Onkyo SV-909PRO (circa 1992)
Onkyo's Integra flagship claimed a world first - a fully digital Dolby Pro Logic decoder - and backed it with seven discrete amplifiers and three separate power transformers.
Overview
Onkyo's own 1992 literature made the claim plainly: the Integra TX-SV909PRO was the world's first full digital Dolby Pro Logic receiver. The argument was technical. Every Pro Logic receiver before it, Onkyo's copy pointed out, did its decoding in the analog domain. The TX-SV909PRO decoded entirely in digital, which the company said bought improved signal-to-noise ratio, lower distortion, and greater channel separation. Channel separation is the one that counts. Pro Logic depends on keeping dialogue pinned to the center and effects steered to the surrounds, and the analog decoders of the day were the weak link there.
The second world-first claim is the more interesting one for collectors. Onkyo teamed up with Nimbus Records to make the TX-SV909PRO the first receiver to carry the Ambisonic Surround Sound System. It is a decoding scheme built for music rather than film, recreating a 360° soundstage with what the company described as a smooth front-to-rear transition. Ambisonic recordings, encoded from a single-point microphone array, decode to four channels with the same left/right relationships as the original session. Onkyo's literature name-checked Nimbus releases as the software to hear it with. It was a bet on a format that never reached mass adoption, which is why the receiver is a curiosity now.
Physically, this is a heavy piece of Integra-series construction. The amplifier section has seven discrete power amplifier sections, one per channel, fed by three independent heavy-duty power transformers. Onkyo's own copy is blunt about why. IC-based output stages would have been cheaper and simpler, and the company framed the discrete, multi-transformer layout as a deliberate sacrifice of cost for sonic quality and construction integrity. The center channel is driven at the same power level as the front mains - Onkyo's literature cites 110 watts to the center - so dialogue comes through at full strength rather than as a diluted mix of the left and right channels. The seven-channel topology also allows true multiple-room, multiple-source operation: full five-channel Pro Logic in the main room while a second zone runs a stereo CD independently.
The front panel centers on a large status window that reports the receiver's complete operating state, much of it in small text. The tone and balance controls show up as bar graphs rather than simple indicators. HiFI-Stereo (November 1992, p.60) filed the TX-SV909PRO as an audio/video receiver in its test reports, with Julian Hirsch handling the bench work. Around the same period, Onkyo's advertising in Audio (July 1993, p.3) leaned hard on the cinema angle, promising sound effects that reach beyond the confines of the listening room. That is marketing copy, not a measured verdict.
No production years, original retail price, or full manufacturer specification sheet for the SV-909PRO has surfaced in the archive. What survives is Onkyo's own 1992 Integra literature and the period review coverage.
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