Appendix C: Calibrating the 888/24 I/O (Pro Tools 4.x)
21
Level
Use this to select the output level rel-
ative to the Headroom for the audio wave-
form generator.
Wave Type
Use this to select the type of au-
dio waveform generated the waveform
generator.
Output Every Channel
If this option is se-
lected and the Oscillator is on, every out-
put will generate an audio waveform signal
at the selected frequency. If this option is
not selected and the Oscillator is on, only
the selected output Channel will generate
the audio waveform signal. If the Oscillator
is off, this option has no effect.
Hardware Setup
Use this to choose which
Digidesign audio interface and card you
wish to adjust using Calibration Tool.
In order to align your system with this soft-
ware, you must have one of the following:
◆
A device (such as sine wave or test tone
generator) that can send a 1 kHz audio
waveform wave into the 888/24 I/O at
0 VU.
– or –
◆
A device (such as a mixing console with
accurate VU meters) that can measure the
level of a 1kHz audio waveform produced
by the 888/24 I/O.
Using an External Tone
Generator
If you have a sine wave generator that can
produce a 0 VU 1 kHz tone, use the follow-
ing calibration procedure:
To calibrate the 888/24 I/O with Calibration
Tool using an external source:
1
Start the Calibration Tool application.
2
In the Headroom field, enter the amount
of headroom you desire. The default setting
for the 888/24 I/O is –18 dB.
3
Send a 1kHz tone into the 888/24 I/O
from your external source.
4
In the software, select 888/24 I/O 1
Channel 1 from the Channel pop-up
menu. You should get some level in the on-
screen level meter.
5
Adjust the 888/24 I/O Channel 1 Input
Level trim pot by inserting a screwdriver
into the Input Level trim pot and turning it
until the Calibration Tool’s on-screen
meter reaches 0 VU and the numeric read-
out says 0.0 dB. The input is now aligned.
6
Repeat this procedure for each
888/24 I/O input by selecting them from
the Channel pop-up menu and adjusting
the appropriate front panel Input Level
trim pot on the 888/24 I/O.
7
When you have finished aligning the in-
puts, connect each output of the
888/24 I/O directly to its input: Connect
Channel 1 output to Channel 1 input, and
so on.
8
Select 1kHz from the oscillator Fre-
quency pop-up menu, and turn the oscilla-
tor on by clicking On.
9
Choose 888/24 I/O 1 Channel 1 from
the Channel pop-up. Adjust the Output
Level trim pots by inserting the Phillips
screwdriver into the pot and turning it un-
til the on-screen meter reaches 0 VU and
the numeric readout says 0.0 dB.
10
Repeat this procedure for each Audio In-
terface output.
