Creative Emu 1820m Manual

							5 - Effects
Core Effects Descriptions
E-MU Digital Audio System91
The wide dynamic range of the RFX Compressor aside, its generally a good idea to 
maintain the hottest signal levels possible without clipping at the input to any audio 
processor.
Parameters
Threshold
Threshold sets the input signal level above which dynamic range compression takes 
place. Everything above the threshold will be brought down in volume. The 
compression threshold ranges from -0 to -60dB, relative to full scale (0dBFS) input.
Setting the Threshold to 0dB disables normal compression, since no signal can exceed 
the maximum possible input level. A Threshold setting of 0dB is still useful, however, 
when using soft-knee compression or gating, since these actions occur below (and their 
thresholds are set relative to) the Threshold parameter.
Gain Reduction Meter
As input signals exceed the Threshold, the rightness character in the bargraph is lit, and 
successive characters are lit for each approximately 3dB in gain reduction imposed by 
the compressor on the input signal. Because this is a compression meter and not a level 
meter, the same input signal level will show widely varying meter readings depending 
on the setting of the Ratio parameter.
Ratio
Sets the ratio of output signal to input 
signal levels, selectable in 16 steps 
from 1:1.1 to 1:INFINITY.
When Neg Compression is set to 
Enabled, the range of compression 
ratios extends beyond INFINITY to 
encompass negative compression 
ratios from 1:-100 down to 1:-1, which 
can be useful for applications like 
ducking and other special effects. 
See the discussion of the Neg 
Compression parameter on page 
96.
Attack
Sets the amount of time that the compressors level detector will take to respond to an 
increase in signal level. The Attack range is adjustable from Instantaneous (essentially a 
peak detector that follows individual samples) to 10 seconds (useful for long-term 
leveling or automatic mixing applications.)
Release
Sets the amount of time that the compressors level detector will take to respond to a 
decrease in signal level. The fastest Release time is 100 microseconds, useful for some 
special effects but highly prone to distortion; more typical release times are in the range 
of 70 milliseconds to 1 second. Release times up to 10 seconds are available for long-
term leveling or automatic mixing applications.
When the Auto-release parameter is in its signal-dependent settings, the Release time 
shown represents the shortest possible release time. In Auto-release modes the displayed 
Release time will be automatically extended depending on the dynamics of the input 
signal.
0dB1.1:1
1.5:1
2:1
3:1
10:1
   :1
-30dB
-80dB
Threshold: -30dB8
fTip: A ratio of 
Infinity:1 combined 
with high threshold and 
fast attack/release 
results in an effective 
peak limiter. 
						

							5 - Effects
Core Effects Descriptions
92Creative Professional
Gain

Caution! The Gain 
control can increase the 
signal level to the point of 
clipping. Excessive signal 
levels can damage 
speakers as well as your 
ears!Sets the compressors output gain in dB, from +60dB boost to-60dB cut. This control 
follows all of the other elements in the compressors signal path, so positive gain boost 
can be used to make up for the gain reduction normally applied to signals above the 
compression threshold. Alternatively, negative gain cut can be used to make up for the 
gain increase that is applied to signals below the threshold in Soft Knee mode.
Auto Makeup Mode: When adjusted downward past the -60dB cut, the Gain 
parameter begins operating in Auto Makeup mode. Auto Makeup mode is used to 
compensate for the drop in output level normally resulting from the gain reduction 
actions of the Threshold and Ratio parameters. Auto Makeup makes it much easier to 
adjust these parameters since there is no need to switch back and forth to the Gain 
parameter in order to perform the gain compensation manually.

