Quick guide

Are your output requirements modest or do you have a small room? Our sealed DS12 standard or compact 12" kits are ideal

Is home theatre your primary interest? Do you most enjoy explosive low frequency effects? Do you have a large room and want to achieve the dynamics of a commercial cinema? On a budget, we recommend our vented 15" DS15 kit. If your budget allows, consider two sealed 15" kits which will give you the same low frequency impact but with increased output in the midbass and even lower distortion.

Do you want the ultimate in low distortion performance and greater output than a single 12" subwoofer? Consider our premium 12" kit which features two drivers. This allows a special driver mounting method which achieves even lower distortion than our other kits.

Music or home theatre?

Music and home theatre subwoofers typically have different requirements. For music applications, our Direct Servo sealed kits are ideal. The deep bass adds to the sound stage and ambience. For home theatre applications, a vented subwoofer is often recommended, since it has higher output in the 20 – 30 Hz region which often contains low frequency effects at high amplitude. Extension below 20 Hz is often not appreciated due to the masking effect of high amplitude signals above 20 Hz. For home theatre only applications on a budget, our vented kits are a good choice. For most audiophiles, a better choice is two sealed subwoofers.

Choosing an output target

For a dedicated home theatre room, a common SPL target is 105 dB peak SPL at the listening position. To match a commercial cinema, your subwoofer should be able to meet this target at 25 Hz as a minimum. Many audiophiles will be satisfied with significantly less output. Even our smallest kit exceeds the output most audiophiles desire. If you are satisfied with the SPL output from conventional hifi speakers, just one of our sealed 12” Direct Servo kits should be adequate.

A simple way to improve your existing speakers.

Most subwoofers on the market are only useful for adding extra bass impact to low frequency effects. As a result, your existing main speakers still need to reproduce bass. All Direct Servo subwoofers are very accurate up to 100 Hz, which means your main speakers can be relieved of bass duties. The result is not only higher output, but lower distortion and greater dynamics.

If you have vented speakers, we recommend plugging the vent. When ordering, specify a 12 dB / octave crossover slope as this will match the acoustic roll off of your main speakers when plugged. If you are using a home theatre receiver, set speakers to “small” so that the bass signal sent to your main speakers will be reduced. In this case, specify a 24 dB / octave crossover slope.

Considering your room

Your listening room will have a big impact on the quality and quantity of bass reproduction that is possible. A small room with very solid construction such as a basement will have maximum SPL but may introduce an uneven response. A large room which is open to other rooms and has light construction will have much less SPL but will also have a more even bass response. In general, rooms with a large air volume require multiple subwoofers to achieve high output.

Direct Servo subwoofer kit comparison

Our standard 12” kit in a sealed box can reach 105 dB in an average 20’ x 20’ room. The vented version achieves 6 dB greater output in the 20 – 30 Hz region with less output below 20 Hz and identical output in the midbass region. Our compact 12” kit has slightly lower midbass output than our standard kit. Our premium 12” kit reaches 5 dB more peak output. Our 15” sealed kit has the same output as our premium kit, but has slightly less sound quality and lacks the advantages of compound driver mounting. In a vented box our 15” kit achieves greater 20 – 30 Hz output.

For larger rooms and high SPL

When one sealed subwoofer isn’t enough, there are a number of viable options:

Vented box for home theatre
Multiple subwoofers
Premium kit

A vented subwoofer will only increase output for home theatre low frequency effects. For most music there is no output advantage. One should also consider that a vent introduces additional sources of distortion which Direct Servo can’t correct. Multiple subwoofers allow flexibility with placement, which may assist in achieving the best integration with room acoustics. This option can also have greater spouse acceptance, since multiple smaller subwoofers can be less obtrusive than a single large box. Our premium kit with push pull driver mounting can further reduce distortion and box vibrations. This is a significant advantage.

top

Sound stage issues

Creating a realistic sound stage is an important aspect of high end audio reproduction. When everything is set up correctly, an appropriate reference sound track can be used to test the depth, width and height of the sound stage. This can be done before and after adding the subwoofer to identity where the potential problem is.

Our recommendation is the Chesky "Best of Chesky jazz and more audiophile test: volume 2".

View Track listing

The following tracks are especially useful:

1) Track 3: this is a recording with a minimal filtering. Natural recordings can inadvertently pick up unwanted infrasonic frequencies. The standard practice has been to filter those with a rumble filter. Some audiophile recording labels avoid doing that and claim such process can degrade sound quality. You should observe some subsonic cone movement and compare the sound to other tracks to see if the presence of the recording is enhanced.

2) Tracks 14-31: These tracks compare the same drum in a dry dead studio (almost completely absorb the reflection from the studio walls) and a live studio. One can try to turn on and off the subwoofer to see how much the sense of depth and room reverberance is enhanced by the subwoofer.

3) Track 45-46: Height of sound stage. This is one of the most difficult tests. Only a few speakers with good room setup can achieve good height in sound stage.

4) Track 47: Spatial clues. Four musicians with 4 different instruments parade around the microphone. For a reasonably good system, you can hear the musicians circling around your front speakers. This is done with a 2 channel recording!

5) Track 51-59: Live recording of sound effects. Test of see if your sound system can put you in these actual live events.