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Overview
The Oxford Reverb plug-in is a highly flexible stereo reverberation
generator, designed to complement existing Sonnox Oxford applications
in providing the user with the highest technical and sonic
performance coupled with artistic and creative facility.
As well as providing stunning presets, the user has full
control over all of its many parameters, including a very
comprehensive early reflections section, and integrated
5-band EQ. The Sonnox Oxford Reverb allows the powerful facility
to create virtual spaces freely, depending on artistic
need, ranging from dry reflection ambiences, room and hall
simulations, sound effects, all the way to wide open reverberant
spaces with a very large range of possible texture and
spatial character.
Features
Extremely flexible reverberation generator.
Detailed control over early reflections.
Bring sounds forward or push them back.
High quality Sonnox Oxford sound.
Incorporated 5-band parametric EQ.
Over 100 realistic, useful presets for music & post-production.
Platforms Supported
Pro Tools HD (TDM), Pro Tools LE (RTAS), M-Powered (RTAS), AU, VST
General By avoiding fixed algorithms and providing user
control of all parameters, the Sonnox Oxford Reverb allows the
professional engineer the powerful facility to build virtual spaces
freely depending on artistic need, ranging from dry reflection
ambiences, room and hall simulations, sound effects, all the way to
wide open reverberant spaces with a very large range of possible
texture and spatial character.
Key Features
Highly flexible reverb generator plug-in with real-time continuous control of virtually all parameters.
Dual independent paths for both ‘Early Reflections' and ‘Reverb Tail' function.
Each reverb path type can be used independently or in combination.
Comprehensive 5 band equaliser (based on the Sonnox Oxford EQ) which includes high and low pass filters.
More
than 120 snapshots for immediate use under the headings of Dry Spaces,
Ambient Effects, Vocal Reverbs, Plates, Rooms, Chambers, Halls,
Churches and Foley Effects.
Click to enlarge
Input Section
The INPUT GAIN fader sets the level of signal fed into the reverb process. The STEREO SEPARATION
fader allows the left and right signals to be mixed in order to reduce
the stereo width, with variation from full stereo to mono.
The LF ROLL-OFF
fader allows reduction in low frequency content for the signal passed
to the reverb processor, but does not affect the dry signal. When set
at 0.0, the low frequencies are completely unaffected.
Early Reflections Section
Four SHAPE buttons allow basic 'virtual room spaces' to be selected. The POSITION fader selects the listening postion on a central front to back axis. The SIZE fader sets the front to back distance for the room. The room proportions remain as the size is adjusted.
The WIDTH
fader sets the stereo separation of room reflections with normal
placement at 0.0%. Separation is increased from normal, going
ultra-wide beyond 100%.
The TAPER fader
controls the loudness of reflections in relation to path lengths. Lower
settings will cause more distant reflections to be quieter, whereas at
maximum, all reflections will have equal level, irrespective of path
lengths.
The FEED ALONG fader sets the
amount reflection density and echo complexity due to re-injection of
distributed sound within the simulated space. The FEEDBACK fader sets the proportion of reflected signal that is re-circulated. The PHASE SELECT button selects the phase of the feedback and its diffusion, characterised as softer or harder reflections.
The ABSORPTION fader controls high frequenxy roll-off, where increased absorption is reminiscent of soft furnishings and drapes.
Tail Mix Section
The COMP DELAY fader sets the time after which the the reverb tail starts. If the ER TRACK
button is selected, then it tracks the early reflection room size
exactly if the fader is set in the middle. Variation from 0.1 and up to
X 2 the room size is available below and above the central X 1 setting.
The ER MIX fader provides a x-fade mix between the dry input signal and the output of the early reflections processor.
The TAIL INPUT fader is the final x-fade mix which feeds the reverb tail processor. It takes signals mixing between the COMP DELAY fader output and the ER MIX fader output.
Reverb Tail Section
The REVERB TIME fader sets the time in seconds for the reverb signal to drop to -60dB. The OVERALL SIZE
fader, independent of reverb time, sets the build-up and density of the
reverb tail. Larger size settings cause a slower density build-up,
whereas for smaller settings, the build-up is much faster with greater
long term tonal artifacts. The DISPERSION fader controls the rate and
build-up of dispersion behaviour, character and sonic texture over
time. Positive values increase dispersion and negative values also
increase dispersion, but with greater left/right differential. No
dispersion effect takes place with the fader set centrally. The PHASE DIFF
fader operates in conjunction with dispersion, controlling the speed of
build-up of differential phase components. Positive values create more
coherent dispersion components, sounding smoother and more natural.
