interactive videos of its output. Here is a single frame of that video showing what happens at On the left you see the simulation for a single corner subwoofer in the left rear corner as indicated by the red color.

While on the right you see our theater with the optimal configuration of three subwoofers. The color coding shows the sound pressure level with blue indicating lower levels and red the highest.

As with our measurements before, we see wild fluctuations in sound pressure in the room depending on the seating location as much as 30 dB difference. The filled horizontal circles in the room are the heads of audience members. Now a much clearer picture emerges. In the one subwoofer configuration to the left, the large differences in seat to seat response is visible as indicated by the strong shift from the color blue in the center to red in the others. We immediately see massive improvement in the way all the audience heads have roughly the same sound pressure as indicated by similar shade of yellow-green color and light orange for the group behind the bar.

Just as the physics predicted in Harman research, multiple subwoofers improved the situation immensely. Your dealer will gather the measurements of your room and work with you to identify all the possible places for subwoofer and the maximum number you would like to potentially deploy. A 3-D model is then created which after sign off will be the basis of the CFD analysis. Top two or three configurations are then furnished as the results of the analysis. What does all of this sound like when you are done?

I suggest going to listen to a system like ours as words do not do it justice. You will hear a type of bass you are not used to. It will be tight without any of the boominess of a typical home theater. Get rid of that 10 dB peak in low frequencies and you will hear detail in vocals and higher frequencies that were being masked. The improvement is not subtle at all. Instead we are using precise science of what makes good audio to solve our acoustic problems which are huge if left alone.

The principals and solutions are simple yet powerful in the way they tame wild fluctuations in our system response resulting in a level of audio performance that few people have experienced. Floyd Tool for their kind permission to use their measurements and their teachings in this article.

Special thanks also go to Keith Yates for his wonderful insight and innovations in this space. Further Reading Presentation on video for audiophiles. Preprint Last edited: Nov 7, Joined Aug 27, Messages Likes Click to expand Open spaces are actually good for bass performance as they increase volume and reduce room modes. But you are right that you can't use the stock placement rules for them. Or use an automated system.

I use Dirac in my open, loft space and it works well and is really quick to set up. Ron Texas Major Contributor. It was fairly difficult to optimize my setup for a single seating position. The article illustrates how difficult it is for multiple seating positions.

What I found helped was doing the subwoofer crawl twice. Once for 30 hz and again for the 90 hz peak in the room to find a spot where 30 hz was good and 90 hz was weak.

Tircuit Member Forum Donor. Joined Jul 11, Messages 84 Likes Wish they had a graph for two subs configuration A, above I can't see getting 4 subs past the SO, but I might be able to sneak a second behind the couch. My AVR has only one sub out, however. Is it kosher to use an RCA splitter? I imagine 2 mismatched subs are better than one, right?