Adcom GFP-345 User manual
HIGH
DEFINITION
PREAMPLIFIER
INTRODUCTION
Please
read
thoroughly
these
operating
instructions
for
the
GFP-345
before
connecting
or
attempting
to
operate
this
unit
For
your
own
benefit,
follow
all
the
instructions
in
this
manual
and
save
it
for
future
reference.
The
ADCOM
GFP-345
is
a
result
of
a
thorough
examination
and
reevaluation
of
all
factors
affecting
the
sonic
performance
of
preamplifiers.
A
great
deal
of
care
was
taken
to
insure
that
the
audio
performance
of
the
GFP-345
could
be
maintained
for
years
to
come
by
the
selection
of
top-quality
components
and
circuit
topologies.
The
result
is
a
preamplifier
which
is
as
musical-sounding
as,
and
which
preserves
the
dynamic
contrasts
of,
an
original
performance.
I^
in
fh
3
at
'°
n
i
nd
°
per
‘*
,,onof
the
GFP-345
are
described
in
the
following
pages.
We
sincerely
hope
you
will
value
and
enjoy
the
considerable
attention
we
have
given
its
design
and
construction.
This
manual
has
been
written
to
help
you
understand
the
correct
operation
of
the
GFP-345.
Please
read
it
carefully
to
fully
comprehend
all
its
features
and
functions
and
thereby
derive
the
maximum
performance
from
its
use
in
your
system.
FEATURES
GFP-345
I!*®^
3
S?«
t
0dei
!
d
L
a
J!f
r
c
«
e
h
'
9hly
innovative
internal
designs
and
circuit
topologies
of
both
the
"Reference
Standard
GFP-565
and
GFP-555H
preamplifiers
-
accordingly,
it
is
setting
new
standards
for
products
in
its
price
category.
Many
of
the
most
significant
performance
characteristics
of
the
GFP-565
and
GFP-555II
have
been
built
into
the
GFP-345.
The
power
supply
and
low
impedance
outputs
were
designed
to
preserve
music
dynamics.
The
amplification
staqes
employ
direct-coupled,
custom-designed,
linear-gain
amplifiers
operating
in
full
Class
A
to
insure
the
minimum
distortion
and
low-noise
required
for
digital-source
material.
Buffered
tape
outputs
insure
input-signal
integrity,
and
precl
ude
interference
with
the
main-source
signal
in
the
preamplifier's
circuits
when
digital
or
cassette
tape
recorders
are
connected
(even
when
these
are
not
operating).
The
optional
phono
preamplifier
(available
as
a
plug-in
board:
the
PHO-802A)
delivers
the
quietest
obtainable
performance
with
unmatched
record-equalization
accuracy
and
lowest
distortion.
Operating
in
full
class
A
its
unrestricted
dynamics
and
musical
accuracy
are
delivered
at
surprisingly
modest
cost.
The
GFP-345
contains
the
highest-quality
components;
never
before
available
in
a
component
of
such
This
should
insure
stable,
dependable
operation
and
long,
trouble-free
life.
moderate
cost.
Low-impedance
power
supply
for
best
regulation
and
optimal
circuit
performance.
This
type
of
design
insures
that
music
dynamics
are
delivered
through
the
preamplifier
without
compression.
•
Thick
power-supply
traces
on
printed
circuit
board
for
minimal
losses
and
improved
voltage
stability.
This
technique
insures
constant
voltage
to
all
the
circuitry,
regardless
of
volume
or
dynamic
demands
of
the
music.
•
AM
capacitors
are
state-of-the-art
electrolytics
and
film
capacitors
with
very
low
ESR
and
unsurpassed
sonic
purity
This
design
feature
provides
an
audible
benefit,
the
lowest
possible
distortion
of
music
signals.
•
Overdesigned
mu-metal-shielded
power
transformer
for
better
regulation.
This
transformer
design
eliminates
stray
hum
fie
ds
for
lowest
noise
and
provides
undiminished
voltage
to
circuits
for
best
performance
under
any
demands
•
Precision
programmable
regulators
for
stabilized,
constant
DC
voltages,
regardless
of
load.
This
type
of
requlator
insures
stable
operation
of
all
circuits
regardless
of
the
dynamic
demands
of
the
music
being
played.
•
Amplifier
stages
use
ADCOM
premium-grade
ICs
selected
for
their
linear
operation
and
sonic
quality.
These
linear
amplifiers
insure
extremely
low
noise,
low
distortion
and
low
DC
offset
for
best
performance
with
either
set
of
hrOOmn
At
ifmirn
•
Amplifiers
are
operated
in
pure
Class-A
mode
to
insure
lowest
distortion
the
level
control.
regardless
of
the
signal
level
or
setting
of
•
Entire
signal
path
is
direct-coupled
from
input
to
output.
Direct
coupling
minimizes
the
number
of
components
signal
must
go
through,
preventing
degradation
of
the
music.
*
I
W
th
Se
,
,
f°'?^
t
"2^
TPUTS
LAB
ar
®
direct
‘
coupled
-
The
V
Provide
a
signal
in
the
most
straightforward,
simplest
patn.
OUTPUTS
NORM
are
capacitor-coupled
using
precision,
high-grade
film
capacitors
for
power
amps
which
can
not
accept
ultra-wide
bandwidth
inputs.
1
•
Low-output-impedance
(100
ohms)
from
both
sets
of
outputs
to
reduce
interaction
of
connecting
cables
and
other
equipment
and
preserve
music
dynamic
contrasts.
•
Five
sets
of
inputs,
front
panel
controlled,
including
TAPE
IN;
six
sets
if
the
EXTERNAL
PROCESSOR
IN
jacks
are
used
also
as
an
auxiliary
input.
•
*f
Pe
°^
tpu,s
{10
°
ohms)
to
P
erf
ectly
interface
with
any
type
of
tape
recorder.
This
technique
allows
^
recorder
-
including
DAT
and
DCC.
and
insures
the
best
recording
characteristics
independently
of
the
cable
used
and
the
load
impedance
of
the
tape
recorder
inputs.
•
Buffered
tape
outputs
to
preserve
input-source-signal
integrity
and
preclude
"loading”
of
the
signal-source
components
and
distortion.
Buffering
prevents
the
degradation
of
the
source
signal
caused
by
most
tape
recorders
when
they
are
connected
to
the
tape
outputs.
The
buffers
insure
that
the
integrity
of
the
internal
signal
path
will
not
be
affected
by
the
tape
recorder
used.
