High Performance Subwoofer Systems for Music and Home Theater Enthusiasts
 
THE SIGNAL SHAPER: Q: You mentioned a signal shaper you call the Bossobass SEQSS. What can you tell us about it? A: The central processor In all of our subwoofer systems is the SEQSS. SEQSS is an acronym for Sealed Equalized Signal Shaper. They are each optimized for a specific system; one for the Blackbird Systems, one for the Raptor Systems and future Systems that are on the drawing board. Using a USA-made custom case, faceplate and rear panel, the SEQSS was conceived, designed and is assembled right here in North Carolina, USA. Each board is hand wired and every component is exhaustively tested before it’s approved as part of a Raptor or Blackbird System. Each unit comes with its own loopback and close mic measurement graphs to assure it’s signal integrity and to show the resulting frequency response curves of the System it was built for. Rather than have some marketing specialist provide a single, irrationally exuberant frequency response, the actual measured response curves of your system will be included as part of your system. The SEQSS creates 9 distinct frequency response curves that alter the input signal to affect the frequency response of the system. The upper graph below shows the 9 standard frequency response curves of the Raptor Systems. The lower graph shows the loopback response of the SEQSS in bypass illustrating that it does not contribute to the signal path roll off at all, being virtually flat to below 2 Hz. The purpose of the SEQSS is to allow you to select the preset signal shape to best affect your system for either the deepest in-room extension or the maximum output, or, simply to select the signal shape that sounds best to you given the source material and listening levels you prefer. Imagine having 9 subwoofers instead of just one. Rather than impose our playback preferences on the ultimate owner of the product, or design a product for maximum output to boast high peak numbers of limited bandwidth frequencies, the options for those choices are left to you, the one who matters. Please visit the TECHNICAL/SPECS page for a detailed look at our comparisons graphs of movie soundtracks digital content versus our subwoofers reproduction of those digits at the seats. shapeimage_2_link_0
Q: Besides how they look aesthetically, are the components of a Blackbird/Raptor module unique in any way vs other subwoofers? A: Absolutely. Every component has been designed and selected to result in the very best performance possible while exhibiting a unique aesthetic and lasting a very long time with minimal maintenance. The baffle ends of the modules (the top and bottom caps that hold the drivers) are custom CNC machined from solid 1-1/2" thick MDF. The top plates are similarly manufactured from 3/4" thick MDF. The finish applied to the baffles and top plates is a powder coat finish process has been tested for light fastness, scratch resistance, abrasion resistance, heat resistance, color consistency, embossing retention and gloss consistency. It offers a finish that is hypoallergenic, anti-fungal, anti-bacterial, holds up to most household cleaners and is moisture resistant. An optional glass top plate is available, another first that we call DriverVu, for obvious reasons. The glass is 1/2” thick with a 1” beveled edge and machined to mate with the stainless steel hardware. It gives a whole new meaning to the word ‘unique’. The top plate stand offs, legs and stacking spacers are brushed stainless steel, impervious to environmental attack, maintenance-free and non-magnetic. The very use of hardware for stacking purposes is in and of itself unique and stainless steel is the highest quality and longest lasting implementation of that design aspect. The custom bamboo cladding is hand made and is manufactured and finished through a 14-step process, top coated with aluminum oxide impregnated urethane. Bamboo is a hard wood and an eco-friendly renewable material. I read an interesting article about bamboo groves being used in conjunction with a water stirring process to clean toxic rivers, lakes, etc. around the world, which led me to the my supplier. You can read about the amazing properties of bamboo on the Going Green page. The binding posts are air sealed, high quality and have a satin nickel finish. They accept up to 8 AWG wire and work very well with banana plugs, spade connectors or bare wire and are mounted on a block of front panel-matching hardwood. shapeimage_3_link_0
 
