Ortofon SPU 1S
Ortofon MC cartridge with integrated body and spherical stylus, designed to mount directly onto classic tonearms with a removable SME-type headshell.
Description
The SPU 1S is a moving coil (MC) cartridge from Ortofon, characterised by its integrated body designed for direct mounting on classic tonearms fitted with a removable SME-type headshell. Unlike bare cartridges that require a separate headshell, it forms a ready-to-install one-piece assembly, continuing the SPU line and its established construction principles.
The spherical stylus, paired with an aluminium cantilever and a tip radius of R 18 µm, defines a classic tracking profile geared more towards diamond longevity and playback stability than towards the fine detail retrieval of elliptical or fine-line profiles. The coil, made from high-purity copper (OFC), and the 2 ohm internal impedance call for the use of an MC phono preamplifier or a step-up transformer suited to a recommended load above 10 ohms. Frequency response is stated as 20 Hz to 20,000 Hz at ± 3 dB. The body, made of a moulded wood and resin composite, contributes to the mechanical damping characteristic of SPU construction.
This cartridge is aimed at turntable enthusiasts equipped with a classic tonearm featuring a removable SME-compatible headshell, looking for an entry-level MC model within the SPU range without compromising on careful construction. It naturally suits systems built around a predominantly vintage or valve-based chain, for which this type of cartridge is traditionally favoured.
Technical specifications
| Type | Low-output MC (moving coil) |
| Stylus | Spherical |
| Cantilever | Aluminium |
| Mounting | Tonearm with SME connection |
| Output voltage (1000 Hz, 5 cm/s) | 0.18 mV |
| Channel balance (1 kHz) | 1.5 dB |
| Channel separation (1 kHz) | 20 dB |
| Channel separation (15 kHz) | 10 dB |
| Frequency response | 20-20,000 Hz ± 3 dB |
| Tracking ability (315 Hz, recommended tracking force) | 60 µm |
| Vertical dynamic compliance | 10 µm/mN |
| Stylus tip radius | R 18 µm |
| Tracking force range | 3.0-5.0 g (30-50 mN) |
| Recommended tracking force | 4.0 g (40 mN) |
| Tracking angle | 20° |
| Internal impedance (DC resistance) | 2 ohms |
| Recommended load impedance | > 10 ohms |
| Cartridge body material | Moulded wood and resin composite |
| Coil wire material | High-purity copper (OFC) |
| Colour | Matt black |
| Weight | 28 g |
What to check before buying used
The wood-resin composite body may show micro-cracks or slight play at the SME mounting point, which should be checked before any installation. The spherical aluminium stylus, more resistant than a fine-line profile, nonetheless retains an R 18 µm tip radius that is susceptible to wear on units with heavy use: check for flat spots under magnification. The moving coil, with its 2 ohm internal impedance, cannot be rewound, and any electrical continuity fault renders the cartridge irreparable, hence the value of testing output on both channels before purchase.
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