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APPENDIX A:
Input Sensitivity Level Setting
Following the directions below will allow the
installer to adjust the input sensitivity of each
amplifier channel pair simply and easily in just a
few minutes using equipment which is commonly
available.
Necessary Equipment
• Digital AC Voltmeter
• CD with a sine-wave test tone recorded at
0 dB reference level in the frequency range
to be amplified for that set of channels
(50 Hz for subwoofer channels, 1 kHz for a
midrange application). Do not use attenuated
test tones (-10 dB, -20 dB, etc.).
The Nine-Step Procedure
1) Disconnect the subwoofer(s) from the
amplifier's speaker output connectors.
2) Turn off all processing (bass/treble, loudness,
EQ, etc.) on the source unit, processors (if
used) and amplifier. Set fader control to center
position and subwoofer level control to 3/4 of
maximum (if used to feed the M1000/1v2).
3) Turn the amplifier's "Input Sens." control all
the way down.
4) Set the source unit volume to 3/4 of full
volume. This will allow for reasonable gain
overlap with moderate clipping at full volume.
5) Using the chart on this page, determine the target
voltage for input sensitivity adjustment according
to the nominal impedance of the subwoofer
system connected to the amplifier outputs.
6) Verify that you have disconnected the
subwoofer(s) before proceeding. Play a track
with an appropriate sine wave (within the
frequency range to be amplified by the
M1000/1v2) at 3/4 source unit volume.
7) Connect the AC voltmeter to the speaker output
connectors of the amplifier. Make sure you test
the voltage at the correct connectors (+ and –).
12 | JL Audio -MD1000/1v2 Owner's Manual
8) Increase the "Input Sens." control until the
target voltage is observed with the voltmeter.
9) Once you have adjusted the M1000/1v2 to
its maximum low-distortion output level,
reconnect the speaker(s). The "Input Sens."
controls can now be adjusted downward if the
amplifier requires attenuation to achieve the
desired system balance.
Do not increase any "Input Sens." setting for
any amplifier channel or channel pair in the
system beyond the maximum level established
during this procedure. Doing so will result in
audible distortion and possible speaker damage.
It will be necessary to re-adjust the
"Input Sens." if any equalizer boost is activated
after setting the "Input Sens." with this
procedure. This applies to any EQ boost circuit,
including source unit tone controls or EQ
circuits. EQ cuts will not require re-adjustment.
Nom. Impedance
4Ω
3Ω
2Ω
1Ω
Target AC Voltage
40.0 V
37.3 V
34.6 V
Not Recommended
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