User Manual

Apogee Duet User’s Guide
Why use a Low Latency Mixer?
A bit of background information concerning latency and computer-based digital recording setups
will help you better understand these functions.
When recording with most computer-based digital audio applications, the delay between the
input and output of the recording system often disturbs the timing of the musicians performing.
This delay, known as latency, means that the musician hears the notes played a few
milliseconds after having actually played them. As anyone who has spoken on a phone call with
echo knows, relatively short delays can confuse the timing of any conversation, spoken or
musical.
Figure A
To illustrate the effect of latency, Figure A depicts the typical signal path of a vocal overdub
session. A vocalist sings into a microphone, which is routed to an analog to digital converter,
then to the audio software application for recording. In the software application, the vocalist’s
live signal is mixed with the playback of previously recorded tracks, routed to a digital to analog
converter, and finally to the vocalist’s headphones. A slight delay accumulates at each
conversion stage, while a much greater amount of delay occurs through the software
application, resulting in the vocalist hearing his performance in headphones delayed by several
milliseconds.
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