For audiophiles looking for uncompromising accuracy, our DS12 kit is the ultimate choice. It features our Direct Servo technology to ensure accuracy and definition. Unlike conventional subwoofers, the distortion is very low. In fact, it is lower than some high end amplifiers. As an audiophile you appreciate that articulate bass is the foundation of a satisfying music or home theatre experience. Perhaps you already own a subwoofer but have been disappointed to discover that it added more than extra depth. Or perhaps you have avoided purchasing a subwoofer because you were unwilling to compromise the accuracy of your system. Rest assured that you have found a subwoofer for audiophiles.

What is an audiophile subwoofer?

An audiophile subwoofer is true to the original. This means a lot more than low distortion. It also means that the dynamic nature of the original should be preserved. All subwoofer drivers are plagued by memory effects. The detrimental effects are clearly audible. Direct Servo dramatically reduces memory effect. The difference is not only a much lower measured distortion on paper, but bass that is true to the original.

Our DS12 kit features our A370 Direct Servo amplifier and our DS12TC or DS12CV high excursion driver.

Better technology

Nearly all subwoofers on the market are based on outdated technology. Our subwoofers are based on our patented Direct Servo technology. Not only does our technology surpass that of conventional subwoofers, it also offers significant improvement to the performance of other servo systems. In our technology section, we describe the differences between Direct Servo and other servo technologies. Our system is better suited to music reproduction than other servo systems.

Better value through intelligent design

Many of our customers marvel that we are able to produce such exceptional subwoofers at such a low price. There are two main reasons we are able to provide such exceptional value:

low overheads - we keep costs as low as possible more
intelligent design

Since our competitor's are still using outdated technology, their options to attempt to make them accurate are limited. As a result, their drivers are very expensive and their amplifiers often use kilowatts of power. DIY enthusiasts understand that there is a trade-off between box size and required amplifier power. Our Direct Servo technology allows us to achieve the same result with significantly less power. As a result, we can achieve the same output as our competitors with much larger power amplifiers. At the same time, our subwoofers don't suffer increased thermal compression and distortion. We don't need to use class D amplifiers and we use higher quality components. We achieve all this while saving you money. more

Component selection

We carefully select all components for performance and value. We have selected components that will return the best value. For instance, the MILLS current sensing resistors, the op amps, and the hand selected MOSFET inputs stage for power amplifiers. We don't cut corners. We also avoid wasting money on "audiophile" components which offer no real advantages.

Our DS12 kit is available in three versions:

The standard kit will suit most audiophiles. Both the standard and compact kit have the option of a sealed or vented configuration. Our premium kit includes two drivers in sealed configuration. The advantage of this kit is that it allows two mounting methods which improve performance over that of a single driver subwoofer.

These kits are best crossover below 90hz. For application requires crossover frequency higher than 100hz, we recommend our 12" LT kits .

Sealed or vented	Our standard and compact kits are available in both sealed and vented configurations. Please specify which you require when ordering, since a different Direct Servo board is used for each. Note: premium kit available only in sealed configuration.
Crossover slope	Two crossover options are available. The default crossover has a 12 dB / octave slope, and will be included unless the 24 dB / octave crossover slope is requested. For use with a home theatre receiver, the default slope is recommended. In situations where there is no other crossover slope included in your system, the 24 dB / octave slope is recommended.
Driver mounting	Driver available with or without rubber gasket View images
Amp voltage	Selectable to suit your country: 115 / 230V View switch

Flexible design

All of our kits feature unique bass extension controls which are not normally provided on subwoofers. This enables the user to customize the output and extension to achieve the best compromise in any room. Most subwoofers neglect to provide bass extension control, and the result is that dynamic headroom is compromised. More info

Sub crossover filter
(12 dB or 24 dB low pass roll-off)

A lot of audiophiles like to run their front speakers full-range. The objective is to avoid any signal degradation on the front speakers. Our recommendation is to have a simple RC network as shown in the FAQ page to relieve the bass burden from the front speakers. In either case, a 24 dB lowpass roll-off version of the kit is recommended. Phase alignment is also very important. One can either use the phase control on the plate amps, or the delay time adjustment on HT receiver to dial in the phase alignment. The phase control on the plate amp is only for phase lag adjustment on the subwoofer. The delay time adjustment on the HT receiver can achieve both phase lead and phase lag adjustment on the subwoofer. As a general rule of thumb*, the sound wavelength of 50 Hz is 20ft. A full wave is 360 degrees. Therefore, if we put the physical distance in the delay time adjustment menu 5 ft further (or closer) than the physical distance is, the HT receiver will put a 90 degrees phase lead (lag).

