Digital Movie Series

Transcript

Research & Development White Paper Rev. 2.1 November 30, 2007 Digital Movie Series DM 1 & DM 2 Virtual Surround Systems Canton Elektronik GmbH & Co. KG, Germany 1 Introduction Canton’s DM 1 and DM 2 Digital Movie Systems are designed to provide consumers with a high quality, home theater surround sound listening experience without the need to locate and wire-up five or more loudspeakers all around the room. The Canton Digital Movie Systems use an advanced psychoacoustic processing algorithm to generate a fully immersive virtual surround sound field with just two main speaker channels. It does this by presenting each of the listener's ears with the same combination of sounds, timbre shifts, and time delays that would be heard from a full surround sound array. The Canton DM 1 system combines the two front speakers into a single horizontal cabinet designed to mount above or below a video screen, while the DM 2 uses separate left and right miniature 'cube' speakers. All the audio processors, source management circuits, digital power amplifiers, and a deep-response subwoofer are combined in a single cabinet that can be placed on the floor in a unobtrusive location. User control and feedback are provided by a compact handheld remote control with an LCD display. This device uses radio frequency (RF) signals to control the DM processor/subwoofer module functions even if it is located out of the line-of-sight. The remote is also capable of traditional infrared (IR) function, and has IR learning capability, allowing it to control other components in the system. Digital Movie System Series Features and Benefit ● Fully contained audio system delivers highly effective surround from just one or two visible front speakers, thanks to complex virtual surround processing ● High-quality audio receiver integrated into system active subwoofer module - 350 watts system power - Dolby Digital and DTS surround decoding - Audio inputs for five source components (3 analog/2 digital) - Integrated FM tuner - Multi-room functionality (Zone 2 output) ● Combined RF and IR handheld remote control with integrated LCD display - Bidirectional RF (radio frequency) technology allows control of system even if subwoofer enclosure is hidden out of sight - Programmable IR (infrared) code sets for control of television and source players (i.e. DVD, cable box, etc.) ● Easy plug and play setup and installation - No need to install and place rear surround speakers - No additional AV receiver necessary - Single remote control replaces entire system of IR remotes. - Programmable IR (infrared) code sets for control of television and source players (i.e. DVD, cable box, etc.) 1.1 System Description and Technical Data Both the Canton DM 1 and DM 2 digital movie systems are active, 2.1-channel music and home theater systems that create a very high quality surround sound field with just two main speaker channels and a subwoofer. Each system includes a pair of full-range satellite speakers for left and right channel, a subwoofer unit which houses all of the amplification and decoding/processing circuitry for the system, and a handheld RF (radio frequency) and IR capable remote device that controls all system functions and provides an LCD display for indication of system status and control functions. Canton Digital Movie Systems White Paper Page 2 of 7 Canton Elektronik GmbH & Co. KG, Germany 2 2.1 Digital Processing Circuitry TruSurround virtual surround technology The Canton DM systems employ the advanced SRS TruSurround XT® surround processing algorithm, which effectively generates the impression of complete surround soundfield using just two front speakers. This technology is based on the science of psychoacoustics, and specifically on the “Head Related Transfer Function” (HRTF) principle. This principle is takes advantage of the way in which the human ear determines the location of an audio source, and exploits this understanding to generate a multi-level two-channel signal that mimics the effective soundfield which would be present in the case of a full 5.1-channel surround system. There are three decisive factors in the way a human being interprets an audio signal - sound pressure level (volume), timbre (acoustic 'color' or tone), and running time (duration). The angle at which a signal reaches the ear will alter these characteristics in such a way that the listener can relatively effectively determine the 'location' of the audio source. This capability is the fundamental basis of the concept of the 'Soundstage' in audio reproduction technology. The SRS TruSurround XT processing circuitry functions by taking a complete 5.1-channel surround sound signal input, and performing complex individual manipulations on all channels in both the frequency and time domains. These channels are then down-mixed into the front L/R channels, effectively mimicking the entire complex sound wave that would have occurred at the listeners' ears, but using only two speaker channels to accomplish this. 2.2 Surround Format Decoding The SRS TruSurround XT engine requires a full 5.1-channel input in order to generate the final surround field. To provide this signal, the Canton digital movie systems employs full decoding circuitry for Dolby Digital and DTS multichannel audio soundtracks. Additionally, the system includes Dolby ProLogic II processing, which effectively generates a complete 5.1-channel signal from two-channel source material. The system includes both optical and coaxial digital audio inputs for digital sources such as a cable/satellite set-top box, digital media server, game system, or digital disc player of any format (CD, DVD, HD-DVD, Blu-Ray). There are also analog inputs for analog audio sources such as a cassette deck or VCR. 