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





Technics RS-M231X cassette deck

Technics presents a stereo cassette deck with a rare combination; 3 major noise reduction systems, and a low price. In addition to the RS-M231X's Dolby B and C noise reduction circuitry is dbx, which doesn't just reduce background tape noise but eliminates it. We've also furnished the RS-M231X with soft-touch transport keys, a metal compatible MX head, and convenient  slider controls for input level and balance adjustment.

dbx, Dolby B and Dolby C
The most effective of the deck's noise reduction systems is dbx, which eliminates tape noise and gives your tape the ability to reproduce up to a 110 dB difference in volume levels (or dynamic range) of a live performance, dbx reduces noise by at least 30 dB, pushing tape hiss below audibility, and increases headroom by about 10 dB so the tape can accept loud music signals without distorting them. The result is concert-like realism.
The RS-M231X is also equipped with a dbx disc decoder, so you can experience the same live-performance excitement from the ever-increasing number of dbx-encoded LPs as you do from dbx-encoded tapes.
Dolby B, the noise reduction system used in many cassette decks and prerecorded tapes, and Dolby C, an improved version of Dolby B, both reduce tape noise, especially in the high frequency range, where tape hiss is most noticeable.

Soft-Touch Controls
The soft-touch controls, which require only a light touch to operate, boast an impressive array of convenience features. Mechanical logic allows you to switch from fast forward or rewind directly to play, without having to touch the "stop" key. For recording, just touch the "record" key instead of "record" and "play". And rewind auto-play begins playback automatically after the tape rewinds to the beginning. The deck also includes cue and review functions, and timer record/playback capability.

Input Level and Balance Slider Controls
The deck's dual slider system provides optimum precision in setting recording levels. For most recording, the master input level slider suffices adjusting both the left and right channels together. For such demanding situations as live recording, where microphones are used, the balance slider adjusts left/right channel balance.

Metal Compatible MX Head
Specially developed for metal tape compatibility, Technics' MX head handles metal tape's high signal and bias level requirements and provides smooth frequency response and wide dynamic range. Of course, this improves the performance of normal and CrO₂ tapes as well.

Other Features:
DC servo motor
Automatic mic/line input selector
Large illuminated level meters
Timer record/playback capability
Oil-damped cassette well door removable for easy maintenance.
Specifications
Track System:  4-track,2-channel stereo recording and playback
Tape Speed:  4,8 cm/s (1-7/8 ips)
Wow and Flutter:  0,048% WRMS
Frequency Response
Metal Tape :  20 - 19,000 Hz; 50 - 17,000 Hz (±3 dB)
CrO₂ Tape :  20 - 18,000 Hz ; 50 - 16,000 Hz (±3 dB)
Normal Tape :  20 - 17,000 Hz ; 50 - 15,000 Hz (±3 dB)
Dynamic Range:  110 dB (at 1 kHz, CrO₂) with dbx in
Max. Input Level Improvement:  10 dB or more with dbx in (at 1 kHz)
Signal-to-Noise Ratio
dbx In :  92 dB
Dolby C NR In  :  75 dB (CCIR)
Dolby B NR In  :  67 dB (CCIR)
NR Out  :  57 dB
Fast Forward and Rewind Time:  approx. 90 sec. C-60 tape
Input Sensitivity/Impedance:
Mic :  0,25 mV, applicable mic. Impedance 400  - 10 k
Line :  60 mV/more than 47 k
Output Level?Impedance:
Line :  400 mv/1,5 k  or less
Headphones :  80 mv (at 8 ), applicable headphone impedance 8  - 600
Bias Frequency:  80 kHz
Motor:  DC servo motor
Heads:  2-head system
MX head for record/playback
Double Gap Ferrite Head for erasure
Power Requirements:  AC 120 V, 50/60 Hz
Power Consumption:  16 W
Dimensions (W x H x D):  430 x 109 x 235 mm (16-7/8" x 4-5/16" x 9-1/4")
Weight:  4,4 kg (9 lbs 11 oz)