*Actual value varies with ambient air temperature

1. DS12 Standard

Our standard kit consists of our DS12TC mid Q driver and A370 Direct Servo plate amplifier. Compared to the low Q driver used in the compact version, higher output can be achieved in the 30 - 50 Hz region, referred to as "midbass." If you are unsure of which of the three versions to choose, we recommend this kit. Sealed and vented kits available. The DS12 standard driver is available in two finishes - black anodized aluminum and natural finish aluminum, which is silver in color. Sub plans are available for this kit in our diy section.

Save additional $20 each kit when buying a pair. Additional $15 discount per kit if paid by Money Order or a check. For vented box, we recommend to use DS1500. DS12 is temporarily out of stock. They are expected to ship again late Aug to early Sep .

	Description	Price	Black cone
	DS12 sealed 2cu ft with 12db/oct A370SE servo amp	$459
	DS12 sealed 2 cu ft with 12-24db/oct A370PEQ servo amp	$489
	DS12 sealed 2 cu ft with 12-24db/oct A370XLR servo amp	$489

The above kits do not include an enclosure. One can purchase a matching enclosure separately. The features are:

1. Three finishes available: black oak grain vinyl veneer, honey oak vinyl veneer, and glossy piano black.
2. 1.5" thick front baffle.
3. 3/4" thick MDF walls
4. 4-way cross bracing.
5. Recessed cutout routed for driver and amplifier so both can be mounted flushed.
6. Interior walls are lined with Dacron and no additional material to buy.
7. Dimension is: 15-3/4"(W)x15-3/4"(H)x16-1/2(D) without the grille. Grille adds 1-1/4" to the depth.

Shown below is honey oak with DS12 driver, and grille taken off.

	Description	Price	Black cone
	1.8 cu ft sealed black oak grain finish enclousre for DS12 and GR sub	$249
	1.8 cu ft sealed honey oak grain finish enclousre for DS12 and GR sub	$249
	1.8 cu ft sealed glossy piano black enclousre for DS12 only	$379

2. DS12 Compact

Our DS12 compact version is provided for those who have space limitations, or prefer the look of a smaller subwoofer. This kit consists of our DS12CV low Q driver and A370 Direct Servo plate amplifier. Compared to the standard kit, midbass output in the 30 - 50 Hz region is reduced. Due to the stronger motor used in this version, output below 30 Hz is not compromised. The DS12CV driver used in this kit is available in natural aluminum finish only. For a sealed sub, a net box volume of 1.5 cu ft should be used. We do not recommend the use of a smaller than 1 cu ft box. If a 1 cu ft box is used, the low bass output will be reduced by 4 - 5 dB compared to a 2 cu ft box. For a compact subwoofer, 1.5 cu ft is a good compromise. This kit is available in both sealed or passive radiator versions - please specify when ordering.

Please note: a vented box alignment is not recommended for this kit. It is not practical to fit an adequately sized vent inside a box of this size. The compromises that would be required would negate any advantages. Passive radiators may be used. Before choosing the passive radiator version, please first review our passive radiator recommendations.

DS12CV is no available at this moment. We are trying to find a supplier to produce those drivers for us.

3. DS12 Dual driver (not available at this moment)

For audiophiles seeking the ultimate in accuracy and output, our dual kit features two of our DS12D driver and our A370 amplifier. The output increase compared to our standard kit is similar to our 15" kit - 3 dB increase with 5 dB extra peak output. The real advantage of this kit is the possibility of using compound driver mounting, which can be used to reduce box vibration and further reduce distortion. While more expensive than our 15" kit with similar output, this kit provides a performance advantage. The difference is not dramatic, but at this level of performance there is little room for improvement. The required net enclosure volume for this kit is 3 cu ft per driver.

