Yamaha CX-630 (late 1970s)
Little is documented about the Yamaha CX-630 in the period press. The model does not appear to have been widely reviewed, and what survives comes mostly from owner accounts and the broader context of Yamaha's CX series. The record shows the CX-630 was the entry-level preamplifier in a three-model line that also included the CX-830 (mid-range) and the CX-1000 (flagship). The line was released in the late 1970s as part of Yamaha's effort to compete with separate preamp/amp combinations from Pioneer, Kenwood, and Sansui.
The preamplifier section is a discrete transistor circuit with dual-mono construction for better channel separation. Yamaha gave the CX-630 a separate power supply for the phono stage, Pure Direct switching that bypasses unnecessary circuitry in the signal path, and a built-in headphone amplifier. On paper, total harmonic distortion is rated at 0.005% at line level. The MM phono section offers 40 dB of gain with an input sensitivity of 2.5 mV and the standard 47 kΩ impedance. The line-level input is specified at 150 mV / 50 kΩ.
Owners commonly pair the CX-630 with the Yamaha M-60 power amplifier. They describe the combination as quiet, clean, and musical, with a dead-silent background and a phono stage that punches above its position in the lineup. The Pure Direct function is frequently cited as making a real difference in signal clarity. On the used market, prices range from roughly $200 to $500 depending on condition and whether original packaging is included. Watch for aging capacitors - all units of this vintage will eventually need servicing - and a scratchy balance control. Parts are increasingly hard to find, though some NOS components still turn up on auction sites.
No original retail price, production years beyond "late 1970s," or dimensions have been documented for the CX-630. Period press coverage is sparse. HiFI-Stereo (February 1991, p.150) discussed the CX-830 as a companion piece for high-end amplification, but the CX-630 itself appears to have received little magazine attention at the time.
Known Specifications
- Type: Control amplifier (preamplifier)
- Total harmonic distortion: 0.005% (line level)
- Line input sensitivity/impedance: 150 mV / 50 kΩ
- Phono gain: 40 dB (MM)
- Phono input sensitivity: 2.5 mV
- Phono input impedance: 47 kΩ
- Phono frequency response: RIAA standard (±1 dB)
- Features: Pure Direct switching, separate phono power supply, built-in headphone amplifier, dual-mono discrete circuitry
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