Alesis BRC Reference Manual page 75

format, to ensure an accurate sample-lock. The BRC can detect
whether or not Drop-Frame is being used. If you select a different
SMPTE format on the BRC than what it is receiving, the result
will be a transposition of the sample rate. Hence, when this
problem is corrected there will be a slight change in pitch, either
up or down depending on which direction the error was made.
When recording digital audio from an external source (using the
Alesis AI-1, for example), it is important to synchronize the clock rate
of the BRC to the incoming signal's source. This can usually be done
by feeding a 48 KHz clock source into the BRC (see sections 2.2B, 2.5
and 4.7C).
To select the type of external synchronization:
1. Press the Edit button (the EDIT button LED will go on to indicate
you are now in Edit mode);
2. Press the EXT SYNC button;
The display will show the current Locate Reference:
Locate Reference
I nternal
3. Use the UP/DOWN buttons to select either Internal or SMPTE as
the Locator Reference;
4. Press the EXT SYNC button again to go to the second page.
Repeatedly pressing EXT SYNC will cause the display to toggle
between the two pages;
The display will show the current Clock Source:
Clock Source
I nternal
5. Use the UP/DOWN buttons to select either Internal, 48 KHz
Input, Video Input or SMPTE Input as the Clock Source;
Note: If the Clock Source is set to Video Input, the SMPTE format on
the BRC is automatically changed to 29.97 fps, since this is the
correct SMPTE format for video. However, you can still change
the BRC's SMPTE format between 29.97 fps and 29.97 fps Drop-
Frame (see section 5.0A). You will not be able to select any other
SMPTE format on the BRC while the clock source is set to Video.
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