Sony CDP-707ESD
Thirty-nine and a half pounds of 1988 engineering, built on the premise that a CD player could be a precision instrument rather than a black box.
Overview
The first thing that registers is the weight: 39.6 lbs., or 18 kg, for a two-channel CD player with no amplifier inside it. That mass comes from a chassis built out of multiple layers of copper bonded to Sony's "G" material — a plastic resin and calcium carbonate compound reinforced with glass fiber — and then bonded again to a steel plate. The base is acoustically, magnetically, and electrically inert by design. A second inner side wall of copper plating encloses the player completely for r.f. and magnetic shielding, and the wire-harness openings are plastic-sealed to keep vibration from traveling between stages. Collectors who have had one apart describe a machine that looks less like consumer audio and more like lab equipment that happens to have a disc tray.
Under the hood, the CDP-707ESD is a true 18-bit machine — both the D/A converter and the digital filter process a full 18 bits, avoiding the bit-register shifts used in so-called quasi-18-bit designs. The arithmetic matters: 16-bit quantization allows 65,536 possible values, and adding two bits raises that to 262,144, which is why 18-bit linear conversion buys roughly 12 dB of extra signal-to-noise headroom at low levels. Fourteen power-supply subregulation stages feed the works, and the dual transformers and motor assembly live in their own chassis compartment, isolated from the digital and analog circuit boards. The laser pickup's linear motor rides in a double suspension system with a ceramic/resin compound in the mounting to damp the resonance of the assembly's fast motion.
The published specs are the kind that made the trade press reach for superlatives. Frequency response is 2 Hz to 20 kHz, ±0.3 dB. Signal-to-noise is 115 dB (EIAJ), dynamic range 100 dB (EIAJ), THD 0.0015% (EIAJ), separation 110 dB, and wow and flutter 0.001% weighted peak. Output is fixed at 2.0 V rms with a variable tap from 0 to 2.0 V rms, and there is both a coaxial digital output at 0.5 V peak-to-peak and an optical output conforming to the EIAJ standard — the digital terminal was configured to the then-new Sony/Philips standard covering CD graphics as well as CD audio. Headphone output is 28 mV. Power draw is a modest 18 watts from 120 V a.c., 60 Hz.
What separated this player from its peers was the feature set. "Disc Memo" stores a message of up to 10 letters, numbers, or symbols tied to a specific disc and displays it whenever that disc is loaded. "Program Bank" stores a playback order for a given disc and plays only those selections automatically. All three work by reading each CD's unique identifying code and matching it to stored instructions, and any of the features can be filed for as many as 226 different discs. Custom Index and Program Bank cannot be used simultaneously on the same disc, though either can be paired with Disc Memo. Twenty selections can be programmed at a time.
The measurements, when Audio (April 1988, p.61) got the unit on the bench, were the real story. THD+N at 0-dB recorded level came in at 0.00135% on one channel and 0.0014% on the other. Two details are worth calling out because they speak to execution rather than spec-sheet bragging: THD+N actually decreased as 20 kHz was approached rather than rising, and spectral analysis showed residual noise at 60, 120, and 180 Hz — the power-supply-related frequencies that betray inadequate filtering — sitting at -130 dB or lower in every case but one. The same review noted no detectable phase error between channels even at 20 kHz, and a 440-Hz tone reproduced at 440.07 Hz.
The analog output filters are linear-phase, three-pole designs, and the player uses single master-clock architecture with an advanced error detection and correction system.
The original price was $1,800, which in 1988 dollars put it firmly in flagship territory. A contemporary review closed with a line that has aged into a buying recommendation: even if you can't afford one, you should listen to the CDP-707ESD, because it is a shining example of what CD technology is all about. That is the pitch for anyone hunting one today. The caveats are the usual ones for a machine this age and this complex — the laser assembly, the belt-driven drawer, and the display are all decades old, and the feature set depends on a microprocessor and memory that no service center stocks parts for. Buyers should expect to verify disc recognition and drawer operation before committing, and collectors note that the 18 kg of copper, steel, and resin is not something to ship casually. But as a document of how far Sony was willing to push redbook playback in 1988, there is very little like it.
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