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