TC Electronic DB4 MKII - Manual (Page 51)

Unwrap HD
English Manual 47
Unwrap HD
The inputs and outputs of this algorithm are dis-
tributed as follows:
Input Output
L
E1
E2
E3
E4
L
R R
C
LFE
SL
SR
Introduction
Unwrap HD in use
Unwrap HD measures phase, delay and spectral
differences between a pair of stereo channels to
create a 5.1 result. For different program material
there will be different optimum settings that best
represent the qualities put into the original mix.
Please familiarize yourself with the controls and
parameter-ranges on known material before you
attempt Unwrap HD.
Setting up
We suggest that you try Unwrap HD with the
Output being monitored through the Downcon-
vert 5.1 (e.g. by loading preset “5.1 Monitor Ma-
trix”). This way you can collapse the 5.1 signal to
stereo or mono, and make sure the result is still
pleasant to listen to.
Try loading some of the Unwrap HD presets.
You can A/B the process by pressing Bypass on
the Unwrap HD Engine, or collapse the signal to
stereo again by selecting Stereo format on the
Downconvert Engine, if it is inserted downstream
as suggested above.
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 lowpass it between
40 and 120 Hz using a 2nd or 4th 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.