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Third-Generation Mbox Technology Guide Table of Contents Design Philosophy Behi

Third-Generation Mbox Technology Guide Table of Contents Design Philosophy Behind the Third-Generation Mbox Family. .....................................................3 The Elements of a Great Audio Interface.......................................................................................3 Converters..................................................................................................................................3 Preamps. .....................................................................................................................................3 Clocking......................................................................................................................................3 Emissions Compliance. ...............................................................................................................3 The Keys to the Mbox Sound.........................................................................................................4 Listening Tests............................................................................................................................4 Premium Components and Efficient Layout. ...............................................................................4 World-Class Clocking and Jitter-Elimination Technology. ...........................................................4 Industrial and Electrical Design. ..................................................................................................4 Power. .........................................................................................................................................4 Hardware Build...........................................................................................................................4 Expertise.....................................................................................................................................5 Signal Path, Internal Layout, and Routing. .....................................................................................6 Mbox Pro Signal Path.................................................................................................................7 Mbox Signal Path. .......................................................................................................................7 Mbox Mini Signal Path................................................................................................................7 Additional Resources.....................................................................................................................8 Appendix........................................................................................................................................9 Mbox Family Specification Comparison. .....................................................................................9 Mbox Pro Input Frequency Response..................................................................................... 10 Mbox Pro Output Frequency Response. .................................................................................. 10 Mbox Pro Input THD.................................................................................................................11 Mbox Pro Output THD..............................................................................................................11 Mbox Input Frequency Response. ........................................................................................... 12 Mbox Output Frequency Response......................................................................................... 12 Mbox Input THD. ...................................................................................................................... 13 Mbox Output THD.................................................................................................................... 13 Mbox Mini Input Frequency Response.................................................................................... 14 Mbox Mini Output Frequency Response. ................................................................................. 14 Mbox Mini Input THD............................................................................................................... 15 Mbox Mini Output THD............................................................................................................ 15 3 Design Philosophy Behind the Third-Generation Mbox Family In designing the new Avid® Mbox® family of audio interfaces, our industry-leading engineering team set out to create best-in-class products that would surpass their previous efforts in this category—as well as those of other manufacturers. To meet this goal, we leveraged technology from our top-of-the-line Pro Tools|HD recording systems, and also drew from our extensive experience developing mobile recording solutions. In addition, we conducted numerous customer surveys and interviews, and incorporated a broad array of user requests into the new Mbox series—from higher audio quality and enhanced integration with Pro Tools® software, to a rock‑solid new chassis and ergonomic front-panel design. Finally, we carefully optimized each member of the Mbox family for its specific function—from serious desktop production to mobile field work. The Elements of a Great Audio Interface It’s important to understand the reasons why some interfaces sound better than others, even when recording at equal sample rates and bit depths. Much of the answer lies in the quality of the components. Converters Even if the performers, instruments, rooms, and microphones are excellent, a recording can suffer if the interface uses poor-quality converters to convert between the analog and digital domains. Low-quality converters create noise and distortion, which degrade the quality of the recording. Excellent converters deliver pure, powerful sound, even when the final playback medium is only 16 bits. Preamps It’s important to use preamps that deliver high gain without introducing unwanted noise and hiss from their internal circuitry. This provides clean, natural-sounding audio regardless of how much gain is required. The signal-to-noise ratio* (expressed in negative values) is an important gauge of the quality of an interface’s converters and preamps; lower (more negative) numbers indicate better performance. Clocking Audio interfaces must clock their converters at regular intervals in order to capture sound accurately. A poorly designed clock can breed jitter, causing the interface to sample audio irregularly. The irregularity results in audio distortion. An excellent clock has minimal jitter, ensuring that