For audiophiles and enthusiasts looking for uncompromising accuracy and exceptionally high output levels in a more budget-friendly package, the F15 subwoofer is the ultimate choice. It features Direct Servo™ to ensure accurate frequency and transient response, precise detail and extremely low distortion levels at even high output levels. As a discerning listener you appreciate that bass is the foundation of a satisfying music or home theater experience. You also appreciate that there is more to a home theater subwoofer than shaking the room, and that music can be far more satisfying with a subwoofer that can play deep.
What makes this subwoofer unique? It's not that it can plumb the depths with authority. There are already many subwoofers on the market which can do that. The difference is that this subwoofer will reproduce bass with a level of realism that matches what our loudspeakers are known for...
We are most proud to represent these astonishing new subwoofers.
Specifications F-15:
|
Frequency Response (Anechoic)
|
14 Hz - 100 Hz (-2dB @ 14 Hz) |
|
Woofer
|
15" high excursion with custom sensing coil |
|
Woofer Material
|
Silver anodized aluminium with rubber surround, Cast aluminium basket, Copper flux modulation shorting rings |
|
Amplifier
|
370w RMS class A/B servo controlled
|
|
Maximum Short Term Peak Power
|
Greater than 500 watts
|
|
Dimensions W x H x D
|
19" x 19" x 20" - (21-1/2" D with grille)
|
|
Shipping Weight
|
90 lbs each |
|
Crossover Slope
|
Selectable 12 or 24 dB / octave
|
|
Crossover Range (Low Pass)
|
Continuously variable 40 - 100 Hz |
|
Rumble Filter (High Pass)
|
14 / 20 / 28 Hz 18 dB / octave
|
|
Phase Response
|
90 degrees phase shift at 20 Hz
|
|
Phase Adjustment
|
0 - 180 degrees continuously variable
|
|
Bass Damping Factor Settings
|
High (Q=0.5), med (Q=0.7), and low (Q=1.1) |
|
Finish
|
Black oak or walnut (PVC) |
|
Warranty
|
5 years on woofer / 2 years on electronics |
Direct Servo technology, US Patent #6,104,817: What is it?
Conventional subwoofers have extremely high distortion. Well regarded conventional subwoofers typically have measured distortion levels exceeding 15% at 20 Hz at 100 dB. This includes many subwoofers costing more than US $3000. We think this is far too high. A well designed servo subwoofer will achieve distortion levels under 3% under the same conditions.
A servo is essential in a subwoofer that aims to be true to the original source material. The benefits are clear:
- No voice coil thermal-induced compression or distortions.
- Spider and surround distortion reduced by 6 - 9 dB
- Flat frequency response that is less dependent on T/S parameters.
- Audiophile bass sound at an affordable price: articulate, tight, transparent, and well-defined bass
These benefits are all unique to a servo controlled subwoofer, and can't be achieved in a practical and affordable way without a servo.
How it works
Direct Servo uses a very thin sensing coil which is wound adjacent to the voice coil. This coil induces a signal which is fed back into the summing points of the amplifier. This signal is used to correct sources of distortion, and this is achieved without placing any active devices such as transistors or operational amplifiers in the signal path. This simplicity eliminates any secondary or mechanical effects which plagues other technologies.
What are memory effects?
A subwoofer driver contains parts which have a memory effect. This means the driver will not respond perfectly to the signal. The spider and surround both contribute to memory effect in a driver. The voice coil which carries the signal that drives the cone also exhibits a memory effect. This is because the temperature of the voice coil changes with operation, and this changes the resistance. The result is a loss of dynamics. As the driver excursion and power input level increases, both effects get worse in conventional subwoofers. Detail and resolution is lost.
Direct Servo corrects both mechanical and thermal memory effects. The result is much lower distortion, and bass that is true to the original, preserving the subtle details, capturing dynamics and revealing a level of detail well beyond the reach of most conventional subwoofers.
How is Direct Servo different?
The primary philosophy is to make audio products as simple as they can be. Less is more. These subwoofers put as little into the signal path as possible. This approach applies to the amplifiers, Direct Servo technology and drivers. Most servo subwoofers use an accelerometer, which is another mechanical system with its own limitations. Also extensive protection circuits are required, and these further degrade the signal. As a result, accelerometer based servos are not as accurate as Direct Servo. The superiority of Direct Servo is derived from its simplicity.
| 
Patented Direct Servo technology
