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| SPL comparison |
| DS1500 Direct Servo subwoofer | |
| 15" subwoofer |
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| The subwoofer of choice for audiophiles |
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For audiophiles looking for uncompromising accuracy, our DS1500 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 DS1500 kit features our A370 Direct Servo amplifier and our DS1500 high excursion driver. |
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Available for both sealed box and vented box configurations. Save additional $30 when buying a pair. Additional $20 discount if paid by Money Order or checks. Save $50 on vented box configuration before end of Jan. If you would like to tune the vented box to a frequency lower than 20hz, please let us know when ordering.
These kits are best crossover below 90hz. For application requires crossover frequency higher than 100hz, we recommend our 12" LT kits . The above kits do not include an enclosure. One can purchase a matching enclosure separately. The features are:
Shown below are with grille taken off.
Better technology Nearly all subwoofers on the market are based on outdated technology.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:
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. With most subwoofers on the market, the quality
of amplification and the components used are not important. Most
subwoofers are not accurate enough to reveal the difference between
components. The distortion from the driver is so high that the quality
of the amplifier is not worth considering. With our subwoofers,
this is very different. We use only audiophile grade components.
When a subwoofer is this good, the amplifier matters.
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low overheads - we keep costs as low as possible 
| Comparison - DS1500 vs DS12 |
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The main advantage of our 15" kits is output. The efficiency is higher due to the larger driver. Peak SPL is 4dB greater than our standard DS12 kit. A larger enclosure is required and we don't currently offer compact versions. Considering our 15" kit is not much more expensive than our 12" kits, they are excellent value. In some cases the increase may allow one to purchase a single 15" kit instead of two 12" kits. It could also mean staying with a sealed configuration rather than vented. |
| Additional options - (please specify when ordering) |
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. Sub crossover filter 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 |
| Construction Options |
Currently we are providing the DS12 as a kit. You have two options for construction:
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. |
| Performance |
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. |
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The above shows the frequency response of our sealed version DS1500 kit. The vented box provides 4-5dB more output from 20 - 30 Hz (using the same amp). Since the response rolls off rapidly below 20 Hz for vented box, the sealed box has more output below 20 Hz. Vented box is ideal for HT in a large room. 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 1.2" peak to peak. The driver design allows for a mechanical limit of 1.8" 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.
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| Specifications |
* Select when ordering |
| Customized Bass extension |
All of our kits feature unique bass extension controls, shown below.
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. The frequency response chart shows measured SPL response. |
| Passive radiator recommendations |
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. |
| Voltage selection |
Before use, correct voltage must be selected. Voltage switch is shown below.
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