the digital audio converters stay rigidly time-locked and minimize related distortion. Emissions Compliance An excellent audio interface will be designed and manufactured to ensure that electronic emissions comply with the emission limits set by national and international standards agencies. It will also comply with the requirements to continue to properly operate with specified levels of emissions from nearby electrical and electronic equipment. It’s not enough to just use premium-quality components—it’s absolutely critical to arrange and connect them with the utmost precision and expertise. This requires a deep level of experience and specialized training. *Beware when comparing signal-to-noise specs from different manufacturers. Some companies only measure the noise introduced by the preamps and ignore the complete signal path; others state the theoretical specs of the converters and not the actual measured specs. This results in a signal-to-noise ratio that is misleading. Avid publishes only “real-world” specs, so users will know how the interface will truly perform before making a purchase. 4 The Keys to the Mbox Sound Listening Tests Before commencing work, our design team engaged in a series of listening tests. We sampled Avid interfaces as well as products from other manufacturers, then worked to develop the clearest, most transparent-sounding interfaces possible. With each subsequent revision of the electronics, our team reconvened for another set of exhaustive listening tests to ensure exceptional performance. Premium Components and Efficient Layout Our engineers started by selecting the best possible components. They sourced the finest D-A and A-D converters, as well as crystal-clear preamps for pure, pristine sound from start to finish. Then they worked to ensure the shortest possible path between components, resulting in superior audio quality. (See signal path diagrams in “Signal Path, Internal Layout, and Routing” section.) World-Class Clocking and Jitter-Elimination Technology The Mbox Pro interface features critically acclaimed JetPLL technology to provide extremely stable synchronization and eliminate jitter that can degrade audio quality. The Mbox and Mbox Mini interfaces also feature high-quality clocks to provide accurate, low-jitter audio sampling and exceptionally low resulting distortion. Industrial and Electrical Design Our engineering team worked hand in hand with our industrial designers to pair an aesthetically pleasing and ergonomic exterior with optimized internal electronics and connections. We carefully considered the position of every element. For example, we placed the preamp jacks on the same side of the interface as the gain pots and controls in order to ensure the shortest possible internal path—rather than routing them amongst other components that could introduce noise and interference. We fine-tuned every detail, down to the routing of every copper trace on the printed circuit boards. We spent months balancing the external design with the internal, in order to deliver an intuitive user experience as well as pristine sound. Power Since the Mbox Pro interface is intended for project studio use, it features an extremely efficient, low-noise power supply. In contrast, the Mbox and Mbox Mini each feature state-of-the-art bus power architecture in order to deliver high performance during mobile use, as well as in the studio. Our engineering team paid exceptional attention to detail when considering the power requirements for each Mbox interface. All microphones draw different levels of power, so we started by sampling a wide variety of popular mics to understand the range of power needs. Then we designed the interfaces to provide adequate phantom power for all possible mics, with a slight bit of headroom. We carefully selected every single power‑drawing component in the interfaces, continually minding the overall power budget. Then we pored over the schematics to analyze hot spots, and cut back wherever possible to ensure power efficiency—without ever compromising performance. Hardware Build In direct response to customer feedback, the third-generation Mbox interfaces are housed in professional‑grade, rugged, metal chassis designed to withstand the rigors of heavy-duty mobile and studio use. All structural components are made of metal; a solid metal extrusion encases a secondary inner metal chassis, which ensures the precise alignment of all internal components. In addition, the metal enclosure—along with proper circuit design, filtering, and layout—provides immunity to emissions from nearby electronics equipment, keeping the sound quality pristine. A molded plastic faceplate and soft-touch knobs enhance the aesthetic and tactile appeal. 5 Expertise Our engineering team relied on their personal experience as musicians and audiophiles to ensure that the Mbox interfaces would yield pleasing, musical results in even the most demanding circumstances. For example, if pushed to the point of distortion when capturing heavy vocals, the distortion sounds musical rather than harsh. These audible performance characteristics further separate Mbox from products by other manufacturers. Like our engineering team, our testing department is full of working musicians, audio engineers, and audiophiles. These power-users rigorously tested the interfaces to make sure that they would perform optimally in a vast array of real-word scenarios—with a wide variety of computers, operating systems, microphones, and other gear. After standing up to their discerning ears and uncompromising scrutiny, we knew the Mbox interfaces would meet the sonic expectations of even the most demanding users. 6 Signal Path, Internal Layout, and Routing In addition to selecting premium components and creating the shortest possible signal path between them, our engineers worked to optimize each model’s signal chain for its intended use, as detailed below. Mbox Pro Signal Path The Mbox Pro audio interface features 8 x 8 simultaneous channels of I/O. There are four microphone inputs with 48V phantom power (two XLR/DI combo, two XLR), plus four 1/4” TRS line inputs. The DSP and software‑based mixer lie at the heart of the Mbox Pro interface, facilitating a huge variety of routing options. The mixer also provides access to a variety of hardware-based low-latency effects. 7 Microphone Input The signal goes from the XLR input into a premium-quality preamp with a pad, which provides over 74 dB of gain range (including the 20 dB pad). From there, the signal goes to a high-pass filter, which is controlled by software via a high-quality relay. Then the signal passes to an insert jack on the back of the interface, so the user can send to external devices, and the return will come in through the same insert. uploads/Industriel/ mbox-guide.pdf