3 Amplification Circuitry The Canton DM 1 and DM 2 systems feature Texas Instruments' PurePath® class D digital amplification modules for all channels. These amplifier circuits are extremely efficient and cool-running, producing up to 100 watts of ondemand power for each of the front left and right speakers, and 150 watts of power for the system subwoofer. Because the amplifiers are completely digital, there is no unnecessary intermediate A/D or D/A conversion required when using digital source material. This ensures optimal signal purity through all processing and pre-amplification since all these functions are performed completely in the digital domain. Only at the final output stage does the PWM (Pulse Width Modulation) power supply convert the signal to analog to drive the loudspeakers, combining high current and responsive power with an extremely high degree of signal purity. 4 System Connectivity The Canton DM 1 and DM 2 system subwoofer housing includes a complete array of connectivity to accommodate a wide range of audio sources, as well as allow for significant expansion of the system if desired. For digital sources, there are two digital inputs, one coaxial and one selectable for either coaxial or optical digital cables. There are also three stereo RCA inputs for analog source components. In addition to the left and right speaker outputs, there are center channel speaker terminals to allow for the addition of a center channel speaker, as well as preamplifier outputs for the surround speakers if a complete 5.1Canton Digital Movie Systems White Paper Page 3 of 7 Canton Elektronik GmbH & Co. KG, Germany channel system is desired. There are also selectable fixed-volume and line-level outputs for analog recording options, or for use with a separate volume controls in multi-room applications. 5 Handheld Remote Controller The RF-IR 1 handheld controller handles all of the control and display functions for the Canton DM digital movie systems. It maintains communication with the DM subwoofer module, which houses all of the system electronics and processing functions. The use of two-way RF (Radio Frequency) signaling allows the system to be used without the need for 'line-of-sight' contact, allowing the subwoofer to be installed or stealth installed in a variety of ways. The RF-IR 1 also features an IR (Infra-Red) transmitter, and is fully capable of learning the remote control codes for up to six additional components, thanks to its integrated IR receiver module. It has an effective range of 25 meters (80 feet) within the home for RF control, and 10m (33 feet) direct line-of-sigth range for all learned IR control sets. The controller features an integrated LCD display to provide all system information, and also to allow for 'soft button' controls which adapt to the current function. This allows the unit to operate with a minimal number of buttons for a clean look that is easy to operate, even in darkened movie rooms. Hard key controls are included for the most used functions, including 'volume up/down', 'Select Up/Down for selecting controlled device, 'power', and 'menu'. There is also a firmware update port to allow for future enhancements, or the addition of future Canton product controls. 6 System Expansion The Canton DM 1 and DM 2 systems can also be expanded through the addition of outboard amplifiers and/or additional full range loudspeakers. There are L/R pre-outs to allow for the addition of high-end external amplifiers if so desired, or for use with surround speakers in an expanded 5.1-channel system. A second set of outputs can be used either as a fixed line out, or as a Zone 2 output, including separate volume control, for use with an amplifier and speaker system in another room. The system has two modes of operation for use with additional speakers. By adding a center channel speaker as well as a pair of surround speakers and amplifiers, the systems can be set to function as a conventional 5.1-channel surround system. For those who wish only to add the rear amplifiers/speakers, there is a "Phantom Center" mode which will generate a very convincing center channel reproduction from the front L/R speakers; this mode is especially recommended for use with the DM 1, because its integrated front speaker cabinet and fixed relative L/R speaker positioning provide extremely satisfying "Phantom Center" results. 7 Full Range Satellite Speakers The heart of each of the full range speakers used in the DM 1 and DM 2 systems is a coaxial active driver system consisting of a 4-inch aluminum cone mid/bass driver and a 1-inch aluminum-manganese dome tweeter. 7.1 AM-90 Mid/Bass Drivers The mid/bass drivers in the DM 1 and DM 2 are a modified version of the 4-inch concave aluminum cones used in the company’s high-end speaker lines. The wave system (cone, dustcap, and surround) is modeled on that used in the company's CD series speakers, with a motor structure that has been subtly redesigned to accommodate the wide frequency and resolution demands of the Digital Movie systems. These drivers also feature Canton's concave dustcap geometry, which helps to maintain greater linearity and better dispersion characteristics across a broad frequency range. All of the wave systems components are computer designed and tested for ideal construction, and the dustcaps are formed from the same material as the cones themselves, providing for multiple resonance paths to prevent the formation of clearly defined standing waves across the driver. Injected rubber is employed for the Canton Digital Movie Systems White Paper Page 4 of 7 Canton Elektronik GmbH & Co. KG, Germany driver surround, delivering improved strength and UV resistance compared to foam surrounds, and superior air sealing compared to silk surrounds. The drivers' treated