Negative values create wider range dispersion where some components
have inverse polarity, which tends to extend the sound field. The PHASE MODULATION fader controls time related variance to the to the reverb character for enhanced realism.
The ABSORPTION
fader controls high frequenxy roll-off, hardness and sofrtness, where
increased absorption is reminiscent of soft furnishings and drapes. The
DIVERSITY fader provides control of front
centre weighting which helps to anchor the reverb to centre stage. The
lowest value gives the greatest centre weighting, narrowing the reverb,
whereas maximum diversity spreads the reverb spacial effects equally
across the sound stage. Output Section
The REVERB MIX fader x-fades between the early reflections process output and that of the reverb tail process. The WET/DRY fader x-fades between the dry signal and the complete reverberation processing. The 100% WET button selects the output of the reverberation processing only.
5 Band Equaliser
Click to enlarge
Clicking on the EQUALISER tab reveals the EQ controls. The EQ processing preceeds just the reverb processor, and has no effect on the dry signal.
Each of the 5 sections allows control of GAIN (boost & cut), FREQ(uency) and Q with 'bell' characteristics. In addition, the LF and HF sections include 'shelf' and filter functions. An IN button on each section allows the effect of its control settings to be auditioned.
System Requirements
Pro Tools
Pro Tools 6.0 or above
Approved Pro Tools CPU, OS and hardware configuration. More details: www.digidesign.com
Mac OSX 10.3 or later
(Leopard supported see Digidesign for details)
Windows XP
/ Vista32RAM 1GB minimum
iLok key with latest drivers
Audio Units
Audio Units compatible application (Logic, Digital Performer etc.)
Mac OSX 10.4 or later
(including Leopard)
RAM 1GB minimum
iLok key with latest drivers
VST
VST compatible application (Cubase, Nuendo, Acid etc.)
Mac OSX 10.4 or later
(including Leopard)
Windows XP
/ Vista32
RAM 1GB minimum
iLok key with latest drivers
PowerCore
TC PowerCore hardware
PowerCore version 3 drivers
AU or VST host application
Mac OSX 10.4 or later (including Leopard)
Windows XP / Vista32
RAM 1GB minimum
iLok key with latest drivers
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Signal Flow
The following diagram illustrates the overall signal flow within the Oxford Reverb application:
Click to enlarge
Controls Layout
The control functions are arranged in operational sections, comprising
of early reflection settings, reverb tail settings and contribution
mixing functions. Mixing functions are conveniently split into separate
sections, for internal signal contribution to the reverb tail section
and overall level control and mixing functions. 
Click to enlarge
Input
INPUT GAIN fader controls the overall input level and reverb gain.
INPUT METER displays the peak input level to the reverb processing after the INPUT GAIN fader.
STEREO SEPARATION fader controls the degree of left and right signal mixing at the input of the entire reverberation processing. At minimum setting the internal input to the reverb is equivalent to a mono mix.
LF ROLL-OFF fader provides the means to reduce the level of LF
programme entering the reverb processing. The control is continuously
variable from minimum position where no LF roll-off occurs to maximum
LF cut at highest setting. The response of the input signal at the Wet/Dry mix stage is unaffected.
Early Reflections
Note: Early Reflections are often referred to as ER.
SHAPE
buttons select the overall shape of the early reflection space. Four
basic space shapes are provided to allow the application of appropriate
overall character to the reverberation.
POSITION fader controls the relative back to front placement of the listening position within the virtual room simulation.
SIZE
fader sets the overall size of the simulated space, as measured between
front and back walls. Room shapes remain in proportion with this size.
WIDTH
fader c ontrols the stereo separation of the room reflections depending
on their particular direction within the stereo field. Normal position
placement occurs with the control at minimum setting. Increasing the
setting provides wider separation. Increasing settings beyond 100%
produces ultra-wide separation, often useful when adding spatial
effects to single mono tracks.
