Crossover Adjustments - Soundstream Reference Series 644S Installation Manual

INSTALLATION STEP 2
BALANCED / UNBALANCED INPUT
The REFERENCE644s amplifier has the ability to accept either standard
Unbalanced RCA signal inputs, or Balanced "Pro Audio" inputs with the use of
the Soundstream BLT Balanced Line Transmitter or some other balanced line
audio source. Before installing your system, you should decide upon which
UNBALANCED INPUT
ADVANTAGES 1. Most preamplifier / source
units have "UNBAL" RCA
outputs. (Industry stan-
dard)
2. No Interface module is nec-
The REFERENCE644s amplifier's signal inputs accept two ranges of input
signal levels: 0.2 - 2.0 Vrms, or 0.5 - 5.0 Vrms for both Balanced and
Unbalanced inputs. The input range switch position and level settings are
dependent upon the preamplifier / source unit output signal level. For the best
system Signal to Noise Ratio, we recommend that the input level controls be
set as far down as possible (rotated counter-clockwise), while maintaining an
acceptable level of output.
Using the "Unbalanced" RCA input
When using the Unbalanced RCA input, the RIGHT channel ( channels 2)
input signal switch MUST be in the "UNBAL" position.
installing the amplifier using this input configuration, we suggest that the
remaining input signal switches be in the "UNBAL" position as well. If you
experience alternator whine or other installation noise with both
switches in the "UNBAL" position, try moving channels 1,3 & 4 input
signal switches to the "BAL" position. This should remove any system
noise due to installation.
Using the "Balanced" RCA input
When using the Balanced 6-pin DIN input, both switches MUST be in the
"BAL" position. Also, we recommend that when using this input configuration,
the "INPUT LEVEL" switch be in the "0.5 - 5V" position, and the gains on the
amplifiers be set to "minimum" (rotated counter-clockwise). The system gains
NOTE: The pin
configuration shown
in the diagram is the
view looking into the
Balanced input jack
on the amplifier.
BALANCED INPUT
1. Improved Signal to Noise
Ratio. (S/N Ratio)
2. Excellent noise cancellation
characteristics.
3. Immune to noise radiated in
Also, when first
10
INSTALLATION STEP 6

CROSSOVER ADJUSTMENTS

The REFERENCE644s amplifier incorporates an on-board staggered
electronic crossover, with RCA outputs to drive an external amplifier.
external electronic crossover is necessary. The high and low pass portions of
the crossover can be set independently of one another.
In most car audio installations, there is a tendency for a "midbass boom."
Because of their interior dimensions, most cars will resonate or ring at these
midbass frequencies. If we design the system so there is less musical
information in this region, the final response is very smooth and natural
sounding. The high pass filter is variable from 60 to 240 Hz at 12 dB/Octave,
while the low pass filter is variable from 30 to 120 Hz at 24 dB/Octave.
For initial crossover setup, try setting the low pass filter to approximately 60
Hz, and the high pass filter(s) to approximately 100 Hz. Change the crossover
points to accommodate a good mixture of frequency response, power
NOTE: RCA signal output in high pass and
24 dB/Oct. Low Pass
full range is derived from Channels 1 & 2
input.
12 dB/Oct. High Pass summed from Channels 1, 2, 3 & 4 input. The
Subwoofer Level adjustment also applies to
AIRBASS ACCESSORY OPTION
Soundstream's new AIRBASS feature can be added to the REFERENCE644s
amplifier. This feature allows wireless RF remote control level adjustment of
the amplifier, while the low pass filter on the amplifier's internal crossover is
engaged. (AIRBASS does not control the level of the RCA signal outputs.)
NOTE: The AIRBASS accessory is intended to be used only while the
REFERENCE644s amplifier is driving a subwoofer(s). When the AIRBASS
accessory is added to a REFERENCE644s, it controls the level of any channel
receiving information from the low pass filter in the amplifier. The Coherent
Installing AIRBASS involves removing the bottom plate of the amplifier,
adding the AIRBASS circuit board, and flipping a switch. The switch is labeled
on the amplifier's main circuit board. DO NOT set the AIRBASS switch to the
"IN" position unless the AIRBASS module has been added. DO NOT move
the AIRBASS switch while the amplifier is "ON". Doing so may damage your
speakers. (Please refer to the AIRBASS owner's / installation manual for
more details.)
In low pass, RCA signal output is
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