Ortofon 2MR 78 Slimline Moving Magnet Cartridge

Ortofon 2MR 78 Slimline Moving Magnet Cartridge for 78 rpm Shellac Records on Rega Tonearms

The Ortofon 2MR 78 Slimline Moving Magnet Cartridge is a mono cartridge built for one job: playing 78 rpm shellac records on turntables with Rega and similar low-profile tonearms. It combines three things a 78 collector needs:

• a stylus with the larger profile that shellac records require
• a narrow housing that meets the low-form-factor requirement of Rega arms
• a strapped mono output that works with the stereo amplifier you already own

This 2MR 78 mono cartridge suits a listener with a shellac collection, a stereo system and a turntable that plays at 78 rpm. It's a moving magnet design with a replaceable stylus, so it connects to a standard MM phono stage. When the stylus wears, you replace the stylus, not the whole cartridge.

What Stylus Does It Use for 78 rpm Shellac?

The 2MR 78 is a spherical-stylus cartridge, with a 65 µm diamond tip radius mounted on an aluminium cantilever. The diamond is the only part of a cartridge that touches the record, so its size and shape decide how it sits in the groove. Ortofon states that 78 rpm shellac records need a larger stylus profile, and the 65 µm spherical tip is the profile it specifies for them. Ortofon designs the 2MR 78 specifically for 78 rpm shellac playback, so treat it as a dedicated 78 cartridge.

Will the Ortofon 2MR 78 Slimline Moving Magnet Cartridge Fit a Rega Tonearm?

The Ortofon 2MR 78 Slimline Moving Magnet Cartridge is a low-profile design shaped for Rega turntables and tonearms, which require low-form-factor cartridges. A taller cartridge body on these arms needs spacers under the tonearm base, which raise the pivot to keep the arm level. The 2MR 78's narrow housing removes that step, so it mounts without spacers or modifications.

The cartridge fixes to the headshell with two screws, which is the half-inch mount format. Its pins connect to the four tonearm lead wires, and the two screws sit half an inch apart. Arms built for direct bayonet connector cartridges, which plug into the tonearm and lock with a single screw, don't take this mounting style. Check your arm's format in its manual or specifications before you buy.

Can It Play True Mono Through a Stereo System?

The 2MR 78 is a true mono cartridge that connects to any stereo playback system without mono-specific equipment. Its generator uses Ortofon's quad coils with split pole pins. A strapped output delivers the same signal from both sets of pole pins, so the left and right channels carry identical mono information from the cartridge itself. You don't need a mono switch or a mono amplifier. The tonearm leads, phono cable and phono stage connect exactly as they would for a stereo cartridge.

Which Tonearm Masses Match the Ortofon 2MR 78 Slimline Moving Magnet Cartridge?

This slimline MM cartridge is a moderate-compliance design, with a dynamic lateral compliance of 18 µm/mN. Ortofon classes 10 to 20 µm/mN as moderate compliance. Compliance and tonearm mass together set the system's resonance frequency. Ortofon treats 7 to 12 Hz as optimal and recommends 10 Hz.

Ortofon's formula, F = 1000 ÷ (2π × √(M × C)), turns the 18 µm/mN figure into a mass target:

• about 14 g of total system mass gives 10 Hz
• about 10 g gives roughly 12 Hz
• about 29 g gives roughly 7 Hz

Total system mass is the tonearm's effective mass plus the cartridge, headshell and screws. To check your arm, add its published effective mass to the cartridge weight in Ortofon's dimensions data and see whether the total falls within the 10 to 29 g window. Ortofon's guide classes arms of 10 g effective mass or below as low mass, and 11 to 25 g as moderate mass. Ortofon warns that a system resonating outside 6.5 to 14 Hz might not work properly.

What Phono Stage Does the Ortofon 2MR 78 Slimline Moving Magnet Cartridge Need?

The Ortofon 2MR 78 Slimline Moving Magnet Cartridge is a 4 mV output design that matches a standard MM phono input, so you won't need a step-up transformer or a moving coil stage. Ortofon specifies a 47 kΩ load resistance and a load capacitance of 150 to 300 pF. The capacitance figure covers the whole connection, which includes the tonearm wiring, the interconnect cable and the phono stage input. If your phono stage offers selectable capacitance, set it so the total lands within that range. Ortofon rates the frequency response at 20 Hz to 20 kHz, +3/−1 dB.

What Tracking Force and Alignment Does It Need?

The 2MR 78 is a cartridge that tracks at 1.6 to 2.0 g, and Ortofon recommends 1.8 g. Set the counterweight to 1.8 g with a stylus force gauge or the arm's calibrated dial. Ortofon rates the cartridge's tracking ability at 70 µm at 315 Hz, which is its measure of how much groove deflection the stylus can follow.

Ortofon designs the stylus assembly for a 20° vertical tracking angle, which assumes the arm sits level over the record. Overhang and offset need setting on the headshell. Ortofon sells a Premium Alignment Tool for this job.

How Is the Stylus Replaced?

The 2MR 78 is a replaceable-stylus cartridge, and its replacement part is the Ortofon Stylus 2M 78. When the diamond wears, you change the stylus assembly rather than buying a new cartridge. Ortofon's cartridge guide recommends thinking about future stylus replacement when choosing a cartridge, and it points to moving magnet designs for that reason.

How Does This Slimline 78 Cartridge Compare With the Alternatives?

The Ortofon 2MR 78 is a specialist model alongside Ortofon's 2M cartridges such as the 2M Red, 2M Blue, 2M Bronze and 2M Black. For a 78 collector with a Rega arm, the realistic alternatives fall into three groups:

• A taller cartridge reopens the spacer question described in the Rega section.
• A cartridge without the larger stylus profile doesn't meet the requirement Ortofon sets for shellac 78s.
• A mono system built around mono-specific equipment adds hardware that the 2MR 78's strapped output makes unnecessary.

Choose the 2MR 78 if your turntable plays at 78 rpm, your tonearm takes low-profile half-inch mount cartridges, and you want true mono through an existing stereo MM phono stage. Look elsewhere if your arm uses a bayonet connector, or if your tonearm's total system mass falls outside the window set by its 18 µm/mN compliance.