Auto Makeup should 
not be used when in 
negative compression 
ranges (see the Neg 
Compression parameter 
on page 
96. Use manual 
Gain control instead.
Auto Makeup looks at the gain reduction implied by the setting of the Threshold and 
Ratio parameters and automatically applies a complementary gain increase so that an 
ideal 0dB input signal results in a 0dB - or lower - output signal. In this mode, indicated 
by the Threshold legend,  the Gain parameter adjusts the output level from 
that 0dB input signal to fall anywhere in the range of 0dB down to -60dB. 
Advanced Parameters
This parameter controls whether the “Advanced Parameters” listed in this section are 
hidden or exposed on the screen. For simple applications, quick edits or for novice 
users, these advanced parameters can be hidden to minimize screen clutter and preclude 
erroneous operation. For special and exotic applications and for experienced users, 
these parameters can be exposed to allow access to all the gory details of the 
compressors operation.
Note that even when this parameter is set to “Off”, the settings of the advanced param-
eters are still active; the only effect of this parameter is to hide them from the screen.
Soft Knee
This parameter sets the depth of the compression transition region, giving an adjustable 
hard or soft “knee” to the compressors gain curve. Setting the depth of this region 
results in a knee shape that can be varied from a sharp transition to one that is imper-
ceptibly gradual.
With the default value of Off, the Soft Knee parameter causes the gain curve to switch 
immediately at the Threshold point from no compression (1:1) to full compression 
(1:Ratio), representing the hard knee effect. By adjusting the parameter value, an 
additional knee threshold can be created 1dB to 60dB below the regular compression 
Threshold. Between these two thresholds the effective compression ratio increases 
smoothly along the curve of a circular arc, from 1:1 at the lower knee threshold to the 
full compression of 1:Ratio at the upper Threshold. Both the Soft Knee depth and the 
Ratio will affect the particular shape of the knee: shallower depths and higher Ratios will 
create a sharper knee, while greater depths and lower ratios create a softer knee.  
						

							5 - Effects
Core Effects Descriptions
E-MU Digital Audio System93
fTip: Setting a high 
Ratio with the Threshold 
at 0dB and the Soft Knee 
at -60dB creates a 
compressor whose ratio 
varies smoothly from 
gentle compression at 
lower signal levels to 
peak limiting at maximum 
signal levelIn the region between the lower knee and upper Threshold, a variable amount of gain 
reduction is applied depending on the signal level and Ratio setting. To keep this gain 
reduction from “dragging down” the signal levels at the Threshold point, a comple-
mentary gain boost is automatically applied to all signal levels below the Threshold 
when the Soft Knee is enabled. This gain increase with depth and Ratio is illustrated by 
the upward arrows in the diagrams, and is similar to the action of the Auto Makeup 
Gain parameter. Thus signal levels below the Threshold increase as the Soft Knee depth 
and/or Ratio is increased (but see the Gate parameter, below.)
0dB
Threshold -10dB
Threshold -20dB
Threshold -30dBKnee
-20dB
-80dB
Threshold: -20dB
Ratio = 4:1
Soft Knee
(Varying the Soft Knee Threshold)
0dB
Ratio = 1.5:1
Ratio = 4:1
Ratio = 10:1
-20dB
-35dB
-80dBThreshold: -20dB
Soft Knee
(Varying the Compression Ratio)
Soft Knee:
Threshold -15dB
This diagram shows the effect of varying the Soft Knee Threshold. Compres-
sion is 1:1 (no compression) at the Knee Threshold and smoothly transforms into the 
selected compression ratio at the Compression Threshold. The upward arrow shows 
the additional gain added to signals below the Threshold.
This diagram shows the effect of varying the Compression Ratio with a 
fixed Soft Knee Threshold. The knee transforms from a linear slope to the slope of 
the compression ratio over the Soft Knee Threshold area. The upward arrow 
shows the additional gain added to signals below the Threshold. 
						