Avid Model 230 speakers


Three-Way Acoustic Suspension Speaker
Avid's Model 230 3-way acoustic suspension speaker system employs newly developed Avid drivers consisting of a 12-inch woofer, 4,5-inch cone midrange and 1-inch dome tweeter. The cabinet enclosure and grille assembly are said to be engineered in a unique way to create a truly integrated acoustic system that significantly reduces unwanted cabinet diffraction effects that produce "boxy" sounds in other speaker systems. Special features include modular, zero-distortion dividing network assembly; speaker fuse overload protection; magnetic fluid technology with the Avid tweeter for improved power handling; "forward aligned" shallow-cone 10-inch woofer for reduced cone breakup. Optimum Dispersion Couplers for mid and high frequency drivers; "solid front" grille panels with rolled edges to significantly reduce cabinet edge diffraction.

An optional floor stand is available to properly time-align driver units.

Mitsubishi M-F01 tuner


A miniature FM Stereo tuner with Mighty performance and Quartz-PLL synthesizer tuning.
The M-F01 FM stereo tuner not only guarantees absolutely free from tuning drift thereafter. Unlike conventional FM tuners, whose performance depends very largely upon how well they are tuned system ensures  that it can always without exception, give its very best performance.
The quartz PLL tuning system is the secret of how this exceptional performance is obtained. The quartz crystal gives an extremely accurate  64 MHz signal that is divided by 128 to give a basic 50 kHz frequency. Comparing this reference frequency with one-half the local oscilator frequency enables any phase difference between them to be eliminated, effectively locking them together, this circuit is the phase locked loop (PLL). Under its action, the local oscillator is limited to frequencies that are exactly 100 kHz apart - e.g. 98,7; 98,8; 98,9 MHz etc.
The total harmonic distortion is completely independent of detuning frequency over wide limits, unlike conventional tuners.
Like other members of the Microcomponent series, the M-F01 features unusually clear LED type indicators. Here the locktune indicator is linked with the dial illumination; normally the dial numbers are edge litin white , but as soon as a station is tuned and locked, this is replaced by a gentle green glow. The five Leds on the left indicate signal strength. The pointer lights on either side of the tuning lock indicator go on to show which way the tuning knob should be turned for perfect tuning. As soon as only the tuning lock LED is lit, tuning has been completed, and the stereo LED will go on if the fM station is broadcasting in stereo. Of course you can switch over to mono listening if the station is too far away for good stereo reception - although the M-F01 is so sensitive that this shouldn't happen too often.
Another useful control lets you mute out interstation noise and stations too weak for good reception, so that you only receive stations capable of top-quality reception.

Wide, Flat Frequency response
Most FM tuners have a filter to get rid of the unwanted pilot signal (at 19 kHz), but these also affect the musical signal with frequencies below 19 kHz. In the M-F01 the pilot signal is cancelled out completely without the use of a filter, so that frequency response is flat to within ±1db at 16 kHz.
High performance Front-end
The all-important front end , that captures and processes the signal uses the same high precision five ganged tuning condeser as the prestigious DA-F20. mitsubishi's top tuner, making for great accuracy and stability. The M-F01 rejects spurious signals very effectively thanks to dual gate MOS-FeT's in the RF amplifier and mixer stages, and utilizes four pole linear phase LC filters for low distortion. Outstanding temperature and humidity stability are ensured by the use of aluminium cored coils and teflon trimmer-capacitors in the local oscillator, and glass epoxy printed circuit boards, all representative of the state-of-the-art..
Recording level Check Signal
A test signal at 440 Hz corresponding to 50% modulation of the FM signal is provided for easy level setting when tape recording FM broadcasts.
Specifications
Usable Sensitivity:
Mono :  11,2 dBf (2,0 µV)
Stereo :  22,7 dBf (7,5 µV)
50 dB Quieting Sensitivity:
Mono :  19,2 dBf (5,0 µV)
Stereo :  39,2 dBf (50 µV)
Signal-to-Noise Ratio:
Mono :  80 dB
Stereo :  77 dB
Frequency Response: 30 - 16,000 Hz ±1 dB
Total Harmonic Distortion:
Mono :  0,08%
Stereo :  0,1%
Capture Ratio:  1,0 dB
Alternate Channel Selectivity:  70 dB
Image Response Ratio:  100 dB
IF Response Ratio:  100 dB
Spurious Response ratio:  100 dB
AM Suppression:  65 dB
Stereo Separation:
At 1 kHz :  50 dB
At 10 kHz :  40 dB
Subcarrier Product Ratio:  80 dB
Output Level/Impednce
Fixed :  150 mV/5 k  Ω
Variable ;  0 -500 mV/5 k Ω
Power Consumption:  10 W
Dimensions (W x H x D):  270 x 70 x 247 mm (10-5/8" x 2-3/4" x 9-3/4")
Weight:  3,5 kg (7 lb 11 oz)

