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Listening to music
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The classical dynamic loudspeaker does not have a linear phase response. The initial signal is slightly
delayed and this delay depends on the frequency. The passive filters, commonly used to divide the signal to
the different loudspeakers in a box, further the delay the signal in the different frequency ranges. A special
problem is the crossover frequency between the loudspeakers. The consequence is that a music signal is no
longer time coherent when it arrives to the listener. The loudspeaker is no longer phase linear. As music is a
sequence of sudden impulses, all these delays produced by the loudspeakers give instruments and voices
an artificial character. This effect can specially be heard with dynamic music: fast piano or violin passages,
percussive instruments, orchestral music, Jazz etc.
The active amplifier technology with Adaptive Output Impedance System (AOI) and Compensated Phase
Response (CPR) lead to a time coherent or phase linear reproduction about nearly the whole frequency
range. Therefore the sound reproduction is accurate and natural.
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Time coherent loudspeakers can reproduce the soundstage accurately. Stereo and Surround recordings use
time delays to deceive the ear that the original soundstage is present. When a loudspeaker has additional
delays, the reproduction of space will be smeared.
What has to be considered is that phase distortions can simulate an additional spaciousness, not contained
on the recording. With phase linear speakers this pseudo space will be absent and sometimes "missed" and
the recording seems "drier".
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The usual dynamic loudspeaker works as a mass-spring system: an electrical input will drive the stiff
membrane from the zero point in one direction and back in the other direction. The membrane (the mass)
tends to oscillate over the predicted point because it is held back by the mechanical (spring) of the
loudspeaker. The exact impulse will not be produced immediately. Music is based on continuously changing
oscillations why a dynamic loudspeaker has a poor impulse behaviour. An important benefit of the active
amplifier with AOI and CPR is the dramatic improvement of the impulse behaviour of the dynamic
loudspeakers, because its movement is directly controlled by the amplifier. With passive systems this control
is nearly absent.
What you will hear is that the sound is very precise and natural and you can listen to the music for hours
without fatigue.
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In most appartments it is not possible to listen to the music at high volumes. Small rooms tend to compress
the sound to an unnatural effect. To get a realistic effect and for everyday-use it is important that a
loudspeaker sounds convincing at moderate levels. You will realize when listening with ELLA, that high
sound pressure levels are not important to get the full range of details in the music. This is another benefit of
the active technology.
© by KLANGWERK GmbH, Zürich, Switzerland
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