TAPER
fader controls the loudness level of the reflections depending on their
relative path lengths. I.e. longer delays are progressively reduced in
level because the sound will have travelled further. Increasing the
taper control will proportionally increase the relative contribution
from long path lengths in relation to short paths. At maximum setting
all paths lengths will have equal level contribution.
FEED ALONG
fader controls the amount of re-injection of distributed sound within
the simulated space. Greater re-injection will result in greater
reflection density and echo complexity and cause the reflections to
continue over a longer period of time.
FEEDBACK
fader controls the proportion of the reflected signal that is
re-circulated within the room simulation. Increasing feedback will
result in longer reflection duration (room reverb time) and greater
room mode frequency response effects (boominess).
PHASE SELECT button modifies the phase relationship of the Feedback
variable. Modified phase (preferred on position) will result in softer
reflections over time and produce greater modal and spatial dispersion,
synonymous with natural rooms containing objects that disperse
reflections and tend to break up room behaviour. Normal phase (off
position) will result in harder reflections and greater modal frequency
behaviour.
ABSORPTION fader controls the
high frequency roll-off that naturally occurs over time due to
absorption. Higher settings (greater absorption) relate to spaces
containing soft furnishings and wall coverings, low settings (less
absorption) relate to empty spaces with hard reflective surfaces etc.
Tail Mix
Facility is provided to drive the input of the reverb tail processor
with a combination of signals comprising of; untreated input signal,
delay compensated input signal and the output of the early reflections
processing. Two levels of cross fade control are provided for this
mixing function, so that relative contributions can be varied freely
without disturbing overall levels.
COMP DELAY fader s ets the timing of the delay compensated input contribution to the reverb tail processing.
With the ER TRACK button
selected the delay compensated input signal tracks the notional size of
the early reflection processing section. The available control is from
zero to 2 times the early reflection Size setting, with mid position (1) representing the normalised time alignment setting.
With ER TRACK unselected, theCOMP DELAY control is uncoupled from the early reflection Size setting and provides an independent delay up to a maximum of 30 meters.
ER MIX fader provides a cross fade between the untreated input signal and the output of the early reflections processor.
TAIL INPUT fader provides a cross fade between a delay compensated versions of the input signal provided by the COMP DELAY fader and the mixed signal resulting from the ER MIX stage.
Please note that a combination of the input signal and delayed signal
together can cause unwanted frequency combing effects when the ER SIZE is set for smaller spaces. It is therefore best to arrange the ER MIX and TAIL INPUT controls to predominately use either a mix of the ER and the input, or the ER and the delayed input when simulating smaller spaces.
Reverb Tail
All parameters of the reverb tail section are fully compensated, so
that they may be adjusted in isolation without mutual interaction with
other control settings. This means that settings such as REVERB TIME or LF ROLL-OFF will produce constant results even if other factors such as DISPERSION or OVERALL SIZE are varied.
REVERB TIME fader sets the overall reverberation time in seconds as referred to a decay of –60dB ref the input stimulus.
OVERALL SIZE
fader sets the overall size of the delays within the reverb tail
section, providing the means to modify the character of the reverb
independently of reverb time and absorption parameters. Larger size
settings generally provide the greatest impression of space but result
in slower density build up in the short term. Shorter size settings
produce faster density build up over time, but exhibit greater tonal
artefacts in the longer term.
DISPERSION
fader controls the rate and character of the build up of dispersion
behaviour, complexity and sonic texture over time. At mid position (0)
no extra dispersion is added. Positive values cause increasing
dispersion and complexity over time. Negative values also cause
increasing dispersion but it is modified to produce greater
differential dispersion between left and right signals.
PHASE DIFF fader operates in conjunction with the DISPERSION,
setting to control the build up of phase difference between left and
right stereo signals. The greater the setting, the faster phase
differences will build up over time, and cause a widening and deepening
of the stereo sound field.
Positive values will create a
build up of left and right difference, which is largely limited within
the same absolute polarity across the sound field as the original
programme signal. This is most useful for producing a natural reverb
sound fields that spread between the confines of the stereo speaker
width.
Negative values produce a wider range of phase dispersion that includes
components that have inverse polarity with respect to input programme
and left and right outputs. This is useful for producing sound fields
that seem to extend beyond the stereo speakers to produce an enhanced
sense of immersion within the simulated space.
