DIATONE DA-U750 (1975)

 

The Diatone DA-U750, released by Mitsubishi in 1975, was one of the company’s top integrated amplifier and one of the finest examples of 1970s Japanese amplifier engineering. Although Diatone is best known for its loudspeakers, the DA-U750 demonstrated the brand’s serious commitment to high-end amplifier design, incorporating technology later used in the separate DA-P10 and DA-A10 series. One of its most distinctive features was the dual-block internal construction, with the preamplifier and power amplifier sections physically separated at the front and rear of the chassis. The power amplifier block was independently shielded to minimize heat and magnetic interference from the power supply, improving stability, reliability, and long-term performance. The fully direct-coupled pure complementary OCL power amplifier used carefully matched transistor pairs in both the driver and output stages to reduce distortion and preserve dynamic range, delivering 90W + 90W into 4Ω. The equalizer amplifier employed proprietary ultra-low-noise transistors developed using Mitsubishi’s low-concentration diffusion technology, achieving improved noise performance and excellent phono sensitivity. Diatone also designed the amplifier using simulated cartridges and speakers to optimize real-world dynamic performance rather than relying only on laboratory measurements. Additional features included precision tone and presence controls with selectable turnover frequencies, a high-accuracy 22-contact attenuator, multiple low-cut and high-cut filters, extensive input and tape dubbing facilities, and beautifully machined solid metalic knobs. Combining advanced engineering with luxurious construction, the DA-U750 remains one of the most respected vintage Diatone integrated amplifiers. Size (W/H/D) 425x148x387mm | Weight 17kg | Original sale price in Japan ¥ 98,800

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Lo-D D-E90 (1980) | Excite Over! E90

 

The Lo-D (Hitachi) D-E90 cassette deck, released in 1980, represented the brand’s commitment to advanced analog audio engineering and user-focused design. By the late 1970s, Lo-D had already established itself as a pioneer in cassette deck technology, including the development of Japan’s — and arguably the world’s — first 3-head cassette deck equipped with a combination head in 1973. Building on that legacy, the D-E90 evolved from the successful D-90s model and brought premium 3-head recording technology to the mid-range hi-fi market at a more accessible price point. At the heart of the D-E90 was Lo-D’s renowned closed-gap metal recording and playback head system. This advanced ferrite combination head used newly developed High Bs ferrite material with high magnetic flux density, allowing separate recording and playback functions within a compact design. The recording head featured a precision 6μ gap, while the playback head used an ultra-fine 1μ gap for enhanced detail retrieval and frequency response. Finished with a mirror-polished titanium spray coating, the head assembly delivered smooth tape travel, highly stable tape-to-head contact, and minimal monitoring delay. Direct coupling between the head and the amplifier’s first-stage FET further improved signal-to-noise performance and audio clarity.

The transport mechanism utilized a sophisticated dual-motor, dual-capstan system designed for highly accurate tape handling. A DC servo motor controlled the capstan drive, while separate DC motors handled fast-forward, rewind, and take-up functions. Dual capstans and pinch rollers positioned on both sides of the tape path ensured excellent tape stability and minimized modulation noise and level fluctuation. This precision engineering enabled an impressive wow and flutter specification of just 0.038%, delivering exceptionally stable playback performance. Lo-D also equipped the D-E90 with an advanced microprocessor-controlled transport system that expanded upon traditional IC logic circuitry. Feather-touch electronic controls provided smooth operation, while several innovative convenience features enhanced usability. For noise reduction, the deck featured Dolby B Noise Reduction. Tape support covered four formulations: normal, chrome, ferrochrome, and metal tapes. Instead of the fully automated ATRS calibration system found on Lo-D’s flagship models, the D-E90 provided manual bias fine adjustment and REC CAL recording sensitivity calibration, allowing users to optimize recordings for different cassette brands and tape types. Additional features included a timer recording safeguard that flashed an indicator to help prevent accidental erasure after timer activation, along with a distinctive level display combining large analog VU meters and a five-point LED peak indicator system for accurate monitoring. Despite being positioned as a mid-range cassette deck, the Lo-D D-E90 offered a remarkably complete feature set, precision engineering, and refined sound quality. Its slim, elegant styling gave it a sophisticated appearance that complemented its clean, balanced recording and playback characteristics. The D-E90 would later serve as the foundation for the more advanced D-1100MB, further cementing its place in the evolution of high-performance Japanese cassette decks. Specifications: Recording/Playback Head: 1.4mm Close-Gap Metal R&P Combination Head + Erase Head: Ferrite Guard Double-Gap Metal Erase Head | Motor: DC Servo Motor (for Capstan) x 1, DC Motor (for Reel) x 1 | Wow & Flutter: 0.038% (WRMS) | Frequency Response: 20-21,000Hz (Metal), 20-20,000Hz (Chrome), 20-18,000Hz (Ferric-Chrome/Normal) | S/N Ratio (Metal Tape 3% Distortion Level Audible Correction): 69dB (DOLBY-NR-ON), 61dB (DOLBY-NR-OFF) | External dimensions: Width 435 x Height 110 x Depth 266 | Weight: 6.0g | Original sale price in Japan ¥79,800 (998 DM Germany) | Remote control unit RB-100 (¥6,000) sold separately 

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SHARP VC-FX61 (1989)

 

The VC-F61 from Sharp, introduced in 1989 achieves a horizontal resolution of over 400 lines in S-VHS video mde. It achieves sharp, high-definition images approaching those of broadcast-grade 1-inch video. The unit and remote control feature jog shuttles, and a flying erase head that allows for easy editing of recorded footage frame by frame. List of features include: S-VHS video, 145x high-speed FF/REW, Movie sync terminal, Y/C separation comb filter, HiFi Stereo audio, jog shuttle, digital auto tracking, flying erase head, On-screen display, insert dubbing, Tape remaining time display, 36x speed video search.

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