Koetsu Onyx “Short Body” Review

The Koetsu Onyx “Short Body” refers to the later, more compact stone-bodied versions of the Onyx cartridge that followed the rare early “Long Body” models. These short-body examples typically date from the later Yoshiaki Sugano period into the early years under his son Fumihiko, before (or without) the full Platinum magnet upgrade that defines the current Onyx Platinum. They represent an important evolutionary step in the Koetsu stone-body lineage.

Design & Context

The original Long Body Onyx used large Alnico magnets that required an elongated housing. Once stronger rare-earth magnets (primarily samarium-cobalt) became practical, Koetsu could shorten the body while maintaining or improving performance. The resulting Short Body Onyx retains the hand-carved natural onyx stone housing but in the more compact form familiar from modern stone models.

Typical characteristics of genuine Short Body (non-Platinum) examples include:

• Natural onyx stone body
• Samarium-cobalt or similar non-platinum magnet
• Copper or early silver-plated copper coils
• Boron cantilever with proprietary stylus
• Output generally in the 0.4–0.5 mV range (higher than modern Platinum models)
• Weight typically around 11–13 g
• Medium compliance suited to medium-to-higher mass tonearms

These cartridges are handmade and vary somewhat from example to example. Condition of the stylus, suspension, and cantilever is critical, as is originality.

Sound Quality

The Short Body Onyx sits sonically between the warmer, denser, more romantic Long Body Alnico versions and the more refined, higher-resolution modern Onyx Platinum.

It delivers the classic Koetsu virtues in a more balanced and controlled package:

• Rich, lush, and highly engaging midrange with excellent body and harmonic density on voices and acoustic instruments
• Full, weighty bass with good extension and a sense of bloom, though generally tighter and better defined than the earliest Long Body examples
• Smooth, non-fatiguing treble that favors natural tone over maximum air or etched detail
• Large, three-dimensional soundstage with strong instrumental presence and emotional involvement
• A musical, flowing presentation that prioritizes beauty and coherence

Compared with the Long Body, the Short Body is typically a bit more open, better controlled in the bass, and slightly less “dark” or heavily romantic. Compared with the current Onyx Platinum (platinum magnets, tightly matched silver-sheathed coils), it is usually warmer, denser, and less resolving in the extreme highs and low-level detail, while retaining more of the traditional Koetsu midrange magic that many listeners prize.

Owners and enthusiasts who prefer the classic Sugano-era tonal balance often favor well-preserved Short Body examples over the more modern Platinum versions for their combination of richness and relative practicality.

Practical Considerations

Like all low-output Koetsus, the Short Body Onyx benefits from a high-quality phono stage or step-up transformer and careful loading (often in the 30–100 ohm range, though it can be system-dependent). It pairs best with medium-to-higher mass tonearms. Because these are older handmade cartridges, professional evaluation of the stylus and suspension is strongly recommended before purchase. Retipping or rebuilding by specialists familiar with Koetsu geometry can restore performance, though originality is highly valued by collectors.

Strengths

• Classic Koetsu midrange beauty and musicality in a more compact form
• Rich, engaging, and non-fatiguing presentation
• Better bass control and overall balance than the earliest Long Body versions
• Strong emotional connection with acoustic, jazz, and vocal recordings
• Historical significance as a bridge between early and modern stone-body Koetsus

Limitations

• Rarer and more variable in condition than current production models
• Less resolving and airy than modern Onyx Platinum or top contemporary MCs
• Requires careful system matching and setup
• Secondary-market pricing reflects scarcity and condition

Verdict

The Koetsu Onyx Short Body is a highly musical and characterful moving-coil cartridge that captures much of the romantic magic of the early stone-bodied Koetsus in a more practical and refined package than the rare Long Body. It offers a compelling middle ground for listeners who love the classic Sugano tonal signature—lush midrange, rich harmonics, and emotional engagement—while wanting better control and balance than the very earliest examples.

For those seeking the traditional Koetsu experience without moving all the way to the modern Platinum series (or who specifically prefer the warmer non-Platinum voicing), a well-preserved Short Body Onyx remains a special and rewarding choice. As with any vintage high-end cartridge, condition, originality, and proper setup are essential to realizing its full potential.