PHASE MOD
fader controls the application of internal phase modulation to the
reverb algorithm. This adds a very slight variance to the reverb
character over time, which enhances realism and presence under many
conditions.
ABSORPTION fader controls
the high frequency absorption effect within the reverb section. Higher
value settings produce greater overall HF roll-off and faster relative
absorption over time, synonymous with natural spaces containing a
variety of absorption materials such as wall coverings, curtains or
furnishings etc. DIVERSITY fader provides statistical front centre
weighting to the reverb tail, which is often required to anchor the
reverb effect to centre stage of stereo sound field mixes. Centre
weighting is greatest with the diversity control in minimum position
where the reverb image will seem narrowest. In maximum position no
centre weighting occurs and the reverb image is therefore equally
spread across the sound stage, producing the greatest spatial diversity
and the widest perceived image.
Output
REVERB MIX fader provides a cross fade between the early reflections and reverb tail for the final output.
WET/DRY fader provides a cross fade between the input signal and the output of the whole reverberation processing.
100% WET
button forces the output to reverb only. This is convenient when used
in mixing applications where the reverb commonly forms part of an
auxiliary mix where the dry signal is present on the main mix buss.
OUTPUT METER displays the peak output level from the reverb plug-in.
Reverb Equalisation
The Equalisation section comprises of 5 bands with the upper and lower
sections selectable between band pass, shelving and 12dB/octave
filtering functions. The EQ processing proceeds the reverb processing
and therefore the dry signal remains unaffected by Equalisation
settings.
IN buttons t oggle the EQ of the associated section in and out for comparison purposes.
GAIN
knobs Control the effective gain of the EQ curve from –20dB to +20dB.
The default curves for all EQ sections are band pass or 'bell' shaped,
where boost and cut curves are mirror images.
BELL, /12 & SHELF buttons present on LF and HF sections, intercancel and allow additional curve characteristics to be selected. These are 12dB/Octave filters and shelving EQ.
Q control knobs allows continuous control of the Q value for sections performing bell or band pass function.
FREQ(uency)
knobs rovide continuous control of the centre frequency for band pass
functions and turnover frequency for shelving and filtering functions.
Reverb Principles
Artificial reverberation models tend to fall into two main categories,
which can be described as convolution and reflection simulation
modelling. Both processes seek to achieve a degree of realism and
virtual space by modelling room characteristics. The convolution model
achieves this by recording the actual impulse response (due to
reflections and dispersion) of existing spaces and imposing the
resulting transfer characteristic on to the programme to reproduce the
character of the space. However this model does not lend itself easily
to the user interaction required for the artistic creation of
reverberation effects that are commonly needed in production. Another
important factor is that the user cannot readily simplify a convolution
to avoid conflicts that often occur between the recorded ambience and
the simulated reverb.
The Sonnox Oxford Reverb belongs to the reflection simulation model as
this allows the wide and varied user control intended from this device,
in the pursuit of a high degree of artistic interaction and creative
freedom.
Operation
Generally speaking simulation models employ two sections to generate
spatial effects. The first section produces the early reflections that
we use to perceive the dimensional space of environments and a reverb
tail section is used to produce the longer term diffuse tails that
occur in real environments, when the reflection complexity has become
so dense that it is no longer possible to discern discrete events.
It is the combination of the effects of these two sections that create
the impression of space, environmental timbre and texture. One useful
way to regard this is that the early reflections create a kind of ‘wire
frame' model that we lock on to in order to fix the dimension of the
space and the reverb tail forms the ‘plaster' that fills in the model
and gives the space volume and long term character. Adjustment Procedure
The Sonnox Oxford reverb provides for a very large degree of parameter
control so that the professional user has the facility to produce
reverberation ranging from subtle ambience and dry spaces all the way
up to making dramatic sound effects. To get this degree of user
facility a significant number of controls need to be present on the GUI
panel.
Although this may seem daunting initially, with experience the nature
of the controls and the sonic effects they produce should quickly
become self-evident. The best method to gain this experience is to
simply operate it, taking note of the effect that results from varying
control parameters. Indeed, it is intentional in the design of this
application that the user should interact with it freely in order to
create exemplary results in the normal course of its daily use, which
uniquely match the artistic requirements of the particular production
in progress at the time.
