TC Electronic Broadcast 6000 - Manual (Page 113)

MDX 5.1
English Manual 109
MDX 5.1
MDX 5.1 algorithm – introduction
MDX 5.1 is a high resolution dynamics processor
for multichannel signals. It presents a sophisti-
cated new angle to dynamic range control, and
is an alternative to traditional compression and
limiting techniques.
MDX 5.1 is capable of bringing up low level de-
tail, rather than boosting everything, and then
having to limit the transients afterwards, see Fig
1. Low level lift can even be applied to specific
channels selectively in one, two or three frequen-
cy bands.
Years of investigation into early listener fatigue
in digital audio has led TC engineers to the con-
clusion that limiters and clippers are non-ideal
matches for digital mastering and delivery. The
blind limiting approach adds pronounced tran-
sient and alias distortion, plus the risk of gen-
erating even more distortion in reproduction
equipment and data reduction systems. Unfor-
tunately, this unfriendly type of distortion cannot
be undone, and with the type of level detection
employed today, it is not even visually detected.
The music industry, for the past ten years, has
witnessed an ignorant quest for loudness rather
than audio fidelity. Today, we stand on the verge
of also damaging music and film heritage in mul-
tichannel formats. MDX 5.1 hopefully helps make
such a scenario less likely. Still, please be cau-
tious with bringing levels to the max. More pro-
cessing may always be added downstream.
Low level detail enhancement for mono and ste-
reo signals can be obtained using the MD4 algo-
rithm in DXP mode.
Fig 1. DXP processing vs. traditional Compres-
sion and Limiting.
Note how already loud signals are unnecessar-
ily affected when relying on limiting and clipping.
Applications
MDX 5.1 offers extensive inter-channel linking
possibilities, and is well suited for both music
and film material. The ingenious topology of Sys-
tem 6000 allows for low latency processing (be-
low 0.5 ms, equivalent to moving a microphone
approximately 16 cm or 6 inches), which makes
MDX 5.1 advantageous even for live or theatrical
applications.
On the Main page, MDX 5.1 features Input Gain
controls for the Main Channels and for the LFE
Channel. This enables gain and normalization to
be performed in the 48 bit domain prior to low
level processing and output limiting. These gain
controls therefore operate in a safe location, well
protected from generating output overloads.
Use the Input Gains as overload protected level
trims in a critical realtime system, such as broad-
cast, OB, live music or theatre.
On the Link pages, the 5 Main channels (L, C, R,
SL and SR) can be linked in numerous ways. The
concept is to assign channels to Sidechains. If
all channels are assigned to the same Sidechain,
processing is identical on all of them. If a channel
is assigned to a different Sidechain, processing
on that channel may be different from process-
ing on the other channels.
On the DXP pages, MDX 5.1 has separate con-
trols for Sidechain 1 to 3 plus LFE. This enables,