The Marantz 4240 is one of their Quadraphonic offerings in the 4xxx series. The Model 4240 is a high quality stereo + quadradial receiver and incorporates Marantz’s exclusive Vari-matrix circuit which simulates 4-channel sound from normal 2-channel stereo programs, and is capable or reproducing 4-channel sound from any matrix encoded source. It can also reproduce any discrete 4-channel program as well as regular stereo and monaural programs. An optional plug-in decoder adapts the 4240 for any specific matrix system such as Columbias SQ.
The 4240 debuted in 1974 and was on the market until 1978. The receiver had a retail price of $599.95. It had options for an SQA1 Quad Decoder and the SQA2 Quad Decoder as well as the RC4 Remote Control. Of course you could also purchase the WC-22 wood cabinet. With the mode selector you could choose between Mono, 2 Channel, Discrete, Vari Matrix or SQ Decoder modes. The 4240 also has a Dolby selector on the front panel.
The Gyro Touch tuning flywheel was used in this model as it was in many of the Marantz models of that era. While not overly powerful the 4240 put out 40 watts per channel in 2 channel mode and 17 watts per channel in quad mode. The 4240 is not really known as one of Marantz’s better receivers but, of course, that is relative to their other high quality models. It doesn’t have a protection relay in it so your speakers and the outputs are only protected by fuses which isn’t optimal. The output transistors are TO-66 case transistors which are not really sufficient and are no longer available either.
Despite its shortcomings the Marantz 4240 Quadradial does have followers. Of course, any quad collector would want one. They sell for about $250.00 to $400.00.