Ortofon - 2M 78 Mono Cartridge

A 65 µm spherical tip for shellac 78s, in a true mono body that runs on an ordinary stereo phono stage.

The 2M 78 exists for one job: playing 78rpm shellac records with a stylus that actually fits their grooves. The tip is a spherical diamond of R 65 µm — roughly three and a half times the radius of the 2M Mono’s R 18 µm tip — sized to ride the wide coarse groove of a shellac disc rather than drop to the worn bottom of it. It will not fit a microgroove LP, and it is not intended to.

Like the 2M Mono it is a true mono design using a strapped output, so both sets of pole pins deliver the same signal and the cartridge works on any ordinary stereo phono stage without a mono switch. Channel balance and separation are published as not applicable. Everything else — 4mV output, 700 ohms, 350mH, 18 µm/mN compliance, 1.8g, the 47k ohm load and the 7.2g body — is identical to the 2M Mono, because the two share a body and differ only in the stylus assembly.

That shared fitting is the practical point for anyone with both shellac and mono LPs. One cartridge body plus the two styli covers the whole span, at considerably less than the cost of two complete cartridges, and swapping between them takes seconds with no realignment.

One caveat we will make ourselves, because Ortofon does not: 78s were cut to a range of pre-RIAA equalisation curves, and a standard RIAA phono stage will replay them with a noticeably wrong tonal balance. The cartridge gets the mechanical side right; the equalisation is a separate problem, and one worth talking to us about if you are building a shellac setup. Ortofon publishes nothing on the subject.

Features

• Spherical diamond, R 65 µm, sized for the coarse groove of shellac 78s
• True mono design with a strapped output — works on any ordinary stereo phono stage
• Aluminium cantilever
• 4mV output into a standard 47k Ω moving magnet input
• Shares its body and stylus fitting with the 2M Mono — one body plus two styli covers shellac and mono LPs
• Threaded half-inch mounting plate; two screws, no nuts
• Also available in 2MR form for Rega-style tonearms, premounted on an SH-4 headshell, and as a bottom-mount Verso

Specifications

• Type: True mono moving magnet cartridge with strapped output, for 78rpm shellac records
• Output Voltage: 4mV at 1kHz, 5cm/sec
• Channel Balance at 1kHz: Not applicable — Ortofon publishes N/A
• Channel Separation at 1kHz: Not applicable — Ortofon publishes N/A
• Frequency Range: 20Hz – 20,000Hz at −3dB (Ortofon 2M brochure; dropped from the current product page). Treat this as a nominal figure — 78rpm source material rarely carries useful content much above 8kHz
• Frequency Response: 20Hz – 20kHz, +3 / −1dB
• Tracking Ability at 315Hz: 70 µm at recommended tracking force
• Compliance: 18 µm/mN, dynamic lateral
• Stylus Type: Spherical. Note Ortofon specifies this one as spherical rather than nude spherical, unlike the 2M Mono — the wording is consistent across its sites and appears deliberate
• Stylus Tip Radius: R 65 µm
• Cantilever: Aluminium
• Tracking Force Range: 1.6 – 2.0g (16 – 20mN)
• Recommended Tracking Force: 1.8g (18mN)
• Tracking Angle: 20°
• Internal Impedance, DC Resistance: 700 Ω
• Internal Inductance: 350mH
• Recommended Load Resistance: 47k Ω
• Recommended Load Capacitance: 150 – 300pF
• Cartridge Body: Polymer and aluminium
• Colour: Black / Grey
• Cartridge Weight: 7.2g
• Replacement Stylus: Stylus 2M 78
• Stylus Interchange: Belongs to the Mono / 78 group. The same body accepts the Stylus 2M Mono with its R 18 µm nude spherical tip for mono microgroove LPs
• Equalisation: 78rpm discs were cut to a range of pre-RIAA curves, and a standard RIAA phono stage will replay them with a wrong tonal balance. This is our own advice, not Ortofon’s — Ortofon publishes no equalisation guidance for this cartridge at all
• Mounting: Half inch (1/2″) mount. The 2M threaded mounting plate is 3mm thick, so no nuts are needed. Ortofon supplies a pair of M2.5 screws with a 5mm thread length, to be used with headshells up to 3.5mm thick. Ortofon warns against overtightening and against aluminium screws, which can seize in the threaded holes
• Stylus Life: Ortofon rates its styli at up to 1000 hours with proper care, and notes that DJ use — scratching and back-cueing — should be reckoned at about 500 hours at most. This is a general figure across the range rather than a per-model specification. No separate figure is published for this tip, which runs in abrasive shellac and should not be expected to match a diamond tracking clean vinyl
• Cleaning: Ortofon specifically warns against propyl alcohol and other cleaning fluids, which can seriously damage the diamond cement and the suspension system
• Design: The 2M series was developed with the Danish industrial design house Møller Jensen Design. Ortofon does not publish the year the series launched
• Origin: Ortofon A/S of Nakskov, Denmark. Ortofon states that all its cartridges are designed and crafted in Denmark
• Warranty: Ortofon Inc. covers cartridges bought from an authorised US dealer for one year against defects in workmanship and materials, and excludes expendable items — which on any normal reading excludes the stylus. Note that Ortofon’s own webshop terms quote a two-year warranty instead; a US dealer purchase falls under the one-year terms
• Not Published: Any equalisation guidance; any groove width figure for 78s; whether the diamond is nude or bonded; coil system and coil wire material; suitability for vinyl-pressed or transcription discs as distinct from shellac; the compliance measurement frequency
• Note: Ortofon publishes no groove width figure and makes no statement about vinyl-pressed 78s, later pressings, or the many transcription and lateral-cut discs that need other tip radii. In practice 78 groove sizes vary considerably, and there is no manufacturer basis for claiming a single 65 µm tip suits every 78