fabric spider assemblies feature improved weave geometry to aid longitudinal movement while minimizing unwanted lateral displacement. The entire driver structure is secured with a basket made of glass-bead reinforced polycarbonate that exhibits superior damping and stiffness across the entire operating range of the speaker. On woofers, because of the large excursions, internal air cavities within the motor and driver assembly are subject to significant compression and rarefaction, which can have a dramatic impact on the sound quality. To resolve these pressure differences, Canton’s engineers have designed and implemented a variety of systems in the woofer design, such as vented pole piece structure, former vents and open-air spiders. The final moving element in the midrange and woofer systems is the voice coil and the cylindrical former that gives it its shape and connects it to the diaphragm. Canton midrange drivers and woofers use aluminum voice coil formers exclusively, giving them high strength, low mass and excellent heat dissipation. The voice coils are extremely fine gauge copper wire with braided lead-out wires for durability. The lead wires leave the coil 180 degrees apart to maintain balance and symmetry, and encompass a gentle arc to evenly distribute stresses with excursion, and to extend the life of the driver. The Canton DM 1 and DM 2 series midrange/woofer drivers use well-proven magnetic motor assemblies that are developed with extensive computer design and modeling applications, combined with precision engineering, to develop a symmetrical and powerful magnetic flux across an extremely narrow voice coil gap. This allows for a substantial increase in length of the diaphragm and coil excursions, extending the optimal operating range of the driver by sustaining linear operation at ever increasing power levels and excursion. 7.2 ADT-25 Tweeter The Canton Digital Movie Systems speakers employ a dedicated version of the company's exclusive ADT-25 dome tweeter. The 1-inch driver is made from an alloy of aluminum and manganese for an extremely light and rigid structure that has excellent power handling and dispersion characteristics. The tweeter combines the dome and voice coil former into a single structure for lower mass, significantly improved heat dispersion, and elimination of the problems associated with glued junctions in this critical area. During its development, this transducer was simulated using finiteelement analysis programs to optimize the shape of the dome and structure of the magnet system. Analysis of structure deformation and acoustic properties led to a more rigid shape of the dome which shows a better behavior at high frequencies and power levels than conventional metal domes. The dome system employs an underhung voice coil construction, providing improved linearity inside the air gap, where the magnetic field is most homogeneous and the voice coil size is smaller than the air gap height. To increase the efficiency, the voice coil is wound with a double layer of extremely flexible and lightweight copper wire, which is less susceptible to material fatigue and has a very low mass. At the same time the material thickness of the copper wire is selected to optimize its resistance to thermal loads. For the motor-system, the air gap of the magnet was designed to be very narrow, providing increased magnetic field intensity inside the gap. This is enabled through the use of a physical alignment process during manufacturing that makes it possible to perfectly center the coil in the gap. Additionally, the cross-section of the coil and former is much thinner than conventional designs. These factors provide for high linearity and excellent efficiency. Furthermore, the use of extensive computer modeling and simulation techniques allowed for significant improvement of the symmetry of the magnetic flux density within the air gap. The force factor of the system was computed to predict the symmetry of the force on the voice coil versus the voice coil excursion. These calculations allowed for improved optimization of the system linearity by simulating the interaction of the underhang voice coil and the homogeneous magnetic flux density inside the air gap across the excursion range. 7.3 Cabinet Design 7.3.1 DM 1 Bass Reflex Enclosure The DM 1 left and right satellite speakers are each contained in a single, dual-chamber cabinet intended for easy mounting above or below the display device. The enclosure, and internal baffles are constructed of extremely inert MDF (medium density fiberboard) for reduced Canton Digital Movie Systems White Paper Page 5 of 7 Canton Elektronik GmbH & Co. KG, Germany distortion due to cabinet resonance. The cabinet can be mounted on-wall with the included wall bracket, or on a shelf or display stand with the optional TS 360 F tabletop stand. Each of the DM 1 speaker housing's dual internal chambers employs a bass reflex design that uses two 4-inch passive drivers. The use of dual passive radiator drivers greatly enhances the lower midrange and upper bass performance of the speakers without port noise or compromises in linearity that are problematic with many ported designs. These passive drivers feature the same aluminum wave system components as the AM-90 mid/bass drivers, making them an ideal match for the active components of the speaker. By placing the passive drivers in the in-board positions, the active coaxial drivers are arranged at opposite ends of the speaker cabinet to provide excellent channel separation, imaging, and performance for the TruSurround virtual surround processing system, while still maintaining the simplicity of a single enclosure. 