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APPENDIX
Tutorial
As an example, distortion figures for digital I/O applications are
given for the EBU Limiter Preset running the EBU Broadcast
setup.
THD+N@40Hz: -124dB for -18dBFS in, -96dB for -9dBFS in,
-90dB for 0dBFS in.
THD+N@1kHz: -124dB for -18dBFS in, -99dB for -9dBFS in,
-96dB for 0dBFS in.
THD+N@20kHz: -124dB for -18dBFS in, -124dB for -9dBFS in,
-122dB for 0dBFS in.
Mono generation is accomplished by the EBU 90 degree
Mono preset. You may build additional inserts like AGC, EQ,
De-esser etc. into the presets.
All presets exist in two versions: The On-Air versions have
brick-wall Output peak handling set at Abs. Peak Max. The
Production versions have DIN45406 peak handling set at Abs.
Peak Max. -3dB.
If you want to off-set the spectral balance (Eq) of low level sig-
nals, use the Band Levels on page no. 2 of the Compressor block.
If you want to off-set the spectral balance of high level signals,
use the Threshold and Ratio on page no. 2 of the Compressor
block.
Transmission
For Transmission applications you should first go to the REF
LEVELS page and load a suitable setup, e.g. EBU Broadcast or
digital TX. Also check that the Hi-Cut filter on Input page no. 2
are positioned correctly, and the Delay on Input page no. 1 is set
between 2 and 3 ms and turned ON.
For DAB applications the Hi-Cut filter should be turned off.
For NICAM applications normally only turn on the Lo-Cut filter
at the In page no. 1.
For FM transmission we recommend setting the Lo-Cut filter
between 20 and 40Hz. If you use a digital composite generator,
normally the DBMAX should handle Emphasis generation, HF
Limiting and Soft Clipping to maximize the signal and avoid
overshoots. Emphasis should be generated as a combination of
tuning band 3-5 Threshold/Ratio settings in the Compressor and
the TX Limiter in Insert 4.
FM transmission is by nature a trade-off between Level, HF
amount and Distortion. If you insist on a high sound level, please
bear in mind that an overly clipped or multi-band manipulated
signal may easily create listening fatigue.
It may prove wiser to back off a couple of dB in order to get a
cleaner and brighter sound.
When you use the built-in Dynamic Emphasis capability in the
DBMAX, please observe that Emphasis is NOT indicated on the
digital Outputs, because the AES/EBU specification has no
definition of 50µs or 75µs Emphasis.
For a digital transmission like in a NICAM or DAB environment,
setup appropriate Dither on the Out page. The receiving device
will have a preference for a given resolution from the DBMAX.
For redundancy in Transmission, an Input relay by-passes the
unit in event of power failure.
We are currently evaluating different digital stereo generators in
order to match the characteristics of the reconstruction filter in
selected devices.
If you have specific requirements or information about your
setup, feel free to contact TC Electronic at
The DBMAX for mastering is a very potent tool. Please be care-
ful not to overmaximize your source material just because you
can.
Listening fatigue is typically the consequence of a very dense
sound image.
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