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ADCOM GFA—Z OWNERS MANUAL
Your ADCOM GFA-Z power amplifier represents the finest thinking
in amplifier design. At 100 watts per channel, the GPA-2 offers an
exceptional value, superior performance at a reasonable price. Such
a product from ADCOM is only natural. Throughout its many years in
audio, ADCOM has always been associated with state-of-the-art com—
ponents utilizing advanced technology and realistic cost designs.
Its innovation and technology have expanded into such varied areas
as speaker systems, tuners, speaker switching systems and phone
cartridges (most recent is the ADCOM CrosscoilTM high output moving
This manual represents the same kind of innovative thinking
reflected in other ADCOM products. We have-written it to reflect
the kinds nf questions and possible problems you might encounter in.
enjoying the full benefits of your ADCOM GFA—Z power amp. We ask
that you thoroughly read this manual before plugging in the amplifier.
For those in a hurry, please read Sections 1 through 4.
WHAT TO DO WHEN YOU OPEN THE BOX
Before eaCh GFA-Z left the factory, it was carefully inspected
for physical imperfections as a routine part of ADCOM's quality
control. This, along with full electrical testing, should ensure a
product flawless in both appearance and performance.
After you have unpacked the amplifier, inspect it for any
physical damage. Save the shipping carton and all packing materials
as they are designed to reduce to a minimum the possibility of
In the unlikely event that damage has occured, immediately
notify your dealer and request the name of the carrier so that a
written claim to cover the damages can be initiated.
THE RIGHT TO ANY CLAIM AGATNST A PUBLIC CARRIER CAN BE
FORFEITED IF THE CARRIER IS NOT NOTIFIED PROMTTLY AND IF THE SHIP-
PING CARTON AND PACKING MATERIALS ARE NOT AVAILABLE FOR INSPECTION
BY THE CARRIER. SAVE ALL PACKING MATERIALS UNTIL THE CLAIM HAS
WHERE TO PUT IT (AND WHERE NOT TO!)
The GPA-2 utilizes large internal heat sinks to dissipate heat
from the power transistors. The top, side, and bottom panel of the
amplifier has slots to allow air to circulate inside the amplifier.
Adequate air must be available to assure cool operation of the amp‘
Therefore, the GPA-2 should not be completely enclosed with other
heat producing components and although the amplifier can be mounted
in any position. adequate space around the amplifier should be main-
tained. We recommend at least 3 inches on the top and 1 inch on the
sides for air circulation. If the GFA-2 is going to be mounted in
an enclosed cabinet, it is recommended that the back of the cabinet
have vents to allow air to circulate around the amplifier. With these
considerations in mind, the GFA-2 should perform quite happily in any
habitable enviroment. Of course, such normal considerations as pro—
tection from excessive dust or moisture should always be considered.
The ADCOM GFA-z power amplifier has been carefully designed with high
quality components so that long term undiminished performance may be
expected from the amp, whcn it is operated in accordance with the
WHAT NOT TO DO!
CAUTION: Burn out of the output stage because of failure
to observe the following precautions will void the warranty
There is no such thing as absolute reliability or protectiOn when
amplifiers are abused. While the GFA-2 amplifier has been designed
to withstand most conditions it may not be impervious to gross abuse.
There is one condition which must always be avoided: This condition
is called RF Detection and will almost certainly cause failure of the
output devices if initiated. Because ADCOM amplifiers have an extremly
wide bandwidth, it is almosL impossible to protect against burnout if
abused. The following acts cause RF Detection and MUST BE AVOIDED:
1. Connecting the inputs or outputs while amplifier is on.
2. Using the "thumb test". It is a dangerous habit to connect
cables to the inputs, touching the other end of the cable
while the amplifier is on. This may not only cause ampli—
fier failure but may destroy your loudspeakers due to the
high power surge emitted from the amplifier.
It is wise to follow the procedure of completely hooking up your
system before turning anything nnl A Few simple precautions will con
tribute to trouble free performance. Because of the high power of the-
GPA—2, ADCOM will not be responsible for any damage to speakers or
other components due to their inability to handle the amplifier's
power or for any other misuse.
WHY WE BUILT IT THE WAY WE DID
The ADCOM GFA-2 represents a departure from many of the other
currently available amplifier designs. This departure is the result
of careful studies into available designs, circuits and parts. The
major feature of the GFA-Z amplifier is the dual power supply con-
figuration. Each channel has an independent power transformer and
associated circuits. This dual power supply design allows each
channel to work independently of the other. Most power amplifiers