The GFP-565 was designed to offer more than simply excellent performance for the price asked. It was Adcom’s attempt at manufacturing a preamplifier which could compare favorably to the most expensive state-of-the-art products offered by other high-end manufacturers.
“The fewer circuits a musical signal encounters on its way to your loudspeakers, the greater its musical purity. That, in brief, is the inspiration for Adcom’s GFP-565, the world’s first affordable reference-class preamplifier with direct path, linear gain circuitry.
The GFP-565 results from a complete rethinking of conventional preamplifier designs and the development of several exceptional strategies for improved performance. For example, circuit paths, often a little-understood but important contributor to outstanding sound quality, are as short as possible to minimize any sonic deterioration. Internal wiring is almost non-existent: high quality, gold-plated input and output connectors are mounted directly on the copper plated glass-epoxy circuit boards.
A high current, very low impedance power supply delivers DC operating voltages to all circuit sections via massive solid copper buss bars. Programmable regulators and low ESR capacitors help avoid even minute voltage drops and current losses that can effect sound quality.
Proprietary, high speed linear gain amplifiers, individually selected for low noise and minimal DC offset, operate exclusively in class “A” mode for maximum musical resolution. High current buffers at both main and tape outputs assure superior dynamics regardless of any unusual cable or load idiosyncrasy.
Five high level inputs and a phono input combine with a separate external processor loop for extraordinary flexibility. And, of course, you may listen to one input while recording from another.
In combination with any of Adcom’s power amplifiers, the GFP-565 lets you experience the exceptionally lifelike sound which has astonished even the most demanding critics. And that’s a detail you can’t afford to overlook.”
The GFP-565 was designed to satisfy purists, who normally demand as simple a signal path as possible, as well as those audiophiles in need of a full-featured preamp. These two seemingly contradictory requirements were addressed by supplying the 565 with three sets of outputs. The bypass outputs are intended for the purists. No tone controls or filters corrupt the signal path when the bypass outputs are used, but the balance control is still operational. The bypass outputs are also direct-coupled, eliminating any possibility of sonic degradation normally associated with coupling capacitors.
The bypass outputs still allow the use of an external processing loop, so they are not absolutely purist in the sense of minimizing every possible switch contact. A mono switch and loudness contour are also available when the bypass outputs are used, but the contour switch and its associated filter components are connected to a tap on the volume control, so these components and switch contacts are not in the signal path.
For those in need of the tone controls, two additional outputs providing those features are included. The normal output is capacitor-coupled with a high-quality film device, whereas the lab output is direct-coupled. The tone controls provide boost or cut below 300Hz and above 3kHz, with a minor side effect on information between those two frequencies. A high-cut filter is also provided via the main and lab outputs. The filter characteristic is very gentle, being only 2.7dB down at 20kHz. This might be just enough high-frequency cut to remove some of the “edge” from a cheap CD player, but one would hope that anyone purchasing the GFP-565 would be using sources worthy of its own performance.
Six inputs are provided on the GFP-565, including phono, CD, tuner, tape 1 and 2, and video/aux. Separate selector switches are provided for listening and recording, and since two tape outputs are also included, tape copying in either direction is possible.
Adcom GFP-565 Technical Specifications:
Output Impedance Main Out…..100 ohms Tape Out…..475 ohms
Output Level (Rated) Main Out…..2.0 V
Output Level (Maximum) Main Out…..10.0 V
Frequency Response ( ±0.5 dB) High Level 5 Hz – 90kHz Phono 5Hz – 70kHz
THD+Noise (at Rated Output, 20 Hz – 20 kHz) High Level…..0.0025% Phono…..0.009%
IMD (SMPTE, at Rated Output) High Level…..0.0025% Phono…..0.0025%
Signal-to-Noise (at Rated Output, “A” Weighted) High Level…..>100dB
Tape Output THD + Noise (at 2.0 V, 20Hz – 20kHz) …..0.003%
Tape Output IMD (SMPTE) at 2.0 V…..0.002%
Tone Controls Bass (20Hz)…..±10dB Treble (20 kHz)…..±9dB
Loudness (Volume Control at 9:00 o’clock) 100Hz…..+5dB 20Hz…..+10dB
Crosstalk (1 kHz) …..-105 dB
Separation (1 kHz, at Rated Output) …..>75 dB
Hi Filter (20 kHz) …..-2.7 dB Phono…..>95dB
Input Impedance High Level…..22kohms Phono…..47kohms
Input Sensitivity (at Rated Output) High Level…..205 mV Phono…..23mV
RIAA Accuracy (20Hz – 20kHz)…..±0.1 dB
Chassis Dimensions: 17″ (432mm) x 11 3/8″ (289 mm) x 3″ (76 mm), Weight…..11 lbs. (5 kg)
Asking $595 for this very high quality Adcom Pre-amplifier in excellent condition.