Nakamichi 680ZX: The Unconventional Maestro of Magnetic Tape
Step back to the twilight of the 1970s, a golden era for analog audio. Amidst a sea of cassette deck manufacturers, one name consistently rose above the din, whispered with reverence by audiophiles: Nakamichi. Their 6xx series, including models from the 660ZX to the revered 682ZX, represented the pinnacle of cassette technology, commanding premium prices from $995 to a then-staggering $1,800 USD.
But Nakamichi wasn’t a company to follow conventional wisdom. Unlike rivals who clearly tiered their product lines from “good” to “best,” Nakamichi imbued each 6xx model with unique strengths, all sharing the famous second-generation Nakamichi transport and other high-quality components. Among these, the Nakamichi 680ZX stood out, a machine brimming with personality and unorthodox engineering.
A Design That Means Business
One glance at the 680ZX and you know you’re in the presence of a serious recording instrument. Its unordinary, purposeful design eschews fleeting trends. The transport buttons, crafted from metal with deeply engraved symbols, feel almost indestructible, a testament to lasting quality. Other controls, like the Dolby B switch (no Dolby C here, a sign of its late-70s vintage) and tape/source selectors, are robustly made, though the tiny plastic covers on these switches, victims of aging adhesive, require a gentle touch to prevent loss – a charming quirk of age. The cassette compartment itself is a visual treat, bathed in the soft, inviting glow of a green bulb, creating an ambiance few non-Nakamichi decks could replicate. (Modern enthusiasts, of course, might opt for a diffuse LED replacement, offering a different, yet equally appealing, aesthetic.)
A Tale of Two Speeds: Innovation or Enigma?
The 680ZX holds a fascinating quirk: dual running speeds. Alongside the standard 4.76 cm/s, it offers a half-speed option of approximately 2.4 cm/s (or 15/16 ips). Nakamichi claimed that even at this slower speed, the deck could capture high frequencies up to an impressive 15 kHz. Indeed, measurements on personal units have shown it reaching around 16 kHz on normal and chrome tapes (-3 dB, ref. 1 kHz, -20 dB signal).
This begs the question: why? One can’t help but wonder at the Japanese company’s reasoning. Was it for specialized professional applications, like extended voice recording? It’s hard to imagine a dedicated audiophile, having invested $1,550 (around 2,920 Deutsche Marks in June 1979), willingly opting for a slower speed that inherently meant a somewhat decreased frequency response, higher wow & flutter, and consequently, a less expansive soundstage with fewer fine details. Perhaps its best justification lay in archiving lengthy FM radio broadcasts.
Intelligent Engineering, Sans Microcontrollers
Beyond its speed eccentricities, the 680ZX boasted Random Access Music Memory (RAMM) – a sophisticated, if somewhat elaborately named, track search function allowing users to skip forward or backward multiple selections. It also supported cue and review, letting users audibly monitor the tape at high or low speed, a feature more commonly found in professional studio environments.
Calibration was a hands-on affair. The 680ZX featured a manual level calibration system based on a 400 Hz oscillator and six front-panel accessible trimmers (with an additional six for half-speed calibration). The goal was simple: align the VU/Peak meters to the designated mark for both channels. But here lay another Nakamichi innovation: initiating level calibration also activated the Auto Azimuth Alignment system. This ingenious mechanism, utilizing the same 400 Hz tone, employed a motor and pulley to physically adjust the record head’s angle relative to the playback head, ensuring perfect alignment – crucial for compensating for minute manufacturing inconsistencies in so-called “sandwich” heads. A flashing “play” bulb (no LEDs in the 680ZX’s main indicators) signaled the system was at work, settling after a few seconds to allow for level adjustment.
Remarkably, all this sophisticated functionality was orchestrated not by microcontrollers, but by TTL (Transistor-Transistor Logic) circuits. While this resulted in a rather large “logic” PCB, it also meant that finding replacement parts, even today, can be surprisingly feasible. And by all accounts, this logic board was exceptionally reliable.
The Mesmerizing Glow of Precision
Perhaps the visual pièce de résistance of the 680ZX is its fluorescent VU/Peak meters. Housed in a sturdy steel box, these displays, driven by two PCBs and a vacuum tube display, are nothing short of spectacular. The deck can operate in peak hold mode or a VU mode that simultaneously shows peak values. These meters are incredibly fast, with one segment darting ahead of the main VU bar to indicate the true peak value – an ingeniously implemented system that remains one of the best cassette deck indicators ever conceived.
The Heartbeat: Nakamichi’s Legendary Transport
The transport mechanism in the 680ZX is the classic second-generation Nakamichi type. Built with aluminum sheet base panels and plastic connecting parts, Nakamichi claimed this design was the result of extensive research into combating transport-born vibrations. It featured a closed-loop dual capstan system, with capstans of slightly different diameters to resonate at different frequencies, further minimizing interference. The entire system was belt-driven, with a separate motor for the reels.
This venerable mechanism saw service in many other Nakamichi decks of its generation (480, 580, 582) and even later models (LX3, LX5), and formed the basis for the transports in the legendary Dragon and ZX9 (which added a direct-drive capstan motor). Compared to the sheer metal-on-metal solidity of, say, a Studer/Revox transport, the Nakamichi might appear almost toy-like with its aluminum and plastic construction. Yet, it works exceptionally well, and many of these transports continue to function reliably for decades, often without major servicing.
Maintenance, however, does reveal some quirks. After years of use, the plastic connecting parts can develop small cracks, though these are usually easily remedied with a touch of cyanoacrylate glue. Motors are generally durable, with most issues stemming from old grease on pulley shafts or rollers. The idler reel drive, a critical component, is of exceptionally high quality; original Nakamichi idlers have been known to perform flawlessly for over 30 years with minimal slippage! Replacing this idler, however, is a task for the patient, requiring significant disassembly, spring removal, and careful cleaning and lubrication of the entire transport. Interestingly, the capstans on the 680ZX don’t show signs of post-manufacturing balancing, unlike those in the Nakamichi 480, suggesting they were made with even greater initial precision.
One Small Omission
If there’s one area where the 680ZX concedes a point, it’s the lack of user-adjustable bias from the front panel. Accessing bias trimmers requires removing the deck’s cover. Many audiophiles might have preferred a single-speed machine with this convenient tweakability over the two-speed configuration without it.
The Nakamichi Sound: More Than Just Playback
Ultimately, the Nakamichi 680ZX embodies the true “Nakamichi spirit”: elegant and transparent, gentle yet strong. Pitting it against other excellent decks of the era – a Sony TC-K990ES, NAD 6300, JVC TD-V1010, or Technics RS-B100 – reveals the subtle yet distinct qualities that elevate a very good machine to an outstanding one. No musical passage makes the 680ZX “sweat”; it handles everything with an effortless grace born of deep engineering experience. Bass notes are authoritative, and the high-frequency extension readily explains why Nakamichi never felt the need to implement the HX Pro system – they simply didn’t require it. The three-dimensional soundstage is impeccable, as are timbre and rhythm. Listeners often report being able to feel the “air” around individual instruments.
It’s often said that Nakamichi decks aren’t strictly “neutral.” Instead, they impart a soul to the music, a character that transcends the inherent limitations of the cassette format. The 680ZX doesn’t just reproduce music; it plays it, making recordings softer, more listenable, and deeply engaging, even if the original production was otherwise.
In the end, the Nakamichi 680ZX is more than just a vintage cassette deck. It’s a testament to a time when audio engineering pushed boundaries with creativity and a relentless pursuit of sonic excellence. It’s a machine that can still, decades later, sing you a sweet, captivating lullaby.