Optonica SM-4646 1978-1979 - Nero

Sharp Optonica SM‑4646 — the flagship amplifier

The SM‑4646 was a true powerhouse for its time: the absolute top‑of‑the‑line model of the Optonica series, built with an almost audiophile philosophy by the standards of the era. It features three dedicated transformers (“Delta Power”): one reserved for the pure Class‑A pre/driver stage, and two independent ones — one per channel — for the output stages in a dual‑mono configuration, ensuring maximum channel separation and stability.

Power output: 70W + 70W RMS into 8Ω, up to 90W of peak musical power. Damping factor: above 50, for precise loudspeaker control. Volume control: 4‑section attenuator (“4‑gang”), a superior solution compared to standard potentiometers. Pre/power section: separable.

It was awarded the French Laurier d’Or at the time for functionality, design, and performance. A rare and sought‑after piece — unsurprisingly: limited production and the demanding construction (three transformers instead of the usual single one) make it hard to find today, especially in conditions like these.

Specialized magazines of the late ’70s (such as HiFi Jahrbuch, Audio, Stereo Review, Radio Electronics) reported that:

• The Optonica SM‑4646 was considered superior to the average Pioneer integrated amplifiers in the same price range, especially thanks to:
• dual‑mono power supply with 3 transformers,
• Class‑A preamp section,
• advanced phono stage,
• very high real‑world power output,
• 16 kg build quality.

Comparative tests of the time placed it in the high‑end segment, often above more commercial models from Pioneer, Kenwood, and Sony. Some magazines described it as an “underrated top performer”, penalized only by the limited market presence of the Optonica brand.

Therefore, what I’m offering is a rare and desirable piece — not by chance: limited production and the demanding construction (three transformers instead of the standard single one) make it difficult to find today, especially in conditions like these.

Preferably sold together with the ST‑1616 tuner, which you can find in my other listing. Why buy them together: the SM‑4646 amplifier is a model that is hard to find on the market, especially in cosmetic and functional condition like this. The amplifier + tuner pair is already matched both aesthetically and functionally, making it ideal for anyone who wants to recreate a coherent vintage hi‑fi setup without having to search for individual components. If purchased together, I’m open to considering offers.

Perfect working order, checked by a technician, used daily without any issues. It shows only normal signs of age, fully consistent with the piece’s vintage.