Adcom GFP-555 preamplifier

 Preamplifier A remarkable combination of exceptional performance, flexibility and value

The GFP-555's musical performance is outstanding - by any measurement or listening criterion. For example,… one of the most satisfying preamps around in terms of overall tonal balance. You can go back to it after a few weeks and still feel it to be basically right; it reveals most associated equipment as more colored than itself.

At the same time, the GFP-555 is surprisingly affordable.

Superb construction, incorporating regulated power supplies with large filter capacitors, provides superior performance no matter how widely the musical signal or AC line voltage may fluctuate.

As for flexibility, you can listen to any source while taping from another. There's an unusual number of inputs and outputs, plus adjustable phono gain and capacitance.

Outstanding performance

The GFP-555's musical performance is outstanding - by any measurement or listening criterion - and at the same time it offers a full array of meaningful controls and features.

What's more, the GFP-555 does it all at a surprisingly affordable price. Surprising, that is, only to those who aren't yet familiar with the Adcom approach to design and performance Musical performance, in particular.

Gai path - simple and direct

The GFP-555's gain path is simple and direct from input to output. The use of a minimum number of components - each of the highest quality - means low waveform distortion and less phase shift

The gain stages employ the most innovative state-of-the-art. Linear amplifiers ever used in high fidelity components. These individually selected instrument-grade devices are in a class by themselves.

The speed of the gain stages is almost fifty times faster than CD or LP signals.  And the noise and distortion measurements are incredibly low. Direct coupling makes possible a frequency response from below 1 Hz to beyond 400,000 Hz

 

Specifications

Total Harmonic Distortion:  0,005%

Intermodulation Distortion:  0,005%

Signal-to-Noise Ratio

Phono :  better than 85 dB (re 0,5 V output)

Tuner, CD, Tape :  better than 100 dB (re 2 V output)

Tone Controls

Bass :  ±9 dB at 40 Hz

Treble :  ±9,5 dB at 15 kHz

Contour:  =6 dB at 50 Hz

Frequency Response:  1 Hz - 100 kHz ±0,1 dB

High Filter:  -2,5 dB at 20 kHz (6 dB/octave)

Low Filter :  -5 dB at 20 Hz (6 dB/octave)

Input Sensitivity for 0,5 V output

Phono High MC/MM :  0,4 mV

Phono Low MMC :  0,13 mV

High :  40 mV

Maximum Output Level :  10 volts

Input Impedance

High MC'/MM :  47 Ω

Low MC :  100 Ω

Output Impednce:  470 Ω

Phono Overload (at 1 kHz High MC/MM):  140 mV

Phono Input Capacitance:  10 pF, 175 pF, 275 pF (adjustable)

Line Voltage:  120 V 60 Hz (available in 230 V /50 Hz)

Dimensions (W x H x D):  432 x 83 x 324 mm (17" x 3-1/4" x 12-3/4")

Weight:  6,4 kg (14 lbs)

Adcom GTP-400 tuner/preamplifier

Adcom brings the superior performance of its separates into a price range previously associated with ordinary receivers with the introduction of the new GTP-400 Tuner/preamplifier. By combining the GTP-400 with one of Adcom's power amplifiers, you can now afford the clear sound, powerful dynamics and exceptional performance for which Adcom has been called "legendary" by the critics. The CTP-400 will put more power into your hands than you ever thought possible .. And its sound is truly revolutionary.

Because receivers have limited space, they cannot be equipped with the heavy duty, high-current, high-voltage power supplies available in the best separate components. And if a receiver was so equipped, it would generate unacceptable levels of heat and hum, inevitably degrading all performance parameters. Consequently, the overall performance of receivers is always compromised for the seeming advantage of all-in-one convenience and affordability.

