Apple iMac - Manual (Page 38)

C H A P T E R 3
Devices and Ports
38 Sound System
Total harmonic distortion plus noise (THD+N) as a percentage of full scale for
various outputs are shown in Table 3-3.
The signal-to-noise ratios (SNR) for various inputs and outputs are shown in
Table 3-4. The values shown are unweighted; values with A weighting would
be about 8 dB higher.
Table 3-3 Distortion specifications
Connector and level
Total harmonic distortion
and noise
Line input 0.03%
Line output 0.03%
Headphone jack, open circuit 0.03%
Headphone jack, 32-ohm headphones,
–20 dBFS level 0.1%
Headphone jack, 32-ohm headphones,
–1.5 dBFS level 1.0%
Table 3-4 Noise specifications
Connector and level Signal-to-noise ratio
Line output 92 dB
Headphone jacks 86 dB
Line input 85 dB
Internal CD 82 dB