Listening rooms are not ideal. Because of room geometr y and construction there will be areas with severe peaks at some
frequencies and severe troughs at others. If you site loudspeakers in such areas the response will be highly non-linear . It is easier
to treat high frequency irregularities by the use of drapes, sof t furnishings etc., but very hard to do the same at bass frequencies
due to the ver y long wavelengths - at 40 Hz the wavelength is almost 9 metres.
T o help locate standing waves in your listening room, one idea is to sit in the listening seat and recruit a friend with a deep voice
to speak as he moves around the area where you propose to site your subwoofer - you will soon find out where to site it!
Where the voice sounds most natural is a good place to star t.
Although the subwoofer's bass output is enhanced by walls or corners, so of ten is coloration . As the drive unit faces downward,
the floor will influence the sound. The sur face under the subwoofer should be stable and unobstructed. If the carpet is very thick,
consider placing the subwoofer on a solid sur face such as a marble slab. If you place the subwoofer where it amplifies the
irregularities of the room or the main speakers the result will be bloated, coloured bass. If acoustic guitar and male voice sounds
coloured when the subwoofer is operating and less coloured when in standby , you need to address the positioning first before
adjusting any controls.
Make sure that all loudspeaker channels are connected in phase. If there is a doubt about the way the
loudspeakers are connected, check their phasing by playing a mono source - the sound should appear from a point midway
between the front loudspeakers. If this position is indefinite, reverse the connections to one speaker . Correctly connected
loudspeakers give a definite centre sound source with fuller bodied tenor and bass registers.
Phase at ver y low frequencies is not straightforward to detect. Initially we suggest you
temporarily set the low pass filter to ‘off ’ and the phase to 0º and play some bass heavy music in Stereo through the main speakers
and the s ubw oofe r . F r om t he l iste nin g po siti on , sw itch t he p hase b etw een 0º and 180º. The setting which appears to give the greater
bass output is correct. Now follow the instructions below for setting the low pass filter .
This channel was originally an additional bass channel with its own dedicated subwoofer . In practice however , if any
speakers are set to ‘Small’, the LFE channel is combined with the bass from those channels and fed into the subwoofer . When you
set the LFE level from your AV processor , use care as the LFE channel contains power ful low frequencies which, although normal
in a cinema, may overload a domestic subwoofer . If , during a programme, you hear popping or thumping noises from the
subwoofer , turn the A V P rocessor volume level down and back off the LFE level. If this does not cure the problem, lower the
subwoofer volume level.
not
Loudspeaker Phasing:
Setting the Phase of the Subwoofer:
LFE:
Low P ass Filter
Setting Loudspeaker Sizes:
: If you are using a digital AV processor the initial subwoofer setting should be ‘ OFF ’ as the processor will have its
own bass management system.
Most digital AV P rocessors ask you to specify the size of speakers in the various channels. These are
usually ‘Large’ or ‘Small’. This sets the bass management for the system. All Opus² regular loudspeakers can be set to 'Large'
Smaller loudspeakers (and possibly also the M1) should be set to 'Small' for the F ront channels, as the subwoofer will be better at
providing clean, deep bass. Choose 'Small' for the surround channels and also for the Centre channel, so that any bass from these
channels will be directed to the subwoofer . Set the ‘Subwoofer’ option on the processor to 'On’ or 'Y es'.
Af ter experimenting with various sources you may need to adjust the LPF settings. Try to ensure the subwoofer blends into the
sound stage. Setting the subwoofer to Standby should reduce the bass extension, not change the bass level - as always personal
taste plays an impor tant part.
Once the loudspeaker settings have been finalised, put the AV amplifier into its “T est” mode (see instructions supplied with your
processor .) Adjust the levels until all channels are reproduced at equal loudness.
When adjusting the subwoofer output level avoid setting too high a level or you will swamp the sound with bass which be tiring to
listen to and may limit the subwoofer ’s ability to respond to large bass transients. Set a sensible level going the subwoofer
from the processor . The volume display should be around at normal listening levels.
Setting levels:
into
50
Setting Up Y our Active Subwoofers
Setting up of the subwoofer should be per formed with all tone controls and filters on your amplifier or processor set ‘ flat’.
Opus²
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Placement
Setting Loudspeak er Sizes
Front And Effects Channels
Subwoofer
The front loudspeakers are placed on either side of the television screen, 2 to 3 metres apart. The speakers should be angled
slightly so they are aimed towards the listeners.
W e recommend placing the rear effects speakers in a high position, behind the listener ’s head. If the rear or side walls are a long
way from the listening seat, consider stand mounting the loudspeakers. If the centre loudspeaker is ver y high or low , angle it
towards the listener's ear level. The front faces of the centre and surround loudspeakers should also be in line as far as possible.
As the ear is unable to detect the direction from which deep bass originates, this allows you freedom to position the unit. V ar ying
the distance from the wall alters the bass. Placing the subwoofer across a corner boosts the bass but may impair clarity . The
per formance of Home Theatre systems can often be enhanced by using a pair of subwoofers.
Many digital AV P rocessors ask you to specify the size of speakers in all channels - usually ‘Large’ or ‘Small’.
The Opus² M2, 1, 2, and 3 may be safely set to 'Large'. The Opus² M1 and T ri- Centre may be set to 'Large' for smaller systems or
rooms, or 'Small' for large scale systems. The AvC, A vS and T ri-Surround speakers should be set to ‘Small’. As always personal
preference will play its par t
If you are not using a subwoofer: Set the F ront Speakers to ‘Large’. Set the ‘Subwoofer ’ option on the processor to 'Off' or ‘No'. The
F ront channels will now receive all the system bass.
If you are using a subwoofer: When set to ‘Small’ all the system bass will go into the subwoofer . If you choose ‘Large’ the F ront
channel bass will be reproduced from the F ront speakers.
Once the loudspeaker settings have been finalised, put the AV amplifier into its “T est” mode (see instructions supplied with your
processor). Adjust the level of each channel until all channels are reproduced at equal loudness.
Y ou may need to adjust the subwoofer output level. A void setting too high a level or you will swamp the sound with bass and may
limit the subwoofer ’s ability to respond to large bass transients. Y ou should also set a sensible level going into the subwoofer from
the AV processor .
Setting Up a Home Theatre System
REAR
RIGHT
REAR
LEFT
SUB
WOOFER
AL TERNA TIVE
POSITIONS
AL TERNA TIVE
POSITIONS
CENTRE
FRONT
LEFT
FRONT
RIGHT
Some of this chapter may appear to repeat the content of the Subwoofer pages - the context however is differ ent.
Opus²
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