It is fully appreciated that during the modification of an existing
set-up or the building of a new sound from scratch, the dividing line
between something that is just ‘ok' and something that is exactly
‘perfect' is often very subtle and subject to the artistic requirements
of the production and the environment in which it has been recorded or
produced. The finer detail of the set-up procedure should therefore
remain at the sole discretion of the user and should not be limited by
existing set-ups or any particular doctrine.
Realistic Room Simulation Example
Most realistic room space simulations will consist of a mixture of
appropriate early reflections and reverb tail. However the control set
provided in the Sonnox Oxford reverb allows many ways to achieve a wide
range of artistic effects that will suit a great many situations, many
of which may involve almost completely opposing approaches.
Experimentation is the key to mastering these and therefore the
following procedures should be viewed as initial guidelines for
familiarisation purposes only. Early Reflection Set-Up
A good method to achieve the correct balance is to listen to the early reflections
first by setting the REVERB MIX fader to the ER position
and adjusting the WET/DRY setting for a comfortable mix.
Start with a neutral setting with WIDTH and TAPER in mid position, FEED ALONG and FEEDBACK at minimum and ROLL-OFF at minimum (most HF content).
It should now be possible to perceive the space changing with the SIZE fader. Set this somewhere appropriate initially.
Go through the SHAPE settings noting the difference and decide on one that most suits what you are after.
At this point the FEED ALONG
setting can be increased, noting the effect it has on overall
complexity in the reflections and the timbre of the space. For
realistic spaces, settings around the mid position are often best, but
experimentation of the full range is encouraged.
Listening carefully to the resulting reflections, adjust the FEEDBACK with the PHASE is set to On (default),
to introduce some reiteration into the space, noting that the space
becomes more resonant and the reflections more diffuse. Without
feedback the reflections will end abruptly when the reflections are
finished. This is useful for creating dry spaces often appropriate for
percussion tracks. However for realistic spaces an amount of feedback
is required to produce a more natural dispersion and timbre. Too much
feedback will result in ringing effects, which can be particularly
intrusive for smaller spaces.
To give the space a realistic absorption and frequency response character, start increasing the ROLL-OFF
fader to tailor the HF response caused by the reflections over time.
There is no fixed rule for what works best as creative freedom should
take precedence, however generally speaking larger spaces require
greater absorption settings than small spaces, since a major cause of
absorption in real spaces is the distance the sound travels in the air.
The WIDTH and TAPER
controls can now be adjusted to make an appropriate stereo spread and
reflection character to the simulation. Some interplay between the FEED ALONG and TAPER
may be required to arrive at the best overall sound character, as both
can give the effect of increasing the prominence of the reflections.
At this point it is worth adjusting the POSTION
slider to form a placement for the listening position in the virtual
space. It should be possible to perceive the effect of entering the
space as the setting moves off the back wall (minimum setting) into the
virtual space. It is important to bear in mind that the primary
reflection from the back wall can get quite fast in smaller spaces if
the position is too far forwards, so although the simulation may sound
correct when 100% wet, frequency combing effects may occur when it
eventually gets combined with the dry signal in a mix. Generally
speaking simulations with the source and destination at the back wall
(minimum setting) will always survive the addition of the dry signal,
but under some circumstances forward settings may not. Therefore
it is safest to start with the position at minimum initially and make
the adjustment whilst using the reverb in a mix situation.
Finally
it's a good idea to run through all the settings, making final
adjustments by offsetting one parameter against another in order to get
precisely the result that sounds best with the programme. Remembering
that often very small changes can make the difference between something
stunningly good or just average!
At this point you should have an early reflection sound that
produces a realistic perception of space, but may lack long-term
reverberation and complexity.
Some additional important points regarding the Sonnox Oxford early reflections processing:
It
is sometimes useful to use an early reflection model on it's own
(without any reverb tail) where significant environmental reverberation
already exists on the recorded track to be treated. In this case the
recorded reverb can often be included within the simulated space
without conflict, giving the perception that the track was actually
recorded in stereo.
The perception of large spaces can be alternatively constructed with relatively small SIZE settings by the application of large amounts of FEED ALONG and FEEDBACK.
