Detailed Manual for Adcom GFA 7805 and 7807 Stereo Amplifiers

DESCRIPTION OF UNIT: REAR PANEL

(1) Inputs

The GFA-7805 and GFA 7807 have both balanced and unbal- anced inputs for each channel. The unbalanced connection is made via the gold plated RCA jack and the balanced con- nection is made via the XLR input connection. Each channel also has a switch which selects the type of input for each channel. Make sure the switch is in the appropriate posi- tion for the type of connection you have choosen. For best performance, always use high quality interconnects. Your ADCOM dealer can help select the best cable for your needs.

(2) Outputs

The GFA-7805’s and GFA-7807’s connections to the loudspeakers are made through high-grade, 5-way, gold-plated binding post terminals. There are two terminals for each speaker, which are colored RED for the positive (+) output and BLACK for the negative (-) output.

The binding posts will accept a variety of connector types. The most secure and prevalent of these is the “U”-type spade connectors (at least 0.25’’ wide and maximum width of 0.57”). The terminal will also accept bare wire (up to AWG1O) and “banana” type plugs (single or dual).

(3) I2V DC Trigger

The GFA-7805 and GFA-7807 are very high power amplifiers and as such must be directly connected to the wall outlet or an appropriate surge protector or AC line conditioner.

It must never be connected to the ‘switched’ outlets on the rear panel of a pre-amplifier. Usually this would mean that when you turn on/off your pre-amplifier you would have to turn on/off your power amplifier separately. We have, however, provided the ability to control the OFF/ON function of the GFA-7805/7807 by a l2V DC output jack on the rear of certain ADCOM pre-amplifiers. When using this feature the front panel Power Switch must be left in the in “on” position. To connect the preamplifier 12V DC output jack to the amplifier 12V DC jack, you will need a monaural mini phone plug to monaural mini phone plug cable. Contact your dealer for information on using this feature with ADCOM and other brand pre-amplifiers.

(4) AC Fuse

The AC Fuse protects the electronic circuits of the GFA- 7805/7807. This fuse, normally, will fail only if there

is an overload within the GFA-7805/7807. If your fuse fails please contact your dealer or ADCOM directly for a replacement or servicing.

(5) AC Power Cord

The AC cord provides power to operate all the GFA- 7805/7807’s circuits. Its plug can be connected to a standard wall outlet provided the outlet supplies a voltage compatible with the power requirements printed on the rear panel of the GFA-7805/7807.

DESCRIPTION OF UNIT: FRONT PANEL

(6) On/Off Switch

The On/Off Switch controls power to the power transformer and circuits of the GFA-7805/7807. Whenever the GFA-7805/7807 is energized the Power LED (7)

will glow. To turn the GFA-7805/7807 on, press the push-button. It will remain in the “engaged” position while the unit is energized. To turn the GFA-7805/7807 off, press the push-button in and release and it will move to the “disengaged” position.

(7) Power LED

This LED will glow whenever the On/Off Switch (6) is turned on and the GFA-7805/7807 is energized. The Power LED indicates that there is AC voltage being fed to the amplifier, but it does not signify that all the amplifier’s circuits are in operation. If, for example, one of the Thermal Protection LEDs (9) glows, that amplifier channel will not produce sound even though the Power LED may still glow. When the GFA-7805/7807 is turned off, the Power LED will take some time to fade out completely. It may take up to 30 seconds to fully extinguish. Additionally, the internal power transformer is provided with a thermostat which will interrupt power into the transformer if its temperature exceeds 125°C. This high temperature will seldom, if ever, be encountered unless the amplifier is subjected to abnormal conditions, such as operation into loads of less than 3 ohms at very high listening levels, etc. If the AC Fuse (4) has not failed, the Power LED is out, and the Thermal Protection LED (9) does not glow, this would indicate that the thermostat within the transformer has opened.

Once the temperature within the transformer decreases to a normal level, the thermostat will reset itself

GFA7807 specifications

The Adcom GFA-7807 is a high-performance power amplifier known for its exceptional sound quality and engineering. As part of Adcom's renowned lineup of audio equipment, the GFA-7807 is celebrated for its ability to deliver powerful and accurate audio reproduction, appealing to audiophiles and casual listeners alike.

One of the standout features of the GFA-7807 is its impressive power output. It provides 200 watts per channel at 8 ohms and can deliver up to 350 watts per channel at 4 ohms. This robust power handling allows it to drive even the most demanding speakers with ease, ensuring that the music remains dynamic and detailed, regardless of the volume level. This amplifier's ability to maintain its performance under high loads is a crucial attribute for high-end audio setups.

The GFA-7807 employs a Class AB amplification design, which balances the benefits of both Class A and Class B amplifiers. This design helps minimize distortion and crossover issues, ensuring that the output remains clean and precise, particularly in the midrange frequencies. The amplifier's low total harmonic distortion (THD) rating further enhances its audio fidelity, making it an excellent choice for critical listening.

In terms of build quality, the Adcom GFA-7807 is constructed with rugged components designed to withstand the rigors of prolonged use. The sturdy chassis and high-quality connectors contribute to its durability, while also minimizing interference and maintaining signal integrity. The amplifier is also equipped with extensive protection circuits, which guard against short circuits, thermal overload, and other potential damage conditions.

Another noteworthy characteristic of the GFA-7807 is its versatility. It features multiple input options, including balanced XLR and unbalanced RCA connectors, allowing for seamless integration into various audio systems. Additionally, its rack-mountable design makes it an ideal choice for professional setups and home theaters alike.

Overall, the Adcom GFA-7807 power amplifier stands out in the audio landscape due to its impressive power handling, low distortion, rugged construction, and versatility. Whether used in a high-fidelity music system or a home theater, it delivers a remarkable listening experience that captures the essence of the original recording, making it a must-consider option for enthusiasts looking to elevate their audio setups.