Mitsubishi M-T01 cassette deck


In designing the cassette tape deck for our microcomponent series we have not been too concerned with reducing the size; instead, while maintaining the same attractive, warm champagne gold hairline finish we have designed it to the same dimensions as the M-A01 power amplifier
Front Loading Format
Rather than adopt the horizontal insert type of cassette loading often used on compact cassette formats ,  inconvenient for tape head cleaning and subject to tape snarl-ups, the M-T01 features frontal loading, with full tape visibility and a hinged tape head cover that protects the head assembly from dust and higes down for easy access.
Feather-Touch Microswitch Controls
For smooth and rapid switching between different operatingirectly. To go from fast rewind into the play mode  just press the appropriate feather touch microswitches; the changeover is almost instantaneous, with no tape spillage. All operations are just as simple and foolproof.
ASPS
Mitsubishi's automatic spacing pause system ASPS puts a few seconds of silent spacing between different music selections without having to alter recording levels or go out of the recording mode.
Closed-Loop Dual-capstan Drive
For the last word in stable tape drive, greatly reducing drop-outs and changes in level due to variations in tape tension over the heads the tape is held between two capstans and their corresponding pinch rollers on the take-up and supply sides, unlike the normal single-capstan plus pinch roller combination. The mechanism itself is mounted on a high precision die-cast metal base, and is highly resistant to vibration and other harmful influences. This, and a phase locked loop (PLL) with a quartz-crystal oscillator as the standard for controlling the speed of the DC servomotor, bring wow and flutter down to a completely negligible 0,05% WRMS. The recording/playback head is of sendust, with excellent magnetic and wear-resistant properties, and is largely responsible for the good frequency response.
Peak level Meters
The fast-response peak reading meters on the M-T01 make it easy to achieve recordings with the maximum of Signal-to-Noise ratio and the minimum of distortion by giving accurate indication of critical peak signal levels.
Specifications:
Drive mechanism:  Closed loop dual capstan system
Noise Reduction System:  Dolby noise reduction system
Tape Speed:  4,75 cm/sec (1-7/8"  IPS)
Recording System:  AC bias (85 kHz)
Erasing Systen:  AC erasing (85 kHz)
Tracks:  4-track, 2-channel
Playback Equalization
Normal Position :  3,180u sec/ 120 µ sec
Fe-Cr Position :  3,180u sec/ 70 µ sec
Special Position :  3,180u sec/ 70 µ sec
Input Level /Impedance
MIC :  0,3 mV/1,8 k Ω
Line :  100 mV/120 k Ω
Output level/Impedance
Line :  420 mV/22 k Ω
Headphones :  1,5 mW/8 Ω
Motors:  PLL DC servo motor;  DC governed motor
Magnetic Heads
Record/Playback :  Sendust alloy
Erase :  Ferrite
Wow and Flutter:  0,045% (WRMS) ±0,09% (Wp-p, DIN)
Signal-to-Noise Ratio:
Weighted (Dolby NR Out):  56 dB (RMS); 52 dB (DIN)
Weighted (Dolby NR In ) :  64 dB (RMS)
Frequency Response:
Normal Position :  30 Hz - 15 kHz (40 Hz to 13 kHz ±3 dB)
Fe-Cr Position :  30 Hz - 17 kHz (40 Hz to 15 kHz ±3 dB)
Soecial Position : 30 Hz - 17 kHz (40 Hz to 15 kHz ±3 dB)
Power Consumption: 20 W
Dimensions (W x H x D):  270 x 140 x 246 mm (10-5/8" x 6-1/2" x 9-11/16")
Weight:  6,3 kg (14 lbs)