Whilst such sounds may produce less faithful emulations of real spaces,
great sound effects and very dense general ambiences may be generated
this way.
Moderate duration early reflections built using fairly small Size settings and large amounts of Feed along
with no feedback can be very useful for percussion ambiences, since
they end abruptly and thus avoid creating intrusive ‘hubbub' from
reverb run on.
The effect of very large
spaces with long reverb tails can be constructed with the early
reflection processing alone by using large SIZE settings, moderate FEED ALONG and large amounts of FEEDBACK.
Although such spaces will be less diffuse than reverb tail models
(because they always contain cyclic reflections), they are still very
useful for creating the impression of extremely large spaces and
generating rich sound effects.
The STEREO SEPARATOIN
control mixes left and right signals together at the input of the
processing. This is useful where the virtual space is required to be
fixed regardless of input programme panning. But where the programme is
a viable stereo source (either panned or natural) better placement
within the reverb sound field will be achieved with higher separation
settings.
Reverb Tail Set-Up
The major difference between the early reflection processing and the
reverb tail is that the latter contains no geometrically based
dimensional information. Being constructed of mutually unrelated terms,
it is designed to generate almost characterless spectral diffusion and
spatial dispersion. Therefore its main purpose is to reiterate the
sonic character and spatial cues provided by the input programme and
the early reflection processing, with the minimum of disturbance
throughout its decay period.
However nuances in the way this is achieved play important roles in the
resulting texture, timbre and spatial quality we perceive in the
reverberation effect. Rather than providing the user with either a
fixed model or a limited selection of algorithms, the Sonnox Oxford
reverb offers full control over the parameters that most affect the
sonic character of the reverb tail. This provides the user with the
maximum creative facility. Tail Mix Section
The first thing is to decide what drives the reverb tail section.
Generally there is a mixture of two approaches to driving the reverb
tail section we can consider. Either we want to carry the character of the early reflections into the reverb tail. Or we want to just add reverberation to the input signal so that the character of the input programme is carried into the reverb tail.
In practice we almost always need a mixture of both of these depending on the desired result.
The REVERB TAIL
section of the GUI controls this function by providing the ability to
mix, the output of the early reflections processing with the input
signal and a delayed version of the input signal. Therefore it is
possible to create a mixture of all three signals, any combination, or
just a single source.
The delayed input signal controlled by the COMP DELAY function is normally set in ER TRACK
mode so that the input drive to the reverb tail largely coincides with
the initial output signals from the early reflection section. The
following is a suggested way to set up the reverb tail.
Set the ER MIX fader to the DRY position, the TAIL INPUT to DLY INP, and the COMP DELAY
to its middle position. This ensures that the input drive to the tail
section is the compensated version of the input signal. This is a good
starting point as it is the character of the input that we need to
address first.
Set the REVERB MIX
to its middle position, so that we hear an equal contribution from the
early and reverb tail signals. This is useful because we are initially
concerned with making the overall reverb tail match the timing
requirements of the early reflection sound we have already made.
Set OVERALL SIZE, DISPERSION and PHASE DIFF faders to their middle settings. Set PHASE MOD and ABSORPTION to minimum and DIVERSITY to maximum. This is a neutral starting point where the effect of controls are most easily heard when we get to adjust them.
By increasing the REVERB TIME
control the tail can heard to extend to the period set on the control.
Set this to something that matches the sound you are aiming for. At the
moment the tail will sound rather grainy and its stereo image will be
largely in the centre of the sound field.
Moving the DISPERSION
control in the positive direction will result in increased complexity
and smoothness in the longer term. The higher the setting the faster
the complexity builds over time. Set this somewhere that provides the
required effect, bearing in mind that real spaces take a period of time
to build complexity, especially if they are large and reflective.
Adjust the PHASE DIFF
control and note that the tail image begins to spread across the stereo
field. The higher the setting the quicker the spread will occur over
time. Generally speaking large settings are better in mix situations
because they produce a wide sound field quickly. However for very large
spaces or sound effects a slower spread from middle to sides can often
produce a more realistic effect. The included set up ‘far away' is a
good illustration of this. It is also worth experimenting with negative
settings noting that the spatial effects build into far wider and more
diverse stereo sound fields. Negative settings are often more effective
when you are aiming for greater perceived immersion within the
simulated space.
