Technics RS-B605 (1987 to 1990)
A Japanese-built stereo cassette deck with high-end noise reduction and precision tape handling, sold for ¥54,800 in 1987.
Overview
At 4.3kg, the Technics RS-B605 sits solidly on the shelf—light enough for portability, heavy enough to signal serious engineering. This stereo cassette deck, manufactured in Japan from 1987 to 1990, was built for listeners who demanded more than basic tape playback. With a frequency response stretching to 19 kHz on metal tape and a dbx noise reduction system that pushes the signal-to-noise ratio to 92 dB, the RS-B605 was positioned as a high-performance option in Technics’ late-’80s lineup. Its 0.06% wow and flutter (W.R.M.S.) rating suggests tight speed stability, important for maintaining pitch integrity during playback, while the inclusion of Dolby B, Dolby C, and dbx systems gave users flexibility across tape types. Input sensitivity is rated at 60 mV for line and 0.25 mV for microphone, with impedance matched to standard consumer gear of the era, and the 400 mV line output ensures compatibility with most preamps. Housed in a 430 x 114.5 x 287 mm chassis finished in Technics Brown, the deck draws 17W from a 100 VAC supply—modest power demands for a machine packing this many features.
High Hardness Permalloy Heads with Double-Gap Ferrite Erase
The RS-B605 uses a high hardness permalloy head for recording and playback, a material chosen for its durability and consistent high-frequency response. This type of head holds up well over time, resisting wear even with frequent use, and contributes to the deck’s ability to reproduce frequencies up to 19 kHz on metal tape. Paired with it is a double-gap ferrite erase head, which ensures complete signal erasure across both tracks, minimizing crosstalk and residual noise. The combination reflects a design philosophy focused on fidelity and reliability, particularly when working with high-output tapes that demand precise magnetic control.
dbx, Dolby C, and HX-PRO Noise Reduction Integration
One of the RS-B605’s standout features is its triple noise reduction support: Dolby B, Dolby C, and dbx. Dolby B offers about 10 dB of noise reduction, effective for high-frequency hiss on standard tapes, while Dolby C improves on that with up to 20 dB reduction, better suited for CrO₂ and metal formulations. But it’s the dbx system that delivers the most dramatic improvement—measured at 92 dB signal-to-noise ratio when engaged, it nearly eliminates tape hiss entirely, though it requires careful calibration to avoid "pumping" artifacts. Complementing these is Dolby HX-PRO, a pre-emphasis system that dynamically reduces bias current during high-frequency passages, increasing headroom and reducing distortion.
ClassAA Recording Amplifier and Custom Regenerative IC
The RS-B605 features a ClassAA recording equalizer amplifier, a circuit design unique to Technics that separates voltage control and current drive functions into dedicated amplifier stages. This architecture ensures the output waveform is determined solely by the voltage amplifier, which remains unaffected by load variations, resulting in cleaner, more stable recording signals. To further refine performance, Technics developed a single-chip custom IC for the regenerative equalizer amplifier, minimizing component count and improving signal path consistency. This level of circuit specialization was uncommon in mid-tier decks and suggests Technics intended the RS-B605 to appeal to semi-professional users and critical listeners.
2-Motor Full Logic Transport with FL Peak Metering
Transport operation is handled by a quiet 2-motor full logic mechanism, which uses electronic sensors and solenoids to control tape movement without mechanical linkages. This design reduces wear and improves reliability over time, though it depends heavily on rubber components like drive belts and idlers—common failure points in aging units. The deck includes a wide-range 3-color FL (Fluorescent) peak level meter, offering visual feedback across a broad dynamic range with distinct color zones for optimal level setting. LED indicators provide additional status feedback, and the electronic counter allows for basic cueing and timing. A music selector function enables quick navigation to the start of the current or next track, a convenience feature for mixtape enthusiasts HiFI-Stereo (May 1989, p.100).
Timer Rec & Play, Auto Rec Mute, and L/R Mic Inputs
Beyond core recording functions, the RS-B605 includes several usability features aimed at home recording and automation. The timer record and playback function allows scheduled operation, useful for capturing radio broadcasts or creating timed playback sequences. Auto Rec Mute automatically silences the record path when no input signal is detected, preventing blank tape sections from being recorded—a small but practical touch. The deck also offers L/R independent microphone inputs, a rarity at this price point, enabling stereo mic recording without an external mixer. This flexibility made the RS-B605 a viable option for field recording, voiceovers, or live performance capture, especially when paired with high-sensitivity dynamic or condenser mics.
Historical Context
Introduced at a price of ¥54,800 around 1987, the RS-B605 arrived during the twilight of the high-fidelity cassette era. By this time, CDs had begun their ascent, but cassette decks still held appeal for their portability, recording capability, and lower cost. It was built in Japan, a mark of quality assurance during a period when offshore manufacturing was becoming more common among competitors.
Collectibility & Value
Service manuals and instruction guides are available through online archives, making restoration feasible for technically inclined owners. Spare parts such as the plunger (Pos.25) and idler assembly (Pos.24) are offered by specialty vendors like WebSpareParts, though prices—$14 and $39 respectively—can add up. A replacement power cable is available for under €6, suggesting basic maintenance is still supported. Common issues include degraded rubber components, particularly the pinch roller and drive belt, which can cause the deck to stop during playback. One owner noted that a stable power regulator contributes to "firm bass" and "crisp, clear treble," implying that power supply integrity is key to optimal performance. On the market, conditions vary widely: a unit in excellent used condition was listed on Reverb for $135 plus $35 shipping, while a Catawiki auction closed at €135 against an expert estimate of €150. A Reddit user in December 2024 reported picking up a unit for just $38, calling it a "good deal"—a sign that values remain accessible for now, though they may rise as working examples become scarcer.
eBay Listings
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