Onkyo 2500-II (circa 1979)
The Onkyo 2500-II - styled TX-2500-II in the period literature - is an AM/FM stereo receiver from Onkyo's late-1970s lineup. Almost everything documented about it comes from one place: Audio magazine's February 1979 test report (p.74, p.79). Beyond that review, the record is thin. No production years, original price or sales history are documented, and the model is easily confused with its sibling, the TX-2500.
Onkyo's specification sheet, reproduced in that review, rated the FM tuner's usable sensitivity at 11.2 dBf mono and 19.2 dBf stereo, with 50-dB quieting at 17.2 dBf mono and 37.2 dBf stereo. FM signal-to-noise was claimed at 65 dB mono and 60 dB stereo. The AM section was rated at 25 µV sensitivity with 45 dB image rejection. Phono overload was specified at 150 mV (1 kHz), with phono S/N of 85 dB and high-level S/N of 95 dB.
Audio's bench measurements treated the amp section well. The phono preamp held flat to within ±0.1 dB from 30 Hz to 15 kHz. Phono input sensitivity measured 0.35 mV for 1-watt output, and high-level input sensitivity measured 24 mV for the same output. The reviewer considered the amplifier section the best part of the unit and singled out its tonal quality for praise. The tuner came off second-best in that internal match-up, but the reviewer still thought it respectable.
Known specs at a glance:
- Type: AM/FM stereo receiver
- FM usable sensitivity (rated): 11.2 dBf mono / 19.2 dBf stereo
- FM 50-dB quieting (rated): 17.2 dBf mono / 37.2 dBf stereo
- Phono overload (rated): 150 mV at 1 kHz
- Measured phono response accuracy: ±0.1 dB, 30 Hz–15 kHz
- Measured input sensitivity (1 W out): 0.35 mV phono / 24 mV high-level
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