•
H.
r
°
n
,H
Pa
:
e,
.;
SWitChab,e
proc
l
essor
l0
°P'
Sh
ortens
the
signal
path
by
switching
the
processor
in
and
out
of
the
circuit
directly
on
the
main
circuit
board.
Allows
the
processor
to
be
removed
totally
from
the
circuit
when
not
needed.
•
All
high-grade
construction
parts
including
1%.
Roederstein
metal-film
resistors
and
all
metallized-film.
precision
capacitors
throughout.
These
components
helps
the
GFP-345
achieve
lower
noise
levels
and
lower
signal
degradation
than
preamps
selling
for
many
times
its
price.
•
Extremely-low-noise,
optional
phono
preamplifier
board
(PHO-802A)
with
virtually
zero
RIAA
error,
optimized
for
high-output
mov.ng-co.l
and
moving-magnet
cartridges
plus
direct-coupled
signal
output
for
maximum
bass
impact
and
dynamic
response.
These
features
will
provide
the
flattest,
lowest-noise.
lowest-distortion
response
from
a
phono
cartridge
and
musically
satisfying
reproduction
from
any
vinyl
record.
•
J-°^‘
,mpedance
-
RIAA-equalization
network.
This
unique
network
insures
the
lowest
achievable
noise
level
in
a
pnono
preamp.
UNPACKING
THE
GFP-345
ariu
r
wn^rr:nnni
the
'T^
it
^
as
1
car
«
,ul|
y
inspected
'or
physical
imperfections
and
electrical
performance
as
fnsure
a
orolct
fS2S«
«
VCo
"
tro,
-
™
S-
al
°"9
with
full
operational
and
mechanical
testing,
should
insure
a
product
flawless
in
both
appearance
and
performance.
After
you
have
unpacked
the
GFP-345
inspect
it
for
poss
i
b
Hty
oTt^a
n
s
do
rtet
km
damn
no
TZT
al
!
p
acking
materials
as
the
Y
are
intended
to
reduce
to
a
minimum
the
^
a
^
.
6
pr0dUC
'
ever
need
t0
^
shipped
again.
In
the
unlikely
event
damage
has
damage
<UnbeiJSiat^
*
^
'
m
y
and
request
the
name
of
,he
carrier
so
tha
»
a
written
claim
to
cover
shipping
RIGHT
TO
A
CLAIM
AGAINST
A
PUBLIC
CARRIER
CAN
BE
FORFEITED
IF
THE
CARRIER
IS
NOT
NOTIFIPn
^cdc^i!
IN
WRITING
AND
IF
THE
SHIPPING
CARTON
AND
PACKING
MATERIALS
ARE
NOT
AVAILABLE
FOR
INSPECTION
BY
THE
CARRIER.
SAVE
ALL
PACKING
MATERIALS
UNTIL
THE
CLAIM
HAS
BEEN^SETTLED.^
INSTALLING
THE
GFP-345
Although
the
GFP-345
does
not
generate
much
heat,
you
will
help
insure
its
long-term,
trouble-free
operation
if
vou
keen
should
SrbeSS?
9
?
T
h
radiators
or
h
ot-airducts,
and
provide
reasonable
ventilation.
The
GFP-345
p
'
acad
w,t
.
h
0,her
heat-producing
components
in
a
cabinet
or
enclosure
lacking
free
air
flow.
If
placed
the
component
hea,
'
producmg
component
’
such
33
a
power
amplifier,
please
allow
a
minimum
of
three
Inches
between
For
use
in
professional
installations,
the
GFP-345
may
be
mounted
in
a
standard
19-inch
rack-mount
adaptors
available
through
ADCOM
dealers.
rack
using
the
optional
RM-3
CONNECTING
THE
GFP-345
7
m
d
S
pe
"
d
°
n
the
quality
of
the
'
nterc
onnection
of
both
the
preamplifier
and
its
associated
equ£ment.
All
the
input-
and
output-signal
connections
should
be
made
only
with
hiqh-aualitv
low-loss
audio
cables.
LEFT
CHANNEL
and
RIGHT
CHANNEL
inputs
and
outputs
are
cleaHy
labelled
on
the
r2r
panel
2
NOTE
WHENEVER
CONNECTIONS
TO
OR
FROM
THE
GFP-345
ARE
BEING
MADE,
BE
CERTAIN
ALL
ASSOCIATED
COMPONENTS
ARE
TURNED
OFF.
GND
O
Ground
connection
to
chassis
is
provided
primarily
to
connect
phonograph
(turntable)
ground
terminals.
Most
turntables
are
supplied
with
a
separate
ground
wire
to
help
eliminate
hum.
Connect
the
separate
ground
wire,
if
supplied
with
your
turntable,
to
the
GND
Q
terminal.
The
GND
Q
terminal
can
also
be
used
to
connect
the
chassis
of
the
GFP-345
directly
to
the
center
screw
of
your
AC
wall
outlet
or
other
good
“earth”
connection
such
as
a
water
pipe
or
radiator.
This
earth
connection
may
be
useful
in
areas
of
high
RF
interference,
and
may
help
to
minimize
noise
particularly
when
playing
low-
output-level
phonograph
cartridges
(see
section
PHONO
(PHO-8Q2A
OPTION)
©
following).
NOTE
Although
the
GNO
Q
connection
is
probably
the
best
place
at
which
to
connect
your
system
to
a
good
earth
ground,
it
should
be
pointed
out
that
only
one
connection
to
an
earth
ground
is
to
be
made
in
any
system.
Otherwise
what
is
commonly
known
as
a
“ground-loop”
will
be
caused
and
hum
and
noise
may
increase
sufficiently
to
become
a
nuisance.
In
any
system,
only
one
ground
connection
can
be
made
to
earth.
If
one
of
your
components
is
supplied
with
a
three-prong
AC
connector
which
is
plugged
into
the
AC
wall
outlet,
earth
connection
will
be
made
through
this
plug
and
additional
ground
connections
are
not
recommended.
Similarly,
if
the
system's
units
are
mounted
in
a
rack
and
ground
connection
between
chassis
is
made
through
the
rack
mounting,
special
techniques
must
be
undertaken
to
minimize
ground-loops
and
subsequent
noise.
A
detailed
discussion
of
ground-loops
with
methods
for
their
elimination
is
beyond
the
scope
of
this
manual.
AUX
1
©
This
set
of
input
jacks
is
for
use
with
a
high-level
signal
source,
such
as
a
tape
player,
the
audio
signal
from
a
video-disc
player,
or
video-cassette
recorder
(VCR).
The
load
impedance
of
this
input
is
approximately
22,000
ohms.
