Turbosound TQ-440 - Manual (Page 13)

user manual
QLight    series
TQ-440 manual
page 13
Choosing the best location
It was stated earlier that the TQ-440’s tightly controlled directivity gives it essentially point and
shoot qualities. Every room has its own unique set of characteristics that affect any sound
introduced into the room. These include reverberation reflections and decay time, sound
absorption of materials used, temperature and humidity, etc. A degree of experimentation with
different locations (if possible) is best, especially if you are permanently installing the speaker and
have particular requirements where you want to concentrate the sound into a specific area.
Any boundary like a wall or floor will lift certain frequencies. If you are fixing the unit to a wall, or
in a corner then a lift at the bass end is to be expected and it may sound rather boomy. Either
reduce the low end by means of a graphic equaliser or move the speaker.
Rooms with a lot of soft furnishings, curtains and drapes will absorb sound, especially at high
frequencies. These rooms can sound rather dead and may appear to need more amplifier power to
generate high SPL’s but have the advantage that the sound needs less equalisation and is easier to
control. In this case the listener receives mainly
direct sound, that is the sound emanating directly
from the loudspeaker, with little reflected sound.
If the room has a lot of hard, exposed surfaces such as wooden floors, brick or plaster walls or
glass windows, these will reflect the sound, causing it to bounce around the room and sounding
over bright. These rooms also tend to have various resonances that will be excited by high SPL’s.
Listening in the middle of the room you will hear a lot of
reflected sound in comparison with the
direct sound. Care is needed with speaker positioning, SPL’s and equalisation. If the room is large
and very reverberant then bass roll-off below about 250 Hz may be required to ensure a
reasonable level of intelligibility.
For long, narrow rooms the traditional left and right stacks (floor, wall mounted or flown) can
suffice with good stereo imaging in the centre of the room. For multi-tier venues such as theatres,
speakers should be flown or wall mounted to project into each tier. In highly reverberant rooms
often a central cluster is the best option. This acts as a virtual point source with all the sound
emanating from one point in the room, but path lengths should be carefully calculated.
The relationship between sound pressure level and distance is an “inverse square law” so
remember that every time the distance from the sound source is doubled the sound level
decreases by 6dB. For every 3dB increase of speaker output you need a doubling of input power
and you can work out the Wattage input needed to give the required SPL levels at various
distances from the loudspeaker(s).
When speakers are flown in free space then boundary effects are minimised. The result is a
smooth frequency response without any boost at odd frequencies, but the bass end may appear
subjectively light. In this case you will need floor mounted sub-bass, to bring the low end up.