    
When the Blackbird & Raptor modules are stacked in a corner (as they were designed to be), the increase in output becomes even higher due to gain realized by the 4 boundaries presented by the 2 walls, the  floor and the ceiling. The result is a higher output, lower power requirement system that reduces 2nd harmonic distortion while residing in a relatively small footprint.
Boundary Gain is a phenomenon that occurs when a subwoofer is placed in the corner of a room. In this case, there will be three virtual images formed from the original drivers in the subwoofer, one on the floor and one each on the adjacent walls. This concentration of the original source plus the three additional “virtual” sources combines to create a new single source of considerably improved efficiency. Depending on the integrity of the walls and floor, the increase can be anywhere from  4 to 64 times! When a stack is employed, the three virtual sources become 4 by addition of the ceiling as a reflective surface. Not only will this increase efficiency, it has the effect of eliminating the typical standing wave that occurs at twice the distance from floor to ceiling, which is around 70 Hz in a room with a typical 8 feet ceiling height. Since 70 Hz is right in the middle of the typical 80 Hz crossover used in Home Theater, the benefits of stacking are certainly worth consideration.
Q: Why is the amplifier used in the Blackbird/Raptor systems so powerful and not built-in like other subs? A: The Blackbird and Raptor systems, when stacked in the corner of a room, as they were designed to be, are quite efficient from 20-100Hz so that during playback of most movies and soundtracks, the system will literally be coasting. However, the system was not designed to only handle "most" recorded source. During playback of many movies with intense Low Frequency Effects, the Subwoofer System will be called upon to accurately reproduce large transients comprised of extremely low frequencies simultaneously with frequencies across the entire subwoofer bandwidth. To achieve this feat requires a perfect concert of subwoofer design, room gain influences and... lots of amplifier reserve power. Until now, buying a subwoofer has meant having to accept an underpowered device that is designed to either roll off well before the first two octaves, or to immediately go into one of its on-board protection modes to prevent the signal from being reproduced. In order to provide the Blackbird/Raptor drivers with enough signal below 20Hz, the SEQSS signal shaper is designed to boost those frequencies relative to the upper frequencies by a user-selectable amount of +6dB (4 times), +8dB (7 times) or +10dB (10 times). Assuming for a moment that your optimum setting of the SEQSS Signal Shaper is +10dB of Boost and NO High Pass Filter, the input signal would be boosted by 10 times from approximately 20 Hz all the way to the bottom of the signal chain. Let’s also assume, for the sake of fleshing out our specific scenario, that your calibration requires the amplifier to provide 900 watts to handle transient peaks above 30 Hz. That means that when the soundtrack effect includes strong content to 3 Hz, the amplifier will be called upon to provide 900W times 10 (10dB BOOST) = 9,000 watts for all of the content in the effect that is below 20 Hz and down to 3 Hz. This unprecedented amplifier headroom will immediately be perceived during playback of high dynamic range music as well. Dynamic range is the difference in a recording between the quietest level and the peak level. Modern digital formats have huge dynamic range headroom, and many recordists utilize that feature. Digital recordings can easily have a peak-to-average range of 30dB, a whopping 1,000 times difference from quietest to loudest sounds! When used sensibly, which means proper setup, calibration and finding and respecting your systems limits, having enough amplifier power always results in higher fidelity playback. Q: Why use a cylinder-shaped enclosure? A: Box-type enclosures require extensive internal bracing to prevent unwanted panel resonances. They also require the use of thick and heavy material from which to fabricate the panels and bracing. No doubt, this is an acceptable and proven method because flat panels are easier to plan, cut, finish, box and ship. The down sides are that they are extremely heavy when properly designed and built, adding cost to shipping. In addition to that obvious point, cubes have the appearance of bulk visually and it is difficult to design a cube-shaped subwoofer that can be significantly distinguished from any other cube-shaped subwoofer. A cylinders physical properties are such that it does not require internal bracing, does not require thick, heavy material for its construction, has the appearance of much less bulk due to the curved lines and it can be designed to achieve a one-of-a-kind form factor that separates it from ordinary audio products. Q: Why 2 drivers, and why face them opposite from each other? A: Two drivers, when coupled closely enough with twice the amplifier power, offer 4 times the output. This means that for equal output they have far less mechanical stress, resulting in far less mechanical stress-induced distortions. When the two drivers are facing opposite to each other, Newton's third law of motion, which dictates for every action there is an equal and opposite reaction, prevails, reducing the mechanical vibrations caused by the motions of the drivers to virtually zero. Q: Why do the drivers fire one-up, one-down vs all of the other subwoofers with dual-opposing drivers? A: Both the Raven and the Blackbird designs are built around the opposite-firing drivers firing one-up, one-down. The advantages of opposite-firing drivers are explained above. The advantage of one-up, one-down vs side-firing is realized by the drivers proximity to the two walls of the corner of a room. If you orient the drivers to a side-firing or a front/back firing design, each driver is at a different distance from each of the walls, regardless of how you place that subwoofer in the corner. With the up/down-firing design, both drivers are equal distances from both walls. Among other advantages, the primary advantage to the end user is a far less placement-critical final response. Where conventional designs might be placement sensitive by inches, Raptor and Blackbird are not, allowing for a general corner placement that will not vary the final frequency response if moved slightly within that corner. Q: Speaking of the drivers, can you give any details about them? A: Over the course of 12 years, I’ve purchased and tested nearly 100 drivers from manufacturers from around the globe, including the United States, Canada, Europe, South America and Asia. Along the way I’ve learned a bit about how drivers work and, through extensive experimentation, what combinations of motor design, parameters and materials are best suited to a home theater subwoofer system.
Q: I’ve read that multiple placement is better for smoothing in-room response, so why stack the modules? A: The truth is that it all began when someone contacted me with a request for help in designing a high powered system that could fit in a very limited footprint. After seeing the design of his theater, I immediately thought of a stack of modules. The idea, of course was to get as much output as possible in as small a footprint as possible, so going vertical made the most sense. I also envisioned the stacks of modules as sort of high-tech neo-columns, which, as it turned out, is a very good description. Although multiple placement of subwoofers to smooth the in-room response is a tested and valid method, all of the tests conducted have been 2-dimensional studies, ignoring the potential including the rooms ceiling boundary, or in other words, ignoring the room as a 3-dimensional space, which, of course, it is. As it turned out, stacking modules had more potential than just concentrating high output in a small, vertical column. The more we thought about those potential benefits, the more the idea of a stackable columnar system evolved. The Raptor and Blackbird Systems were designed to do three things. First, as explained above, it orients the drivers to properly utilize a corner while minimizing cancellations from non-equidistant reflections off the walls. Second, when stacked, there is a significant increase in free output from the close-coupling of the subwoofers, while assuring that all of the drivers remain equidistant to the walls. Third, the placement options of a conventional subwoofer, which places the driver relatively low to the floor, typically causes a standing wave to be allowed to form, equal in wave length to two times the distance from the floor to the ceiling. A stacked Raptor or Blackbird system is designed to not only eliminate that standing wave, but to create a monolithic low frequency source that actually adds the ceiling as a fourth virtual primary point source across the frequency range that would normally be where the standing wave resides. The typical front-firing subwoofer places the center of the driver at 7 to 8 feet from standard ceiling height. Twice that distance is right at the wavelength of 75-80Hz, the typical crossover point for most systems. The difference between forcing the ceiling to become a constructive point source vs allowing the ceiling-to-floor boundaries to create a standing wave is of exponential significance. Overcoming and utilizing a rooms influences is the greatest challenge to a successful system setup and to enjoyable listening. When you consider that turning a rooms negative influence into a positive influence may result in a swing of hundreds of times output at a particular point in your frequency response, the merits of flexibility in this regard become very evident. Some rooms will do better with multiple placement vs a stacked configuration. That’s why the Raptor and Blackbird Systems were designed to offer both options. Stacking, multiple stacks or multiple separate placement, all are easily accommodated in a single system that’s designed for either solution. Please see the TECHNICAL/SPECS page for a detailed look at our stacking test. shapeimage_7_link_0
THE power plaNt:
Blackbird’s front accent strip is made from solid American walnut, finished with semi-gloss urethane to protect it and to bring out the ageless beauty of the color and grain, each piece being one-of-a-kind and adding the perfect finishing touch. An all-new curved front panel covered with hole punch pleather has been designed for the latest Raptor and is being used exclusively to achieve and all-black look that will blend with just about any decor.
9 preset curves from (+0/-3dB)16-200 Hz to (+0/-3dB) 32-120 Hz
Bossobass SEQSS Sealed EQ’d Signal Shaper DETAILS: 1RU, 6 pounds 115V-60 Hz Signal boost selection: +6dB, +8dB, +10dB (Specifically designed for each System) High Pass Filter Selection: None, 10 Hz, 18 Hz High Pass Filter Order 12dB/Octave (2nd order) Push Button ON/OFF LED “On” Indicator Light Frequency Response: Flat To Below 2 Hz Input: 1-RCA Outputs: 2-XLR We’ve always believed that most audio enthusiasts prefer to know the real information vs a marketing department version. In that spirit, we recorded an in-depth discussion of the design philosophy that inspired the Raven, Raptor and Blackbird Systems. The highlights appear below. For those who are less-technically inclined, you may skip this page and move on to the Blackbird Systems, Raptor and Raptor Systems pages.
Boundary gain of +18dB (64 times!) less the sound transmission losses of the boundary due to the boundary construction method.
 
