Weiss Enginering Ltd.
DSP501/DSP502
4.2
The Weiss Room Equalizer
A room equalizer is used to change the acoustic behaviour of a listening room to some extent. Usually it is
best to first take other measures to enhance the characteristics of a room, e.g. by applying absorbers and/or
diffusors to the walls, the floor and the ceiling of a room. This plugin is not applicable on headphones.
In a residential environment such a room treatment can be difficult as one may not like to change the looks
of a room. This is where a room equalizer comes in handy. The goal is to tame the so called room modes,
which are discrete low frequencies where the room resonates.
The frequencies where modes appear depend on the geometric shape of the room.
The
amroc
room mode calculator tool by amcoustics allows you to enter the dimensions of a room and
calculates the potential frequencies of room modes:
The number of different room mode frequencies can be quite large - depending on the room geometry and
acoustic properties of the room. In addition the room modes which actually cause problems depend on the
positioning of the speakers, the radiation pattern of the speakers and the listening position. Thus the room
equalizer based treatment of a room can be quite complex.
One approach is to first find the potential frequencies of the room modes with the help of e.g. the website
given above. After that the room modes at those different frequencies can be excited with single frequency
tones. If the room resonance can be excited at a frequency that frequency then can be suppressed to some
extent with the room EQ.
See section 2.3.6 for instructions about how to find room modes with a slow sine wave sweep.
If a room mode is very pronounced then the room EQ can be set by listening to a music track which is suited
to excite that room mode. This would be the simplest method to set the room EQ.
Another approach is to measure the room response with the given speaker positions and listening positions.
With those measurements the necessary room EQ settings can be calculated. We are working with the
Illusonic company to license their room measuring software for the purpose of calculating the necessary
room EQ settings.
4.3
The Weiss Crosstalk Cancellation (XTC)
The so called binaural technology has a long history. Decades ago many live or radio drama recordings
have been made using a dummy head microphone as displayed in fig. 23. This head has microphones built
into its ears, which allow to record an event in a similar way a listener would hear it.
The idea now is to bring the two recorded
channels unchanged to the ears of a lis-
tener. The left channel shall go to the left
ear only and the right channel to the right
ear only. This means there must not be any
crosstalk from left to right or right to left.
With such a setup it is possible to repro-
duce the recorded live event with incredi-
ble realism. A headphone allows to trans-
mit the signals to the ears without any
crosstalk.
Only, the headphone based playback got
other problems, causing such a playback
of a dummy head recording often to be un-
satisfying.
If it would be possible to play back the
recording via speakers then the headphone
related problems would be gone.
Figure 23: Dummy head microphone
User Manual and
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