Polycom Vortex EF2241 Application Note page 14

Please follow our instructions for wiring the Vortex device to the codec (See "Wiring
from iPower to Vortex device"). Failure to do so may induce noise into the signals sent
and received from the codec.
3. Raise the gain on the appropriate Input of the Vortex device to +10 dB.
4. Lower the gain on the appropriate Output of the Vortex device to -10 dB.
It is important to set the gain structure correctly so that you don't clip the input audio
stage of the codec and that the Vortex device gets a good signal to perform processing
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