This
input
can
also
be
converted
for
use
with
an
analog
disc
turntable
if
the
optional
PHO-802A
board
is
installed
onto
the
main
PCB
of
the
GFP-345.
This
is
a
procedure
best
left
to
your
dealer,
or
ADCOM
authorized
service
personnel.
It
is
not
recommended
you
undertake
the
installation
of
the
PHO-802A
board
within
the
GFP-345
yourself.
PHONO
(PHO-802A
OPTION)
©
To
use
an
analog
disc
turntable
with
the
GFP-345
requires
installation
of
the
optional
PHO-802A
phono
preamp
board
onto
the
main
PCB
of
the
GFP-345.
Once
the
PHO-802A
board
is
installed,
the
input
jacks
marked
AUX
1
©
are
then
usable
with
any
high-output
moving-coil
or
moving-magnet
phono
cartridge.
These
two
standard
RCA
jacks
will
accept
all
common
RCA
plugs,
one
for
each
channel,
left
and
the
right,
usually
supplied
at
the
ends
of
the
turntable's
cables.
LEFT
CHANNEL
and
RIGHT
CHANNEL
inputs
are
clearly
labelled
and
their
routing,
even
when
the
PHO-802A
board
is
installed,
will
remain
left
and
right
as
indicated.
Determine
the
exact
color
coding
or
markings
on
your
turntable’s
cables
for
left
and
right
channels
in
order
to
insure
the
correct
connections.
The
PHO-802A
circuit
is
designed
to
accept
the
signal
from
any
high-output
moving-coil,
moving-magnet,
induced-magnet,
moving-iron
or
variable-reluctance
car¬
tridge,
the
output
from
which
is
rated
at
2.2
mV/cm
or
higher.
The
PHO-802A-input
electrical
impedance
characteristics
are
the
standard
47,000
ohms
with
lOOpF
shunt
capacitance.
ADCOM
high-output
moving-coil
cartridges,
for
example,
are
ideally
suited
for
use
with
this
phono
preamplifier.
Low-output
moving-coil
cartridges
which
normally
require
a
pre^
preamplifier
(sometimes
referred
to
as
a
"head-amp''),
or
step-up
transformer
must
have
these
auxiliary
devices
connected
before
the
RCA
jacks
feeding
the
input
to
the
PHO-802A
board.
A
pre-preamplifier,
or
step-up
transformer
provides
the
additional
gain
required
by
very-low-output
moving-
coil
cartridges
to
operate
with
a
standard
preamplifier
circuit.
A
pre-amplifier,
or
step-up
transformer,
is
not
necessary
and
must
not
be
used
with
high-output
moving-coil
cartridges
or
moving-magnet,
induced-magnet,
etc.
cartridges.
If
you
are
uncertain
as
to
which
type
of
cartridge
you
will
be
using,
please
consult
the
instruction
manual
or
specification
sheet
which
was
included
with
your
cartridge,
or
contact
the
dealer
from
whom
you
purchased
the
cartridge,
or
the
cartridge
manufacturer.
Some
turntables
are
supplied
with
a
separate
ground
wire,
which
must
be
connected
to
ground,
to
reduce
hum.
If
the
turntable
is
provided
with
this
separate
ground
wire
simply
connect
it
to
the
GND
©
screw
on
the
rear
panel
of
the
GFP-345
directly
to
the
left
of
the
AUX
1
inputs
(now
converted
to
PHONO).
There
are
simplified
instructions
on
the
main
PCB
of
the
GFP-345
to
facilitate
installation
of
the
PHO-802A
board.
Detailed
instructions
are
also
supplied
in
the
section
INSTALLING
THE
PHO-802A
BOARD
IN
THE
GFP-345
at
the
end
of
this
manual.
3
CD
Q
Iia!»r
et
.hl
SK
iaCkS
'?l
0r
USe
W
j
th
a
Com
P
act
Disc
(
CD
>
P'ayer
Or
other
similar
high-level
signal
source,
such
as
a
tape
approximatet/
22
OOOohrlT
3
P
'
ayer
’
°
r
vide
°-
cassette
record
e
r
(^R).
The
load
impedance
of
this
input
is
TUNER
O
Although
this
pair
of
inputs
is
provided
for
your
tuner,
they
may
be
used
with
any
other
high-level
source
such
as
a
taoe
Playe
'
0rO,herSiml,ar
signal
source.
The
load
impedance
of,his
input
AUX2
0
T
Vided
f
?:
any
°
thef
high-level
source
you
may
have
available
such
as
a
tape
player,
an
additional
CD
&
Sp°ut
C
°
P
3yer
°
r
h6r
S
'
m
'
3r
h
'
9h
'
level
source
-
The
load
impedance
of
this
input
is
identical
to
that
of
the
TAPE
IN
O
Ibolfthe
c
a
nO
inmi
ann!
iC
Xh
n
Sensitiv
‘
,y
and
electd
cal
characteristics
to
the
CD
O
inputs
and
the
comments
made
tbe
,
C
?
®
,"
puts
app
'
y
;
These
may
be
used
not
on|
y
,or
cassette
or
other
audio
tape
recorders
(such
as
DAT
or
DCC),
but
also
with
any
high-level
signal
source
such
as
a
VCR's
audio
outputs,
etc.
If
you
desire
simple
Payback
ofprerecorded
tapes,
plug
the
left
and
right
outputs
of
your
tape
machine
labelled
“tape
nulh
In
hP
TA
U
pFMn2
e
ffi
.
k
G
|aCk
f
USin9
3
S6t
°
f
Sood-q^ty,
low-loss
audio
cables.
To
select
playback
of
tape
pd
®
b
"
f
P
M
S
N
P
s
*'
,ch
on
the
,ront
P
anel
of
,he
GFP-345.
Whenever
the
TAPE
MON
©
is
activated
the
LED
directly
above
it
will
glow.
Also,
whenever
the
TAPE
MON
©
switch
is
pushed
in
the
INPUT
©
selector
will
be
disconnected
from
the
circuit.
That
is,
whatever
source
has
been
selected
through
the
INPUT
©
selector
will
be
SKTSF
frdm
th
®
c,rcu,,s
of
the
GFP
*
345
and
will
be
supplanted
by
the
source,
or
tape
recorder,
plugged
into
the
TAPE
IN
Q
jacks
on
the
rear
panel
of
the
preamplifier.
TAPE
OUT
O
'^
biph
®
v
®^
i
"
pdt
is
3
®'®
cted
via
,h
«
INPUT
©
selector
knob
will
appear
at
the
TAPE
OUT
O
jacks.