Increasing the PHASE MOD
will provide a degree of variance for the above settings (as though you
were moving the Phase Diff control slowly). This provides a larger
degree of realism to the reverb tail because it prevents it from
becoming spatially static. It keeps our attention on the reverberation
because it changes subtly over time – much like in real spaces where
natural movement of the air or objects within the space continually
modify its characteristics.
To give the space a realistic high frequency profile over time, ABSORPTION
should be applied in the same manner as in the early reflection
settings. In general, larger spaces require greater absorption, however
some larger spaces can reflect considerable HF from the back
extremities of the spaces. It is important to bear in mind that
allowing a large HF content in the reverb tail may accentuate
unnaturally strident or harsh sounds, particularly if there are
sustained HF components in the programme or there is prominent
resonance in the early reflection stages.
The overall spread of the reverb can be adjusted using the DIVERSITY
control. Reducing this control adds statistical weighting to the centre
image, which is often needed to anchor the sound field to centre stage.
It is important to consider the intended speaker layout whilst setting
this control since a large degree of left to right mixing occurs
acoustically in the reproduction room. It is particularly important to
remember that what appears a natural setting for this control will vary
considerably between headphone and speaker listening methods!
Blending Early Reflections & Reverb Tail
Blending the early and late portions of the reverb is basically a matter of taste and suitability to the programme and mix.
Adjust the REVERB MIX
control to fine-tune the contribution from the sections. Generally
speaking the application of more late reverb tail energy will result in
a softer and more diffuse reverberation at the expense of spatial
realism.
The effort now is to decide what
proportion of the early reflection mix will be included in the reverb
tail input. This is particularly crucial since the whole long-term
character of the reverb is affected. Advancing the TAIL INPUT away from DLY INP towards the ER MIX
direction will progressively allow more signal drive from the early
reflection mix stages into the tail section. Generally speaking there
is normally a need for some ER signal in the reverb tail, however this
is not a ‘rule' and the amounts required are most often quite small.
Too much early reflection drive to the tail may cause unwanted ringing
or boominess from the ER section to become intrusive in the longer
term. Too little drive may make the tail lack character. It is all a
question of settings, programme source parameters and artistic taste.
Experimentation is everything.
Throughout the blending process it is a good idea to go back periodically and adjust the reverb tail OVERALL SIZE
parameter in order to get the best timbral blending between the
sections. The overall size parameter can be adjusted all the way from
what sounds like a ‘cymbal resonating' to a wide open space - without
affecting the decay time, so there is great deal of latitude in what
can be achieved. In general there is a trend for larger early
reflection spaces to most suit larger LR overall sizes, because they
exhibit a slower build up of complexity. However this is not a rule, in
practice very subtle changes in the overall size can result in
exemplary realism when resonance within ER and LR sections complement
each other.
Application of LF ROLL-OFF should only be attempted after
an overall reverberation sound has been achieved, as low frequency
spatial cues are very important to our perception of natural spaces. In
the event that the reverb produces excess LF energy (particularly if
the simulation space is very small), or an effect is desired which
favours only HF programme content, LF ROLL-OFF can be applied with discretion depending on the overall requirement of the programme.
Some additional important points regarding the Sonnox Oxford reverb tail processing:
Since the reverb tail is essentially neutral containing no dimensional character, it can be used by itself with very low reverb times to produce general ambiences and ‘characterless' early reflections. In particular, with small to moderate OVERALL SIZE settings, effects ranging from ‘boomy' drum rooms to vocal double tracking and multiplications can be achieved.
If the programme consists of a stereo source that already contains significant
environmental reflection, the Reverb Tail section can be used on its own
to simply adopt the character of the original recording and extend the natural
reverb within the recorded space.
The
reverb tail processing consists of two separate sections for left and
right signals, which under some conditions can perform entirely
independently. If the reverb tail processing is used on its own with
stereo panned sources (without any early reflection contribution), care
should be taken to ensure that STEREO SEPARATION and DIVERSITYcontrols are not both set to maximum, as this could result in a left or right only reverb signal if the source is panned hard to either side.
