Jensen POWERPLUS 420 - Manual (Page 11)

PowerPlus Amplifiers
11
Indicators and Controls
Power Indicator (POWER)
The power indicator provides a visual indication that the amplifier is turned on.
Input Level Control (LEVEL/GAIN)
The INPUT LEVEL control (or GAIN) matches the output of your radio to the
input of the amplifier. After the installation is complete, make sure the input
level control on the amplifier is turned down all the way (counter-clockwise or
all the way to the left). Play a tape or CD (make sure bass and treble settings
or Bass EQ are flat) and turn the volume up slowly until you just start to hear
distortion. Back the volume down just a bit. On the amplifier, slowly turn up the
input level control (clockwise or to the right) until you just start to hear
distortion, then back it down a bit. Now your radio and amplifier levels are
matched.
BASS EQ
The Bass EQ is continuously adjustable from 0 to +12dB @ 45Hz. Adjusting
the Bass Boost level allows different subwoofer/enclosure combinations to be
equalized. Use this control to increase the level of low bass available from your
subwoofer/enclosure combination. Ported and Band Pass enclosures should
be limited to about +6dB to +9dB of boost. Sealed enclosures should be able
to accept the full +12dB of boost, if necessary. The full +12dB of boost should
be reserved for special applications since improper use of the Bass Boost
could damage your subwoofers at high volumes.
Low Pass Filter (LPF)
The Low Pass Filter controls adjust the crossover point. Typical crossover is
between 60Hz and 80Hz for ported and sealed enclosures. Bandpass boxes
will typically use a higher crossover setting between 125Hz and 150Hz. Since
musical tastes vary, you should play music that you would normally listen to in
your vehicle, with the above settings as a starting point. If necessary, set the
crossover by ear.
High Pass Filter (HPF)
The high pass filter will limit the low frequencies being transmitted to your
speakers. This can be useful in number of situations. For example, if you
selected the high pass filter and set the crossover to 40Hz, then you would
have an infra-sonic (sub-sonic) filter at 40Hz, which would be useful with
certain enclosure/subwoofer combinations that were tuned between 45Hz and
50Hz. Other uses might include limiting the low frequencies to smaller
speakers (6 1/2", 6 X 9", etc.) by adjusting the crossover to a higher setting
(80–100Hz).
Crossover (X-OVER)
The Jensen PowerPlus series of amplifiers have built-in low-pass and high-
pass crossover filters for bi-amplifying the system. Adjust the crossover to
accommodate your chosen installation method. Select LPF (low pass filter)
when the amplifier will be driving woofers or subwoofers. Choose FULL or OFF
when crossover mode is not active and the amplifier is in “full range” mode.
Select HPF (high pass filter) when the amplifier will be driving full-range or
separate speakers, and you want to limit the “bass” being transferred to these
speakers.
Mode Switch
PowerPlus 420 and 1302
The 420 and 1302 come equiped with a ST/MO (stereo/mono) MODE switch.
Use STEREO mode when you have a 2-channel input from the source unit.
Use MONO mode when you have a single input from the source unit. See
“Input Wiring” on page 9.
PowerPlus 840 and 1304
The 840 and 1304 come equiped with a 4/3/2 MODE switch and can be
configured for three different input modes: 2 channel, 3 channel or 4 channel.