Sanyo RD-W685: The Forgotten Innovator in Cassette Fidelity

In the late 1970s the cassette was growing from a voice-recording format into a serious choice for hi-fi playback, and Japanese makers raced to improve their decks. Sony, Panasonic and TEAC were the giants. Sanyo carved out a niche with well-engineered, feature-rich decks at accessible prices. The Sanyo RD-W685 is one of them - a compact auto-reverse cassette deck with surprisingly solid audio engineering.

The RD-W685 is not as widely celebrated as some of its contemporaries, but it has a cult following among vintage audio enthusiasts who like its design, mechanical reliability, and clean sound. It was released around 1979, just as cassette decks were picking up features once reserved for reel-to-reel systems - Dolby B noise reduction, dual-capstan transport, and precise tape head alignment - in smaller enclosures.

Technical Specifications

The Sanyo RD-W685 was designed to deliver high-quality playback and recording in a space-efficient form factor, making it ideal for integration into compact stereo systems or as a standalone component in a bedroom or portable setup.

Sound Characteristics and Performance

The deck has a modest footprint and sits in the middle of the range, but it sounds better than its price suggests. The 3-head configuration uses separate record, playback, and erase heads, which gives accurate monitoring while recording and consistent playback. Many single-head auto-reverse decks flip the tape by moving the head. The RD-W685 has fixed heads and a tape inversion mechanism, which preserves head alignment and reduces mechanical wear.

The dual capstan drive system gives excellent speed stability and keeps wow and flutter at levels comparable with higher-end models of the era. The result is tight, well-controlled bass and clear midrange, which suits jazz, classical, and vocal recordings.

With Dolby B noise reduction, tape hiss is effectively suppressed, particularly in the upper frequencies, so recordings sound cleaner. With Dolby engaged, the signal-to-noise ratio reaches a respectable 60 dB. That is enough for enjoyable listening even on pre-recorded tapes or home dubs.

The frequency response of 40Hz–15kHz is solid for a consumer-grade cassette deck of the late '70s, capturing most of the audible spectrum with minimal roll-off. While not quite matching the extension of premium Nakamichi or Revox decks, the RD-W685 holds its own in real-world listening scenarios, especially when paired with high-quality Type II (chrome) tapes and properly calibrated.

Notable Features and Innovations

The Sanyo RD-W685 was packed with user-friendly features that reflected Sanyo's focus on practical innovation:

• True Auto-Reverse Playback and Recording: Unlike half-auto systems, the RD-W685 allows uninterrupted playback and recording on both sides of the tape without manual intervention.
• Dual Capstan Transport: Enhances tape-to-head contact and reduces speed variation, contributing to improved fidelity.
• Dolby B Noise Reduction: Standard on most high-quality decks by this time, but its inclusion here underscores Sanyo’s commitment to audio quality.
• Direct-View Recording Level Meters: Integrated VU meters provide real-time feedback for optimal recording levels, helping prevent distortion.
• Logic-Controlled Operation: Utilizes electronic logic for smooth, reliable tape transport control—reducing mechanical complexity and wear.
• Compact, Stackable Design: Designed to fit neatly into component stereo systems, with a sleek faceplate and intuitive button layout.

Common Issues and Maintenance

As with any vintage cassette deck, the Sanyo RD-W685 benefits from periodic maintenance to restore peak performance:

• Rubber Components Deterioration: The capstan tires and pinch rollers are prone to hardening or cracking after decades of use. Replacement with fresh rubber parts is essential for proper tape tension and speed accuracy.
• Head Alignment Drift: Over time, the tape heads may become misaligned, especially if the deck was used frequently. A professional demagnetization and alignment service can restore clarity and stereo imaging.
• Mechanical Sticking: The auto-reverse mechanism, while robust, can accumulate dust or dried lubricant. Cleaning and relubrication of gears and rails will ensure smooth operation.
• Capacitor Aging: Internal electrolytic capacitors may leak or lose capacitance, potentially affecting power delivery and audio circuitry. A recap by a qualified technician is recommended for long-term reliability.

Clean the tape path regularly with isopropyl alcohol and a lint-free swab. This maintains performance and prevents debris buildup.

Current Market Value and Collectibility

The Sanyo RD-W685 is still a relatively obscure model in the vintage audio market, which cuts both ways for collectors. It is rarely counterfeited and typically sells at modest prices - usually between $75 and $150 in working condition. Fully serviced units with replaced belts and aligned heads may command slightly higher prices, especially with original packaging or documentation.

Collectibility is growing among enthusiasts who like under-the-radar Japanese engineering and compact hi-fi systems. It may never reach the status of a Nakamichi Dragon, but the RD-W685 offers a good mix of functionality, sound quality, and nostalgic appeal.

It is particularly sought after by people building retro bedroom stereos, putting vintage cassette decks into modern setups, or preserving analog recordings with period equipment.

Conclusion and Legacy

The Sanyo RD-W685 did not make headlines in its day. It is a good example of what second-tier Japanese audio brands were doing during the golden age of home hi-fi. It offers reliable auto-reverse operation, solid build quality, and a warm, balanced sound.

The RD-W685 is a working piece of audio history from a time when cassette tapes were becoming a legitimate medium for music lovers. It rewards anyone willing to restore it.

If one turns up in a thrift store or online marketplace, it is worth a look. With a little care, the RD-W685 can still play tapes well.

eBay Listings

Universal Kit 1 SANYO RD-W685

$45.16

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Related Models

• Sanyo DCX-233L (1978)
• Sanyo DCX-3400 (1979)
• Sanyo RD-S40 (1985)
• Sanyo RD-W40 (1982)
• Sanyo RD-W50 (1983)
• Infinity RS-IIA (1977)
• Infinity RS-4.5 (1978)
• Sony TC-K333ESG (1989)
• Sony TC-K333ESJ (1991)
• Sony TC-K333ESX (1991)