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

Yamaha T - 70

 Sound Over Specifications 
Yamaha's unique design philosophy - an approach which has produced a large repertoire of the world's finest audio components - is directly behind the development of Yamaha tuners as well. 
The Yamaha philosophy: to provide the most natural sound reproduction quality above all else. While this may seem an obvious approach, most manufactures actually place considerable emphasis on improving specifications - whether the measured improvement results in a corresponding improvement in sound quality or not. IHF standards, for example, require tuner sensitivity specifications to be measured at 100% FM modulation.  The signal arriving at a tuner's antenna under actual broadcast conditions, however, is only 20% or 30% modulated - a difference that means dramatic changes in sound quality. Rather than aiming for the best specs with a 100% FM modulated signal. Yamaha tuners are designed for the best sound under actual listening conditions. The result is, naturally, that Yamaha tuners offer strikingly superior sound performance. 
One of the most exemplary tuners resulting from Yamaha's unique design philosophy is T-70. This remarkable tuner offers a 10-station random-access preset tuning system which allows presetting of up to 10 Am and FM stations in any combination, exceptionally accurate manual pushbutton tunung, and an improved auto-search function that does away with the arbitrariness of ordinary synthesizer auto-search functions. But all this tuning convenience is made really worthwhile by the t-70's sound. The T-70 incorporates a whole spectrum of new Yamaha technology that achieves significantly improved music reproduction accuracy. The T-70's superior sound, convenience and overall performance clearly reflect Yamaha's firm policy of providing nothing but the purest, most natural sound reproduction.

 Computer Servo Locked Synthesizer Tuning System 
One of the biggest problems with conventional synthesizer tuners is that their crystal oscillator and frequency dividers are producing RF (Radio Frequency) signals within the tuner itself. These frequencies can leak into other parts of the tuner causing distortion, interference and a loss of signal-to-noise ratio. The T-70 offers a brilliant solution to this problem. The reception  frequency is initially locked to a reference frequency generated by a super-accurate "micro-fork" oscillator. The micro-fork is a unique oscillator element, made with a special Yamaha alloy, that offers even greater temperature stability than quartz. Once the desired station is detected, however, the frequency divider and associated PLL  circuitry are turned off, and the T-70's Servo Locked system takes over to lock the tuner to the frequency of the received station. This system generates absolutely no interference - causing internal noise, and yet ensures reliable, drift-free operation. 

RF Servo Gain Control 
The T-70 is exceptionally resistant to intermodulation distortion caused by strong interfering stations thanks to a a unique Yamaha RF Servo Gain Control system. When an interfering station is detected, the RF Servo Gain Control turns on automatically to reduce RF gain by a carefully controlled amount, effectively avoiding this kind of interference. When no interfering signal is present, the T-70 automatically sets the normal RF gain for optimum sensitivity, signal-to-noise ratio and sound quality. 

Ultra-Linear Direct FM Detector 
This high-performance circuit offers a simpler, cleaner signal path as well as improved linearity compared to even the latest pulse-count detector systems. The outstanding low-noise, low-distortion performance provided by this unique Yamaha circuit ensures that the music signal reaches the multiplex stereo decoder stage with no distortion added from the time it reached the tuner's antenna. 

Real-Time Direct CMOS DC NFB PLL Multiplex Demodulator 
Conventional stereo demultiplexing systems involve turning semiconductor analog switches on and off at a 38 kHz rate. Switvhing distortion can be a problem, however, since the switches have a finite switching time and are located in the signal path. 
The T-70 completely overcomes this problem by using extremely high speed CMOS switches located in the negative feedback loop of a high slew rate DC amplifier. The resulting demodulator offers excellent stereo separation, low harmonic and intermodulation distortion, and exceptional transient response for the most natural FM stereo reproduction. 

 AM/FM 10-Station Random Access Preset Tuning 
Up to 10 AM and FM stations can be programmed into the T-70 memory for instant one-touch tuning. Unlike many preset tuning systems which may have 5 preset memories specifically for AM and 5 more for FM, the T-70 random-access system lets you preset any combination of AM and FM stations in any order up to a total of 10.  You can even program all FM or all AM stations if you like. 
This is possible because the T-70 memory not only stores the station's frequency, but the band (AM or FM) as well. If you program 10 stations with your favorite ones first, you'll be able to quickly call them out in order without having to switch back and forth between the AM and FM bands. No other tuner, synthesizer or otherwise, has ever been produced that is easier to use and listen to than the Yamaha T-70. 

Initial Station Set 
In addition to the 10-station random access preset memory system, an initial station set function is provided which lets you pre-program any station to be tuned in every time power to the tuner is switched on.  Preset your favorite station using this function, then whenever you turn the T-70 on you're precisely tuned in - the perfect feature for timer recording from FM broadcasts.  
Additionally, all the T-70's memory is nonvolatile. This means that it will not be cleared or erased even if power to the tuner is completely cut off. And there's no time limit to unpowered memory storage as there is with backup battery, and capacitor supplies. 

Other Features 
Auto DX 
Anti-Interference PLL system 
Tracking Type Pure Pilot Canceller 
Pushbutton auto-search tuning 
Manual single-step tuning 
High-Q low-impedance AM loop antenna 
Selectable AM selectivity 
Built-in recording calibration oscillator 
Signal Quality indicator 

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