7.3.2 DM 2 Sealed Enclosures The DM 2 left and right satellite speakers are each housed in their own separate enclosures. The remarkably small low-resonance enclosures are made of an advanced injection plastic material formed using a newly designed production process, and exhibit significantly increased wall thicknesses and improved acoustic characteristics compared to conventional designs. The enclosures feature a sealed cabinet design for excellent linearity, and a size of just 4-3/4 x 4-3/4 x 5-1/8 inches, making them simple to conceal or place in a variety of locations. The speakers can be mounted on a shelf with the included table-top stand, on-wall with the included wall bracket hardware, or placed in the room on optional LS-80 stands. 8 Subwoofer Both the DM 1 and DM 2 digital movie systems include an 8-inch active subwoofer for linear and high-output deep bass performance. The subwoofer is driven by a powerful and responsive Texas Instruments PurePath® digital amplification module capable of producing up to 150 watts of power for music or movie special effects. 8.1 AW-220 Woofer The bass driver in the Digital Movie Systems' subwoofer is a modified version of Canton's proven aluminum cone design, long used in the company's high-end speaker and subwoofer lines. The AW-220 incorporates engineering techniques developed for the company's Vento and Ergo lines, including improvements to the driver suspension, motor system, and diaphragm. The result of these changes is an 8-inch driver that provides significantly improved power handling, greater bass extension, and a 6-9 dB increase in deep bass output when compared with earlier Canton designs. Features and Benefits; Canton AW-220 bass driver ● High power ferrite motor system with over-hung voice coil for improved linear force range ● Sinusoidal injected rubber surround for improved lateral control, reduced ring-resonance, and increased excursion limits ● Spider assemblies features an improved weave geometry for better lateral control ● Glass-bead reinforced polycarbonate basket for superior damping and stiffness Aluminum has long been Canton's material of choice for its detailed and powerful mid/bass drivers due to its high strength, relatively light weight, and ability to resist deformation even at high power and excursion levels. Thanks to extensive simulation, finite element modeling, and the ability to manufacture its own designs in-house, Canton has managed to dramatically reduce the product development cycle and bring improvements to market much more quickly than would otherwise be possible. In the AW-220, the ability to make simultaneous refinements to the Canton Digital Movie Systems White Paper Page 6 of 7 Canton Elektronik GmbH & Co. KG, Germany driver, amplifier and filtering circuits, and motor system has allowed engineers to design a high-output subwoofer system that still maintains break-up modes for the driver well out of the operating range. This ensures clean, lowdistortion output even at high levels and with the most demanding film and music source materials, despite the relatively small size of the driver and the enclosure itself. Like the cone drivers used in Canton's high-end lines, the AW-220 employs a concave dustcap to provide an uninterrupted effective surface topology for greater linearity and better dispersion characteristics across the entire operating frequency. The dustcap is formed from the same high-grade aluminum as the cones themselves, providing multiple resonance paths to prevent the formation of clearly defined standing waves across the driver, further reducing distortion. The AW-220's driver suspension incorporates Canton's exclusive sinusoidal wave surround, which features a double-curved sine-wave profile rather than the typical half-round used in most drivers. This shape provides a much larger surround surface area for the same driver size, and allows for an increase in excursion limits of 60% - 100%. Additionally, the wave surround experiences significantly less structural deformation at high excursions than conventional designs, leading to an 80% improvement in ring resonance damping in the midrange frequencies, and dramatically lower distortion overall (see figure 3-3, right.) Like all of the company's large cone drivers, the surrounds are formed from high quality injected rubber for improved strength and UV resistance compared to inexpensive foam surrounds. 8.2 Figure 3-3: Surround deformation simulation at 2 kHz (scaled by factor of 2000 for clarity) - half-round (left) vs sinusoidal (right) Subwoofer amplification module and SC Technology In order to take full advantage of its advanced driver and suspension technology, The DM subwoofer employs a high current Texas Instruments PurePath™ digital amplifier module. Capable of delivering as much as 150 watts of highcurrent power, the class D amplifier circuit contributes to the high-output capabilities, and remarkable transient response characteristics of the subwoofer. The subwoofer also includes Canton's well-proven SC technology, which redefines the traditional relationship between enclosure size and operating bandwidth. The circuit consists of an active electronic filter integrated with the amplification module. Through careful analysis and testing of the DM subwoofer enclosure and driver interactions, this filter has been custom tailored to suit the individual acoustical characteristics of the system. In use, the SC circuit efficiently removes unwanted infrasonic information from the amplifier output, eliminating the excessive driver excursion and harmonic distortion that such signals can cause. This not only significantly improves the speaker's linearity and transient response characteristics across the operating range, it effectively extends the usable range of the subwoofer by as much as a full octave. Canton Digital Movie Systems White Paper Page 7 of 7