Yamaha A-100X

The Yamaha A-100X is a high-power integrated amplifier from the company's A series. The paper trail is thin for a unit of this class. What survives is two database listings that agree the model exists and little else. No production years and no original price have turned up in the archive so far. The amplifier appears in the annual index of Audio magazine's 1976 Equipment Profiles section, which confirms it was reviewed in the period press (Audio, December 1976, p.120).

The listings do show a serious, heavy amplifier. HiFi Engine records 120 watts per channel into 8 ohms, a damping factor of 100, and total harmonic distortion of 0.005%. Hifi-wiki says 130 watts into 8 ohms, a damping factor of 150, and 0.003% THD. The two sources also disagree on dimensions (435 x 146 x 438mm vs. 435 x 164 x 438mm - the height is the sticking point) and weight (14.7kg vs. 14.3kg). There is no service manual or third source to break the tie, so no winner gets picked here. Treat the figures as "roughly 120-130W/ch, roughly 14-15kg."

Where the sources don't conflict, the picture is cleaner. The A-100X's phono stage accepted both moving magnet (2.5mV sensitivity, 94dB signal-to-noise) and moving coil (0.15mV, 80dB) cartridges. That put it above typical integrated amps of its generation. Line input sensitivity was 150mV with a 100dB signal-to-noise ratio. HiFi Engine lists frequency response as 20Hz to 20kHz, while hifi-wiki gives the wider 10Hz to 100kHz. Neither includes a tolerance spec. The wider figure likely reflects the extended bandwidth rather than the audible-band response.

Beyond that, the record is bare. No circuit topology, no connector count, no tone control details, no owner impressions. The A-100X appears to have been a flagship-class integrated amp from Yamaha's A series, but exactly where it sat in that lineup, and when, is undocumented. A brochure or manual scan would close the largest gap on this page.

Known specs at a glance:

- Integrated amplifier, Yamaha A series

- Power output: 120-130W/ch into 8Ω (sources conflict)

- THD: 0.005% or 0.003% (sources conflict)

- Damping factor: 100 or 150 (sources conflict)

- Phono: MM (2.5mV) and MC (0.15mV) inputs

- Dimensions: 435 x 146-164 x 438mm (sources conflict)

- Weight: 14.3–14.7kg (sources conflict)