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Lyra's Helikon Mono
Cartridges by Lyra
The Lyra Helikon
Mono is a low-impedance moving coil cartridge that has been designed specifically to play monaural LP records in the highest fidelity possible.
Much great music is available only as monaural recordings, and these outstanding performances are clearly deserving of top-quality playback. Also,
many of the cutting lathes used to master monaural LPs were capable of a wider frequency response and a greater dynamic range than stereo lathes. In many
ways, therefore, monaural LPs benefit more from quality reproduction techniques than stereo LPs do.
The Helikon Mono shares many of the advanced
structural elements as the stereo Helikon, including the one-piece machined alloy body, the full-enclosure removable stylus guard, the non-conductive front
carrier, and the polepiece-less, direct flux dual-disc magnet system. However, the Helikon Mono has a completely unique cantilever/coil/stylus assembly, and
the electrical system has been designed and optimized for mono playback.
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 Helikon Mono has therefore been designed to be completely
insensitive to the vertical axis, which works wonders for the signal/noise ratio without causing any problems. The Mono's coil former is a square permeable
plate which is 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.
The Helikon Mono has been
designed with two totally separate monaural coils, since most monaural cartridges are in fact used with stereo amplifiers and stereo speakers. The separate
coils also help avoid possible ground loops and hum problems that could otherwise be caused if a single coil (as with most other monaural cartridges) is fed
into a stereo two-channel amplification system, thereby tying the two channels together electrically.
If the output from one of the Helikon
Mono's signal coils is connected to the Left channel input of your phono preamp while the other coil is connected to the Right channel input, each channel
of your stereo system will be fed an identical monaural signal, and each of your two speakers will therefore produce an equal mono signal.
preamp does not have a balance control or separate attenuators for each channel, the Helikon Mono's coil arrangement will automatically result in a single
mono "image" located centrally between your speakers. If your stereo preamp incorporates a balance control or separate attenuators for each
channel, turn down either channel and you will be able to hear the mono signal from the other speaker. And for pure monaural playback with a single amplifier
and a single speaker, only one of the two channels (one pair of the cartridge's output pins) needs to be connected to the preamp's phono input.
Feel free to experiment and use the connection method that provides the best sonic results in your system.
The cantilever for the Helikon Mono
is a solid boron rod, and the stylus profile is a line contact, which is unusual for a mono cartridge. However the stylus profile (3 x 70 micrometers, as
opposed to 3 x 30 micrometers for the stereo Helikon) has been chosen to provide optimal playback results on monaural records rather than stereo LPs.
The output impedance of the Helikon Mono is 3 ohms, and the output voltage is 0.25 mV (5.0 cm/sec. RMS horizontal movement measured at 1kHz).