Onkyo TX-4500II (1975)
The Onkyo TX-4500II is a stereo receiver from 1975. It was part of Onkyo's push into the high-fidelity market, and it offered performance, reliability and advanced features for its time. Vintage audio collectors still go after it for its warm sound and heavy construction.
Design and Build Quality
The Onkyo TX-4500II features a classic 1970s aesthetic with a brushed aluminum front panel, large rotary knobs, and a minimalist layout that prioritizes usability. The chassis is built with a heavy-gauge steel frame, contributing to its substantial weight and excellent resistance to vibration and electromagnetic interference. This mechanical stability enhances audio clarity and reduces signal noise—hallmarks of high-end receivers from this period.
The front panel has a large VU meter flanked by the power and input selectors, so you can watch audio levels as they change. The tuning dial is precise and has a smooth action, which reflects the quality of the internal potentiometers and mechanical parts. Onkyo used durable switches and gold-plated connectors throughout.
Technical Specifications
The TX-4500II is a stereo AM/FM receiver combining a preamplifier, power amplifier, and radio tuner in a single chassis. It delivers 70 watts per channel into 8 ohms with less than 0.08% total harmonic distortion (THD), a strong specification for its era. This power output is sufficient to drive a wide range of passive speakers, including inefficient vintage models, without strain.
Frequency response is rated from 20 Hz to 20 kHz, ±1 dB, ensuring full-range audio reproduction that captures both deep bass and crisp highs. The signal-to-noise ratio is an impressive 86 dB, achieved through careful circuit layout and shielding. Input sensitivity is 2.5 mV for the phono input and 150 mV for line-level sources, making it compatible with both moving magnet cartridges and modern line-level devices.
The receiver features multiple input options: two phono inputs (MM), three line inputs, a tape input, and a dedicated tuner input. It also includes a tape monitor function, allowing users to switch between live and recorded audio seamlessly. The inclusion of both front and rear panel speaker terminals supports bi-wiring or dual speaker setups, a feature uncommon in mid-tier receivers of the time.
Audio Performance
The TX-4500II is known for a warm, musical sound. That is often credited to its discrete transistor amplifier stage and analog circuitry. Where modern digital amplifiers aim for clinical accuracy, the TX-4500II adds a subtle richness to vocals and instruments, which suits jazz, classical and rock recordings.
The phono stage is well regarded. It has low noise and accurate RIAA equalization, so vinyl listeners can use the receiver without an external phono preamp. The FM tuner is a high-sensitivity design with a local/distance switch and stereo/mono selection, and it pulls in clear reception even where the signal is weak. The AM band is well filtered, which keeps interference down and gives crisp midrange.
Sound staging is wide and well defined, with precise instrument placement and natural depth. The bass is tight and controlled, without the boominess common in lower-tier receivers of the era. High frequencies are smooth and not harsh.
Features and Functionality
The TX-4500II has dual VU meters. They help you set input levels and avoid distortion. The meters can be switched between monitoring the left/right channels or total output.
The receiver has a loudness contour switch. It boosts bass and treble at lower volumes to make up for the human ear's reduced sensitivity at those frequencies. This was common in 1970s receivers, and it helps in quiet rooms.
A balance control lets you trim left/right channel output, which is handy in rooms with asymmetrical speaker placement. The bass and treble tone controls adjust over a ±12 dB range. They are buffered to prevent signal degradation when bypassed.
The TX-4500II also has a muting switch and a headphone output on the front panel, which not every receiver in this class offered. The headphone amplifier can drive high-impedance headphones, so it works fine for direct listening.
Historical Context and Legacy
In the mid-1970s, manufacturers like Onkyo, Pioneer, Marantz and Sansui competed hard on performance, features and value. The TX-4500II was positioned as a premium model, up against offerings from Yamaha and Sony.
Many of its contemporaries used integrated circuits. The TX-4500II uses discrete components throughout, which many audiophiles believe gives it better sound. It also makes the receiver easier to service today, since failed transistors or capacitors can be replaced individually.
The TX-4500II has developed a cult following over the years, and it sells well on the secondhand market. It is not as rare as some Japanese "unicorn" receivers, but it is getting harder to find in excellent condition because of age-related wear.
Restoration and Maintenance
Like all vintage electronics, the TX-4500II needs periodic maintenance. Common problems are dried-up electrolytic capacitors, worn potentiometers and degraded insulation on internal wiring. A full recap (replacing all the electrolytic capacitors) is often recommended for units that have been stored for long periods.
Cleaning the controls with contact cleaner can restore smooth operation and clear up channel imbalance or crackling. Checking the speaker relay and bias settings helps performance and protects the speakers.
When properly maintained, the TX-4500II can hold its own against modern amplifiers on sound quality, especially with analog sources like vinyl and FM radio.
Conclusion
The Onkyo TX-4500II stands as a testament to 1970s audio engineering, combining robust construction, excellent sound quality, and thoughtful design. It appeals to both audiophiles seeking analog warmth and collectors who appreciate vintage electronics. While it lacks modern conveniences like digital inputs or remote control, its pure analog signal path and timeless performance ensure it remains relevant in today’s high-fidelity landscape.
For anyone building a vintage audio system or restoring classic gear, the TX-4500II makes a good centerpiece for vinyl records and FM broadcasts.
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