							5 - Effects
Core Effects Descriptions
94Creative Professional
Gate
This parameter enables automatic gain reduction on signals that fall from 1 to 120dB 
below the Threshold point (or Soft Knee threshold, if enabled.) This can act effectively 
as a “noise gate” on low-level signals that have been boosted by the action of the Gain 
or Soft Knee parameters. The gating action follows a somewhat soft-kneed contour of its 
own so that turn-on and turn-off at the gate threshold is not too abrupt.
Note that, strictly speaking, the term “gate” is a misnomer in this context, since the 
action of this parameter is simply to cancel out gain increases that resulted from the 
settings of other parameters. This can be seen by the arrows in the diagram as the gain is 
reduced below the Gate threshold back down to the dotted line representing unity gain. 
The result is that if the Gain parameter is set negative or the Soft Knee parameter is 
disabled, the Gate parameter will have no effect.
Comp Lookahead/Delay
This parameter controls compressor 
lookahead or delay by setting the 
relative time offset, in milliseconds, 
between the compressors signal path 
and its sidechain path.
At negative values, this parameter lets 
the level detector in the compressors 
sidechain “look into the future” up to 
100 milliseconds in order to antic-
ipate upcoming peaks in the signal - 
accomplished of course, by inserting 
delay into the signal path. This 
lookahead technique allows the use 
of slower attack times without 
missing signal peaks.
At positive values, the signal path delay is zero; instead, a delay of up to 50 milliseconds 
is inserted into the sidechain path containing the level detector. This delay can be used 
intentionally to cause the compressor to miss signal peaks, retaining the “punch” and 
0dB
-10dB
-20dB
-30dB
-40dB
-50dB
-60dB
-70dB
-80dB
Threshold: -20dB
Ratio = 4:1
Gain = +15dB
Gate
Gate
Threshold
-30dB
In this example, the Gain has been boosted by +15dB. The Gate cancels out the +15dB Gain 
boost below the Gate Threshold. Signal levels above the Gate Threshold will be boosted; 
signal levels below this point will not be boosted and will be 15dB lower in volume.
Lookahead  Delay
Sharp waveform peak is missed by compressor.
Add Lookahead (neg values) to compress peak.
Add Delay (pos values) to allow peak through. 
						

							5 - Effects
Core Effects Descriptions
E-MU Digital Audio System95
“bite” of signal attacks while subsequently compressing the sustained portions of the 
sound.
In general, both positive and negative values of this parameter are useful for applica-
tions where the normal envelope of a signal is being creatively manipulated to achieve 
special effects.
Auto-Release
This parameter causes the effective Release time to be extended automatically based on 
the dynamics of the input signal. This parameter emulates the program-dependent 
release characteristics found on some classic analog compressor/limiters.
When not set “Off”, the Auto-release parameter treats the Release parameter value as a 
minimum release time, extending it by as much as a factor of 10 depending on different, 
selectable characteristics of the input signal:
In Program-dependent mode, release times are increased depending on how often, 
how long and by how much the input signal (“program material”) exceeds the 
Threshold. Release times increase slowly under sustained excursions of the input over 
the Threshold, and typically return back to normal within a few seconds after the signal 
level has fallen below it. This emulates the signal “memory effect” exhibited by some 
electro-optical compressors.
In Compression-dependent mode, the release extension characteristics are similar, but 
in addition depend on the amount of gain reduction being applied to the signal. Thus 
the same signal will cause more release-time extension at higher compression Ratio 
settings than at lower ones.
Uncompressed Waveform
Program-Dependent Release
Short ReleaseLonger Release
With Auto-release turned on, the release time becomes longer after an extended 
period of compression. 
						