Currently we are providing the DS12 as a kit. You have two options for construction:

Have the box built by a local cabinet-maker
Build it yourself for the ultimate in value for money view plans

Either option results in considerable savings. The shipping cost is significantly reduced, and we keep our overheads low. Plans are available in the DIY section.

Unlike conventional subwoofers, the frequency response remains flat at all output levels until the output limits have been reached. Without Direct Servo, a flat response will only be achieved at low output levels.

The vented box provides 6 dB more output from 20 - 30 Hz. Since the response rolls off rapidly below 20 Hz, the sealed box has more output below 20 Hz. The horizontal red line shows the -3 dB point for both charts. An F3 of 14 Hz is achieved for the sealed box and 20 Hz for the vented version.

SPL output

The maximum SPL output capability of a subwoofer is determined by the total swept volume (effective piston area of driver x excursion). Since our Direct Servo kits use high excursion 12" and 15" drivers, the output capability is significant. The distortion performance is very low within the linear excursion range of 1.4" peak to peak. The driver design allows for a mechanical limit of 2.6" peak to peak driver excursion. Some of our competitors use higher excursion drivers which involve compromises in sound quality. Much greater amplifier power is required and the overall expense is increased well beyond the actual increase in output. At the same time, sound quality is compromised. For higher output than one subwoofer can provide, we recommend multiple subwoofers. This approach also has advantages in room acoustics in that they can be placed to achieve the smoothest in-room response.

For a comparison of the output capability of our different drivers and kits, view SPL comparison.

All of our kits feature unique bass extension controls, shown below.

The bass extension controls enable the user to customize the frequency response of the low end. This puts control back in the hands of the user. The controls customize a high pass filter, which attenuates frequencies below a given frequency. If set to 14 Hz, bass below this point will be filtered. The damping control determines the slope, high damping providing the steepest slope.

Why is this necessary?

Very low bass can cause very large cone excursions without contributing useful output. The result is that the output is limited by the large excursions required at very low frequencies. The bass extension filter increases output by reducing unwanted signal. For maximum output, the 28 Hz setting should be used with high damping.

Recommended settings

For sealed subwoofers, the default configuration is the 14 Hz setting with low damping. For home theatre use, a higher setting for both switches may be used. For vented subwoofers, the default configuration is the 20 Hz setting with high damping. In individual situations, other settings may prove more suitable. Experimentation is recommended to determine best fit. Caution is recommended with the choice of settings for vented configurations. If the damping setting is set to a frequency below the tuning point of the subwoofer, cone excursion will not be effectively controlled. Low damping will also not provide sufficient excursion control.

For more information on the EQ used in our subwoofers, view our EQ page.

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Two passive radiators should be used on opposing sides of the enclosure
15" passive radiators or larger should used

Passive radiators achieve greater SPL below 30 Hz. While they normally achieve lower distortion than a conventional sealed subwoofer, they introduce a mechanical system which has a memory effect which Direct Servo can't correct since it is outside of the servo loop. This is not normally considered in conventional subs where the main driver also exhibits memory effects. However, with Direct Servo, memory effects have been dramatically reduced, so this issue is more significant.

For high output and low extension in a small box, this kit with a passive radiator is an attractive option. However, where budget permits, our premium dual driver kit will achieve greater output and even lower distortion without the compromises associated with a passive radiator.

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The following diagram illustrates two possible driver configurations.

Push pull mounting shown above involves reversing the polarity on the wiring of the reversed driver. This configuration reduces distortion when compared to the back to back method. Back to back mounting effectively enables a more rigid box since drivers brace each other if there is a rigid connection of the magnets. Note that both configurations have the advantage of force cancellation since the driver cones move in opposite directions. The result is that in both cases, box vibration is significantly reduced. Two drivers mounted in this way will cause less vibration of the enclosure than a single driver. This is in addition to an increase in output and further reduction in distortion for a given output level.

Where inclusion of the outward-facing magnet and basket is acceptable, the first configuration will provide the ultimate in performance.

Before use, correct voltage must be selected. Voltage switch is shown below.