Adcom GFA-7400 User Manual

© 12VDC Triggering. (GFA-7400 Only)
The GFA-7400 and GFA-7300 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-7400 by a 12Volt DC output jack on the rear of certain ADCOM pre-amplifiers and tuner pre¬
amplifiers. When using this feature the front panel Power Switch must be left in the in “on”
position. To connect you will need a monaural mini phone plug to monaural mini phone plug cable
of appropriate length (not included) to reach from the rear panel of the amplifier to the rear panel
of the pre-amplifier. Contact your dealer for information on using this feature with ADCOM and
other brand pre-amplifiers. Although 12VDC is optimal the circuit will operate from approx. 5 to
30VDC, not to exceed 250mv. Center conductor (tip) is positive (+).
O AC Fuse
The AC Fuse protects the electronic circuits of the GFA-7400/7300. This fuse, normally, will
fail only if there is an overload within the GFA-7400/7300. It may, however, fail if the amplifier
attempts to deliver very high power into very low-impedance loudspeakers. In either case, BE
SURE TO REPLACE THE AC Fuse ONLY WITH AN EXACT REPLACEMENT FUSE. The proper
fuse values are:
GFA-7400:
Fuse Rating BUSS® Littelfuse®
For 115 volt operation.15 Amp 250 Volt.ABC-15/250V.(3AB) 314015/250V
For 230 volt operation. 8 Amp 250 Volt.AGC-8/250V.(3AG) 312008/250V
GFA-7300: Fuse Rating BUSS® Littelfuse®
For 115 volt operation.T8 Amp 250 Volt.MDL-8A/250V.(3AG) 313008/250V
For 230 volt operation.T4 Amp 250 Volt.MDL-4A/250V.(3AG) 313004/250V
WARNING
Before attempting to replace a failed fuse, be certain to unplug the AC Power Cord from the AC
wall outlet to prevent possible electrical shock.
Replace the AC Fuse only with one identical in type and rating as printed on the rear panel. DO
NOT USE ANY SUBSTITUTE FUSES WITH DIFFERENT RATINGS OR VALUES. Failure to
observe this precaution may cause serious damage to the amplifier circuits, MAY CREATE A
FIRE HAZARD, AND MAY VOID THE WARRANTY._
If the Power LED (©) does not glow, it may be an indication that the AC fuse has blown. If
you are using the 12VDC Triggering feature (GFA-7400 Only) it may be possible that there is a
problem with that connection. To determine if the problem is caused by a malfunction in the
12VDC system, remove the small plug inserted into the 12VDC Triggering jack. Press the front
panel power switch to turn off the amp, and immediately re-press the power switch. If the problem
is caused by the 12VDC triggering circuit the amp will turn on and the LED will glow. DO NOT
attempt repair of the 12VDC system. If you are not sure, or the amplifier displays other symptoms,
please consult the RESOLVING PROBLEMS section on page 13.
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Adcom GFA-7400 Specifications

Power

continuous power per channel into 8 ohms	100 watts
continuous power per channel into 4 ohms	150 watts
power consumption quiescent	96 VA
maximum power consumption	1440 VA
power consumption at 100 watts into 8 ohms	1165 VA
power supply voltage	115 VAC - 50/60 Hz

Distortion

IM distortion SMPTE at 8 ohms	≤ 0.075%
IM distortion SMPTE at 4 ohms	≤ 0.075%
IM distortion CCIF at 8 ohms	≤ 0.025%
IM distortion CCIF at 4 ohms	≤ 0.025%
THD + noise at 100 watts into 8 ohms at 20Hz	0.0012%
THD + noise at 100 watts into 8 ohms at 1kHz	0.0012%
THD + noise at 100 watts into 8 ohms at 10kHz	0.02%
THD + noise at 100 watts into 8 ohms at 20kHz	0.025%
THD + noise at 150 watts into 4 ohms at 20Hz	0.025%
THD + noise at 150 watts into 4 ohms at 1kHz	0.025%
THD + noise at 150 watts into 4 ohms at 10kHz	0.035%
THD + noise at 150 watts into 4 ohms at 20kHz	0.045%

Performance

frequency response at 1 watt into 8 ohms	+0, -0.25 dB
power bandwidth	1.5 Hz to 65 kHz
dynamic headroom into 4 ohms	2.5 dB
signal to noise ratio	≥ 110 dB
gain	29 dB
input sensitivity for 1 watt	0.1 volts
input sensitivity for 100 watts	1.0 volts
input impedance	50 kΩ
damping factor	≥ 400
rise time	4.5 µS

Weight and Dimensions

chassis dimensions	5” (127mm) x 17” (432mm) x 14” (355.6mm)
maximum dimensions	5 3/4” (146mm) x 17” (432mm) x 15” (381mm)
weight	42 lb. (19.1 kg)
packed weight	48 lb. (22.8 kg)