Audio-Technica AT33xMONO/I — True Mono moving coil cartridge

The AT33xMONO/I is not a stereo cartridge with its channels summed: its "True Mono" design generates an electrical signal only from the horizontal movement of the stylus. A mono groove carries its information in the lateral swing, while surface noise, dust and record warps move vertically; by not reading that axis, the cartridge leaves much of the noise out and delivers mono with more weight in the bass and a quieter background, without touching the mono button on the preamp.

The stylus is a 0.65 mil nude conical, a tip that matches the constant width and depth of mono grooves and is forgiving with older pressings. The generator combines a neodymium magnet and permendur yoke with PCOCC copper coils and a piano-wire suspension that lowers dynamic load; the die-cast zinc, aluminium and high-rigidity polymer body spreads resonance so no frequency dominates. Output is 0.42 mV, the coil is 10 ohms with 27 µH and the recommended load is 100 ohms or more. It weighs 10.1 grams, tracks at 2.2 grams and its response reaches 30 kHz.

This is a cartridge for anyone with a real mono collection — modern reissues or original pressings — and a moving coil phono stage with enough gain, or a suitable step-up transformer. Do not engage the amplifier's mono mode: the signal is already mono and summing the channels only adds noise. Its 10.1 gram mass calls for a medium or high-mass arm, and the stylus is not user-replaceable: Audio-Technica offers a paid repair service. The /II version shares the approach, with lower output and higher tracking force for older grooves.

Technical specifications:

• Type: moving coil (MC) "True Mono", 1/2 inch mount
• Stylus: nude conical, 0.65 mil
• Cantilever: duralumin pipe
• Frequency response: 20 Hz – 30,000 Hz
• Output voltage: 0.42 mV (1 kHz, 5 cm/s, horizontal signal)
• Tracking force: 2.0-2.4 g (2.2 g standard)
• Coil impedance: 10 ohms (1 kHz)
• DC resistance: 10 ohms
• Inductance: 27 µH (1 kHz)
• Recommended load: ≥ 100 ohms
• Output balance: 1.0 dB (1 kHz)
• Horizontal/vertical output ratio: 25 dB (1 kHz)
• Vertical tracking angle: 20°
• Static / dynamic compliance: 14 / 6 × 10⁻⁶ cm/dyne
• Dimensions: 16.1 × 16.6 × 26.1 mm
• Accessories: non-magnetic screwdriver, brush, 2 washers, M2.6 screws of 8, 10 and 13 mm, protector
• Weight: 10.1 g