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VIRTUALIZER PRO DSP1024P
modulations can clearly be heard when occurring in the midrange frequency band, due to the sensitivity of
human hearing. The ear immediately detects changes in midrange frequencies, while its sensitivity to
frequency modulation in the extreme low end of the frequency spectrum is reduced. Frequency modulation can
also be used to produce wanted effects. The popular chorus effect, for instance, is basically the sum of a
variety of frequency modulations. The original signal is slightly delayed in the chorus algorithm, then added
again and modulated by means of an oscillator. Subsequently, modulating frequencies (of different pitch) are
applied to the original signal, which produces the well-known floating chorus sound. Basically, frequency
modulation is the starting point for all kinds of chorus-type effects: by simply adding the delayed signal, without
modulating the original, you can produce a delay effect. Since chorus effects use very short delay times, the
resulting delay effect is not perceived as such. However, when you increase the delay time, there is a clear gap
between original and effect signals, and delay becomes audible. A highly intensive effect can be achieved by
combining reverb/delay programs with modulation effects. For this reason, the BEHRINGER VIRTUALIZER PRO
also features multi-effects programs combining reverb or delay with, for example, a chorus effect.
In addition to the multi-effects programs and special-purpose effects, most of the VIRTUALIZER PROs effect
programs offer pure reverb programs, because common reverb is still the most important effect for mix-down
or live applications. Therefore, we at BEHRINGER want to provide you with a variety of reverb programs, so that
you have appropriate presets available for each specific application.
Before you can simulate any reverb phenomena, you need to identify the major parameters of natural
reverberation and use them to create a mathematical algorithm. The BEHRINGER VIRTUALIZER PRO
benefits from the newly developed virtual acoustics algorithm. Unlike many other conventional reverb
algorithms, the virtual acoustics algorithm reproduces the essential parameters of typical reverb rooms with
considerably more detail and realism.
4.1.1 Reverberation chambers
Reverberation chambers deliver the most natural form of reverb. In general, every room has its specific acoustic
properties which are not only dependent on its size but also on its shape (architecture) and the materials used
to construct it. For this reason, experts in architectural acoustics design rooms (concert halls, recording
studios, etc.) to produce a specific sound and reverb ambience.
Even today almost all recordings of classical music and a major part of jazz recordings are performed in a
dedicated recording room. Important professional studios sometimes have special reverberation chambers
tuned to produce a specific ambience. They can be built entirely from wood, ceramics or natural stones to
generate a specific sound in a very natural way. Some high-end studios even have facilities to adjust the walls
and ceilings so as to generate distinct reverb ambiences or sound images. However, as the cost of such rooms
are extremely high, newly built studios simply cannot afford a dedicated reverberation chamber.
Understandably, no reverb unit can produce reverberation that is more natural in character than the ambience
generated by a natural reverberation chamber. On the other hand, reverberation chambers do suffer from three
decisive drawbacks:
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It is not possible to modify the reverb sound (except for rooms with adjustable walls and ceilings), so when
using natural reverb you cannot change its decay time or intensity.
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Natural reverberation chambers cannot be used to generate special surreal reverb phenomena, e.g.
extremely long decay times or reverse reverb.
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Reverberation chambers are not portable! If you wish to use one particular reverb ambience, you will have to
record in the specific room that produces it. In a way, each reverberation chamber is unique.
4.1.2 Spring and plate reverb
Due to the disadvantages of natural reverb chambers (see section 4.1.1), two new methods of generating reverb
were invented and used in the 50s and 60s. For the first time ever, plate or spring reverb devices allowed for the
artificial production of reverberation. A reverb plate consists of a thin steel plate or sturdy metal sheet coated
with a gold alloy, which is set in motion by a generator radiating the signal to be processed (reverberated). At
another point somewhere on the plate, the signal is picked up by a transducer and then added to the original
signal. Plate reverb is quite natural in character because the vibrations of the plate are similar to air vibrations
in a (reverberation) room, i.e. they are spread in all directions, are reflected when they reach the plate edges,
and you can basically distinguish between early and later reflections. The result is an almost natural reverb
ambience, however, whose decay time cannot be modified.
4. TECHNICAL BACKGROUND
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