18
| JL Audio - MHD900/5 Owner’s Manual
19
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 MHD900/5). 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
aPPendix b:
Precise Frequency selection Chart
“Filter Freq”
detent
Panel
actual
number
marking
Freq.
(Hz)
Full counter-clockwise: 53
01 . . . . . . . . . . .
“50”
. . . . . . . . . . . .53
02 . . . . . . . . . . . . . . . . . . . . . . . . . . . .53
03 . . . . . . . . . . . . . . . . . . . . . . . . . . . .53
04 . . . . . . . . . . . . . . . . . . . . . . . . . . . .53
05 . . . . . . . . . . . . . . . . . . . . . . . . . . . .54
06 . . . . . . . . . . . . . . . . . . . . . . . . . . . .55
07 . . . . . . . . . . . . . . . . . . . . . . . . . . . .57
08 . . . . . . . . . . . . . . . . . . . . . . . . . . . .58
09 . . . . . . . . . . .
“60”
. . . . . . . . . . . .60
10 . . . . . . . . . . . . . . . . . . . . . . . . . . . .62
11 . . . . . . . . . . . . . . . . . . . . . . . . . . . .64
12 . . . . . . . . . . . . . . . . . . . . . . . . . . . .66
13 . . . . . . . . . . . . . . . . . . . . . . . . . . . .69
14 . . . . . . . . . . . . . . . . . . . . . . . . . . . .71
15 . . . . . . . . . . . . . . . . . . . . . . . . . . . .74
16 . . . . . . . . . . . . . . . . . . . . . . . . . . . .77
17 . . . . . . . . . . .
“80”
. . . . . . . . . . . .80
18 . . . . . . . . . . . . . . . . . . . . . . . . . . . .85
19 . . . . . . . . . . . . . . . . . . . . . . . . . . . .86
20 . . . . . . . . . . . . .
.
. . . . . . . . . . . . . .90
21 . . . . . . . . . . . . . . . . . . . . . . . . . . . .95
22 . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
23 . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
24 . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
25 . . . . . . .
“12 o’clock”
. . . . . . . 116
26 . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
27 . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
28 . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
29 . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
30 . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
31 . . . . . . . . . . . . . . . . . . . . . . . . . . . 180
32 . . . . . . . . . . . . . . . . . . . . . . . . . . . 200
33 . . . . . . . . . . . . . . . . . . . . . . . . . . . 224
34 . . . . . . . . . .
“250”
. . . . . . . . . . 248
35 . . . . . . . . . . . . . . . . . . . . . . . . . . . 293
36 . . . . . . . . . . . . . . . . . . . . . . . . . . . 347
37 . . . . . . . . . . . . . . . . . . . . . . . . . . . 422
38 . . . . . . . . . . . . . . . . . . . . . . . . . . . 459
39 . . . . . . . . . .
“500”
. . . . . . . . . . 504
40 . . . . . . . . . . . . . . . . . . . . . . . . . . . 508
41 . . . . . . . . . . . . . . . . . . . . . . . . . . . 508
Full-clockwise: 508
aPPendix C:
input sensitivity level setting
JL Audio amplifiers utilizing the Regulated
Intelligent Power Supply (R.I.P.S.) allow
delivery of their rated power when connected
to any load impedance from 1.5 - 4Ω per
channel and when connected to a charging
system with any voltage from 11 - 14.5V.
This design is beneficial for many reasons.
One of these reasons is ease of setup.
Because each JL Audio amplifier will always
deliver the same amount of power within
its operational range of supply voltages, the
maximum, unclipped output is very predictable.
This makes setting the gain structure via the
input sensitivity controls very simple. Following
the directions below will allow the user to adjust
the input sensitivity of the amplifier(s) simply
and easily in just a few minutes using equipment
which is commonly available in installation bays.
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). The CleanSweep®
Calibration Disc contains the appropriate
test tones and is available for sale at
http://store.jlaudio.com Do not use attenuated
test tones (-10 dB, -20 dB, etc.).
Do not increase any “Input Sens.” setting 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.
” for the affected channels if any equalizer
boost is activated after setting the “
Input
Sens.
” with this procedure. This applies to any
EQ boost circuit, source unit tone controls or EQ
circuits. EQ cuts will not require re-adjustment.
