AD11
Operation
14
output sample. There is no “attack time;” so the peak level displayed will always accurately indicate
the maximum peak level for signals as short as one sample period.
The “
0
” LED is “digital clipping level” or “0dBFS” (zero dB full-scale digital level). This would
correspond to “Over” or “Clipping” indication on other types of digital meters. It is recommended that
you set the input level so that the peak level occasionally reaches a level between “
-3
” and
“
-1
;” but does not reach “
0
.” If the analog input does exceed the level which corresponds to “0dBFS,”
it wil be “clipped” in a clean manner with minimal overshoot or distortion. In theory, a signal could just
reach “
0
” and not be clipped; but in practice this is very unlikely. Like every other segment on the
AD11’s meters, the “
0
” segment will display the correct level for signals as short as a single sample.
If you wish to employ clipping as part of your recording process, please be certain that the analog
input signal does not 24dBu for balanced XLR inputs, +18dBu for unbalanced XLR inputs, or
+12dBu for balanced or unbalanced ¼” inputs. One simple way to help ensure this is to set the
AD11’s Gain setting to a value higher than “0.” The additional internal gain will insure that the clipping
does not occur at the analog input stage of the AD11.
For 1/4” inputs- TRS (tip-ring-sleeve for balanced signals) or TS (tip-sleeve for unbalanced signals),
12 dB of additional fixed gain is automatically added to the adjustable gain. This allows a total of 24
dB of adjustable gain for line level inputs (taking into account a change of input connection from XLR
to ¼” plug). The ¼” inputs are not recommended for microphone connections.
The phantom power is automatically disabled individually on each channel for gain settings lower
than 20dB. Because the phantom power is selectable on each channel, it is possible to use one
channel of the AD11 for line level inputs and the other channel for a condenser microphone input at
the same time.
As long as the AD11 is operated in the Line level range, there is no possibility of the phantom power
being applied to a Line output feeding the AD11. The Microphone preamplifier is optimized for
balance signals, so connection of the AD11 input to a source other than a balanced low-impedance
source while operating the Gain in the Microphone range will result in degraded performance, and is
therefore not recommended. For example: do not use unbalanced high impedance microphones.
As part of operation of the “safety interlocks” in the phantom power system; it is possible that the
phantom power could be disabled for a short time under a very specific set of circumstances. This
would be:
1.) Phantom power is enabled on one channel and disabled on the other channel.
2.) Phantom power is enabled for the channel on which it was previously disabled.
3.) Phantom power will turn Off on the first channel, and BOTH channels will
“ramp-on.”
This is normally only likely to occur during the set-up phase of operation; so as long as the user
exercises caution and follows the recommended practical of reducing the monitor volume when
changing settings, there should be no operational problems as a result.
When operating the AD11 on “external clock;” please be certain that the “Lock” lamp is illuminated
before exiting Setting mode, or if there appears to be an issue with synchronization. Because the
AD11 defaults to internal clock when external clock is not present; it is possible that the receiving
device may still accept the incoming digital audio signal. In some cases, a lack of synchronization can
result in subtle “clicks” being mixed with the music signal which can be difficult to hear (compared to
more obvious drop-
outs or loud “pops” that can also occur with no “sync”).
When using the AD11 as the Clock Master (AD11 operating on Internal Clock), the Word Clock Out
connection MUST have one 75 Ohm termination. Most Word Clock inputs are either terminated, have
a termination switch, or have an internal jumper setting for this function. For simple systems with only
one receiving device, this means that the input must either be terminated internally, or a 75 Ohm BNC
terminator must be placed on a BNC “T” that is plugged into the receiving device’s Word Clock input.
If the Word Clock output of the AD11 is “chained” using BNC “T” connectors on the clock inputs of
multiple slave devices, the terminat
ion must be “Off” on all devices except the last device in the chain.
There should be only one 75 Ohm termination located at the end of the chain opposite the AD11.