 

The GTP-400 Tuner/preamplifier eliminates all such compromises.. By dividing the tuner/preamplifier from the power amplifier,, low-current, low-voltage elements are totally isolated from high-current, high-voltage elements ensuring sonic quality and superior performance. And because the GTP-400 is designed to be used with any of Adcom's power amplifiers, you have the advantage of choosing the right amount of power for your needs. If 60 watts per channel will drive your speakers to the level you want, consider our least expensive amplifier, the GFA-535. if you need more power, consider the 100 watt GFA-545 or Adcom's legendary 200 watt GFA-555. for the truly power hungry, the GTP-400 will drive two GFA-555's each bridged in mono, for an awesome 600 watts per channel.

 

Designers and engineers usually use Class A audio circuits in components where price is no object. Demanded by those who can distinguish outstanding sonic performance from merely average, Class A circuits are employed in the GTP-400's phono and high-level preamp stages. These circuits provide superior resolution and dramatic musicality. It took Adcom's approach to high performance/high value to make Class A affordable.

 

Several of Adcom's components have been favorably compared to other components costing two and three times more. The GTP-400 promises to keep faith with this tradition of exceptional value by delivering superb performance at a reasonable price.

 

The Preamplifier Section

Optimum Signal-to-Noise ratios at both the phono and high-level inputs ensure superior performance from your tresured Lp's as well as your new compact discs and a wide range of hifi video sources.

Proprietary linear-gain amplifiers in the high level and phono stages operate in full Class A to provide low distortion, low noise and high speed. High accuracy in the RIAA equalization circuit provides superb sound from high output moving coil or moving magnet phono cartridges. A separate recording selector allows listening to one source while recording another. Feedback tone controls and contouring circuits can fine tune your system to room acoustics or individual listening tastes.

 

The Tuner Section

Quartz referenced and digitally synthesized , the tuner has an accuracy 0f 0,00025% providing a significant reduction in audible distortion. Eight FM stations and eight AM stations can be programmed for instant retrieval at the touch of a button. Once a station is tuned in, it's locked in without drift. A touch of another button activates the scan mode, up or down. When reception conditions are marginal, a switchable high-blend circuit reduces background noise and fading of FM stereo signals.

 

The Sound of a Revolution

The price of the GTP-400 with a GFA-535 power amplifier is close to that of a good receiver. But that's as close as they get, beacause no receiver will deliver the wide dynamic range and lasting satisfaction of an Adcom music system. So if you would like to be part of the new movement towards bringing more power into your home, ask your Adcom dealer to demonstarate the GTP-400 with any Adcom power amplifier.

You'll hear what a revolution sound like.

 

Specifications

Preamplifier Section

Total Harmonic Distortion:  less than 0,01%

IM Distortion:  0,005%

Frequency Response:  20 Hz - 20 kHz ±0,1 dB

Max. Output Level:  better than 8 volts

Input Sensitivity for .5V Output:

Phono :  0,8 mV

High  Level :  78 mV

Signal-to-Noise ratio:

For .5V Output; Phono :  80 dB

For 2V Output; High level :  better than 95 dB

Output Impedance:  100 Ω

Tuner Section

IHF Sensitivity Mono :  11 dBf

Signal Strength for -50 dB Quieting

Mono :  13,5 dBf

Stereo :  37 dBf

Capture Ratio:  1,7 dB

Alternate Channel Selectivity:  75 dB

Separation at 1 kHz:  50 dB

Total Harmonic Distortion

Stereo at 1 kHz :  0,1%

Signal-to-Noise Ratio:

Mono :  80 dB

Stereo :  75 dB

Frequency Response:  30 Hz - 15 kHz ±0,5 dB

Antenna Impedance:  75 Ω or 300 Ω

Voltage:  117 V at 60 Hz ( 220 V at 50 Hz)

Dimensions (W x H x D):  432 x 80x 325 mm (17" x 3-1/4" x 12-3/4")

Weight:  6,8 kg (15 lbs) shipping

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

ADCOM ACE-515 (1987)

