Antex Electronics StudioCard AV Pro, StudioCard 2000, & SC-22 - Manual (Page 81)

C h a p t e r 4 L e v e l s a n d H e a d r o o m
4-4 Antex StudioCard Copyright © 1997
Levels and
Headroom
The purpose of this section is to explain signal levels and
headroom as they pertain to the StudioCard so that you can
make recordings with optimum quality and signal-to-noise ratio.
The information is this section is written assuming you are
familiar with decibels: a unit of amplitude measurement
commonly used when working with audio. Many sources exist
describing decibels, including information on the Antex web
page,
www.antex.com .
The Numbers The balanced input and output signal levels of the StudioCard
are +4dBu nominal, +24dBu maximum. For unbalanced
inputs, the signal levels are –10dBV nominal and 10dBV
maximum. The difference between nominal and maximum
level is referred to as headroom; the StudioCard is designed to
have 20dB of headroom.
Headroom is required to handle peaks and transients in an
analog signal to prevent the input signal from exceeding the
range of the A/D converter. When this happens, sound quality
degrades very rapidly, and is termed “digital clipping”.
These levels were selected for the StudioCard because
SMPTE (Society of Motion Picture and Television Engineers) is
working to standardize -20dB as the nominal recording level for
all digital recording. A headroom figure of 20dB is more than
many users are accustomed to, and has implications on
volume and signal to noise performance as explained below.