Ortofon SPU Mono CG 25 DI MKII MC Cartridge

The Ortofon SPU Mono CG 25 DI MKII is a moving-coil cartridge in an SPU housing, designed exclusively for mono records with a 25 µm spherical stylus tip.

"CG 25 Di" refers to the stylus radius: 25 µm, suited to most mono pressings from the late 1950s through the 1970s.

Why the SPU Mono CG 25 DI MKII?

A true mono cartridge tracks purely horizontally and cancels out the vertical groove noise that a stereo cartridge picks up on mono pressings. With a 25 µm radius, the stylus is tailored to common post-war mono pressings – not too narrow, not too wide.

What you'll hear

Mono recordings without the characteristic noise and hiss that stereo cartridges generate on the same grooves. Jazz and classical mono pressings gain in calm, focus and body.

Who is the SPU Mono CG 25 DI MKII for?

For collectors with mono pressings from the late 1950s to the 1970s and a second tonearm or interchangeable headshell. Straight talk: for very early shellac or 78 rpm pressings with wider grooves, its sibling, the CG 65 Di with a larger radius, is the better choice.

Our verdict

The right mono tool for the great majority of post-war mono collections. Needs a phono stage capable of handling low output, but rewards you with noticeably cleaner mono sound.

Technical specifications

• Type: MC cartridge, mono (SPU design) – not suitable for stereo records
• Stylus tip: Spherical, R 25 µm
• Output voltage (1 kHz, 5 cm/s): 1.5 mV
• Internal impedance (DC): 6 ohms
• Recommended load impedance: 100 ohms
• Stylus compliance (lateral): 7 µm/mN
• Frequency response: 20–20,000 Hz (+3/−1 dB)
• Tracking force: 3.5 g (3.0–4.0 g)
• Tracking angle: 20°
• Coil wire: OFC (oxygen-free copper)
• Housing: wood-resin composite, bayonet/SME universal mount
• Weight: 35 g

Frequently asked questions

Can I play stereo records with the Mono CG 25 DI MKII?

Ortofon explicitly advises against it – the stylus tip is designed for mono grooves and can permanently damage the groove on stereo pressings. Use it exclusively for mono repertoire.

What phono stage does this cartridge need?

An MC-capable phono stage with a load impedance of around 100 ohms. At 1.5 mV, the CG 25 Di sits in the mid output range, considerably louder than the classic low-output SPUs.

Why buy the Ortofon SPU Mono CG 25 DI MKII from HD Zürisee?

Because we'll tell you which stylus radius suits your mono collection, and set the cartridge up properly on a second tonearm. Mauri handles mounting and alignment for you in Wädenswil.

Goes well with

For interchangeable headshells, turntable accessories, for the groove, record cleaning, and more from the world of vinyl.