XTA GQ600 - Manual (Page 9)

GQ600 Page 7
Effect of H.F. trim gain control, with frequency set at minimum.
1/3 Octave Centre Frequencies
The 1/3 octave ISO centre frequencies used on most graphic equalisers are normally 'rounded
off' to whole numbers. This leads to unequal spacing of filters if these marked frequencies are
used to calculate filter values.
The GQ600 uses true 1/3 octave frequencies based on 1kHz as a reference, and each filter is
automatically tested and adjusted when required, to achieve a centre frequency accuracy of
within ±3% of these true 1/3 octave frequencies. These are as follows:
Marked True Marked True Marked True
25 24.80 250 250 2k5 2k52
31 31.25 315 315 3k15 3k175
40 39.38 400 396.7 4k 4k
50 49.61 500 500 5k 5k04
63 62.5 630 630 6k3 6k35
80 78.75 800 793.7 8k 8k
100 99.21 1k 1k 10k 10k08
125 125 1k25 1k26 12k5 12k70
160 157.5 1k6 1k587 16k 16k
200 198.4 2k 2k 20k 20k16