Onkyo Integra 732 (c. 1971)
The Onkyo Integra 732 is a pre-main amplifier, an integrated amp, from Onkyo's early-1970s Integra line. Several sources date it to around 1971, though the exact production span isn't firmly pinned down. The single spec sheet on file lists a price of ¥100,000 at introduction. The 732 belongs to the 1970-73 generation of Onkyo designs, which used structural wood in the chassis, sheet-aluminum front panels, and lathe-turned cylindrical knobs with knurling. No plastic inserts, no recessed controls.
Spec-wise, the 732 is serious. Rated output is 56W + 56W into 8 Ω at 1 kHz, with dynamic power claimed at 150W (IHF, 8 Ω). Total harmonic distortion is listed at 0.1% or less at rated output, dropping to 0.03% at 10W. Frequency response spans 10 Hz to 80 kHz, with power bandwidth to 100 kHz (IHF, −3 dB, 0.2%). The damping factor is a healthy 100 (DC–20 kHz), and it handles loads from 4 to 16 Ω. It weighs 12.5 kg and measures 437 × 136 × 355 mm.
The preamp section is where the 732 gets interesting for collectors. Onkyo called the circuit “Pure Con” — all stages directly connected, with a full-stage direct-coupled differential amplifier in the main section. It has a built-in MC head amp, which was genuinely forward-thinking for 1971; Phono inputs are comprehensive: Phono 1 accepts 2 mV at 30 kΩ or 50 kΩ, Phono 2 offers MM at 2 mV/50 kΩ and MC at a sensitive 83 µV/80 Ω. There’s also a MIC input (1.8 mV/50 kΩ). The tone controls are stepped, 2 dB per detent, with bass ±10 dB at 30 or 100 Hz and treble ±10 dB at 10 or 30 kHz, plus selectable turnover frequencies (125 Hz/400 Hz bass, 2.5 kHz/8 kHz treble) and cancel positions. RIAA deviation is within ±0.5 dB from 30 Hz to 15 kHz.
Owners on forums describe it as working well, with good power and rich sound. One StereoNET forum voice put it this way: the 732 "ticked all the boxes, from a technical standpoint and was way ahead of most amplifiers available at the time. It was also rather well priced." No formal period reviews have surfaced in the archive, and market pricing data is thin.
One eBay listing calls the 732 a "power amp," while the audio-database spec sheet identifies it as a pre-main amplifier. The spec sheet is the more authoritative source. The full preamp section (tone controls, phono stages, MIC input) confirms it's an integrated amplifier, not a bare power amp.
Known specs, in brief:
- Rated output: 56W + 56W (8 Ω, 1 kHz)
- Dynamic power: 150W (IHF, 8 Ω)
- THD: 0.1% or less (rated output), 0.03% or less (10W)
- Frequency response: 10 Hz – 80 kHz
- S/N ratio: 110 dB or more (IHF A)
- Damping factor: 100 (DC – 20 kHz)
- Built-in MC head amp (83 µV/80 Ω sensitivity)
- Dimensions: 437 × 136 × 355 mm; 12.5 kg
- Original price: ¥100,000 (c. 1971)
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