Cartridges — Benz Micro RUBY Z

The Ruby Z is a Benz Micro moving-coil cartridge of low output and the fourth generation of the company's Ruby series. Ernst Benz, an aviator and inventor, started the firm in the 1980s, and Albert Lukaschek took it over in 1994. The Ruby Z is sold in two outputs - the low-output ZL, which is this model, and a ZH version rated at 0.7 mV for phono stages with 50 to 60 dB of gain. American pricing stood at USD 4,000 and later at USD 4,800.

Key specs that matter

Output is 0.35 mV at 3.54 cm/s, and internal impedance is 38 ohm. Benz Micro asks for a load above 400 ohm. Frequency response runs from 10 Hz to 50 kHz within 1 dB, while separation between channels exceeds 35 dB at 1 kHz. Dynamic compliance is 15 micron per mN. The cartridge weighs 10.7 g, and tracking force is 1.8 to 2.0 g, with an outer limit of 2.2 g. Vertical tracking angle is 20 degrees.

Engineering and use context

Benz Micro machines the vented body from zebra wood, and the company chose this timber because it rates it second only to ebony for resonance behaviour. A solid boron rod 0.28 mm in diameter forms the cantilever. Its nude, mirror-polished Micro Ridge diamond has a 5 x 120 micron tip. The generator is built around a square plate cut from ruby jewel, the element that gives the series its name, with coils of pure copper wire. A special o-ring seal acts as the damper for the cantilever system. The same square ruby plate generator is used in other upper Benz Micro cartridges such as the Gullwing and the LP. Coils are wound by hand under strong magnification, and bodies and chassis parts are made and assembled in-house. Benz Micro allows about 40 hours of playing time for the suspension to settle and its warranty against manufacturing faults runs two years. The designation S Class was added with a later update of the model, which improved tracking.

Pairing

With its low output, the ZL needs a phono preamplifier offering at least 60 dB of gain, or else a transformer ahead of a moving-magnet stage. The moderate compliance and roughly 10 g body weight point to tonearms of medium to high effective mass, and the low coil impedance gives wide freedom in choosing the load resistor.

Alternatives

Within the Benz Micro range, the LP-S is another low-output moving-coil cartridge from the same maker built around the square ruby plate generator.