JL Audio HD900/5 User Manual
Page 19
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the nine-step Procedure
(follow this procedure for each pair of channels)
1) Disconnect the Speaker Connector Plugs.
2) Turn off all processing on the source unit
(bass/treble, loudness, EQ, etc.). Set fader
control to center position and subwoofer
level control to 3/4 of maximum (if
used to drive the HD900/5). Disconnect
the HD-RLC Remote Level Control
temporarily (if one is being used).
3) Switch the “Input Voltage” to “Low” and
turn the “Input Sens.” control on both sets of
channels all the way down.
4) Set the source unit volume to 3/4 of full
volume. If the subwoofer channel is being
driven by a source unit’s dedicated subwoofer
output, also adjust the source unit’s subwoofer
level control to 3/4 of maximum output. This
will allow for reasonable gain overlap with
moderate clipping at full volume.
5) Using the chart below, determine the
target voltage for input sensitivity
adjustment according to the nominal
impedance of the speaker system
connected to each set of outputs.
6) Verify that you have disconnected the Speaker
Connector Plugs before proceeding. Play a
track with an appropriate sine wave (within the
frequency range to be amplified by each set of
channels) at 3/4 source unit volume.
7) Connect the AC voltmeter to the “Front
Speaker Outputs” or “Rear Speaker Outputs”
connectors of the amplifier. If the channel pair
is operating in stereo, it is only necessary to
measure one channel in the pair. If bridged,
make sure you test the voltage at the correct
connectors (L+ and R–).
8) Increase the “Input Sens.” control until
the target voltage is delivered for that
set of channels. If excessive voltage is
read with the control at minimum (full
counterclockwise), switch the “Input
Voltage” switch to “High” and re-adjust.
9) Once you have adjusted each set of channels to
its maximum unclipped output level, reconnect
the speaker(s). The “Input Sens.” controls can
now be adjusted downward any set of channels
requires attenuation to achieve the desired
system balance.
nom.
impedance
Front or rear
cHannels
subwooFer
cHannel
stereo
bridged
mono
8Ω
20.0 V
40.0 V
44.7 V
6Ω
20.0 V
32.0 V
44.7 V
4Ω
20.0 V
24.6 V
44.7 V
3Ω
16.0 V
21.2 V
38.7 V
2Ω
12.3 V
not recommended
31.6 V
1.5Ω
10.6 V
not recommended
27.4 V