Marantz Model 7 Tube Preamp

Revered by modern designers of tube equipment, this classic Marantz Model 7 tube preamplifier was in production from December 1958 though 1965.

My dad was the original owner.  This preamp was part of his prized and meticulously maintained stereo system.

 It was largely engineered by Saul Marantz himself, as his chief engineer, Sid Smith, was busy with other projects.  Mr. Marantz also created the striking front panel -the model number is not on the front panel, just the inscription “Marantz Stereo Console,” with the word “Stereo” in fancy script. 

 A breakthrough in preamplifier design, the Model 7 was the first to use switched tone control arrays using discrete capacitors and resistors. They were designed to be completely out of the circuit in their flat positions. The bass and treble curves were chosen to provide minimal midrange frequency response alteration. Each preamplifier was carefully tested at the factory and supplied with an individualized performance card with measurements.

 It offers dual phono inputs, two tuner inputs, and a “TV” input. The front panel has four knobs on each side flanking four toggle switches. The right-side knobs provide independent bass and treble adjustments for each channel. The left-side knobs allow source selection, volume, balance, and stereo/mono modes. The center toggle switches are a tape monitor, three-position phono equalization switches, and high- and low-pass filters. 

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