Reference Guide

280 Recording
Input monitoring
Next, you say "2." In the time it takes you do that, the ADC has converted the "1" to digital form and
the Wave In driver has fed it to SONAR for processing. SONAR processes the buffer right away and
passes the processed data right back to the Wave Out driver.
Finally, you say "3." By this time the original "1" has been converted back to analog audio by the
DAC, and that analog signal is mixed in with the "3" you have just said. The ultimate result is that
you hear a "1" and "3" mixed together at the line output of card—seemingly sounding like an echo,
but actually just an artifact of the signal flow through the system.
You can eliminate the echo by muting the line-in from playing back (see “To eliminate the echo from
input monitoring” on page 281); you’ll send only the processed signal to the sound card outputs. This
technique introduces a little extra latency to what you hear coming out of your sound card, but if you
use WDM or ASIO drivers with your sound cards, the latency is negligible.
The feedback problem results whenever you have a loop in your mixer path: the output of your mixer
is patched into the input of your sound card. Feedback can happen with or without input monitoring,
but since input monitoring can add several levels of gain to the signal flow, it’s of greater concern
when you have input monitoring enabled. Input monitoring is disabled by default when you install
SONAR, and you enable it with the following procedure.
say “2”
SONAR
say “3”
SONAR