You've probably invested a lot of time and money putting together your stereo system.  So obtaining the best performance, electrical protection, and reliability from all this valuable gear is more than an option, it's a necessity. But, regardless of how sophisticated the design of your electronic equipment is, it may not be performing to full potential if it's plugged directly into an ordinary AC outlet.  Standard AC outlets often supply raw and unprocessed power that not only can diminish the clarity of audio signals, but it can also cause damage to the sensitive Integrated Circuits (ICs) inside your valuable equipment. ADCOM's ACE-515 AC Enhancer continuously avoids many of the problems caused by unreliable AC power supplies by filtering and conditioning the AC power, and eliminating "spikes" injected into the line by refrigerators, air conditioners, heating systems, atmospheric disturbances, etc.  A little-publicized fact is that many industrial centers, because of the machinery they use, inject a large number of "spikes" and other interference into the power lines. Similarly, radio transmitters can "pollute" power lines with  interference. These disturbances can be carried by power lines over very long distances and can affect AC outlets miles away. ADCOM's ACE-515 will provide, even if these disruptive signals are present at your AC outlet, both superior performance and additional protection for all the sensitive electronic equipment connected to it (up to 1800 watts total).

 Performance

The ACE-515 can not only protect but actually improve the performance capabilities of your audio or video systems. As it filters the line voltage from your AC receptacle, eliminating noise and interference, such as radio frequency interference (RFI) and electromagnetic interference (EMI), it will reduce the residual noise in the system, enhancing both audio and video clarity. Simply stated, the ACE-515 provides your electronics with the purest input power so it can deliver its purest performance.

 Protection

ADCOM has also designed the ACE-515 to protect your electronic equipment from potentially damaging high-voltage spikes and surges. The spike and surge protection built into its circuits is fast acting (less than 10 billionths of a second), and thorough (works on both sides of the AC line, and to Ground as well). For use with your audio system, the AC Enhancer is supplied with a special sequential turn-on/turn-off circuit designed to protect your speakers from turn-on/turn-off "thumps" which originate in one or more accessories and could otherwise be amplified to disturbing levels. The sequence was designed so that when you initiate the turn-on cycle, the CE-515 will energize the accessories immediately and delay power to your amplifier for 10 seconds - until the circuits in your accessories have stabilized. Only then will the amplifiers be turned on; so the thump often heard through the speakers while circuits are stabilizing will not be amplified. Similarly, when you initiate the turn-off sequence, the ACE-515 will remove AC power from the amplifier at once and hold the accessory power on for 30 seconds - until the power amplifier has completely discharged. This on/off process automatically provides your system components with power in the safest possible sequence and eliminates the need to do all this manually. And this sequencing can be advantageous when you're powering a video theater or computer system as well.

Only the ADCOM ACE-515 AC power enhancer has all of these important features:

High power-handling capability (up to 1800 W total).

Surge, spike, RFI and EMI filtering.

Correct, sequential turn-on and turn-off of your equipment.

All heavy duty electrical and structural components, outlets, power cord, etc.

Massive anodized aluminum front panel, heavy gauge steel chassis.

Safety Certification: ETL listed, and approved under UL Standard Number 498.

Specifications

Electrical:

Input Power:  120VAC, ±20%, 50/60Hz

Protection:  15A Circuit breaker

Internal Power Consumption:  Less than 10W

Control Input:  120VAC, ±20%, 50/60Hz, fused at 1 Amp

Output:  Amplifiers, 10 Amps maximum per pole continuous.

Accessories, 2.5 Amps maximum continuous

Time Delays:  Delay-on-make 10 seconds ±20%.

Delay-on-break 30 seconds ±20%

Environmental:  Operating temperature, 0 degrees C to +50 degrees C.

Storage temperature, 40 degrees C to +80 degrees C

Filter:

Filter provides reduction of both Transverse and Common Mode noise, interference and spikes (voltage transients).

