Installation guide

Chapter 4: Connecting Your Studio 21
48 kHz This is a standard sampling rate of many
professional audio devices. It is recommended
for use with devices that cannot receive digital
transfers at 44.1 kHz.
44.1 kHz This is the compact disc standard sam-
pling rate and the Pro Tools default sample rate.
To avoid the need for sample rate conversion,
you should use this rate when you are recording
material that will ultimately be published on a
compact disc.
Level Meters
The 888/24 I/O level meters monitor the chan-
nel outputs of Pro Tools. Input levels are moni-
tored on-screen in the Pro Tools software.
The 888/24 I/O is factory calibrated so that a
meter reading of –18 dB corresponds to the
888/24 I/O nominal operating level (which can
be set to either +4 dBu or –10 dBV). If you sent
the output to an analog device with a VU meter,
this would correspond to “0 VU” on the VU
meter.
The red LED indicators on the audio interface
indicate both full-code (highest level before
clipping) and clipping of Pro Tools output sig-
nals. The on-screen meters in Pro Tools software
indicate clipping when at least three consecu-
tive full-code samples follow each other.
Input Level Trims
The 888/24 I/O analog inputs are factory cali-
brated at a –18 dB nominal level, referenced to a
full code signal. This means that at the nominal
reference input level (either +4 dBu or –10 dBV),
you have 18 dB of headroom before clipping.
The input level trim pots allow adjustment of
the 888/24 I/O input levels to match the operat-
ing level of your external equipment. Adjust-
ments can be made with a Phillips screwdriver.
Output Level Trims
The 888/24 I/O analog outputs are factory cali-
brated at a –18 dB nominal level, referenced to a
full code signal. This means that at the nominal
reference output level (either +4 dBu or
–10 dBV), you have 18 dB of headroom before
clipping. The output level trim pots allow ad-
justment of the 888/24 I/O output levels to
match the operating level of your external
equipment. Adjustments can be made with a
Phillips screwdriver.
To calibrate the input and output levels of the
888/24 I/O to match your mixing console or
other devices in your studio, use Calibration
Mode and the Signal Generator TDM Plug-In in
Pro Tools.
When you are using an external digital
source such as a DAT recorder, the front
panel of the 888/24 I/O indicates only the
internal oscillator sample rate, not that of
the external digital source.
Instructions for calibrating the 888/24 I/O
appear in Chapter 7, “Calibrating the
888/24 I/O.”
TDM_Install.book Page 21 Saturday, January 13, 2001 9:35 PM