Tieline i-Mix G3, Основное руководство по эксплуатации

Страница: 269 / 355

Section 30: Outputs Tab
T
ieline
Page 269
T E C H N O L O G Y
Remember, the
PA ON
button will need to be switched on for audio to be
sent to the analog outputs if operating in this mode. For an example of a
matrix that would take advantage of this sort of functionality, please see the
section in this manual titled Manual Default Program TLM400.
Important Note:
If you use the
Mix (Send/Return) Pan Matrix
when the
Ch1
and
Ch2 PA
Control
boxes are checked, it is important to note that any settings you make
will not only affect the
PA OUTPUT BALANCE
digipot but also the
BALANCE
digipot on each of the first four inputs of the codec. In other words it will also
affect the sources monitored via the headphone outputs.
30.3. Automatic Gain Control
As a default setting, automatic gain control (AGC) is enabled on the outputs of
T
ieline
codecs. AGC is independent of Intelligent Gain Control (
IGC
).
AGC is triggered if audio signals ap20dBu (+16 vu). This is to avoid
distortion of audio, which occurs if signals go beyond the analog stage limit of
+21dBu.
ACG has a very fast reaction time and will decrease high audio levels by
approximately 1dB every 2 milliseconds, up to a maximum of 44 dB of
attenuation. AGC tries to return levels to normal once the output dips below
+15dBu (+11 vu). This will increase the levels by 1dB every 2 milliseconds.
Another way of expressing AGC in as follows:
Output = Mix x AGC.
•
If output > +16 vu (+20dBu), AGC decreases levels by 1dB to a maximum of
– 44dB.
•
If output < +11 vu (+15dBu), ACG increases levels by 1dB to a maximum
0dB.
30.4. Relationship of IGC to AGC
T
ieline
recommends the use of both
IGC
and AGC in most situations.
IGC
is a
transparent level adjustment mechanism across each codec input that keeps
levels in check, without coloring audio content with unwanted additional
processing. It also allows each input to be adjusted individually, retaining the
levels of other inputs when one is adjusted. This is different to AGC which is
across the outputs, and for which any gain reduction affects the mix of all audio
inputs simultaneously.
These thresholds are complementary to the settings for
IGC,
which is across
codec inputs. If
IGC
is enabled in
T
ieline
codecs it is enabled at +14dBu.
Enabling
IGC
avoids hard clipping of signals, which occurs in the digital input