Equalisation
Equalisation of the reverb signal contribution is included to affect
changes in the overall character of the simulation, either in response
to artistic need or to enhance the realism of real space simulations.
Almost all real environments exhibit complex frequency response
characters that are generated by the reflection timing of the room
spaces and objects within the area. The actual perceived frequency
response is highly dependant on the position of the sound sources and
the listener within the space.
Much of the most complex frequency response character is generated by
the early reflections processing within the reverb application, but
because simulation models have a reduced quantity of reflection nodes
in comparison to real spaces, much of the overall resonance and tonal
character may be absent from the total simulation.
Whilst the clean, unobtrusive nature and reduced tonal interference of
the simulation reverb often blends more effectively in music
production, post production and Foley situations often require an
accentuated realism and much of this is provided by the overall
frequency character of the spaces. Indeed this partially explains the
success of convolution reverbs in the post production field.
All of the set-up examples contained in the Post category are examples
of combinational reverbs which use equalisation to enhance the realism
of spaces by providing the resonance's and response aberrations one
would associate with the simulated spaces.
Equalisation Set-Up
Because the response of the reverb section is more unpredictable and
fragile than the EQ, it is generally better to achieve a convincing
set-up for the main reverb before starting out on any equalisation. Reverb EQ Destined for Music Production
For music production the role of the EQ is mainly that of subtle
modification to the overall sound. This often entails reducing
intrusive low frequencies, providing tonal matching within the mix or
creating sound effects by accentuating reverberation within various
registers of the musical ranges. Equalisation may also allow the
reduction of unwanted artefacts due to the ‘run-on' of resonances
within the programme, particularly in percussive sounds.
As an artistic tool equalisation can be used to create a wide variety
of effects limited only by the engineer's imagination and
experimentation is definitely to be encouraged. Reverb EQ Destined for Post Production.
For post production effects and simulation of real spaces the EQ serves
to accentuate or even insert tonal aberrations that we associate with
particular spaces. Often we don't notice these aberrations when we are
actually in the spaces, but when adding simulations to dry sounds in a
post production environment their absence can be a real limitation to
effectiveness. There is no hard and fast way to achieve successful
results, as there are several possible approaches to the problem. The
following are presented as helpful hints.
The
major room node responses should be obtained using the appropriate room
shape and size within the early reflection set-up stage. It is
important that these match the overall space characteristic even if the
frequency characteristics are significantly different – because we will
use the EQ to modify these later.
Odd shaped
or complex spaces may be initially created using the a combination of
reverb tail and delay comp to simulate late reflections from distant
areas of the space, i.e. L –shaped spaces, rooms with several distinct
areas etc. Reducing the overall size of the late reverb setting can
produce a wide range of resonances that suit smaller spaces.
Most
rooms have a dominant resonance at lower frequencies and several
resonances of lesser gains in the lower and upper mid ranges. The
smaller the space the higher the frequency these are likely to be. They
may be very large reaching 10dB or even 20dB and they may have high Q
values in the 7 to 12 range. Experimentation will reveal whether the EQ
matches natural expectations in the space.
Higher
mid frequency resonances and dips are normally associated with near
surfaces, for instance a nearby wall or door. These reflection effects
can be initially created using the position control in the early
reflection settings and added to, modified or accentuated with EQ if
required. For high Q resonances of this type, quite small gain values
are often most appropriate.
Overall gentle
response changes often accompany smaller rooms that contain large
amounts of soft furnishings (i.e. living rooms etc.). This effect can
often be accentuated by the addition of LF boosting with lower Q values
between 0.5 and 1.5, or by introducing a band pass low Q cut in the mid
ranges.
Very large spaces may exhibit a
reverberation that focuses mainly in the mid ranges. A combination of
high absorption settings and LF roll-off can often simulate this
effect. A small rise of around 1 or 2dB in the mid ranges may also be
appropriate.
There is a high degree of
response interplay between the resonance's produced in the reverb and
the EQ. Very often extremely small changes to reverb size settings and
EQ centre frequencies can produce very significant changes in the
overall perception of the space. It is definitely worth experimenting
with this when reaching the final phases of producing a sound.
Website www.sonnoxplugins.com
Tuesday, 10-Mar-2009 15:42:29 GMT
- © 2007 - 2009 Sonnox Ltd
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