NAD 6240 (1986–1987/1989)

Production dates are uncertain. Some sources say 1986-87, others 1986-89. A 1987 German brochure confirms the deck was on the market that year, and the original retail price was approximately 600 DM. It was made in Japan and runs on 120V AC.

The 6240 has adjustable bias and playback trim, which the more basic NAD decks don't. That lets the user fine-tune the deck for Type I, II, and IV tapes, and NAD's own setup instructions recommend calibrating with a 12 kHz test tone. It also has Dolby B and C noise reduction, as noted in HiFI-Stereo (1989, p.99). Inside, the main capstan is driven by a flat section drive belt. Those belts age, so it's a common replacement part now.

Electrical specifications like frequency response, THD, and signal-to-noise ratio are not documented in any source found so far. A service manual exists, and spare belts are still available.