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





Adcom GFA-565 power amp

Adcom stereo components have a loyal and devoted following, having earned a reputation among audiophiles, engineers and musicians for extraordinary performance at affordable prices. Now Adcom introduces its newest amplifier, the no compromise GFA-565, for those in pursuit of absolute power and sonic perfection, but who prefer not paying a king;s ransom.

The evolution od Adcom's GFA-565

Adcom's new mono GFA-565 evolves from the design of the critically acclaimed GFA-555, greatly extending its capabilities. Representing brute strength, it delivers 300 watts at 8 ohms, 450 watts at 4 ohms and an awesome 850 watts at 2 ohms. most significantly, it will accurately drive even esoteric loudspeakers which present loads as low as 1 ohm.

Inspired by the GFA-555, the new GFA-565's well-regulated, high-current power supply has an enormous reserve capacity to meet tremendous dynamic demands, resulting in distortion free reproduction on a continuous basis.

Why use Two Mono Amplifiers?

The ability to deliver very high power into complex loads is a prereguisite for superior sound reproduction. power supplies capable of delivering the energy necessary for high power, high-current amplifiers are massive. but there are prectical limits to the size and weight of stereo amplifiers designed for home use, as well as heat dissipation and reliability constraints. consequently, the use of two Adcom GFA-565 mono amplifiers offers optimum sound definition, detail and dynamics, satisfying even the most demanding perfectionist.

More Sound. Less Money

Like the GFA-555, the new Adcom GFA-565 sound superior to amplifiers costing two and three times as much. it is so powerful and pure that it may be the last amplifier you ever buy, even if you upgrade your loudspeakers several times over the years. And that makes the GFA-565 an extraordinary bargain considering its exceptional performance.

 

High-Current Output Stage

More and more of today's high performance loudspeakers exhibit very low impedances and particularly difficult loads. many so-called esoteric amplifiers are incapable of delivering large amounts of undistorted power continuously into these complex loads thereby defeating the objectives of the loudspeaker's design. The GFA-565's highly advanced, triple darlington output stage featuring 20 rugged, discrete output transitors is designed to deliver extremely high-current at low impedances and reactive loads. No protection circuitry or current limiting devices are incorporated which would restrict the delivery of full power output. Protection against short term overloads, short circuits or long term, excessive output is achieved by non-interfering power supply fuses and thermal circuit breakers.

 

Well regulated, High-Current Power Supply

Advancements in CD technology and the introduction of digital audio tape have created opprtunities to reproduce the full dynamics and psychoacoustic experience of a live musical performance. To realize the full potential of this technology, amplifiers and loudspeakers must be capable of delivering tremendous energy continuously, not just for tiny fractions of a second. The massive power supply of GFA-565, featuring 70,000 microfarads of filter capacitance and a huge 1,25 kVA toroidal power transformer, has enormous reserve power capability. this is a no compromise power supply that eliminates all audible limitations. Hum, vibration and noise, the byproducts of lasser power supplies, have also been reduced to an absolute minimum. For most home applications, the optional variable speed cooling fan is unnecessary, making the GFA-565 a silent performer despite its formidable power.

Instananeous Distortion Alert

A highly accurate LED on the front panel is activated by a unique monitor circuit if any form of distortion - THD, IM, TIM, SID, etc. - exceeds 1 percent. this will provide ample warning that the music system is being operated beyond its design parameters.

Specifications:

Continuous Power Output (20 Hz - 20 kHz, less than 0,02% THD)

300 watts/channel at 8 Ω

450 watts/channel at 4 Ω

850 watts/channel at 2 Ω

Signal-to-Noise  Ratio:  better than 106 dB (A-weighted, full output)

Input Impedance:  50 - 700 Ω

Input Sensitivity:

For Rated Output :  2,15 V

For 1 Watt :  130 mV

Damping Factor:  better than 1000 at 8 Ω  (20 Hz - 20 kHz)

Dynamic Headroom (at 4 Ω):  1,6 dB

Voltage:  120 V, 60 Hz (availaable in 220 V, 50 Hz on special order)

Dimensions (W x H x D) :  432 x 210 x 292 mm (17" x 8-1/4" x 11-1/2")

Weight (shipping):  20,5 kg (45 lbs)

Optional:

Top mounted, automatically variable, ventilating fan (565 FAN)

Rear mounted, symmetrical balanced line input circuit (565 BAL)

Rack mount adaptors (RM-8)

White front panel and switch



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