Harman Kardon HK-680i
Documentation on the Harman Kardon HK-680i is thin. What the record shows: this was a substantial integrated amplifier rated at approximately 110 watts per channel, with a frequency response spec of 10 Hz–100 kHz ±3 dB and a signal-to-noise ratio of 105 dB. It was a hefty piece — 20.3 kg — and measured 440(W) x 159(H) x 417(D) mm. A classified ad in Audio (June 1983, p.105) listed a used HK-680i at $500, alongside other Harman Kardon components of the era.
A period equipment listing in HiFI-Stereo (1981, p.34) described an "hk680i AM-FM Stereo Receiver" with 125 W/ch continuous output into 8 ohms from 20–20,000 Hz at 0.05% THD, plus two-speaker switching, tape monitoring and dubbing, and a subsonic filter. That same listing appears in a second chunk from the same publication. However, the Archive's fact sheet identifies the HK-680i as an integrated amplifier — not a receiver — and gives a different power figure (110W + 110W). The discrepancy may reflect a difference between the amplifier-only model and a receiver variant, or an error in the period OCR. Given the conflicting identity, the amplifier specs from the fact sheet are the safer record.
Beyond that, almost nothing else is documented: no production years, no original price, no circuit details, and no independent test reports beyond the fragment above. What survives suggests a high-power, wideband Harman Kardon integrated amp from the early 1980s, built to the brand's usual standard of heft.
- Power output: approx. 110W + 110W
- Frequency response: 10 Hz–100 kHz ±3 dB
- S/N ratio: 105 dB
- Dimensions: 440(W) x 159(H) x 417(D) mm
- Weight: 20.3 kg
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