Crossovers
Input Level control
The input level control, 7V – 0,2 V,
matches the output of your radio to
the input of the amplifier. After instal-
lation is complete, make sure the in-
put of the amplifier is turned down all
the way ( counter-clockwise at 7V ).
The DLS Reference amplifiers include high pass
filter (HP) and low pass filters (LP). The highpass
filter on RA25 can also be used as a subsonic filter.
The slope of all filters are 12 dB / octave.
The high pass filters can be switched off if you want to
run the amplifier in full range mode.
This is the crossover configuration on RA25 & RA30:
RA25:
HP-filter 20 - 150 Hz
RA30 CH 1 & 2:
RA30 CH 3 & 4:
HP-filter 45 -125 Hz
LP-filter 40 - 125 Hz
Subsonic filter 25 Hz
The
HPF
( high pass filter )
blocks
very low frequencies from
reaching the speakers. It is
mostly used at say 60 Hz to
protect small speakers ( like 6
inch and smaller ) from deep
bass. It can also be used as
subsonic filter to take away the
very deepest frequencies from a
bass box. The typical setting is
then around 25 – 40 Hz.
High Pass Filter / Subsonic filter
Low Pass Filter
The
LP-filter
( low pass filter) is
mostly used for subwoofers. It will
allow low frequencies only and
blocks higher frequencies.
A typical setting is 50 – 80 Hz.
The filter can be switched IN-OUT
and is available on RA30 sub
channel only.
6
Play a tape or CD, make sure all bass or treble
settings or equalizer are flat, and turn the volume
of the radio up until you just start to hear distortion.
Turn the volume control down just a bit. On the
amplifier increase the input level control ( clockwise
or to the right ) until you just start to hear distortion,
then back the level control just a bit. Now your ra-
dio and amplifier levels are matched.
Grand bass 40 Hz
Grand Bass
is used to increase the bass volume
with a center frequency of 40 HZ. You can select
the amplification between 0 dB ( no amplification )
and +18 dB (full amplification).
The phase control on RA30 sub
channel 3&4 can be set
continuously from 0 - 180
degrees. This is very useful when
you want to adjust the bass
sound for best front stage image.
Start on 0 and turn the control
slowly clockwise until you
experience that the bass sound
is coming from the front. If you
dont get the result you want, also
try to phase reverse the
subwoofer connections and
make a new adjustment.
Phase control
RA25 & RA30
This function is used to
compensate for the bass box
function and to adjust for your
own taste of bass. Set level
control at 0 dB if you want it
to be inoperative. This
function is operative only on
RA30, channels 3 & 4.
PHASE
0
180
DEGREE
BASS
0
+18
dB
GAIN
7V
0,2V
HP-filter
FREQUENCY
20 150
Hz
LP-filter
FREQUENCY
40 125
Hz
