Key Features
The 4020A’s FM section is built around three ceramic intermediate frequency filters rather than the one or two typically found in budget tuners of its era. The use of three filters improves adjacent-channel selectivity — the ability to receive a desired station cleanly when a stronger station occupies an adjacent frequency — which was already a practical concern on the increasingly busy FM dial of the early 1980s. The linear-phase response of the filters also contributes to low distortion, particularly in stereo. Stereo decoding is handled by a phase-locked loop IC, which NAD chose for its low intermodulation between high audio frequencies and the 19kHz stereo pilot tone — an area where earlier multiplex decoder designs could introduce audible artefacts. A phase-compensated crosstalk cancellation circuit is additionally employed to maintain stereo separation at both low and high frequencies, not only at the 1kHz midpoint typically specified by manufacturers.
Tuning is analogue, using a large flywheel-coupled tuning knob that provides a smooth and stable action. Rather than a conventional moving-coil tuning meter — which adds cost and can be fragile — the 4020A uses a three-LED tuning indicator: two amber LEDs illuminate when the tuner is offset to either side of a station, and a green LED indicates optimal tuning within 0.025MHz of the station frequency. This is a simple and reliable arrangement that works effectively in practice. Mono and muting switches are provided on the front panel; the mono switch is useful for improving signal quality on weaker or more distant stations where the stereo decoder would otherwise introduce noise, and the muting switch suppresses inter-station noise during tuning.
The rear panel provides both 75Ω and 300Ω FM aerial connections, as well as the AM aerial terminals for an external AM loop aerial in addition to the fitted rod. A de-emphasis switch selects between 25µs, 50µs, and 75µs settings — the 50µs setting is correct for UK and European FM broadcasts, while 75µs is the standard for North American broadcasts. Line outputs are via RCA phono sockets. The 4020A was designed to be used with a proper external FM aerial for best performance, and buyers in areas of strong FM signal coverage will find a simple half-wave dipole entirely adequate, while those in weaker reception areas may benefit from a rooftop aerial and low-loss downlead.
Technical Specifications
(Source: HiFi Engine; cross-referenced with NAD 4020A manufacturer’s specification sheet via ManualsLib and Radiomuseum.org)
- Type: AM/FM stereo tuner
- Tuning Bands: FM, MW (AM)
- Tuning Scale: Analogue
- FM Tuning Range: 88–108MHz
- FM Sensitivity (Mono, -30dB THD+N): 10.9dBf (1.9µV / 75Ω)
- FM Sensitivity (Mono, 50dB S/N): 16dBf (3.5µV / 75Ω)
- FM Signal to Noise Ratio: 70dB
- FM Distortion: 0.3%
- FM Selectivity: 65dB
- FM Frequency Response: 30Hz–15kHz
- AM (MW) Usable Sensitivity: 250µV
- AM Selectivity: 30dB
- AM Image Rejection: 50dB
- AM IF Rejection: 40dB
- De-emphasis: Switchable — 25µs, 50µs, 75µs
- FM Aerial Connections: 75Ω (coaxial) and 300Ω (screw terminals)
- AM Aerial: Rod aerial fitted; external loop aerial terminals on rear
- Line Output: RCA phono sockets
- Dimensions (W × H × D): 420 × 96 × 240mm
- Weight: 4.2kg
- Year of Production: circa 1980
- Country of Origin: Taiwan
Why Buy From Us
With over 40 years of experience in the Hi-Fi industry, we are well placed to assess and test equipment of this type. Every item we list is fully inspected and tested before sale — this unit was checked by Andrew in our workshop.
When you buy from us you can expect:
- Full inspection and testing prior to listing — not simply a visual check
- A 3-month guarantee on every item we sell
- Transparent descriptions with no omissions
- Professional packaging to ensure safe delivery
- After-sales support available by phone or email should you have any questions
Summary
A fully functional example of NAD’s well-regarded 4020A AM/FM stereo tuner, a product that built its reputation on measured engineering and consistent real-world performance rather than on elaborate features or headline specifications. The triple IF filter configuration, PLL stereo decoder, and phase-compensated crosstalk cancellation delivered sound quality that compared favourably with considerably more expensive tuners of the period. Cosmetic marks on the top cover are consistent with age and reflected in the grading. The AM rod aerial is fitted; a suitable FM aerial will be required separately for FM reception. This is a single-unit listing. Please feel free to get in touch with any questions prior to purchase.