It
should
be
pointed
ou
,
that
re
9
ard|
ess
of
the
positionthe
TAPE
MON
©
switch
is
in,
whatever
source
is
selected
via
the
INPUT
©
selector
All
8
T
X
PE
OUT
°
iaCkS
-
TheTAPE
M0N
°
SWitCh
only
CO
"
trols
the
P^y^ckcircuitsof
theGFP-345^
tapp
unSffifc?
h
.•
If
y
°
U
are
rn
°7
,0nn9
3
recordin
2
which
is
being
made
on
a
tape
or
cassette
machine,
by
using
the
TAPE
MON
©
function,
you
must
leave
the
INPUT
©
selector
on
the
source
selected
for
recording
or
the
recording
thr^nLT^nnT
P
e
H
r
,n
P
.h
e
;
'
S
’
,
he
changing
of
SOurce
selection
through
the
INPUT
©
selector
switch
will
interrupt
T
9
,ed
tP
the
tape
or
cassette
recorder
via
the
TAPE
OUT
O
jacks.
To
hook-up
the
TAPE
OUT
Q
to
your
cassette
or
tape
recorder,
connect
the
right
and
left
jacks
on
the
cassette
or
tape
recorder
labelled
“line
in"
or
“record
in"
L6FT
CHA
,T
EL
and
RIGHT
CHANNEL
TAPE
OUT
o
jacks
on
the
rear
panel
on
the
GF^is
It
recording
P
°
r,ant
^
Y
°
U
^
°
n
Y
high
"
quallty
’
low
*
loss
interconnecting
cables
in
order
not
to
degrade
the
quality
of
the
NOTE
T
^|
PE
?!^
T
®
circuds
are
actively
“buffered"
in
order
to
insure
that
the
signal
within
the
circuitry
of
the
GFP-
345
will
not
be
compromised
regardless
of
whether
the
tape
recorder
is
in
use
or
not.
Therefore,
you
can
listen
‘J®
source
which,
yot.are
recording
without
fear
of
deg
rading
the
signal
either
in
the
recording
or
the
listening
mode.
In
addition,
the
buffered
outputs
will
prevent
the
normal
degradation
that
tape
recorder
inputs
cause
an
audio
signal
in
a
preamplifier
when
the
tape
recorder
circuits
are
turned
off
and
not
in
operation.
EXTERNAL
PROCESSOR
IN
©/
EXTERNAL
PROCESSOR
OUT
©
J,
h
'®
-"Puts
and
outputs
is
provided
for
use
with
any
"signalprocessor"
such
as
an
equalizer,
time-delay
unit.
EEfTT*
d6
^
er
:
®
T
he
^^NAL
PROCESSOR
IN
0
/
EXTERNAL
PROCESSOR
OUT
©
jacks
are
selected
and
controlled
by
the
front-panel
button
labelled
EXT
PROC
©.
Pushina
in
the
EXT
PROC
©
button
will
connect
whatever
processor
is
plugged
into
the
EXTERNAL
PROCESSOR
IN
©/EXTERNAL
PROCESSOR
OUT
to
C
TCU'try
of
the
GFP-345.
Whenever
the
EXT
PROC
©
button
is
pushed
In.
activating
this
circuit,
the
red
li^F^FRNAi
1
ppnr
r
Ji*
as,
"
B
]
h
®
0(7
PROC
®
button
will
disconnect
the
EXTERNAL
PROCESSOR
IN
St
PROr®
L
hMn°
CES
^
OR
^
U
h
T
®
jacks
from
the
circuitry
of
the
preamplifier
It
is
important
to
note
that
when
the
EXT
PROC
©
button
is
released,
both
sets
of
jacks
(EXTERNAL
PROCESSOR
IN
©/EXTERNAL
PROCESSOR
OUT
©)
E*?"
0
?*
removed
,rom
,he
circui,r
V
of
Preamplifier
(and,
so,
consequently
whatever
processor
is
plugged
into
these
jacks)
to
prevent
any
possible
degradation
of
the
signal
selected
through
the
INPUT
©
selector
switch.
4
To
connect
the
processor,
equalizer
or
surround-sound
decoder,
etc.,
to
the
GFP-345
always
use
high-quality
low-loss
PROCESSOR
OUT
©
£2?
°V^
***
P
[°f
SSO
I
,
ab
*"
ed
"‘"P*"
Hn*n".
or
"source-
into
the
EXTERNAL
Ph
°
UT
®
k
,
th
®
r
ear
pane
0f
lhe
GFP
‘
345
'
observing
the
left
and
right
labelling
on
both
sets
of
jacks
PRnrpstqnR
iw
rfi
h
n
S,9n
.t
processor
marked
“output,
"out"
or
"line-out"
to
the
GFP-345
jacks
labelled
EXTERNAL
Fp^°"-M
e
K^hese
connections
have
been
effected
simply
pushing
in
the
EXT
PROC
©
button
on
the
front
panel
of
the
GFP-345
will
bring
the
processor
into
the
circuit.
NOTE
11
n0
processor
is
plugged
into
the
EXTERNAL
PROCESSOR
IN
©
and
EXTERNAL
PROCESSOR
OUT
©
jacks,
and
the
EXT
PROC
©
button
is
pushed
in,
all
the
inputs
of
the
GFP-345
will
be
disconnected
and
no
output
signal
will
be
present
at
either
the
OUTPUTS
NORM
©
or
the
OUTPUTS
LAB
®
*
n
£
SOund
wil1
be
heard
throu
9h
the
s
y
s,em
-
Whenever
a
signal
processor
is
not
being
used,
the
EXT
PROC
©
button
should
always
be
in
the
out
position.
!
v
^r,
r
'
n
°
P
rocessor
is
connected
to
the
EXTERNAL
PROCESSOR
IN
©and
Kt
PRnr
L
flft
R
?
C
.f
SS
.?
R
OUT
0
jacks,
to
use
the
EXT
PROC
©
button
as
a
mute
function.
By
pressing
in
the
relMMd
°
®
bU
*
®
S
'
9
W
66
m,errupted
until
,he
EXT
PROC
©
button
once
again,
pushed
in
and
3.
Normally,
the
GFP-345
does
not
invert
polarity;
that
is,
if
a
positive-going
signal
is
present
at
any
of
its
inputs,
or^^^
8
i
t
i
V
f^Sl
n9
signal
at
the
ou,puts
-
However,
if
a
signal
processor
is
connected
to
the
EXTERNAL
PROCESSOR
IN
©
and
EXTERNAL
PROCESSOR
OUT
©
jacks,
and
its
circuitry
inverts
polarity
the
signals
present
at
the
OUTPUTS
NORM
©
and
OUTPUTS
LAB
©
will
also
be
inverted
in
polarity
(check
the
Instruction
Manual
of
your
signal
processor
to
determine
if
it
does
or
does
not
invert
polarity).