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24dB ((256 times!) added potential boundary gain, less the floor-to-ceiling standing wave non-linearity
 
The surround is an all-new hybrid half roll/tall profile made from an all-new rubber compound  and is designed to allow full linear excursion without reaching its  maximum potential. We decided, after testing every available material and profile, to design the surround from  scratch and specifically for our systems. To get the equivalent excursion from a typical half roll surround, we would have had to sacrifice cone surface area, yet we found that the typical tall-narrow surround traded cone area for linear performance. Experimentation culminated in the best combination of profile, material, thickness, cone area and performance.
 
Dual Nomex spiders were designed and spaced to prevent rocking during maximum throw and a quick return to zero after signal input ceases, just what a spider is meant to provide.
 
The cone is a rather conventional non-pressed paper overlaid with an all-new coating. It’s light yet stiff enough to withstand the violent excursions required for state-of-the-art low frequency reproduction to single digit Hertz.
 
We designed an all-new 6 spoke aluminum basket that’s light yet strong and the new motor design includes three huge aluminum Faraday rings to smooth the free air response and to reduce non-linear response in the crossover region.
 
A single Raptor module yields up to 9 liters of displacement to Blackbirds 6.5. These are not arbitrary quantities. Conventional wisdom generally dictates that, when designing a sealed subwoofer, longer throw, therefore more displacement, is automatically better. Our philosophy is instead to hit the target cleanly with no wasted costs, effort or raw materials. With available technology, it isn’t difficult to to build an overkill driver. The challenge is to design a driver that performs up to the requirements of the system it was designed for, using just enough raw materials, honing the assembly process to a standard of quality that will keep them in the system and working and out of the landfill.