The Koetsu Onyx is a handcrafted moving coil phono cartridge made in Japan, representing Koetsu’s distinctive tradition of using natural stone in high-performance cartridge design. Its striking body combines the individuality of natural materials with generations of Japanese craftsmanship.

Natural Stone Bodies and Polished Finish

Koetsu stone body cartridges are made from carefully selected blocks of natural stone. Onyx Platinum, Blue Lace, and Tiger Eye Platinum use different stones, each chosen for its grain and coloration. The stone is machined into the cartridge body and polished to a fine finish that reveals its natural pattern. Variations from one block to the next give every finished cartridge an individual appearance.

The stone is the body of the cartridge, rather than a decorative covering. Its material and finish distinguish these models from Koetsu’s rosewood and Urushi lacquered cartridges.

Silver Cladding Process

The stone body cartridges use closely matched copper coils and cores. A thin silver sheath is drawn over the copper coil wire; this is distinct from applying a simple surface plating. The generator also uses platinum magnets. These construction details are shared across the stone body models.

Loading Impedance and Tonearm Mass

The preferred phono stage loading and tonearm pairing depend on the complete playback system. Because stone body cartridges have substantial mass, tonearm compatibility should be checked for the particular cartridge and arm. Loading can then be adjusted by listening within the manufacturer’s recommended range for the model.

Type

Moving Coil

Body

Precious Natural Stones

Coils

Silver Wire

Magnet

Platinum Magnet

Stylus

Sugano Design

Output

0.3~0.4 mV at 1kHz 5 cm/sec

Frequency Range

20Hz – 100kHz

Channel Separation

25 db at 1kHz

Resistance

6 ohm

Channel Balance (db / 1kHz)

0.5 db / 1kHz

Tracking Force

1.8 to 2.0 pond (at 20° Celsius)

Cantilever

Boron, pre-aged rubber damper

Compliance

6 x 10 – 6 cm/dyne at 100Hz

Weight

12.0~13.0 grams (weight varies by unit)

Recommended Load

5 – 40 ohm with Step up, 100 – 1000 ohm MC Phono

Recommended Tonearm Mass

Medium to high, 12 to 20 grams