The Model 7 was a breakthrough in preamplifier design at its introduction in 1958. Largely engineered by Saul Marantz, the Model 7 offered dual phono inputs, two tuner inputs, and in a stroke of prescience, a “TV” input. In 1958. The front panel featured an array of four knobs on each side flanking four toggle switches. The right-side knobs provided independent bass and treble adjustment for each channel. The left-side knobs allowed source selection, volume, balance, and stereo/mono modes. The center toggle switches were tape monitor, a three-position phono equalization switch (78, Columbia, RIAA), and high- and low-pass filters. Minimalism in preamplifier design had clearly not yet taken hold.

The model number was not on the front panel, just the inscription “Marantz Stereo Console,” with the word “Stereo” in fancy script. The front-panel layout was created by Mr. Marantz, who had a background in drafting, graphic arts, and industrial design.

The circuit was based on three 12AX7s per channel. The phonostage was particularly innovative in its three-stage circuit, which was soon dubbed “the Marantz circuit.” Phono gain was 64.5dB (22.5dB line). The frequency response was 20Hz–20kHz +/- 0.5dB. Noise was -80dB with a 10mV phono input. The unit weighed 20 pounds.

In production for more than 12 years, the Model 7 was the most popular preamplifier of its time, with sales of more than 130,000 units—a staggering number considering its price of $385 ($3211 in 2016 dollars). Throughout its 12-year run, the Model 7 remained essentially the same as the prototype, with only minor production updates over the years. The Model 7C simply signified that the chassis was mounted in a wooden case.