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Diagram One 6. Controls & System Setup
Subwoofer Controls
Accompanying the mains and signal input sockets
on the subwoofer connection panel are a level
control, a crossover frequency control, an auto
power switch and a phase reversal switch. Their
function and use is described in the following
paragraphs.
Subwoofer Level
The level control adjusts the volume of the
subwoofer relative to the satellites. Begin with
the level control set to around 50%. Detailed
subwoofer adjustment guidelines can be found in
the following paragraphs.
Subwoofer Crossover Frequency
The crossover frequency control adjusts the upper
frequency at which the subwoofer output is filtered
for the full-range speakers to take over. If the Linear
Sub is to be used exclusively in an audio-visual
system the crossover frequency should be set at
80Hz.
If the Linear Sub is to augment the low frequency
performance of a pair full range speakers, the
crossover frequency should be set to match their
low frequency roll-off frequency. The larger the
speaker, the lower its low frequency roll-off will be. Finding the optimal
crossover frequency setting will require experiment and adjustment, but
reasonable initial values for different speaker types are as follows:
Large floor stand speaker (Linear 3): 35Hz
Medium stand mount loudspeakers: 50Hz
Small stand mount speakers (Linear 1): 70Hz
Subwoofer Phase
The phase switch reverses the subwoofer acoustic polarity. With the switch
set to 0° the subwoofer output is in phase with the full range speakers. With
the switch set to 180° the subwoofer output is out of phase. Reversing the
subwoofer phase can help optimise the sound of subwoofer systems. Further
subwoofer phase advice can be found below.
Subwoofer Auto Power
The subwoofer mains power switch incorporates an automatic switch-on/
off function. With the switch set to “Auto” the subwoofer will switch on
automatically when an audio signal is present. It will switch off again when
no signal has been present for around 10 minutes. With “on” selected the
subwoofer remains switched-on permanently.
Note: There is necessarily a short delay between auto switch-on and audible
sound from the subwoofer.
System Setup
Before listening to your system make one final check of the cables and
connections. If all appears well begin listening at a relatively low volume to
confirm that the system is operating as expected. Only increase the volume
if you are happy that the sound at low volume is fundamentally as expected.
If you are unhappy, turn the system off and re-check all the cables and
connections.
The Linear Sub may take a little time to reach normal operating temperatures
and to “run-in”. Your ears too will take some time to adjust to the new
sound, so it is unwise therefore to make rapid judgements about the
performance of the system.
The most important aspect of Linear Sub setup is its integration with the
full-range speakers. Assuming the locations chosen for these are satisfactory,
adjusting the subwoofer’s location in the room, its volume level and phase,
and, if it is used in a conventional stereo system, its the crossover frequency,
should enable a good end result to be achieved.
Select a few short examples of familiar programme material - both movie and
music - to use while adjusting the setup. Listen also from a variety of different
positions in the room. Check for balance and consistency of sound - neither
too much nor too little bass across the range of programme material and
listening positions. Experimentation and careful listening is the key to finding
a good subwoofer setup.
