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Introduction
Ever since I bought my first Squeezebox from Slim Devices several years ago, I wanted a version with built-in speakers. I was not alone. Members of the extremely active Squeezebox community have built quite a few homebrew Squeezebox "boom boxes" over the years, mashing together Squeezebox hardware with amplifiers, speakers and power supplies from a variety of sources. After Logitech acquired Slim Devices and I was hired on, I was excited to be part of the team that would build the Logitech Squeezebox Boom all-in-one network music player.
The Logitech Squeezebox Boom.
Over the past months, our team has worked extremely hard to build a compact, self-contained, high-performance network audio system. With advanced digital signal processing, a high-quality bi-amplified speaker design, an easy-to-use user interface, line input and subwoofer output, Squeezebox Boom is a system that can go in any room of the house and sound great.
After a quick tour of the high-level architecture and disassembly photos of the Squeezebox Boom, this paper will describe the audio architecture starting from a digital PCM signal (after any MP3, OGG, FLAC or other decoding), and will follow the signal through the digital signal processing (DSP) chain, digital-to-analog converters (DACs), power amplifiers, the speaker drivers and acoustical enclosure.
The DSP signal flow in Squeezebox Boom contains several processing stages that optimize the sonic experience. The primary DSP stages that will be discussed are: volume processing, bass management, StereoXL stereo enhancement, woofer-tweeter crossover, subwoofer processing, and driver protection.
Although we believe Squeezebox Boom sounds great today, because of the extremely flexible and upgradeable nature of the Squeezebox architecture, we can roll in new features on an ongoing basis to meet our customers' needs. Some of the future enhancements could include: automatic loudness filter for low-volume listening; dynamic range compression for low-volume listening; multi-band equalization; dynamic range compression for high-noise environments; and whatever else we can think up to help improve the overall experience.