							5 - Effects
Core Effects Descriptions
96Creative Professional
Max Compression
This parameter is used to limit the amount of gain reduction that the compressor can 
apply. The limit is set as a maximum number of dB of gain reduction, from 3dB to 
UNLIMITED.
This feature emulates the phenomenon of the compression “tail” found in the gain 
curves of some classic analog compressor/limiters. The phenomenon results from the 
inability of these devices to apply more than a certain amount of compression to the 
input signal. When the device “runs out” of enough gain reduction to compress a very 
high level signal, it resumes a 1:1 gain curve again. This “deficiency” has the unexpected 
sonic benefit of restoring some dynamics to the compressed signal - but only on the 
highest input peaks - thus adding some “life” back into otherwise over-compressed 
signals.
ENote: You may need 
to use the Gain 
parameter to keep these 
restored peaks from 
clipping the compressor 
output since Auto 
Makeup gain doesnt 
automatically take the 
compressor tail into 
account.Unlike analog compressors, the Max Compression parameter allows you to adjust the 
amount of gain reduction before the compressor returns to a 1:1 gain curve. The 
diagram shows three settings of the Max Compression parameter; the compressor “gives 
up” and returns to 1:1 after 6, 15 and 24dB of compression have been exhausted, 
respectively.
The parameter is most useful at higher compression ratios, allowing the gain curve to be 
carefully tailored to the dynamics of the signal as well as the Threshold and Ratio 
parameters. The limit set by the Max Compression parameter does not apply to gain 
reduction performed in the Soft Knee region of the gain curve.
Neg Compression
When the Neg Compression 
parameter is Enabled, the range of 
compression values available to 
the Ratio parameter extends 
beyond INFINITE to encompass 
negative compression ratios from 
1:-100 down to 1:-1. Using 
negative compression ratios 
results in an output signal that 
actually gets quieter as the input 
signal rises above the threshold. 
This action can be useful for appli-
cations like ducking and for other 
special effects.
0dB
-30dB
-80dB
Threshold: -30dB
Max. Compression
Max. Comp. = 6dB
Max. Comp. = 15dB
Max. Comp. = 24dB
Ratio = 4:1
0dB
-30dB
-80dB
Threshold: -30dB
Neg. Comp: Enabled
-10:1
-5:1
-3:1
-2:1
-1.5:1
-1:1
Ratio 
						

							5 - Effects
Core Effects Descriptions
E-MU Digital Audio System97
The diagram above shows the gain curves using a Threshold at -30dB and a range of 
negative compression ratios.
At just past 1:INFINITE,  the setting of 1:-100 causes input signals approaching 0dB to 
be only slightly decreased below -30dB. In contrast, the compression ratio of 1:-1 causes 
a 2dB gain reduction for each 1dB of additional input signal level, resulting in an output 
signal level that is folded down over the Threshold.
Input Mode
The Input Mode parameter allows the compressor signal path and sidechain to be 
driven in common or by separate inputs. This is a feature of many compressors and is 
useful for a range of applications and special effects.
By default, the Input Mode of the compressor is Stereo. In this mode the two 
independent left and right signal paths are gain controlled by a parallel sidechain path 
common to both inputs that contains the compressors level detector. This single level 
detector works on the higher of the two input signal levels, so that signal peaks are 
properly compressed and no L/R image shift results from compression operations.
When the Input Mode is set to L In/R Sidechain, the signal path is fed exclusively from 
the left channel and the sidechain is fed exclusively from the right channel. This allows 
dynamics control between two completely independent signals. In this mode both the 
compressors left and right outputs are fed by the mono signal from the left input 
channels signal path.
Splitting the signal path and sidechain makes possible applications where the two 
signals may be completely unrelated, such as ducking. Other split-sidechain applica-
tions result from situations where a stereo input signal has had different processing 
applied between left and right channels. One example would be to place a stereo 
equalizer ahead of the compressor in order to implement a version of de-essing or “de-
booming”. See page 
100.
Create a Ducker
To create a ducker, in which a background signals level is reduced in the presence of a 
foreground signal, first set the Input Mode parameter to L In/R Sidechain. Then send 
feeds from the background signal to the left input, and from the foreground signal to 
the right side input. Set the Ratio parameter to -1:1 (or lower for less background 
reduction), and dial in a low Threshold such as -50, so any foreground signal above -
50dB will cause gain reduction in the background signal. This technique works best 
with slow Attack and Release times — use a liberal amount of Compression Lookahead 
to keep the background from masking the beginning of foreground sounds.
LL
Out
R
R
Ducker
Sidechain
Gain
Cell
Foreground Signal
 Pan +90 (R) Background Signal
 Pan -90 (L)
Stereo Strip
Creating a Ducker 
						

