Yamaha C-70 and N-70
Vintage Yamaha Natural Sound set comprising the C-70 preamplifier and the M-70 power amplifier, for a high-end separates hi-fi system.
Description
The Yamaha C-70 and M-70 duo forms a set of vintage separate electronics belonging to the marque's Natural Sound series. On one side, the C-70 control preamplifier manages sources and settings; on the other, the M-70 power amplifier handles pure amplification of the signals to the speakers. This two-unit architecture was characteristic of high-end hi-fi systems of the 1980s.
The C-70 preamplifier features fully independent MM and MC phono stages, allowing two cartridges of different types to be connected without compromise on either. It also has an ERE equaliser paired with a 12 dB per octave subsonic filter, useful for eliminating parasitic infrasound arising from vinyl playback, as well as a two-band parametric equaliser for fine-tuning tonal balance. The Varigain volume control rounds out this set of controls designed for analogue listening.
The M-70 power amplifier is built on ZDR (Zero Distortion Rule) technology paired with Linear Transfer Bias and the X Power Amplifier system, solutions developed by Yamaha to limit distortion and improve the linearity of the amplified signal. The A/B speaker selectors, with independent level controls on the left and right channels, allow two pairs of speakers to be driven with separate adjustment for each.
This set is aimed at vintage hi-fi enthusiasts wishing to put together a period separates system, particularly those with a phono source using several MM or MC cartridges, or wishing to make use of more advanced tone and filtering controls than those found on a typical integrated amplifier. The ability to drive two pairs of speakers with independent adjustment also suits installations with two listening zones.
Technical specifications
| Phono stages | Independent MM/MC |
| Equaliser | ERE with 12 dB/oct subsonic filter |
| Tone control | 2-band parametric |
| Volume | Varigain |
| Amplification technology | ZDR (Zero Distortion Rule) |
| Bias | Linear Transfer Bias |
| Amplification system | X Power Amplifier |
| Speaker outputs | A/B selectors with independent left/right levels |
| Series | Natural Sound |
What to check before buying used
When buying such a used set, it is worth checking the condition of the potentiometers, particularly the Varigain volume control and the parametric equaliser, which are often prone to crackling after several decades of use. The capacitors in the M-70 power amplifier, a component sensitive to ageing, also deserve particular attention, as does the proper operation of the A/B speaker selectors and the MM/MC phono stages, which should deliver a clean signal without excessive background noise.
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