What is stereo?

There are now two system of high fidelity, monophonic (monaural) and stereophonic. Monophonic is a system that starts from one microphone and is fed through a single high fidelity set. Stereophonic is a double system. Two separate microphones are placed at different sides of the orchestra and two different systems are used to keep the two signals or channels separated. Two separate speakers are used, placed on different sides of you room. Stereo is much like 3-D photography, two slightly different sound reach your ears giving you a new dimension in sound.

H.H. Scott '59

Akai X-150D (1969)

Superb recording capacity of the cross-field head.
All silicon transistor pre-amplifier.
Robust mechanism for absolute durability.
One whole panel and finely oil-finished wooden cabinet that matches furniture and stereo set.

These are the features of Akai's "Custom Deck" X-150D, a high capacity stereo tape deck with excellent design that will complete your Hi-Fi set.
Outstanding features
4-track stereo/monaural recording and playback (for playback, the X-150D requires external power amplifier and speakers).
3 speeds... 1⅞, 3¾, and 7½ ips (15 ips optional).
3 heads... Erase, recording/playback and bias heads (CROSS-FIELD HEAD SYSTEM).
Hysteresis synchronous 2-speed motor.
Wide CROSS-FIELD frequency response.
All silicon transistor pre-amplifier.
Shield type head for high S/N ratio.
two lever system for sure operation and robust construction.
Track selector knob for simple selection between stereo and monaural.
Automatic shut off, instant stop control.
Tape cleaner.
Equalizer for each tape speed.
DIN jack.
Stereo headphone jack input.
3-digit index counter with reset button, and VU meters.
One whole panel and finely oil-finished wooden cabinet.
Vertical and horizontal operation mode.
Universal voltage selector (from 100 V to 240 V, 50/60 cps)

The cross-field head created a sensation in the tape recorder market by making possible a wide range recording never before heard on any conventional tape recorder.
What is superior about cross-field recording? How does it differ from typical recording methods as far as construction is concerned?
On these, explanation is given below in sequences:
In the typical recording system, signal current and the bias current are combined together and applied to the recording head. It is well known that the purpose of bias current is to record, at high sensitivity, a signal applied on the tape with little distortion and minimizing noise generation.
However, the bias current providing such an advantage also has an undesirable character. That is the wide magnetic field of the bias current affects the recorded signal, resulting in weakening or even erasing the signal. This phenomenon is particularly noticeable at high frequencies.
In the cross-field system, the signal current is applied to the recording head while the bias current is applied to the bias head. these two heads are located in different positions as determined inter-relatively, so that the magnetic field of the bias will not affect the signal recorded on the tape, even when sufficient bias is applied. This allows teh recorded signal to remain on the tape with high fidelity.

Tape speed: 1⅞, 3¾, and 7½ ips (15 ips optional)
Wow and Flutter:
Less than 0,12% (RMS at 7½ ips),
less than 0,15% (RMS at 3¾ ips),
less than 0,20% (RMS at 1⅞ ips)
Frequency Response:
30 - 9,000 Hz ±3 dB at 1⅞ ips,
30 - 18,000 Hz ±3 dB at 3¾ ips,
30 - 23,000 Hz ±3 dB at 7½ ips
Signal to Noise Ratio: Better than 50 dB
Input Level: MIC (more than 0,5 mV), LINE (more than 60 mV)
Output Level: 0 VU (1,23 V RMS)
Equalization: Correct equalization for playback of tapes recorded to the NAB curve.
Recording Bias Frequency: 60 kc
recording Level Indicator: VU meter x 2
Recording Sytem: CROSS-FIELD bias system, 4-track stereo/mono system
Fast FF and Rewind Time: 90 sec. using 1,200 feet tape at 50 cycles, 75 sec. at 60 cycles
Max. Recording Time:
8 hours monaural recording at 1⅞ ips (1,200 feet recording tape),
4 hours stereo recording at 1⅞ ips.
Recording playback head (4-track stereo/monarual, low impedance 1,000 ohms at 1,000 cps),
Bias head (4-track stereo, low impedance 500 ohms at 60 kc),
Erase head (4-track stereo, low impedance 300 ohms at 60 kc).
Motor: Hysteresis synchronous 2 -speed motor
Transistor: 11 silicon transistor, 2 diode, 2 rectifier.
Power Supply: AC 100 yo240 V, 50/60 cycles
Power Consumption: 55 VA
Dimensions (H x W x D): 13½ x 13½ x 9 inches, (340 x 340 x230 mm)
Weight: 30,8 lbs, (14,0 kg)

Nessun commento:

Posta un commento