A Briefing on Ortofon's SPU Cartridges Ortofon’s SPU cartridges continue the tradition of the first ever Moving Coil cartridges as originally engineered by Mr. Robert Gudmandsen and produced by Ortofon in the late 1950s. Praised for their refined linearity and full body, these cartridges have remained a favorite throughout the years, both for modern and vintage high-end applications. The latest incarnation of SPU cartridges feature a wood-based integrated headshell to further reduce resonance and provide an authentic and attractive aesthetic.
The Sound Of Excellence In the late 1950s the iconic SPU cartridge range featured Ortofon’s newly introduced low coil resistance and impedance concept. As a basis for reproducing superb high frequencies, this concept has been continually improved and refi ned in the decades since. With the recent launch of both the SPU Anniversary 85 and MC Rondo cartridges, Ortofon has introduced a new era of wood-based housing structures. The benefi ts of this natural material for cartridge housings mimic the centuries old tradition of hand crafted musical instruments with all the acoustic benefits.
The new developed Ortofon Synergy SPU-cartridge continues the predecessor’s concept whilst adding a new large sound image. The addition of unsurpassed technical data adds up to a highly sophisticated package. The exceptional black polished Urushi painting on the new SPU-housing suggests a precious jewel-like appearance. The musical instrument theme continues - the superb black glazing paint is of a quality found only on famous name pianos. Not only is the visual impression most attractive but the new transducer system allows extraordinary Synergy of sonorous sound. Very low coil-resistance combined with unusually high output (achieved by using Neodymium magnets in a soft iron circuit with high saturation) was decisive for reaching the high signal to noise ratio acheived with the new Synergy SPU-cartridge.
By controlling the cantilever and armature movements in air-gap with very high-magnetic induction, Ortofon has used its comprehensive expertise in designing the right type of damping for the new system. The nude, finely polished elliptical diamond in combination with the aluminium cantilever has both had essential infl uence on the fi nal frequency-response.
Details on the Ortofon Mono CG 25 DI MKII The Mono CG 25 DI MKII is an SPU-style Moving Coil (MC) cartridge with a spherical stylus profile, for the playback of early 25µm mono recordings. The CG 25 DI MKII provides an authentic method of playing back these early vinyl recordings with a remarkable level of sonic accuracy. This cartridge features a 1.5mV output, which makes it suitable for use with a variety of medium-gain moving coil transformers.
Ortofon Mono CG 25 DI MKII Technical Data
Output voltage at 1000 Hz, 5cm/sec. 1,5 mV
Frequency range at - 3dB 20-18.000 Hz
Frequency response FIM distortion at recommended 20-15.000 Hz + 3 / - 1 dB
Tracking ability at 315Hz at recommended tracking force *) > 60 µm