Benchmark DAC3 HGC - Page 52

Instruction Manual for DAC3 HGC and DAC3 L with 2.X Firmware Page 52
Graph 6 - Differential Phase
This plot demonstrates the inter-channel phase accuracy of the DAC3. This is a highly expanded
scale, spanning only +/- 1 degree at 45 kHz. From this plot, the inter-channel phase accuracy is
calculated to be +/- 0.25 degrees at 20 kHz, and +/- 0.43 degrees at 40 kHz.
The phase accuracy of the DAC3 approaches the phase accuracy of the Audio Precision AP2722
test set. For this reason, the phase error in the AP must be subtracted from the measurement. The
green trace assigns the left channel to channel 1 of the AP, and the right channel to channel 2 of
the AP. The red trace reverses the inputs. The two traces must be averaged to remove the phase
errors of the AP test set.
DAC3 converters are phase-accurate between boxes. Three DAC3 converters can be used as a
group to form a phase-accurate 5.1 surround system. Four DAC3 converters can be combined to
form a 7.1 system. The phase accuracy between any two channels will match the typical phase
accuracy shown above.
Audio Precision
DAC3 - Differential Phase
Fs = 96 kHz
DAC3 - Differential Phase.at27
ColorSweep Trace Line Style Thick
Data Axis Comment Cursor1 Cursor2
1 1
Green Solid 4
Anlr.Phase Left Left to Right *+0.24 deg *+0.42 deg
2
1 Red Solid 4 Anlr.Phase Left Right to Left
-0.25 deg -0.43 deg
-1
+1
-0.8
-0.6
-0.4
-0.2
+0
+0.2
+0.4
+0.6
+0.8
+0.24
+0.42
d
e
g
2.5k
45k 5k
7.5k
10k 12.5k 15k
17.5k 20k
22.5k
25k 27.5k
30k 32.5k 35k
37.5k
40k 42.5k
20.2555k
40.0511k
Hz
dx=19.7956 kHz
dy=+0.18 deg