Rockford Fosgate 100X2 - Manual (Page 26)

switch from the clean power source.
Problem
Engine Noise (Whine)
Solution
1. Disconnect the speakers from the amplifier. Connect a
test speaker to the amplifier output terminals. If the
noise goes away, check your speaker leads, speakers
and crossovers.
2. Use a "shorting plug" to mute the input signal at the
amplifier. If the noise goes away:
a. Bypass all of the other equipment (i.e., crossovers
and equalizers) and connect the head unit directly to
the amp. If the noise disappears, reconnect the
equipment, being sure to test for noise after each
install. Logic indicates that the last unit installed is
the culprit. Refer to the unit's owner's manual for
more information.
b. Connect a new RCA line from the head unit to the
amplifier. If there is no noise, replace the RCA cable.
c. Run the RCA cable on a different route.
d. Run a new RCA line from your head unit so there is
only one grounding point. If the noise disappears,
install the radio, using only one (1) grounding point.
Isolate the radio chassis from the grounding on the
dash, and use an antenna grounding loop isolator
on the antenna.
If noise persists, see your Authorized Rockford Fosgate
Dealer.
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