Lyra Atlas Mono Cartridge
The Lyra Atlas Mono is a special, built-to-order, mono version of Atlas for real mono playback of monaural/monophonic (mono) microgroove, vinyl records. It is recommended that the Atlas Mono is used with high-gain, low noise phono stages, or alternatively a step-up transformer designed for phono cartridges of 2 - 3 ohms or less.
On mono records, the vertical axis of the groove contains no musical information, but it will frequently have noise, in the form of groove damage and dirt. The Atlas Mono has therefore been designed to be completely insensitive to the vertical axis, which greatly improves the signal/noise ratio without any downside on monaural records.
The coil former is a square permeable plate oriented parallel to the record surface rather than the 45-degree angle used for most stereo cartridges, while the coils are wound so that they only generate a signal when there is horizontal movement of the stylus and cantilever when tracking a record.
Designer: Jonathan Carr
Builder: Yoshinori Mishima (final build, testing), Akiko Ishiyama (preliminary build)
Type: Medium weight, medium compliance, low-impedance, low-output moving coil cartridge
Stylus: Lyra-designed long-footprint variable-radius line-contact nude diamond (3um x 70um profile, block dimensions 0.08 x 0.12 x 0.5mm), slot-mounted Cantilever system: Diamond-coated solid boron rod with short one-point wire suspension, directly mounted into cartridge body via high-pressure knife-edge system
Coils: Two individually isolated monophonic/monaural 6N high-purity copper coils wound in parallel (on top of each other) on a square-shaped chemically-purified high-purity iron former with 3.0 ohms self-impedance
Output voltage: 0.25mV@5cm/sec., 2.4μH inductance degrees (CBS test record, other test records may alter results)
Frequency range: 10Hz ~ 50kHz
Compliance: Approx. 12x10-6cm/dyne at 100Hz
Vertical tracking angle: 20 degrees
Cartridge body: One-piece machining from solid titanium billet, with reduced-surface higher-pressure headshell contact area, predominately non-parallel and asymmetrical shaping, phase-interference resonance-controlling mechanism, and body threaded directly for mounting screws
Cartridge mounting screws: 2.6 mm 0.45 pitch JIS standard
Distance from mounting holes to stylus tip: 9.5mm
Cartridge weight (without stylus cover): 11.6g
Recommended tracking force: 1.65 ~ 1.78g (1.72g recommended)
Recommended load directly into MC phono input: Determine by listening,
Recommended load via step-up transformer: Use a step-up transformer designed for 2 - 3 ohms cartridge impedance. The transformer output must be connected to standard 47kohm MM-level RIAA input, preferably via short, low-capacitance cable
Recommended tonearms: High-quality pivoted or linear tangential tonearms with rigid bearing(s), adjustable anti-skating force, preferably VTA