Kenwood Corporation

Lore & Background

Kenwood was established on 21 December 1946 as the Kasuga Radio Co. Ltd. in Komagane, Nagano Prefecture, Japan. In 1960, the company was renamed Trio Corporation. During the early 1960s, Trio's products were rebranded and sold by the Lafayette Radio Company, which focused on citizens band (CB) radio. A&A Trading Co. imported Japanese-made electronics for RadioShack. William "Bill" Kasuga, a bilingual Japanese-speaking manager at A&A, partnered with George Aratani and Yoichi Nakase to establish a company as the exclusive importer of Trio products. The name "Kenwood" was invented by Kasuga as a combination of "Ken" (a name common to Japan and North America that was, at the time, considered acceptable to American consumers due to the Kenmore appliance brand) and "Wood" (referring to the material, as well as suggesting a relation to Hollywood, California). Kenwood became more widely recognized than Trio, leading to the company's rebranding. In 1986, Trio acquired Kenwood and subsequently rebranded as the Kenwood Corporation. George Aratani was the first chairman of Kenwood USA Corporation and was later replaced by Kasuga. In October 2008, Kenwood merged with JVC to form a new holding company, JVCKenwood.

Kenwood introduced its Sovereign line of components in 2001. In 2007, it discontinued its line of consumer audio receivers, home theatre systems, and other home electronics. The company launched a series of "Integrated Amplifier" stereo power amplifiers in 1977 and continued their production through the mid-1980s. The design for most of these products featured a true dual-mono path for stereo output (where no electrical components are shared between left- and right-channel amplification). Front plates were typically made in brushed aluminium with aluminium knobs and switches, glass covers, and in some cases analog VU meters. Kenwood also produced the NV-301 and NV-701 series compact hi-fi systems in 2000.

Reader's Guide

Kenwood's significance lies in its long history of manufacturing audio and communications equipment, from early transistor amplifiers to amateur radio transceivers and professional two-way radios. The company's KA Series hi-fi systems, produced from 1977 through the mid-1980s, are notable for their true dual-mono path design, which separated left- and right-channel amplification entirely. Kenwood also introduced the first car stereo speaker to use a honeycombed linear plane diaphragm. In the amateur radio field, Kenwood offered lines of HF, VHF/UHF, and portable models, including some with built-in digital data modes and modems. The company's communications product range includes hand-portable and mobile terminals, repeaters, infrastructure, and application solutions, covering standards such as DECT, PMR446, DPMR446, DPMR, Project 25, DMR, and NXDN. Kenwood's legacy includes its role in providing wireless radio equipment for the McLaren F1 championship and carrying amateur wireless equipment on the Mir space station in 1995. The company's merger with JVC in 2008 created JVCKenwood, which continues to produce audio and communications gear.

Did You Know?

• Kenwood was originally founded as Kasuga Radio Co. Ltd. on 21 December 1946.
• The name 'Kenwood' was invented by William Kasuga as a combination of 'Ken' and 'Wood'.
• Kenwood introduced the industry's first transistor amplifier in 1962.
• The Mir space station carried Kenwood's amateur wireless equipment in 1995.

Compression Architecture and Channel Capacity

AAC distinguishes itself from its predecessor MP3 through a fundamentally different mathematical approach to audio compression. While MP3 relies on a hybrid coding scheme that blends the modified discrete cosine transform with the fast Fourier transform, AAC employs a purely MDCT-based algorithm. This architectural choice translates directly into superior compression efficiency, meaning listeners can enjoy noticeably better sound quality at identical bit rates compared to MP3. The format's channel architecture is remarkably expansive: a single AAC stream can carry up to 48 full-bandwidth audio channels with sample rates reaching 96 kHz, alongside 16 dedicated low-frequency effects channels capped at 120 Hz, 16 coupling or dialog channels, and 16 separate data streams. For stereo content, joint stereo mode delivers satisfactory quality at 96 kbit/s, while hi-fi transparency requires at least 128 kbit/s in variable bit rate mode. ITU testing confirmed AAC meets transparency benchmarks at 128 kbit/s for stereo and 384 kbit/s for 5.1 surround. The ecosystem has since grown with extensions like HE-AAC for improved efficiency and AAC-LD for low-delay applications.

Standardization and Profile Evolution

The path to becoming an international standard was neither instantaneous nor linear. AAC first entered the MPEG-2 family in April 1997 as Part 7, formally designated ISO/IEC 13818-7:1997. Because MPEG-2 already contained Part 3 covering backward-compatible audio, this new addition was labeled MPEG-2 NBC, signaling its incompatibility with the earlier MPEG-1 formats like MP1, MP2, and MP3. The original specification laid out three distinct profiles: the Low-Complexity variant built around AT&T's Perceptual Audio Coding foundation augmented with temporal noise shaping and a Kaiser window, the Main profile adding recursive predictors on each filterbank tap, and the Scalable Sampling Rate profile using a four-band PQMF filterbank structure. Two years later in 1999, the standard was absorbed into the MPEG-4 family as Part 3, introducing Audio Object Types for interoperability with formats like TwinVQ and CELP, plus Perceptual Noise Substitution. Subsequent amendments in 2000, 2003, and 2006 progressively added AAC-LD, bit-sliced arithmetic coding, parametric audio, and the HE-AAC v2 profile with parametric stereo, while maintaining backward compatibility throughout.

Ubiquity Across Consumer Platforms

Few audio codecs have achieved the breadth of real-world deployment that AAC has. It was selected as the default or standard audio format on Apple's iTunes Store, Nintendo's Wii, DSi, and 3DS handhelds, and Sony's PlayStation 3 console. Its reach extends well beyond those flagship choices: the iPhone, iPod, PlayStation Portable, Vita, and PlayStation 5 all support the format, as do Android devices, older cell phones, and dedicated digital audio players including Sony Walkman and SanDisk Clip. On the software side, mainstream media players such as VLC, Winamp, and Windows Media Player handle AAC files natively, while in-dash car audio systems and major streaming platforms—Spotify, Apple Music, YouTube, and YouTube Music—rely on it for audio delivery. Encoded AAC audio is most commonly wrapped in an MP4 container and identified by the familiar .m4a file extension. The basic Low-Complexity profile, known as AAC-LC, is the variant most widely supported across this vast ecosystem, making it the de facto standard for digital audio distribution in the early twenty-first century.

A Collaborative Scientific Heritage

The mathematical groundwork for AAC stretches back to 1972, when Nasir Ahmed proposed the discrete cosine transform as a tool for lossy compression. Working with T. Natarajan and K. R. Rao, Ahmed refined the concept and published their findings in 1974. A decade and a half later, J. P. Princen, A. W. Johnson, and A. B. Bradley built upon earlier 1986 work to propose the modified discrete cosine transform in 1987, the very algorithm that would become AAC's computational backbone. The 1992 introduction of MP3 represented the first major commercial application of transform-based audio coding, though it relied on a hybrid MDCT-and-FFT approach. AAC's development was a genuinely multinational collaboration: AT&T Labs, Dolby, Fraunhofer IIS, and Sony Corporation worked together to shape the standard, which the Moving Picture Experts Group declared an international specification in April 1997. Lars Liljeryd's method for dramatically reducing the information needed to represent digitized music or speech further advanced the technology. In later years, a broader coalition including Bell Labs, LG Electronics, NEC, Nokia, Panasonic, ETRI, JVC Kenwood, Philips, Microsoft, and NTT contributed refinements, ensuring the standard remained a living, evolving document.