Delay - RME Audio ADI-96 PRO User Manual

9.3 Delay

Function
Delay of the audio signal per channel from 0 ms up to 170 ms, activation of Look Ahead.
Application
Allows to correct the time alignment of left and right channel, for example when doing micro-
phone recordings. Allows to correct the time alignment of PA systems. Allows to produce stereo
effects by delaying one channel. Activates the Look Ahead mode for optimized sound quality
with Expander and Auto Level Control.
Settings
Place the cursor in the Overview window on DLY and press Enter.
Menu
Options
The delay of the audio signal can be set from 0 ms up to 170 ms per channel.
Typical Settings
When doing a stereo microphone recording where the mics don't have an identical distance to
the sound source the Delay function allows to delay one channel so the signal at the digital
output of the ADI-96 PRO is time aligned again.
The speed of sound is about 340 m/s. A difference of one meter in the above situation already
requires a correction by 3 ms! The Correlation meter (see chapter 7.6 Correlator) is a valuable
help in fine tuning the neccessary correction, but for the coarse values you'll also need a
calculator and a foot rule.
Other time alignment problems may require to delay both channels in an identical manner. The
maximum setting of 170 ms enables a simultaneous output of loudspeakers in a distance of 56
meters together with loudspeakers placed near the listening person.
The human ear will detect a signal as monaural when amplitude (loudness) and time related
output of left and right channel are identical. When one channel is delayed up to 10 ms the
signal which formerly seemed to come out of the middle will fall apart into two signals, indi-
vidually sent by left and right channel. This may be used as some kind of simple stereo effect
generator, but a very good generator needs some more tricks like modulation on the delay,
short reverb and changes in the frequency response, which are not available here.
One way to achieve a very ecfficient stereo manipulation is to use the M/S processing (encod-
ing), as the stereo informations on the right channel can be single processed by Compressor
and Delay within the ADI. See chapter 7.1.
Expander and ALC will enter the Look Ahead mode in case the Delay is activated and the delay
time is at least 0.1 ms. Informations on how to set up the Delay for best performance with Ex-
pander and Auto Level Control can be found in chapter 9.8.
User's Guide ADI-96 PRO © RME
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