Antares MDT user manual

							MDT UserÕs Manual71 Clip Sentry
and a gain decrease indicated by the I/O Curve results in a gain decrease in
the overall output.
In this way, the AP Þlter modes are able to accomplish compression and
expansion computations without artifacts from the parametric equalizer
Þlters.
However, these effects are limited to the I/O Curve operating within plus
and minus 12 dB of the 45 degree 1:1 diagonal. Operating above +12 dB of
the diagonal causes the parametric equalizer artifacts to again dominate the
output as they would in the non-AP case. This is not a serious problem.
Operating below -12 dB is more of a problem: Because there is a zero degree
phase shift in the center of each pass band, these frequencies will be
handled properly. However, the phase changes in the crossover and stop
band of each Þlter will cause the sound at these frequencies to not be
correctly subtracted, leaving a signiÞcantly audible sound in the output.
Clip Sentry
Because MDT simulates the smooth sound of analog compressors, it is easy
to create data that exceeds to +1,-1 digital range. This is because of the
behavior of the Attack Time slider, which allows you to control the rate of
gain reduction due to a sudden increase in sound level. As in the analog
world, even a fast attack time will let through a faster transient. Since most
users jack-up the output gain to compensate for compression, these fast
transients almost always result in clipped data.
Clip Sentry is a high speed digital limiter designed to prevent clipping by a
reducing gain only when clipping is about it occur. 
When Clip Sentry is activated by pressing the Clip Sentry button, the audio
data is routed through a new buffer, creating delayed output data. Before
each sample is put into the buffer, it is multiplied by the current gain. If an
clipping occurs, then the current gain is gradually reduced so that when the
culprit audio data appears at the output end of the buffer, the new current
gain does not create clipping. The current gain is then gradually restored
using a release time algorithm. 
						

							MDT UserÕs Manual72 Stereo Sound Processing
The current gain is a combination of gain from the gain curve and the gain
slider. The Clip Sentry processing occurs in the sequence described in the
diagram:
From this diagram, you see that the Gain Curve is broken up into two parts.
The Þrst part is a new curve that has gain reduction only. This reduction is
compensated for by the second part, a gain increase after Clip Sentry.
Hence, the data coming into Clip Sentry is never clipped. The only existing
limitation of MDT 4.00 is that the maximum curve gain plus the Gain Slider
cannot exceed +48dB.
Clip Sentry can attenuate the gain by as much as -30dB to stop clipping. 
Stereo Sound Processing
The left and right channels of stereo signals are processed completely
separately except for a single exception: they both share the same levels.
The signal level computation is described in the Þrst section of this chapter
using the compute level ßowchart. In the case of stereo data, the data
presented to the compute level algorithm alternates between the left and
right channels: L, R, L, R, L, ...
As a result of this arrangement, the same gain will be applied to both
channels of the stereo data at any instant in time.
Another result is that incorrect compression/expansion results will occur if
the two channels contain differing material, or if the channels are not scaled
relative to one-another. In these cases, the louder channel (over the period
of the time scales involved) will dominate the computation. 
Compressor process with 
Gain reduction, only, 
from Gain Curve.
Gain Curve gain 
increase and 
Gain Slider.CLIP 
SENTRY 
						

							MDT UserÕs Manuallxxiii
Symbols
ÒSoft KneeÓ Compressor 17
Òsoft kneeÓ compressor 36
ÒTubeÓ Compander 18, 36
ÒtubeÓ companders 37
Numerics
3 Band 56
3 band 68
3 Band AP 57
3 band AP 70
5 Band 57, 68
5 Band AP 57, 70
A
AP Filter Modes 70
AP mode 40
Attack Slider 53
Attack Time 31
attack time 19
auto read 50
auto touch 50
Automation 49, 53
B
Bypass Button 54
C
Clip 48
clip light 48
Clip Sentry 48, 71
Clip Sentry Buf Len 48
Clip Sentry Buf Len (mS) slider 55
Clip Sentry Button 54
Clip Sentry Release 48
Clip Sentry Release (mS) slider 55
Clipping Indicator 55
Compare Button 62
Compression 13
compression ratio 14, 30
Compressor 30
Compressor with Noise Gate 35
Control Surface Support 56
D
De-esser 45
delay 48
Delay Window 56
Delete SettingsÉ 29 
						

							lxxivMDT UserÕs Manual
digital Þlters 40
DSP Plug-ins 22
Dynamic EQ 47
dynamic range 13, 30
E
effect of changing attack time 19
effect of changing release time 19
Expander/Gate 34
expansion 18
F
Filter Mode Menu 56
Filter Modes 40, 68
Þlter pass band center frequencies 69
Flat 43
Flat Button 58
Flat button 49
Full Band 56
Full Band Filter Mode 68
G
Gain Adjust Algorithm 65
gain reduction 14, 30
Gain Slider 58
Gain slider 31
H
high speed digital limiter 48
I
I/O Curve 23, 25, 66
I/O Curve position and gain 26
In/Out Grid 15, 16, 25
input level offset 66
Input Level Offset Arrows 27
Input Offset 43, 44
Input  Offset Adjust Arrows 58
Input Offset Arrow 50
Input Offset Display 28
Input Offset Levels 49
Installing The JVP 11
inverse gain functions 24
Inverted Gain Curves 51
L
Levelx 50
look-ahead peak averaging 22
lower terminator 24, 35 
						

							MDT UserÕs Manuallxxv
M
MDT As A  Compressor 15
MDT Basics 21
mixing 13
Multiband Applications 39
multiband center frequencies 69
Multiband Compressor 40
multiband mode 39
Multiband Peak Level Indicators 39
O
Owner Registration 11
P
Peak Level Indicator 22, 28
processing algorithms 65
pumping 19
R
Ratio 14
Release Time 31
release time 19, 22
Reset 43
Reset Button 61
Reset button 49
Reset Settings 29
S
Save Settings AsÉ 29
Setting Menu 28
Settings menu 49
Single Band Applications 30
Spectral Enhancer 45, 46
Stereo Sound Processing 72
T
TDM Settings 62
Technical Support 11
Theory of Operation 65
Threshold 14
threshold 24
Tonal Balance 43
Tonal Balance In Multiband Mode 42
transfer characteristic 23
Tutorial 21
U
upper terminator 24 
						

							lxxviMDT UserÕs Manual
V
Variable 43, 44
Variable Button 63
Variable button 49