SPL Parametric Equalizer Owner's Manual page 17

The frequency control (Hz) will set the center-frequency
when working in Parametric, Band-pass and Notch mode
where-as in Low-pass mode it will determine the upper, and
in High-pass the lower corner frequency.
Below is a chart for pinpointing the exact frequencies.
The scale has 11 marks. The center position (12 o´clock) is
number 6:
Band 1 Band 2
1 10,789 15,778
2 19,819 24,895
3 113,85 166,49
4 179,64 283,45
5 243,46 356,03
6 305,82 482,53
7 414,48 606,12
8 561,75 886,36
9 886,36 1398,5
Band 3 Band 4
32,436 110,74
79,621 195,90
195,90 1084,7
590,24 1918,9
778,09 2370,6
957,26 3161,1
1261,9 4204,5
1782,5 5592,3
2697,3 9212,4
OPTIMIZER
Fig. 6:
3. frequency range
from 34Hz to 7100Hz
at +/-12dB
Fig. 7:
4. frequency range from
112Hz to 23000Hz
at +/-12dB
Chart for precise adjustment
of frequencies with the Hz
control.
Numbers 1-11 representthe
scale marks around the pot.
The center position is mark
#6.
17