SONY TC-6900

Commentary

A tape deck developed with an emphasis on reverse function.

It uses a direct drive system in which the motor shaft directly acts as a capstan, and reliability is enhanced by eliminating transmission and deceleration mechanisms.
An AC servo motor with a frequency generator (FG) attached to the shaft of an eddy current an eddy current type motor. By reducing the rotational speed and controlling the rotational speed with a servo amplifier, stable rotation with less vibration is achieved. The reel motor is also an eddy current type.

The head section has a four head configuration with recording, playback, and erasing heads in the forward direction and a reproducing head in the reverse direction.
With a streamlined head configuration and sufficient wrap angle, stable head touch and tape travel are achieved.

An F & F head has been adopted for the head. The F & F head has a structure in which both the core part and the guard part are ferrite. It has approximately 200 times more abrasion resistance than the conventional laminate type. In addition, it is fused and welded with the same hardness of strain-free glass developed independently, there is no collapse or disturbance of the gap edge, and gap width and gap position accuracy are also improved. In addition, the head touch is improved by the black mirror finish on the front surface of the head, and in addition, the adhesion of dust is prevented.

Using the center capstan method, in which the capstan is laid out between two playheads, the sound quality and characteristics in both forward and reverse directions are almost the same. In addition, an auto-positioning pinch roller, in which the pinch roller automatically moves to the best point depending on the direction of tape travel, is used to ensure stable travel and excellent head touch.

On the side of the head is a scrape filter, positioned so that it is always in contact with the tape and rotates, and the moment of inertia of this roller absorbs the microvibration energy of the tape.
In addition, by effectively shortening the tape vibration span with two scrape filters, modulation noise harmful to sound quality is suppressed.

A logic control system is adopted. In this system, the rotating state of the reel motor is passed through by a frequency generator, and after the tape completely stops, it automatically moves to another operation. This prevents the tape from becoming painful and improves operability.

An originally developed FET is used for the first stage of the amplifier section, and an F & F head is directly connected to this FET using a direct coupling method. Since there is no element such as a condenser between the head and the first stage FET, the minute output of the head can be transmitted directly to the amplifier, and the sound quality is improved.

It is equipped with a tape selector with independent bias and equalizer, with two levels of bias (High and Low) and two levels of equalizer (Normal and SLH).

Playback reverse and repeat playback are available.
The reverse method of TC-6900 is a sensing foil reverse method that reverses when the metal foil touches the guide. If you attach the sensing foil to the end of the tape, it will reverse automatically. In addition, if you attach the sensing foil to the head of the tape and set the AUTO REV switch to CONT REV, you can repeat playback, play back and forth with REV, and play one way with NON REV.
In addition, it is equipped with an error erasure prevention device that stops operation when the sensing foil touches the guide during recording.

Equipped with an auto shut-off mechanism. When a tape is wound around one reel, the mechanical power is automatically turned off. At the same time, the same time, the operation lever and all the mechanisms linked to it are released and the STOP state is set.
This reduces deformation of the pinch roller and load on the mechanism.

Equipped with a tension arm, it absorbs the vibration of the tape at the start and realizes stable tape tension.
In addition, since it is linked with an electric mechanism, it is automatically shut off when the tape is wound.

With a playback volume, the playback output can be varied, and with a center click, the reference level can be obtained easily.

Since the microphone input circuit and line input circuit are independent, it is possible to mix the microphone input and line input.

Equipped with a microphone attenuator, it can be attenuated by 20 dB by pulling the microphone input level knob.

Tape can be temporarily stopped during recording and playback. Moreover, it is equipped with a lock function so that operations such as recording standby can be performed.

It uses a built-in reel lock mechanism that does not require a reel cap and locks the reel securely by simply pulling and turning the reel shaft.

Equipped with left and right independent VU meters.

Equipped with a lamp that indicates whether the direction is square or opposite.

Equipped with a 4-digit tape counter that can return to 0000 with one touch operation.

Model Rating

Type	Tape deck
Tape Speed	19cm/s, 9.5cm/s
Available recording time	No. 7 tape (550m), at 9.5cm/s Stereo round-trip : 3 hours Monaural 2 round trip : 6 hours
Fast-forward and rewind time	60 seconds (370m tape)
Maximum reel used	No. 7 (178 mm)
Track system	4 Track Stereo / Mono
Heads	Recording : F & F heads Play : 2 F & F Heads Erasing : erase heads
Motor	AC servo motor for capstan 2 reel motors
Recording bias frequency	160 kHz AC
Total S/N	53 dB (General Tape) 56 dB (SLH tape)
Overall strain rate	1.2%
Frequency characteristic	General Tape 19cm/s : 9.5cm/s: 20 Hz to 25 kHz (30 Hz to 20 kHz ± 3 dB) 20 Hz to 17 kHz SLH Tape 19cm/s : 9.5cm/s: 20 Hz to 30 kHz (30 Hz to 25 kHz ± 3 dB) 20 Hz to 20 kHz
Wow and flutter	0.05%WRMS(19cm/s) 0.09%WRMS(9.5cm/s)
Minimum Input Level / Impedance	Microphone : 0.2 mv (-72dB) / low impedance Line : 0.06 V (-22dB) / 100k Ω
Output Level / Impedance	Line : 0.43 V (-5dB, reference), 0.775 V (0 dB, maximum) / 100k Ω Headphone : 8 Ω
Semiconductor used	Transistor : 46 IC : 1 FET : 2 Diode : 44 pcs Thermistor : 1
Pwer	Power switch not linked : 1 system (300W)
Pwer	100 VAC, 50Hz/60Hz
Power consumption	70W
External dimensions	Width 425x Height 458x Depth 213 mm
Weight	20.8kg
Attachment	Reel 7 Connection code (RK-74) Head cleaning rod Power cord
Sold Separately	Dust Protector DP-26 (¥ 4,800)