Marantz Model 1 mono preamplifier
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Taken from High Fidelity Magazine, May 1955

Marantz Audio Consolette

Specifications (furnished by manufacturer): a deluxe self- powered control preamplifier-equaliser. Inputs: one for high impedance microphone; one for low-output and one for high-output magnetic cartridge: four high-level inputs marked Tuner, Tape, TV and Extra. Controls; selector switch with three positions for low-level inputs and four for high-level inputs; loudness compensation control; volume; bass (+17 to -10 db, 5O cycles); cut-off filter switch (Off, 10,7, and 5 kc cycles); treble (±l0 db, 10,000 cycles); record turnover (flat, FFRR, AES, Ortho-RIAA, Col LP, 800); AC power on-off switch; record roll-off (flat, FFRR 78, AES, Ortho-RIAA, LP-NAB, Early 78). Outputs: low-impedance output to amplifier, high-impedance output, unaffected by volume, tone and filter controls for tape recorder. Three switched AC power outlets on power supply chassis. Response: ±1db, 20 to 40,000 cycles. Distortion; 1% maximum IM at I5 volts output; virtually unmeasurable at normal levels. Noise: four microvolts equivalent maximum open circuit noise at first phono grid. Tubes. 2-12AX7, 12AU7 Price: $155.00 with cabinet: $142.50 without. Manufacturer; Marantz Company, 44-15 Vernon Blvd., Long Island City 1, New York.

The Audio Consolette is built like a piece of broadcast equipment; our first impression was one of solid, uncompromising quality and workmanship. Further examination confirmed this impression, and disclosed that it is also a versatile audio front end designed with intelligence and a lot of common sense.

For example: this unit is obviously going to be used in deluxe sound systems, which are more than likely to have two magnetic phono pickups; it would be sensible to furnish two magnetic phono channels in any high-quality preamplifier-control. All too few provide this facility— the Marantz unit is one that does. And it has a microphone channel, too. Then there are font high-level input channels; this ought to be enough for even the most complex system. (That’s a total of seven switched input channels!)

We approve of the volume-loudness control setup, too. There are actually two controls: one is a straight uncompensated volume control; (the other is a continuously- adjustable compensation control that does not affect the over-all sound level but adds bass and treble boost in varying degrees as desired. This does away with the need for input level controls. It is, in our opinion, a most satisfactory way of dealing with the loudness compensation problem simply and effectively. You select the sound source, adjust the volume as you want it, and turn the loudness knob until it sounds right. Since the boost is added primarily at very low and very high frequencies the control is often useful as a tone control with special characteristics.

Bass and treble tone controls checked out for us with genuine flat response in their centre positions. Inflection frequencies - those at which the controls began to have effect - were lower than usual in the bass and higher than usual in the treble. This results in generally improved performance in the middle range but limits the maximum boost and cut available; no disadvantage in this case because of the other response, shaping controls furnished.

The round knob in the centre is the range switch. Turned fully to the left it is removed from the circuit. Other positions successively to the right furnish moderately sharp cut-offs beginning at 10,000, 7,000 and 5,000 cycles with an attenuation rate of 12 db per octave; useful in gently eliminating scratch, etc.

Individual turnover and roll-off controls for record equalization furnish a choice of 36 curves. Equalization extends to well below 50 cycles, which is unusual and which will be appreciated by those having speaker systems capable of showing up this feature. The phono preamp section is more than adequate; it has enough gain and low enough noise, too, to handle very low-output cartridges without transformers.

With a bit of head-scratching, we can think of three other facilities that might be included in a front end selling for this price. First, a rumble filter can be useful in some circumstances. Second, we believe the recorder output signal should be at low impedance, not high. Finally, there are times (when dubbing old records to ape, for instance) when it might be handy to have the scratch filter and tone controls in the tape recorder output circuit; they're bypassed now, along with the volume control.

These arc minor points we like the Audio Consolette very much. It merits respect not only for its fine performance in conjunction with a hi-fi system, but in itself as a fine example of good engineering and construction. - R.A.

Manufacturer’s comment: There is no adjustable rumble filter, but the phon equaliser circuits have been designed specifically for a rapidly falling response below 20 cycles to reduce subsonic rumble interference.

The recorder output signal is switched directly from the high-level inputs and, therefore, is of the same impedance as the original source. On phono and microphone positions the recorder output will be affected very little by normal cable capacities (less than 1dB loss at 20 kc with a 3,500 mmf load).

Most users seem to prefer an output isolated from the action of tone control circuits for recording purposes. However, if it is desired to use these controls, it is possible to parallel the cables from the main output to both amplifier and recorder.