Lexicon LEXICON480LV4 Owner's Manual page 40

becomes stronger than the earlier part of the envelope,
resulting in a inverse sound.
Note that none of these shape effects are audible
unless RTMID is set short enough. Generally, RTMID
should be set to a value of about 1.2 seconds for small
rooms, and up to 2.4 seconds or so for halls. SIZE
should also be set to a value appropriate to the desired
hall size (note, however, that small sizes color the
reverberation).15 meters makes a very small room,
and 38 meters is useful for a large hall.
Used with care SHAPE and SPREAD allow the 480L to
produce superior ambience—a sound which is spa-
cious and has great depth—without the long RT60 of a
church.
Creating a Realistic Ambient Sound
When you set out to create an ambient sound, the first
and most important decision is how big a space you
want. The best way to start is to listen to several presets
and choose the one which sounds closest to what you
have in mind. If necessary, use SIZE to make a slightly
larger or smaller sound, as needed.
Next use RTMID to fine-tune the amount of time the
reverberation takes to die away at the end of musical
phrases. Actual halls vary a great deal in their actual RT
MID values. The setting of the BASS MULTIPLY is also
critical in matching the sound of an existing hall. An
ideal concert hall would have a BASS MULTIPLY
setting of 1.2. It is rare when actual physical spaces
exceed 1.5. Many (if not most) good recording environ-
ments have values of BASS MULTIPLY of 1.0 or less,
and a value of 0.8 should be tried when attempting to
match an existing hall.
There are two additional controls to deal with. SHAPE
and SPREAD adjust the effective reverb time when the
music is running. Higher values of SHAPE and
SPREAD produce a longer effective reverb time.
Longer effective reverb times give greater spacious-
ness to the sound.
The Early Reflection Myth
The importance of early reflections in reverberation
has become accepted as indisputable fact. We call it a
myth. Much of the myth of early reflections is a result of
attempts to emulate the sound of discrete reflections
Banks 1-4: the Reverb Programs
from the floor, stage area, and ceiling of a real hall. This
sounds reasonable in theory, but it has been our
experience that the resulting preechoes are much
different from the early reflections present in real halls,
and recorded music is often better off without them.
The reason for the difference is not difficult to discover.
Early reflections in artificial reverberation are usually
discrete--simply a delayed version of the original
sound. Transients such as clicks or drums are clearly
heard as discrete reflections, resulting in a coarse,
grainy sound. But the reflective surfaces of real halls
are complicated in shape, and the reflections they
produce are smoothed or diffused. Their time and
frequency responses are altered, making them much
more interesting. In a very good hall, discrete reflec-
tions are hard to identify as such.
Another major disadvantage of discrete early reflec-
tions is that the same reflection pattern is applied to
every instrument which is fed into the reverberation
unit, and each instrument has its timbre altered in
exactly the same way. In a real hall, every instrument
has a different set of early reflections, and each inst-
rument will have its timbre altered in a different way.
Some engineers find any type of early reflection undes-
ireable. In classical music, many recordings are now
made with the orchestra in the middle of the hall, with
the specific intention of avoiding early reflections. Too
much early reflected energy makes the sound muddy,
and does not add to richness or spaciousness. This is
in part because reflections and reverberation also exist
in the playback room.
The 480L reverberation algorithm still offers the option
of adding early reflections (preechoes) but we have
made them diffused clusters of preechoes. The density
of the cluster is set by the DIFFUSION control. We
recommend that these preechoes be used with cau-
tion, unless you are trying to match the sound of the
reverberation to a particular location where such re-
flections are strong.
When creating new reverberation sounds of your own,
don't forget that an Effects program can be put in series
with the reverberation (using the Cascade con-
figuration described in Chapter 2). The result can be
extremely interesting. Also, try using the Effects pro-
gram to give high frequencies a different envelope from
low frequencies.
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