KENWOOD L-D1 (1992) | L Series

The Kenwood L-D1 is one of those CD players that immediately tells you it was designed for a very different era of digital audio. Introduced in 1992 as the flagship of Kenwood's L Series, it combined a massive 20 kg chassis, top-loading direct-drive transport, LaserDisc-derived spindle motor and fully discrete audio circuitry into a machine that feels as much like a statement component as a conventional CD player. It represents Kenwood's attempt to define what a genuinely uncompromising CD player could be at the beginning of the 1990s.

Kenwood L-D1 Main Specifications

Format: CD player

Disc rotation speed: 200–500 rpm

Frequency response: 4 Hz–20 kHz

Signal-to-noise ratio: ≥108 dB (EIAJ)

Dynamic range: ≥100 dB (EIAJ)

Total harmonic distortion: ≤0.001% at 1 kHz (EIAJ)

Channel separation: ≥100 dB

Variable output: 2.5 V / 0.1 Ω

Digital outputs: Coaxial and optical

Power consumption: 25 W

Dimensions: 476 × 128 × 430 mm

Weight: 20.0 kg

Remote control: Wireless

Additional functions: Automatic A/B-side tape editing; switchable digital outputs

Original sale price in Germany 6.400 DM

The numbers are impressive, but they only tell part of the story. The real attraction of the L-D1 is the extraordinary amount of mechanical and electrical engineering that went into achieving them. The L-D1's Most Important Feature: The Transport. Look at the transport first, and it becomes clear why the L-D1 occupies such a special position in Kenwood's catalog. This was Kenwood's first top-loading CD player, abandoning the conventional tray mechanism used by its earlier models. The disc is placed directly onto a machined aluminum turntable and secured by a substantial approximately 100 g clamper. The turntable measures 130 mm in diameter, and its additional mass provides approximately 20 times the moment of inertia of a conventional system. Kenwood's philosophy was straightforward: make the mechanical platform exceptionally stable so that the servo system would have less work to do correcting disc movement. A LaserDisc Motor Inside a CD Player. The spindle motor is equally unusual. Kenwood borrowed the basic motor technology from its high-end LaserDisc players: a three-phase, eight-pole, twelve-slot outer-rotor brushless design with a 6 mm shaft. This was a motor designed for a much more demanding physical job. LaserDiscs were vastly heavier than CDs and had to be rotated at considerably higher speeds, giving Kenwood a substantial mechanical platform from which to develop the L-D1's transport. The motor's high torque, low cogging characteristics and large diameter were intended to provide fast servo response and minimize shaft wobble. It is an excellent example of the early-1990s Japanese high-end approach: if a component could be made more substantial, more rigid or more precisely controlled, Kenwood was willing to do it. The optical pickup was treated with the same philosophy. Instead of a lightweight structure, Kenwood used a bridge-like aluminum die-cast assembly spanning the disc and supported by a robust 5 mm guide. A belt-driven coreless motor moves the pickup along the guide, with the design intended to minimize cogging and provide smooth movement. Kenwood also used a discrete high-performance amplifier for the pickup actuator drive rather than relying on a conventional op-amp IC arrangement. The stated objective was accurate pickup movement while avoiding unwanted interference through the power and ground lines. Super C4 and the Discrete Analog Stage. The analog section reveals another side of the L-D1. Kenwood used its Super C4 (Super Constant Current Cascode Circuit), developed for the L-A1 integrated amplifier in the same L Series. Rather than building the audio stage primarily around conventional operational-amplifier ICs, Kenwood employed a full discrete amplifier design. The DAC section uses Philips' PDM-converted bitstream 1-bit DAC7 architecture, with independent left and right channel treatment and an 8× oversampling digital filter. Independent switched capacitors were also used for the two channels, with the stated aim of improving channel separation and sound-field reproduction. The published specification of 0.1 Ω output impedance is another indication of how aggressively Kenwood approached the analog output stage. The Chassis: Where the 20 kg Comes From. The L-D1's weight is not cosmetic ballast. The transport is mounted on a 4 mm aluminum die-cast mechanism chassis, supported by an 8 mm aluminum extruded frame. The front panel itself is made from 5 mm aluminum extrusion. Inside, Kenwood divided the machine into four separate chambers for the mechanism, digital control, digital/analog power supply, and power supply/analog demodulation sections. Steel partitions and substantial aluminum panels were used to increase rigidity and reduce interference between the various sections. The result is a machine whose construction is immediately apparent when handling it. At 20 kg, the L-D1 has the physical presence normally associated with serious amplifiers rather than a CD player. Separate Transformers for Separate Jobs. Power-supply architecture was another priority. The digital and analog sections use separate transformers, while the microcontroller and display circuitry receive dedicated transformer supplies. This arrangement was intended to prevent the digital and analog systems from interfering with one another. Combined with the divided chassis and heavy mechanical construction, it demonstrates how comprehensively Kenwood approached the L-D1. Rather than concentrating only on the DAC or output stage, the company attempted to control the entire environment in which the digital signal was read and converted.

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