TC Electronic Broadcast 6000 - Manual (Page 142)

Unwrap HD
138 System 6000 MKII Algorithms
This way you can check all speakers one by one
with pink noise first, and also collapse the 5.1
signal to stereo or mono to make sure the result
is still hearable. Try loading some of the UnWrap
HD presets. You can A/B the process by press-
ing Bypass on the UnWrap HD Engine, or col-
lapse the signal to stereo again by selecting Ste-
reo format on the Toolbox Engine, if it is inserted
downstream as suggested.
Basic conversion options
Some conversion options are of a profound na-
ture, e.g. if the process is thought of as purely
additive, if the ability to collapse to mono or ste-
reo again is important, or if an LFE channel or
Center channel should be derived at all.
Using the additive approach, UnWrap HD pre-
serves the Left and Right channels bit transpar-
ent all the way down to the LSB of a 24 bit input.
If the original stereo-mix is later requested, it
can be obtained using only these two channels.
If subsequent down-mix capability using all the
channels is essential, this option is available too.
In both cases, the LFE channel can be fully ex-
ploited, omitted or anything in between, as can
the Center.
Program related conversion options
It has been the goal to provide presets that can
make most kind of program material present
itself better and more engaging in 5.1 than in
stereo. From old to recent pop and rock music,
sound effects, drama, unique classical record-
ings to highly ambient modern tracks, from ultra
dry to wet source material, UnWrap HD comes
with settings to complement most situations.
Add to the default presets the capability to time-
align all channels at sample precision, widen or
narrow the image, control the amount of Center
and LFE channel to be used, change filters and
envelopes, and you begin to get an idea of the
power behind this algorithm.
Time alignment
When all Delays are set at “0”, all Outputs from
UnWrap HD are aligned with sample precision.
The basic Delay through the algorithm in this
case is 3.6 ms at 44.1 and 48 kHz. Try offsetting
the Delays in samples and ms, and note the shift
in image.
Delays may be used...
– on the Surround channels to ensure that
sounds appear to originate from the front
speakers.
– on the Center channel to compensate for its
position.
– on the LFE channel to compensate for speak-
er position or to advance/delay it for artistic
reasons.
When the front channels are not assigned the
same Delay, please note that a subsequent ste-
reo down-mix may not work so well.
Bit Transparency
When 0 % L/R Processing is selected, Input
Trims and Output Levels are at 0 dB, the inputs
are bit transparently cloned to the L Front and R
Front Outputs.
Main page
Input trims are provided to carefully match the
L/R balance. If working from analog tape, adjust
balance with a 1 kHz calibration tone. If work-
ing from a digital master with stereo levels at full
scale, it may be necessary to adjust down Input
levels a little bit to avoid UnWrap HD overloads.
The L/R Processing parameter determines how
much the L and R front channels are processed.
At 0 % UnWrap HD only adds sound to the 4
other channels preserving the original L and R as
they were. Somewhere between 60 and 70 % the
width of the original mix is typically preserved
even though a Center channel is added. Tip: A/B
the width soloing the three front channels and
toggle by-pass.
UnWrap HD may derive an LFE signal from the
Input. It is recommended to low-pass it between
40 and 120 Hz using a 2 nd or 4 th order filter.
Center page
To better separate and optimize the Center Out-
put, EQ and contour controls are provided.
First set the Ref. Level control at the approximate
reference level of the Input signal. For a typical
level, set Ref. Level at -10 to -18 dB. With a full
scale digital Input, Ref. Level would be set high,
typically 0 to -12 dB. With a quiet or highly dy-
namic Input, set it between -15 and -25 dB.