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





Audio Research D-70 power amplifier

If a preamplifier is viewed as the control center of a music system, then an amplifier can be regarded as the "engine" which power the system.. There is a misnomer among the audio community that amplifiers have no distinct "sonic signature" of their own, and that amplifiers varying widely in design and construction exhibit only minimal sound differences. Whit thirty years of design experience Audio Research has discovered this is not the case.

Claims for amplifier similarity have been strictly based on static performance measurements made into purely resistive loads. This is a poor test basis, similar to comparing a racing engine to a road model at identical idling speeds and concluding that they are equal in performance. In fact, amplifiers vary widely in their sonic character and recent advances in amplifier technology make this easily demonstrable .

From a performance standpoint, amplifiers must meet the same criteria for preamplifiers including clarity. High Definition , harmonic accuracy and dynamic range. Perfect linearity under difficult load coditions is impossible to achieve. However, Audio Research has been responsible in extending amplifier performance to new limits for nearly two decades.

 

Design Criteria

When designing a high performance power amplifier, the engineer is faced with four primary considerations:

  • Audio quality
  • Construction quality
  • Power
  • Costs.

So successfully blended are these criteria that Audio Research amplifiers now extend state-of-the-art. Performance without sacrifice in power, construction quality or at unreasonable cost.

Because Audio Research has given continuous attention to improving all aspects of amplifier design for many years. Audio Research now manufactures amplifiers which appear modest in price compared to state-of-the-art. Models of just a few years ago. Yet the performance capabilities of these amplifiers are so great that they overwhelm recent state-of-the-art. Amplifieres built without cost constraints.

 


Features

Patented Audio research cross-coupled and fully balanced circuitry

Front panel power switch relay coupled for smooth and reliable turn-on

Front panel LED indicators for line and screen

Front panel fusing for line and screen

Sonically selected components for optimum sound performance

Near military grade construction used hroughout

 


Specifications

Power Output:  65 watts per channel minimum continuous at 16 ohms from 20 Hz - 20 kHz with less than 1% Total Harmonic Distortion

Power Bandwidth:  10 Hz to 60 kHz (-3 dB points)

Input Sensitivity:  95 V RMS for rated output

Input impedance:  75 k Ω nominal

Noise:  greater than 90 dB below rated power, broadband unweighted

Dimensions (W x H x D):  19" x 7" x 16,5"


 

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