Onkyo TX-2500MKII (1978–1981)
A late-1970s stereo receiver with advanced tuner features and a distinctive 1978-era redesign, noted for strong build and well-regarded sound.
Overview
The Onkyo TX-2500MKII is a stereo receiver produced from 1978 to 1981, representing the second model in a four-receiver lineup from Onkyo during that period. It was positioned as a mid-to-high-tier model, offering improved preamp and tuner specifications over earlier versions, along with increased output power. Known for its "Accutouch" tuning system, PLL MPX decoder, and servo-locking tuner, the unit combines precise FM/AM reception with a hands-on tuning experience that automatically fine-tunes once released. Owners have described it as an excellent-sounding, underrated receiver that often compares favorably to contemporary models from Marantz and Pioneer.
Specifications
| Years of manufacture | 1978 - 1981 |
| Original price | $450 |
| Power Output | 2x 100W (DIN) |
| THD | 0.5% at rated power |
| IMD | 0.5% at rated power |
| Damping factor | 40 (8 Ohm, 1 kHz, 10W output) |
| Power bandwidth | 2 Hz ... 60 kHz (± 1 dB) |
| Frequency response | 20Hz to 30kHz |
| Bass control | ±12 dB at 100 Hz |
| Treble control | ±10 dB at 10 kHz |
| High filter | 6 kHz |
| S/N ratio | 85 dB |
| Tuning range (FM) | 87.5–108 MHz |
| Tuning range (AM) | 530–1605 kHz |
| Usable sensitivity (FM) | 2 µV (mono) |
| IF frequency (FM) | 10.7 MHz |
| Capture ratio | 2 dB |
| Image rejection (FM) | 45 dB |
| IF rejection (FM) | 80 dB |
| Adjacent channel attenuation (FM) | 60 dB |
| Stereo separation (1 kHz, FM) | 37 dB |
| Pilot cancellation | 60 dB |
| Componentry | 1 FET, 54 transistors, 6 ICs, 47 diodes |
| Dimensions | 48.3 x 16 x 37.1 cm |
| Weight | 12 kg |
Design
The TX-2500MKII features a 1978-era visual redesign with enhanced internal specifications, particularly in the preamp and tuner sections. Its tuner uses a 3-gang varicap, two IF amplifier stages, 4-element ceramic filters, and an Onkyo-made low-pass filter. The "Accutouch" tuning knob temporarily disables locking circuits for fast manual tuning and re-engages servo-locking to fine-tune and illuminate the TUNED indicator automatically. The unit includes one-step on/off muting and is built around a beefy transformer for robust power delivery.
Context
The TX-2500MKII was the second of four receivers in Onkyo’s 1978–1980 range, sitting alongside models like the TX-1500MKII. It was marketed as a technically advanced receiver with superior tuner performance and increased output, targeting audiophiles seeking precision and power in a single chassis.
Market
Listed originally at $450, the TX-2500MKII has appeared in recent sales around $200, with some calling it a steal at that price. It is considered somewhat rare and is regarded as a desirable, collectible receiver from the late 1970s and early 1980s. Service and owner’s manuals are available, though replacement parts like tuner meters and dial lamps can be difficult to source.
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