Noise:  Begins attenuation above 10kHz, down 40dB at 150kHz

Maximum ContinuousAC RMS Voltage:  130

Maximum Continuous DC Voltage:  175

Transient Energy Dissipation:  11 Joules(10/1000uS)

Peak Current:  1200A

Response Time:  Less than 10 nanoseconds

Maximum Clamping Voltage:  390 at 10A (8/20uS)

Generic:

Mechanical Dimensions (W x H x D):  432 x 76 x 150 mm, (17" x  3" x 5-15/16")

Maximum Dimensions (W x H x D):  432 x 81 x 171 mm, (17" x 3-3/16" x  6-3/4")

Weight:  2,7 kg (6 lbs.)

Main AC Cord:  1,8 m (6 ft)

Control AC Cord:  1,8 m (6 ft)

Outlets.....Three, 3 prong, grounded, polarized; Four, 2-prong. polarized; Seven, total

Also available with optional white front panel. 

ADCOM GCD-575 (1988)

Adcom GDC-575 CD player has been worth waiting for. Now there's a CD player with analog audio circuits as technically advanced as its digital stages. Since the human ear can only appreciate musical sounds in their analog format, Adcom began with the objective of producing the first affordable CD player whose direct-coupled audio output would deliver the long anticipated technical benefits of digital sound.

Designers and engineers usually use Class "A" audio circuits where price is no object. In its purest form, Class "A" offers a highly sophisticated level of audio amplification, often demanded by those who can distinguish outstanding sonic performance from the merely average. Adcom's GCD-575 employs a no-compromise, Class "A" analog audio amplifier section which provides superior resolution by more clearly defining low-level information. This higher resolution makes an audibly dramatic difference in the musicality of CD reproduction. To achieve this result, the analog audio circuits in the GCD-575 were based on the same proprietary high speed linear amplifiers used in Adcom's GFP-555 pre-amplifier, universally recognized for its outstanding musical integrity.

Importantly, Adcom's CD player is designed with a low output impedance (100 ohms) so that it can operate up to its maximum capability with a wide variety of associated equipment. It is not only compatible with virtually all input stages of amplifiers, preamplifiers, tuner/preamplifiers, etc. , but also permits the use of longer interconnecting audio cables, when required, with minimal signal deterioration.

Additionally the GCD-575 is supplied with a high quality, low-loss audio cable to prevent the sonic smear that conventional audio cables tend to cause. The use of this special cable and the 100 ohm output impedance permits the GCD-575 to be used with Adcom's SLC-505 passive straight line controller. If no other source equipment will be used, the variable output can be used directly into your power amplifier, bypassing the preamplifier circuits normally required by other CD players.

A muli-winding power transformer, connected to three separate tightly regulated power supplies for the audio, digital and display circuitry, insures isolation of the different functions and optimal operation of each without interference.

The four special heavy feet installed on the GCD-575 are reversible metal castings. On one side, the flat surface insures a wide contact area. The revers side is cast with buil-in "Iso-points" which, when used in a three-foot configuration, operates as a "tripod" support system.

A special polarity-inverting switch permits you to reverse the normal positive polarity to negative (inverted) polarity. This corrects playback of CDs in which the polarity was incorrectly recorded (inverted), or for use in systems in which one of the components causes a reversal of correct polarity

Specifications

Frequency response: 5 - 20,000 Hz +0,1; -0,5 dB

Signal-to-noise ratio: 105 dB

Dynamic range: 98 dB

THD: 0,0025%

IMD (70 Hz difference): 0,00018% at 5 kHz

Channel separation (1kHz): 95 dB

Interchannel Phase Shift: less than 1,8 ° at 20 kHz

Output impedance:

Fixed: 100Ω

Variable: 100Ω

Digital: 75Ω

Output level:

Fixed: 2,5 V RMS

Variable: greater than 4,5 V RMS

Digital: 0,5 V peak-to-peak

Laser: GaAIAs semiconductor

Sampling rate: 176,4 kHz

Quantized bits: 16-bit linear

Power: 120 V AC, 60 Hz (available in 220/240, 50 Hz)

Dimensions (W x H x D): 430 x 87 x 285 mm (17" x 3-7/16" x 11-1/4")

Weight: 5,5 kg (12 lbs)