4.
Usually,
there
should
be
no
appreciable
level
difference
whenever
a
signal
processor
is
connected
into
or
out
of
the
circuitry
of
the
GFP-345
(through
the
use
of
the
EXT
PROC
©
button),
so
long
as
the
processor
was
designed
with
an
absolute
gam
of
1
and
adequate
input
and
output
impedances
to
fulfill
this
function.
If
a
level
difference
can
be
detected
when
switching
a
processor
in
and
out
of
the
circuit,
and
this
is
disturbing
to
you
please
contact
the
manufacturer
of
the
processor
you
are
using
to
see
if
a
correction
of
this
level
difference
carl
d©
enectea.
5
It
is
also
possible
to
employ
the
EXTERNAL
PROCESSOR
IN
©
jacks
as
an
additional
set
of
inputs,
since
Sf5£55'
a
pRn
t
^2S
,
rl^f«-
U,
l
ry
*
before
j
beLEVEL
©
and
BALANCE
©
controls.
If
you
wish
to
use
the
S
^
R
N
®
,acks
88
an
add,tional
lf1
P
ut
.
simply
plug
the
signal
source
into
the
EXTERNAL
PROCESSOR
IN
©jacks
as
you
would
any
of
the
other
inputs
(CD
©,
TUNER
©.
etc.)
and
select
that
source
by
pushing
In
the
EXT
PROC
©
button.
Whatever
other
selection
of
sources
has
been
made
through
the
INPUT
p
selector
wiM
be
disconnected
and
the
source
plugged
into
the
EXTERNAL
PROCESSOR
IN
©
jacks
will
then
be
fed
through
the
circuits
of
the
GFP-345
and
out
of
the
OUTPUTS
NORM
©
and
OUTPUTS
LAB
©
5
Whatever
processor
is
connected
to
the
EXTERNAL
PROCESSOR
IN
O
and
EXTERNAL
PROCESSOR
OUT
O
jacks
ro'Tnhfh!
i
acks
-
l
f
V
ou
wj
sh
to
insert
an
equalizer
into
the
tape
recorder
circuits
this
must
be
done
through
the
specific
TAPE
IN
©
and
TAPE
OUT
©
jacks
along
with
the
particular
recorder
In
such
an
instance
this
processor
will
not
operate
on
any
other
source
selected
through
the
INPUT
©
selector
but
will
operate
only
on
the
FXTFRNAI
°pinr^nSl^n
n
n
T
te(i
'
simi,arly
'
because
of
the
design
of
the
circuitry
in
the
GFP-345.
and
when
the
TA
QC
,
S
S0R
IN
®
)acks
are
used
an
additional
high-level
input,
this
individual
signal
will
not
appear
at
the
TAPE
OUT
©
jacks,
nor
can
it
be
selected
through
the
INPUT
©
selector
Therefore,
tape
recordings
cannot
be
made
of
the
signa
source
Pegged
into
the
EXTERNAL
PROCESSOR
©
jacks.
To
return
to
usual
operation
of
the
preamplifier
push
and
release
the
EXT
PROC
©
button
and
the
operation
of
all
the
switches
and
selectors
will
return
to
normal
and
the
source
plugged
into
the
EXTERNAL
PROCESSOR
IN
©
jacks
will
be
disconnected
from
the
circuitry
of
the
GFP-345.
OUTPUTS
NORM
©
The
OUTPUTS
NORM
©
are
capacitively
coupled
using
very-high-grade
metallized
film
capacitors.
It
is
ideal
for
use
with
power
amplifiers
which
require
a
bandwith-limited
signal
which
does
not
extend
to
DC.
Although
these
capacitivelv-
coupled
outputs
do
restrict,
somewhat,
the
extremely
low
frequencies,
around
5
Hz
or
10
Hz,
it
does
not,
in
any
way
sonic
detedoration
°
f
^
S
'
9nal
fr
°
m
,he
preampli,ier
Great
care
was
taken
in
the
selection
of
capacitors
to
preclude
any
™
£
tpUtS
,0
V
°
Ur
POWer
arnplifier
'
sim
P'y
interconnect
the
LEFT
CHANNEL
and
RIGHT
CHANNEL
OUTPUTS
NORM
©
jacks
to
the
corresponding
left
and
right
input
jacks
on
the
amplifier.
To
preserve
the
extremely
hiqh
quality
of
the
circuitry
in
the
GFP-345,
it
is
recommended
that
you
use
as
high
a
quality
cable
as
possible
to
make
this
interconnection.
NOTE
Both
the
OUTPUTS
NORM
©
and
the
OUTPUTS
LAB
©
may
be
used
simultaneously
should
you
wish
to
bi-amp
your
speakers,
or
drive
more
than
one
amplifier.
When
using
both
of
these
outputs
simultaneously
there
will
be
no
loading
effects
on
the
preamplifier.
y
OUTPUTS
LAB
©
Tha
?
U
J«
PUTS
L
^
B
®
.
,s
direct-coupled,
with
no
capacitors,
and
was
designed
to
provide
an
output
voltaqe
ideally
ma
c
ed
for
operation
with
the
ADCOM
brand
of
amplifiers.
!t
can
be
used,
however,
to
drive
almost
any
power
amplifier
presently
available
with
input
sensitivities
ranging
from
below
500mV
(0.5V)
to
well
above
2.0V.
To
connect
this
output
to
your
power
amplifier,
please
follow
the
instructions
in
the
section
above
OUTPUTS
NORM
©.
It
should
be
pointed
out
that,
since
the
OUTPUT
LABS
©
is
direct-coupled,
it
is
an
extremely
broadband
circuit
which
l
™
uwii°
W
h|
t0
.
D
?
(d
J[’
e
?’
C
Urren,)
'
There,ore
'
'*
requires
that
your
power
amplifier
(if
it
is
not
an
ADCOM-brand
amplifier)
be
able
to
handle
this
extremely
broadband
signal.
NOTE
Although
the
GFP-345
was
designed
primarily
for
use
with
stereo
power
amplifiers,
it
can
operate
just
as
well
with
wo
mono
power
amplifiers.
When
two
mono
amplifiers
are
used
for
stereophonic
reproduction,
it
is
strongly
suggested
that
they
be
a
matched
pair
with
respect
to
brand,
model,
input
sensitivity
and
power
output.
