Marantz SD-74

Commentary

A 3-head reverse deck equipped with Dolby B/C and dbx.

The head part uses a combination type 3-head system.
In the 3-head system, the optimum gap width is set for both the reproducing head and the recording head to improve the high-frequency characteristics during reproduction and the recording capability during recording. In addition, hard permalloy with excellent magnetic properties is used for the head material to improve MOL.

The reverse mechanism uses a rotary system that rotates the head mount.
The rotary type has the advantage that the same head can be used for both directions, and the azimuth can be adjusted in both directions, making it easy to achieve uniform characteristics.
The reverse position is detected by an infrared photo-sensor system, in which the sensor senses the difference in reflectivity and issues a command for the start of reverse rotation at the moment when the magnetic material disappears and enters the reader tape.

An erasing head is installed on both sides of the rotary type combination head to keep the position of the tape accurately.

The mechanism section focuses on the accuracy of metal parts, and the total accuracy is improved by thoroughly eliminating distortion during molding.
In addition, the flywheel is 1.7 times heavier than the conventional one, reducing sound quality degradation caused by the traveling system.

The drive system is a 3-motor double flywheel system.
In addition, the SD-74 uses a new back tension mechanism called the Dynamic Stability Tension System, which uses a new material, Rulon, to provide dynamically stable tension.
It also has a mechanism that automatically prevents tape from sagging.

A 2Kbyte dedicated microcomputer is used for the drive system of the mechanism to improve the certainty, speed and stability of operation.

By separating the audio circuit from other circuits, the effect on sound quality is reduced.

The audio circuit consists of a DC configuration with only two coupling capacitors. In addition, direct connection from input to output is promoted so that both recording and playback are directly connected to the head.
We have also introduced the latest constant-current drive IC for the recording amplifier, and the amplifier driven by a constant current improves the high-frequency saturation level during recording.

In addition to the Dolby B and Dolby C type noise reduction systems, it is also compatible with the dbx system.
All NR systems can be monitored, so the Dolby B/C is a double circuit.

The display section is equipped with a level meter with a peak hold function and a 4-digit digital counter.
In addition to the normal tape counter, the digital counter is equipped with functions such as displaying the remaining time of the tape, the elapsed time (wrap type), and displaying the number of songs when the music is selected (when the QMS switch is ON).

Features include blank skip, index scan, memory stop / play, repeat (two play button press), blank search, quick rewind, auto-rec mute and timer standby.

Synchronized recording is possible by combining with CD-84 etc.

Equipped with an output level adjustment volume.

It is compatible with the Marantz bus system, and remote control and easy operation are possible by connecting with a machine compatible with the same system.

Model Rating

Type	Cassette deck
Truck type	4-track 2-channel stereo
Heads	1 Recording Head Playhead x1 Erase Head x1
Motor	Capstan motor x1 Reel motor x1 1 Mechanism Drive Motor
Frequency characteristic	20 Hz to 20 kHz (metal) 20 Hz ~ 19 kHz (Chrome) 20 Hz ~ 18 kHz (Normal)
Wow flutter	0.028%(WRMS) ± 0.05% W · Peak (EIAJ)
Signal-to-noise ratio	54 dB (EIAJ, peak recording level hearing correction) Dolby B on : 10 dB improvement (over 5 kHz) Dolby C on : 20 dB improvement (1 kHz to 10 kHz) Dbx on : 30 db improvement (1 khz)
Input Sensitivity / Impedance	Line : 70mV/50k Ω
Output Level / Impedance	Line : 0.7V/2k Ω Headphone : 0.7mW/8 Ω
Pwer	100 VAC, 50Hz/60Hz
Power consumption	30W
External dimensions	Width 416x Height 118x Depth 334 mm
Weight	6.5kg