							5 - Effects
Core Effects Descriptions
98Creative Professional
Example Settings
Here we have provided a few examples to show the varied uses of this useful tool. Bear 
in mind that these examples are simply starting points and that you will undoubtedly 
need to fine tune the parameters to fit the program material and to suit your own taste.
Increase Drum Punch:
Adjust the Threshold control to control the amount of compression.
•Threshold: Adjust so that all hits are being compressed.
•Ratio: 4:1
•Attack: 8 msec (Increase the time to hear more “stick” sound.)
•Release: 60 msec (Adjust according to the tempo of song.)
•Gain: Adjust to make up for lost volume.
•Soft Knee: Adjust as desired.
•Comp. Lookahead: This can be used instead of the Attack control.
•Max. Compression: Unlimited
Smoothing out the Bass Guitar Level:
This setup evens out the volume and prevents the bass guitar from wandering in and out 
of the mix.
•Threshold: -24dB (adjust according to the sound)
•Ratio: 4:1
•Attack: 8 msec
•Release: 70 msec
•Gain: +4dB (adjust according to the sound)
•Soft Knee: Threshold -8dB
•Gate: Off
•Comp. Lookahead: 0 msec
•Auto-release: Comp-dependent
•Max. Compression: 18dB
Peak Limiting:
This setup trims only the very loudest peaks, leaving most of the signal intact.
•Threshold: -37dB (adjust according to the sound)
•Ratio: 2:1 or 3:1 
•Attack: Instantaneous
•Release: 30 msec
•Gain: 0dB
•Soft Knee: Off
•Gate: Off
•Comp. Lookahead: -5 msec
•Max. Compression: Unlimited 
						

							5 - Effects
Core Effects Descriptions
E-MU Digital Audio System99
Vocal Compression/Spoken Word:
This setup compresses the entire dynamic range of the vocal. Whenever there is a signal 
present, there is some compression taking place.
•Threshold: Adjust so that the first bar of the meter comes on even on soft pas-
sages.
•Ratio: 2:1
•Attack: 0.1 msec
•Release: 100 msec
•Gain: Set to compensate for lost gain.
•Soft Knee: Off
•Gate: Off
•Comp. Lookahead: 0 msec
•Auto-release: Off
•Max. Compression: 12dB
Backwards Drums & Cymbals:
This is a special effect which reverses the volume envelope of cymbals and drums.
•Threshold: -37dB (adjust according to the sound)
•Ratio: -1:1 (Neg. Compression enabled)
•Attack: Instantaneous
•Release: 200 msec
•Gain: +19dB
•Soft Knee: Off
•Gate: Off
•Comp. Lookahead: -24 msec
•Auto-release: Off
•Max. Compression: Unlimited 
						

							5 - Effects
Core Effects Descriptions
100Creative Professional
Creating a De-esser:
A de-esser reduces the sibilance or “sss” sound in a vocal part. The sidechain feature of 
the RFX Compressor makes it possible to create a effective de-esser using the compressor 
and the Multimode EQ. The Wet/Dry Mix on each effect should be set to 100%
The idea is to boost the high frequency content going to the sidechain (R input) so that 
the compressor will turn down the volume in the presence of sibilance.
Multimode EQ Settings
EYou can boost the low 
frequencies in the right 
channel to create a “de-
boomer”.The left channel is set flat (no EQ). The right channel boosts hi-frequencies.
•Left Channel: Lowpass mode, Lowpass Rolloff = Off
•Right Channel: Highpass mode, 24dB/oct, HP Frequency = 8173Hz, 
HP Resonance = 36%
Compressor Settings
Lookahead gives the compressor time to react to the vocal sibilance.
•Input Mode: L In/R Sidechain
•Threshold: -32dB (adjust to control amount of de-essing)
•Ratio: 2.5:1
•Attack: Instantaneous
•Release: 40 msec
•Gain: 0dB
•Soft Knee: Off
•Gate: Off
•Comp. Lookahead: -20 msec
•Auto-release: Off
•Max. Compression: Unlimited
In
L
R
Multimode
EQCompressor
Flat
Response
Hi Pass
Sidechain
Gain
Cell
L
Out
R
Mono
Strip
Creating a De-esser