SWITCHED
©
OUTLET
The
SWITCHED
©
outlet
is
controlled
by
the
power
switch
©
on
the
front
panel
of
the
GFP-345.
You
may
plug
the
AC
line
cord
of
your
power
amplifier,
or
any
other
accessory,
which
you
want
to
turn
on
and
off
with
the
power
switch
©
of
the
GFP-345
into
these
outlets.
The
current-carrying
capacity
of
the
switch
©
Is
sufficient
to
handle
the
inrush
current
°J
P
?
™
er
am
P
|lfiers
up
to
the
200-watt-per-channel
class.
It
is
not
recommended
that
very-large-power
amplifiers,
above
the
200-watt
class,
be
plugged
into
these
outlets
(see
NOTE
below
following
UNSWITCHED
©
outlet).
UNSWITCHED
©
OUTLET
The
UNSWITCHED
©
outlet
can
supply
the
AC
power
requirements
of
any
accessory
source
used
with
the
GFP-345,
f^
a
S
r
a
?
P
P
^
yer
anal
°9
The
AC
line
cord
of
the
accessory
may
be
plugged
into
this
outlet.
The
UNSWITCHED
©
outlet
is
not
controlled
by
the
power
switch
©
on
the
front
panel
of
the
GFP-345,
and
power
will
always
be
available
at
this
outlet
so
long
as
the
GFP-345
is
plugged
into
an
energized
wall
outlet,
regardless
of
the
position
of
the
mam
power
switch
©.
The
total
power
drawn
through
the
UNSWITCHED
©
outlet
must
never
exceed
800
watts.
6
NOTE
Most
electronic
or
electrical
devices
state
the
maximum
power
drawn
by
the
device
on
a
plate,
or
label,
on
the
rear
panel
of
the
unit,
near
the
AC
line
cord
which
supplies
power
to
the
unit.
It
is
a
good
idea
to
check
these
requirements
before
plugging
an
amplifier
into
either
the
UNSWITCHED
©
outlet
or
the
SWITCHED
©
outlet.
Most
large-power
amplifiers
should
be
plugged
directly
into
an
AC
wall
outlet.
AC
FUSE
©
The
AC
line
fuse
protects
the
circuits
of
the
GFP-345.
This
fuse
should
be
replaced
only
with
a
fuse
of
the
same
current
value,
type
and
rating
as
thatsupplied
with
the
preamplifier.
The
correct
fuse
type,
current
value
and
rating
is
printed
directly
above
the
AC
FUSE
©
socket
on
the
rear
panel
of
the
GFP-345.
Replacements
with
fuses
of
higher
value
and/
or
different
rating
and/or
type
will
not
protect
the
GFP-345
circuits,
may
void
the
Warranty
and
may
cause
a
fire
hazard.
NOTE
Before
checking
or
replacing
a
blown
fuse,
make
certain
you
UNPLUG
THE
POWER
COR
D
FROM
THE
AC
WALL
OUTLET
TO
PREVENT
POSSIBLE
ELECTRICAL
SHOCK.
POWER
©
SOCKET
The
POWER
©
socket
permits
connection
of
an
ACcord
and
plug,
suitable
to
your
particular
area
or
country,
to
provide
AC
power
to
operate
the
GFP-345
circuits
and
energize
the
SWITCHED
©
and
UNSWITCHED
©
outlets.
The
AC
line
cord
should
be
plugged
into
any
standard
wall
outlet
providing
the
correct
operating
voltage.
To
determine
the
voltage
for
which
the
GFP-345
has
been
set.
check
the
voltage
listing
on
the
upper
right-hand
corner
of
the
GFP-345's
rear
panel.
NOTE
The
GFP-345's
POWER
©
socket
is
“polarized"
and
its
lower,
center
pin
is
grounded
as
required
by
many
standards
and
safety
organizations.
If
at
all
possible,
make
certain
that
there
is
a
matching,
3-prong
plug
on
the
end
of
the
AC
cord
so
that
the
chassis
of
the
GFP-345
will
be
grounded
to
“earth”.
If
a
3-prong
plug
is
not
available
m
your
area,
or
in
your
specific
circumstances,
experiment
with
the
“phasing”,
or
reversing,
of
the
AC
plug
to
achieve
minimal
hum
in
your
system
and
minimal
noise
as
well.
CONTROLLING
THE
GFP-345
Please
refer
to
the
diagram
of
the
front
panel
of
the
GFP-345
to
identify
all
the
controls
and
their
functions.
AC
POWER
SWITCH
©
©
The
"rocker"
AC
power
switch
©
controls
power
to
the
circuits
of
the
GFP-345
and
to
the
SWITCHED
©
outlet
on
the
rear
panel
of
the
GFP-345.
Whenever
the
GFP-345
is
energized,
the
red
LED
©
will
glow.
Push
the
top
of
the
rocker
switch
to
energize
the
GFP-345.
Push
the
bottom
of
the
rocker
switch
to
turn
the
unit
off.
7
INPUT
©
SELECTOR
This
rotary
selector
lets
you
choose
any
input
connected
to
the
GFP-345
and
feed
it.
through
the
circuitry
of
the
GFP-345,
to
both
the
OUTPUTS
NORM
©
and
OUTPUTS
LAB
©
jacks
and,
then,
through
your
amplifier
and
loudspeakers
The
INPUT
©
selector
will
also
feed
the
signal
you
choose
to
the
TAPE
OUT
O
jacks
on
the
rear
panel
of
the
preamplifier.
AI1
on
the
front
panel
of
the
GFP-345
will
affect
the
signal
present
at
the
OUTPUTS
NORM
©
and
OUTPUTS
LAB
©
jacks.
Please
note
that
some
of
these
controls
will
not
affect
the
signal
present
at
the
TAPE
OUT
©
jacks.
TAPE
MON
©
The
TAPE
MON
©
switch
selects
the
TAPE
IN
©
jacks
on
the
rear
panel
of
the
GFP-345.
This
switch
is
meant
to
provide
you
with
the
capability
of
"monitoring"
a
recording
you
are
making
on
a
tape
machine
which
is
provided
with
3-heads
(that
is,
an
erase
head,
record
head
and
separate
playback
head).
With
2-head
machines,
DAT
recorders
and
DCC
machines,
itwill
permit
you
to
verify
that
thereis
a
signal
being
fed
to
the
tape
recorder
and
through
its
circuits
into
the
TAPE
IN
©
jacks.
