Sample Rate; Overs; Metering - Apogee AD-8000 Operating Manual

AD-8000 Operating Manual
If you have the optional Video Sync module installed, the AD-8000 gains the
ability to lock to PAL, NTSC or Monochrome (B&W) external video sync, chosen
by selecting VIDEO. The connected video sync is automatically detected, locked
to and the sync rate is displayed. The unit also gains the ability to do "Pull-Ups"
and "Pull-Downs" — multiplying or dividing the NTSC video sync rate by 1.001 to
compensate for the speed change necessary for film to video (or vice versa) trans-
fers. This is selected with the SAMPLE RATE button.

Sample Rate

Your choice. If you believe this will be your project's final analog to digital con-
version before the final CD mastering, you'll probably want to select 44.1 kHz. If
it's a multitrack project that will be mixed through an analog console, you may
wish to choose 48 kHz for slightly better resolution. x1.001 (pull up) and ÷1.001
(pull down) won't be available unless you have the Video Sync module installed,
as mentioned above.
If you're locking the unit to external word clock (selected by the SYNC
SOURCE button), the sample rate display will reflect the incoming sample rate,
and the LOCK LED will light if the external sync is stable. If the external word
clock is running at a stable, but non-standard rate, i.e. not 44.1 kHz or 48 kHz, the
sample rate indicator closest to the incoming clock rate will flash and the LOCK
LED will light indicating this condition, usually resulting from the word sync source
being varisped. The ERROR LED indicates a problem with the external sync sig-
nal, the incoming digital audio or cable connection. In this condition all outputs
are muted.

Overs

Selecting HOLD or AUTOCLEAR causes the 7 segment over counter displays
to keep track of the number of digital overs on each channel up to a total of 9.
More than 9 overs is indicated as "-". The displays can be reset to "0" by press-
ing the CLEAR METERS button. Selecting AUTOCLEAR causes the displays to
hold the last indication, but they will automatically clear when any audio above
-50 dB is detected after 15 seconds of silence. Over detection is disabled for one
second after each over, to avoid counter saturation. The number of full scale sam-
ples that trigger the over LEDs and the counters are determined by a DIP switch
on the back of the unit (see Appendix I). OFF, we feel, is self explanatory.

Metering

There are six metering modes selectable by the METER button. Peak meter-
ing is always on, but various other functions can be displayed in addition:
1. AVERAGE and 2 SEC HOLD indicates simultaneous peak and average with 2
second peak hold (selected on initial power-up).
2. AVERAGE and HOLD LEDs indicates simultaneous peak and average meter-
ing with infinite peak hold.
3. AVERAGE LED only indicates peak and average. The meters appear solid
from -50 up to the average level, the peak level is indicated by a single LED.
4. 2 SEC HOLD indicates peak and a peak level hold that automatically clears
after 2 seconds.
5. HOLD LED only indicates peak and infinite peak hold. This adds highest
peak infinite hold to the peak indication described above (#1), that can be
cleared by pressing the CLEAR METERS button.
6. No LEDs lit indicates peak mode only, with no peak hold. In this mode, the
meters appear as a solid bar between -50 and the peak level.
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