Adcom GFP-750 User Manual

1.3. Product Features
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Stereo/Reverse/Mono Switch
This switch is used to change the polarity of the input signal in relation to the output signal. The
stereo setting allows normal playback of the input signal. The reverse setting Inverts the phase of the
input signal. The mono setting combines both channels for a monaural input signal or where
speaker placement does not accommodate stereo playback.
Input Selection
The input selection knob has a digital interface that senses movement of the knob. The knob appears to
turn freely as the interface detects the direction the knob is being turned and indexes through the input
sources accordingly. To go from aux 2 to tuner or from tuner \o aux 2, you must index back through the
other input sources.
Passive
This features allows the active gain stages of the preamp to be bypassed. (A slight drop in volume level is
expected when this feature is engaged.) This feature has no effect when the processor feature is en¬
gaged.
Power On/Off
The GFP-750 is turned on by pressing either the remote control power button or toggling the front
panel power switch. The LED above the power switch will come on indicating the unit is on. (The
power status LED will glow slightly dimmer when the unit is muted.)
Processor Switch
Engages the processor loop when activated. See @ for further information.
Balance Control
The GFP-750 balance control feature provides finer balance adjustment allowing for greater balance
accuracy and will not entirely mute either channel.
Infrared Remote Control Sensor Lens
This lens protects the infrared receiver which receives commands from the remote control. The pathway
between the lens and remote control must be free of obstructions for the remote control to operate the
GFP-750.
Volume Control
The front panel volume control knob is motorized. It may be adjusted either by hand or by the volume
buttons on the remote control. The volume knob’s groove always indicates the present volume level. The
volume control knob may be used to reduce the volume level while the GFP-750 is muted without deac¬
tivating the mute feature.
Mute
The GFP-750's mute feature is engaged by pressing the mute button on the remote control. This feature
fully mutes the outputs. To deactivate the mute feature, press the mute button again or either of the two
volume buttons on the remote control. (Turning the front panel volume knob will not deactivate the mute
feature.)
Balanced CD Inputs
Before using the balanced CD inputs, it is necessary to remove the gold jumpers located between pins 1
and 3 in both connectors. (See the figure to the right.) When switching from balanced CD inputs to
unbalanced CD inputs, you must replace the jumpers between pins 1 and 3 as shown.
|l DO NOT USE BOTH BALANCED AND UNBALANCED CD INPUTS AT THE SAME Time. l| _
Gold Jumpers ^
When using the unbalanced CD inputs, jumpers must be installed to short pins 1 and 3 of the to
balanced input jacks. ^
Unbalanced Stereo Inputs gold jumpers
Connect the various outputs from each signal source to these unbalanced stereo inputs. Do
not connect both the unbalanced and balanced CD inputs at the same time. See the section
labeled CONNECTIONS for further information regarding these inputs.
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Adcom GFP-750 Specifications

Audio Output Specifications

output level	1.0 V
THD+N @ rated output (20Hz to 20kHz) balanced	<0.025%
THD+N @ rated output (20Hz to 20kHz) unbalanced	<0.095%
THD+N @ rated output (1kHz) balanced	<0.015%
THD+N @ rated output (1kHz) unbalanced	<0.017%
output impedance balanced	<1200 Ω
output impedance unbalanced	<600 Ω
frequency response (balanced and unbalanced)	20Hz to 20kHz, -0.25dB to +0dB
IM distortions CCIF (balanced)	<0.009%
IM distortions CCIF (unbalanced)	<0.035%
SMPTE (balanced)	<0.05%
SMPTE (unbalanced)	<0.05%
signal to noise ratio (ref. to 1 volt) 'A' weighted (balanced)	>102 dB
signal to noise ratio (ref. to 1 volt) 'A' weighted (unbalanced)	>102 dB

Input Specifications

input impedance balanced	94 kΩ
input impedance unbalanced	47 kΩ
input sensitivity @ rated output balanced	183 mV
input sensitivity @ rated output unbalanced	365 mV

Power and Dimensions

power	115 VAC-50/60Hz
power consumption	30 VA
chassis dimensions	3 1/2” (89 mm) x 17" (432 mm) x 11" (279 mm)
maximum dimensions	4 1/8" (105 mm) x 17" (432 mm) x 12” (305 mm)
weight	6.8 kg
packed weight	7.7 kg