Installation manual

Community S-Series - Operation and Installation Manual - Page 16
Figure 3: Graph Depicting Frequency Response of MUSIC / VOICE
Presence Switch (Note: the Voice/Speech position is represented by the dotted line)
70
80
90
100
110
10 100 1,000 10,000 100,000
Resolution <500 Hz = 10 Hz, >500 Hz = 40 Hz, 1/2 octave smoothing
C-TIP: The VOICE-SPEECH (+4dB) position may be useful when trying to compensate for
absorption loss over very long distances, or just when some additional presence is needed
to achieve the tonal quality you’re seeking. Note: This switch is active in both the PASSIVE
and BI-AMP modes.
SELECTABLE HIGH-PASS OUTPUT ON SUBWOOFERS
S-Series subwoofers are equipped with an industry-standard NL4-compatible locking
connector wired in parallel with a ¼” jack. A second NL4-compatible locking connector is
provided, also wired in parallel to a ¼” jack. This second set of connectors is intended as
OUTPUTS and are associated with the subwoofer’s SWITCHABLE HIGH-PASS OUTPUT.
When the selector switch is set to the PARALLEL INPUT MODE (the down position), both
the NL4-compatible locking connector and the 1/4” jack function exactly as loop-thru
connectors; in other words they are simply wired in parallel with the INPUT
CONNECTORS.
Conversely, when the selector switch is set to HIGH-PASS OUTPUT (the up position), a 1
st
order high-pass filter (6 dB per octave) is inserted into the circuit. The filter has a corner
frequency of 125 Hz with an 8 ohm load.
Using the HIGH-PASS OUTPUT MODE inserts the HIGH-PASS FILTER as mentioned above,
but it also presents a higher impedance load to the amplifier. This can become quite
important, particularly if a pair of full-range loudspeakers and a subwoofer are being
powered from a single amplifier channel. In the PARALLEL INPUT MODE, the impedance of
the combined load could become dangerously low for some amplifiers, potentially causing
the amplifier to shutdown or fail.
The following graph shows the difference in the total load impedance with the high-pass
switch in the HIGH-PASS and PARALLEL INPUT MODE positions. The lower line depicts the
response with the switch in the FLAT position where the load drops below 2 ohms between
30 – 50 Hz and again between 100 – 200 Hz, potentially causing early clipping, amplifier
shutdown, or even amplifier failure. The upper line depicts the response with the switch in
the HIGH-PASS position, where the load impedance has been increased by about 50% by
the subwoofer’s internal crossover circuit, thereby protecting the amplifier from premature
clipping and potential failure.
Frequency in Hertz
dB
SPL