Marantz Audio Consolette (1955)

 The Audio Consolette is a fine electronic instrument, specifically designed to be the central control for music reproducing systems of the highest calibre. Components are of a quality rarely used in commercial equipment. For example; eighteen  of the resistors used are of low-noise carbon-deposit type; Allen-Bradley potentiometers are used throughout. A high-Q toroid is the basic component of the Sharp Cutoff Filter. Terminal board construction is used in the main assembly which, with its associated tubes, is floated on soft rubber shock mounts. The Audio Consolette is constructed on two chassis, the power pack being remote to keep the transformer, etc., away from the main unit.

  

The marantz preamplifier is a noteworthy example of the school of thought which combines the rugged design of telephone equipment, the English spit-and-polish practices, and terminal-panel arrangements of components used in military gear.

 These views of the Marantz preamp show unusual attention to construction detail, precision workmanship,  and case of access to all the components. The separate unit containing the power transformer and rectifier. One the top are three receptacles for plugging in other equipment, all of which can be turned on and off from switch on the front panel of the preamplifier, via the power cable

 Electrically, this preamp is of very conservative design as to tolerances and the liberal use of precision components. Marantz has even gone so fer as to put the power transformer and rectifier in a separate unit, to prevent hum pickup by the preamp circuits.

Front panel controls include a 7-position selector switch, loudnes compensator and volume control, continuously variable bass and treble controls, separate turn-over and roll-off controls, and a treble cut-off selector. Pin jacks at the rear provide two phono inputs and one for a microphone, in addition to the usual facilities.

Specifications

Hum and Noise:  Hum is inaudible oa full gain from all input positions. Total noise voltage at output, from open phono inputs, 1.2 mV to 2.5 mV or the equivalent of 4 µV maximum at first grid. This figure will be reduced considerably with proper input connection.

Intermodulation Distortion:

High Level Inputs  (With volume control at maximum and all controls at flat positions;  60 and 7000 cps. Mixed 4:1)

15 volts output : 1% max

Low level Inputs (With equalization controls set as follows. Bass - AES, Treble-Orho. Output adjusted for 60 and 7000 cps. Mixed 4;1)

15 volt output : 1% max

Frequency Response:  1 dB from 20 to 40,000 cps.

Power Supply:  The remote power supply plugs into the main unit via a 6 conductor cable. Three AC outlets, controlled by the main switch, are provided for other components.

Selector Switch (Seven position input switch)

Micr : For high impedance microphones.

Lo-level Phono : For popular low-level magnetic phono cartridges.

Hi-level Phono : For Pickering, Clarkston, etc.

Extra : A spare high level input.

Tuner : High level input for FM, FM-AM, or AM

Tape : High level input for tape reproduction.

TV : High level input for TV sound.

Bass Recored Equalization:  Six turnover positions

Treble Record Equalization:  Six "roll-off" position

Loudness Compensator:  This is a continuously variable control of unique design which compensates for the Fletcher-Munson Hearing Characteristics curves. Unlike other such controls, its adjustment produces no corresponding change in listening level and may be used independently of the volume control.

Bass Tone Control:  Turnover point, 375 cps.

Treble Tone Control:  Turnover point 2500 cps.

High Frequency Cut-off Filter:  An adjustable low-pass filter (12 dB /octave cut-off)

Four High level Inputs:  For tuner, Tape, TV, atc. Voltage gain 23 dB

Three Low Level Inputs:  Microphone, Low level magnetic and High level Magnetic, Voltage gain 56 dB

Main Output:  This is fed by a cathode-follower which permits a long shielded lead to the main amplifier.

Recorder Output:  A selector-switch controlled output which can be used to feed a tape or other recorder. It is not affected by the volume or tone controls.

Tubes:  2 x 12AX7, 1 x 12AU7