Whenever
the
TAPE
MON
©
switch
is
pushed
in,
the
red
LED
above
this
switch
will
glow
and
the
signal
selected
by
the
INPUT
©
selector
will
be
disconnected
from
the
amplification
circuits
of
the
GFP-345.
Please
note
that
whatever
source
is
selected
via
the
INPUT
©
selector
will
still
appear
at
the
TAPE
OUT
Q
jacks.
EXTPROC©
Pushing
in
this
switch
connects
the
EXTERNAL
PROCESSOR
IN
©
and
EXTERNAL
PROCESSOR
OUT
©
jacks
on
the
rear
panel
of
the
GFP-345.
Please
refer
to
the
section
EXTERNAL
PROCESSOR
IN
©
/EXTERNAL
PROCESSOR
OUT
©
above
for
a
complete
explanation
of
the
function
of
this
circuit.
Whenever
the
EXT
PROC
©
switch
is
in
the
red
LED
above
this
switch
will
glow.
Please
note
that
whenever
the
EXT
PROC
©
switch
is
in
the
out
position,
whatever
processor
is
connected
to
the
EXTERNAL
PROCESSOR
IN
©
/EXTERNAL
PROCESSOR
OUT
©
jacks
will
be
completely
disconnected
from
the
circuit
to
prevent
any
possible
degradation
of
the
signal
being
amplified
by
the
GFP-345.
MONO
©
Pushingin
this
switch
mixes
the
left-
and
right-channel
signals.
This
combined
signal
is
then
fed
to
both
OUTPUTS
NORM
©
and
OUTPUTS
LAB
©
jacks.
The
mono
switch
does
not
insert
switch
contacts
in
series
with
the
signal
path
but
simply
parallels
the
left
and
right
channels.
The
MONO
©
switch
is
useful
in
reducing
FM
noise
and
distortion
on
weak
stations,
or
when
playing
older
analog
mono
recordings,
or
in
checking
relative
phasing
of
your
loudspeakers
It
is
also
useful
when
setting
the
channel
balance
of
your
loudspeakers
using
the
BALANCE
©'
control.
CONTOUR
©
The
CONTOUR
circuit
in
the
GFP-345
differs
markedly
from
conventional
loudness
compensation
circuits.
Recent
studies
show
that
conventional
circuits
overcompensate
for
natural
low-
and
high-frequency
hearing
reduction
at
low
signal
levels.
The
studies
of
Robinson
and
Dadson
of
Harvard
University
have
provided
guidelines
for
a
newer
and
more
accurate
curve
for
loudness
compensation.
In
our
judgement,
a
subtle
boost
of
low
frequencies
(in
the
20-100Hz
range)
and
no
boost
at
high
frequencies,
provides
the
ideal
musical
balance
for
listening
at
low
to
moderate
levels.
The
effects
of
the
circuit
gradually
diminish
as
the
volume
level
is
increased
(that
is,
when
the
LEVEL
©
control
is
turned
clockwise)
Pushing
in
the
CONTOUR
©
switch
activates
this
function.
Whenever
the
CONTOUR
©
switch
is
in
the
out
position
the
CONTOUR
circuit
will
be
disconnected
from
the
circuitry
of
the
GFP-345.
BALANCE
©
The
BALANCE
©
control
permits
you
to
adjust
the
level
of
the
left
channel
versus
the
right
channel
and
vice-versa.
Turning
the
control
counterclockwise
will
reduce
the
level
of
the
right
channel.
Turning
it
clockwise
will
reduce
the
level
of
the
left
channel.
At
the
maximum
counterclockwise
position,
only
the
left
channel
will
operate.
Conversely,
at
the
maximum
clockwise
position,
only
the
right
channel
will
operate.
In
most
cases
the
proper
setting
of
the
BALANCE
©
control
will
be
at
or
near
its
12
o’clock
position.
To
adjust
for
optimum
balance
between
channels,
it
is
easiest
to
use
a
tuber
tuned
to
a
station
in
which
the
announcer
is
speaking.
This
will
almost
alwaysbe
a
mono
signal.
Place
yourself
in
your
normal
listening
position
and
adjust,
or
have
someone
adjust,
the
BALANCE
©
control
until
the
announcer
appears
to
be
centered
between
the
two
speakers.
This
method
will
compensate
for
almost
all
the
variations
within
your
system,
and
the
room,
and
is
the
easiest
of
all
methods
to
use.
Ifvour
system
does
not
include
a
tuner,
the
nextbest
way
is
to
select
a
CD,
push
in
the
MONO
©
button,
place
the
INPUT
©
selector
on
CD
and
adjust
the
BALANCE
©
control
as
described
above.
Once
the
correct
setting
is
chosen,
it
will
need
to
be
changed
only
to
compensate
for
unequal
signal
levels
from
an
outside
music
source,
such
as
a
cassette,
disc,
etc.
LEVEL
©
This
rotary
control
sets
the
level
at
the
OUTPUTS
NORM
©
and
OUTPUTS
LAB
©
and,
consequently,
the
level
heard
through
the
amplifier
and
loudspeakers.
Turning
this
control
clockwise
will
raise
the
level
of
the
signal
chosen
via
the
INPUT
©
selector.
Turning
the
control
counterclockwise
will
reduce
the
level
of
the
signal.
Normally,
when
used
with
8
f“
d
r
P
"
f,erS
.!
ndSP
°
akerS
hav
'
ng
med,ljrn
-to-low
sensitivities,
the
position
o<
this
control
will
beat
its
normal
1230
to
-I
.
30
O
clock
position.
There
are
many
factors
which
will
affect
the
position
of
the
LEVEL
©
control
for
any
qiven
listening
level.
Among
these
are:
the
specific
sensitivity
of
the
power
amplifier
for
maximum
output;
the
sensitivity
(or
efficiency
)
of
the
speakers
being
used;
the
size
of
the
room
in
which
the
speakers
are
located;
the
output
levels
of
the
USe
i?
3nd
plu
"
ed
'
n,
°
the
GFP-345
(cassette
machines,
tape
recorder.
CD
player,
etc.);
the
modulation
,
9
7*7*
J.
y
yourtuner;
etc
-
The
Position
of
the
LEVEL
©
control
is
a
relative
indication
to
permit
/
l
evel
^
ttmg
agam
and
a
9
ain
-
1
1
is
n
°>
an
absolute
indication
of
how
much
power
the
amplifier
9
*
th
f
peakers
or
how
Powerful”
a
system
is.
It
is
quite
possible,
with
different
component
systems,
to
have
°
utpi
f
,rom
an
am
P
|d|
ef,
and
sound
level
from
the
speakers,
but
with
different
LEVEL
©
control
settings
nnjrnu
50
qu
:l
e
C
?
mm
l
°
n
t0
have
t0
set
the
LEVEL
©
contro1
to
a
different
position,
when
switching
from
“
i-
{
%
CD
}
X
°
a
"°’
her
(SUCh
as
a
cassette
machine),
to
achieve
the
same,
or
approximate
volume
level
from
the
'
h'
ar
y
'
‘flT®'’
6
"'
FM
and
AM
stat
'ons
received
by
your
tuner
may
require
adjustment
of
the
LEVEL
of
music
it
broadcasts
°"
^
am
°
Unt
°
f
aud
'°
“
l,m,,,n
9"
and
“compression"
used
by
the
particular
station
and/or
the
type
NOTE
For
the
reasons
described
above,
it
is
good
practice
to
lower
the
LEVEL
©
control
before
changing
the
INPUT
selector
to
a
different
source.
The
design
of
the
GFP-345
makes
it
usable
with
the
gamut
of
power
amplifiers
presently
available,
as
well
with
all
loudspeakers
presently
in
use.
The
LEVEL
©
control
was
designed
to
be
fully
operable
throughout
its
complete
rotation.
CARING
FOR
YOUR
GFR-345
I
5660
l
aken
by
ADC(
?
M
t0
assure
thal
y°
ur
preamplifier
is
as
flawless
in
appearance
as
it
is
electronically.
pane
'
ls
a
heavy-gauge,
high-grade,
anodized-aluminum
extrusion,
bead-blasted
for
durability.
The
bottom
Should
Iprlm
H
P
C
.°
ver
and
rear
panel
are
of
heavy-gauge
steel,
both
painted
and
baked.
If
the
front
panel,
top
or
sides
detergent
solution
V
°
rf,n9erprmted
'
,he
y
can
be
cleaned
with
a
soft,
lintless
cloth,
slightly
dampened
with
a
very
mild
NOTE
DO
NOT
SPRAY
OR
USE
LIQUIDS
OF
ANY
KIND
ON
THE
SURFACES
OF
THE
GFPv345.
SERVICING
3
"'‘if
Service
Department
to
answer
questions
pertinent
to
any
difficulties
you
encounter
in
the
ZT
Ztir
Un,t
f
y
?
U
encounter
Problems
obtaining
advice
or
resolving
your
problems
locally,
please
contact
us
we
mai
rofervm,
.
r
®
co
"\
mendat
'
on
;
lf
y°
ur
problem
cannot
be
resolved
directly
through
instructions
from
us,
we
may
refer
you
to
an
authorized
representative
near
you
for
resolution.
Please
address
mail
inquiries
to:
ADCOM
Service
Corp.
11
Elkins
Road
East
Brunswick,
NJ
08816
U.S.A.
^»n
d
rlT,°
re
6Xped
'
ent
*°
C
°
ntaCt
US
Via
f3X
'
,he
numb€r
is
(908-390-9152).
Please
include
a
return
fax
number
9
INSTALLING
THE
PHO-802A
BOARD
IN
THE
GFP-345
ImITIS'
802A
*
Ph0
??
pre
,
amp
b
°
ard
re
P'
aces
the
standard
AUX
1
©
input.
Any
high-leve!
source
connected
to
the
AUX
1
©
input
must
be
relocated
to
one
of
the
other
high-level
inputs
not
already
in
use.
The
AUX
1
©
input
must
not
subsequently
be
used
for
a
high-level
source
unless
the
PHO-802A
board
is
removed
and
the
jumper
wires
which
must
be
cut
for
use
with
the
PHO-802A,
replaced.
.
cn
must
1.
Begin
installation
by
unplugging
the
GFP-345
power
cord
from
the
AC
wall
outlet
and
remove
its
cover
by
unscrewinq
the
six
Phil
1
1
ps-head
screws
using
a
#2
Phillips
screwdriver.
The
two
hex-head
screws
securing
the
top
cover
to
the
front
panel
must
also
be
removed.
A
2mm
hex-wrench
is
necessary
for
this
operation.
2.
Cut
the
jumper
wires
Bt,
B2
and
B3
on
the
main
PCB
of
the
GFP-345
at
the
middle,
raised
portion,
and
fold
awav
the
cut
ends
to
insure
that
the
ends
do
not
touch
each
other.
1
3.
Remove
the
top
cap-nut
on
each
of
the
screw
studs
shown
in
figure
below
and
position
the
PHO-802A
board
over
the
two5-pin
connectors
so
that
the
corresponding
Til
and
T12
sockets
and
5-pin
connectors
mate
properly
and
the
larqe
upright
capacitors
(black,
2200uF/16V)
are
positioned,
as
shown
in
figure
below,
nearest
the
RCA
input
jacks
on
the
rear
panel
of
the
GFP-345.
You
can
use
the
screw
studs
as
guides.
4.
Press
the
PHO-802A
board
down
firmly
onto
the
two
5-pin
connectors.
5.
Screw
the
two
cap-nuts,
back
onto
the
screw
studs
and
firmly
secure
the
nuts
onto
the
PCS
with
a
5.5mm
nut-driver
or
similar
tool.
Please
note
that
the
bottom
cap-nuts
must
not
be
removed.
The
bottom
cap-nuts
secure
the
screw
studs
L°j^r"
P
CBand
alS
°
aCt
as
spacers
for
,he
ph
°-
802A
board.
They
are
essential
to
prevent
shorting
between
the
PHO-802A
board
and
the
main
GFP-345
PCB.
8.
Replace
the
top
cover
on
the
GFP-345
making
certain
all
the
screws
are
tightened
securely
to
be
sure
that
proper
shielding
of
the
internal
circuitry
of
the
GFP-345
is
effected.
1.
There
are
two
PHONO
labels
supplied
with
both
the
GFP-345
(in
the
plastic
bag
containing
the
instruction
manual
e
c
i‘
a
"
d
a,
f°
!i
the
Packaging
of
the
PHO-802A
board.
Affix
one
PHONO
label
on
the
front
panel
over
the
AUX
1
label
at
the
INPUT
©
selector
so
that
now
it
will
read
PHONO.
The
AUX
1
position
is
the
maximum
counterclockwise
position
of
the
INPUT
©
selector.
8.
Affix
the
second
PHONO
label
over
the
existing
type
above
the
RCA
jacks
on
the
rear
panel
which
reads
AUX
1
©
so
that
now
it
read
PHONO.
Although
this
is
not
absolutely
necessary,
it
will
simplify
identification
of
the
now-PHONO
input
to
the
GFP-345.
10
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