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ISO Frequency Centres
This list, shown in Table 12.1 is a standard list of frequencies that can be used for various things such as the centre frequencies for graphic equalizers. The numbers are used a multipliers for the decades within the audio range. For example, if you were building an equalizer with two-third-octave frequency centres, the filters would have centre frequencies of 25 Hz, 40 Hz, 63 Hz, 100 Hz, 160 Hz, 250 Hz, 400 Hz, 630 Hz, 1000 Hz, 1600 Hz, 2500 Hz, 4000 Hz, 6300 Hz, 10000 Hz, and 16000 Hz.
Oct
Oct
Oct
Oct
OctUse the numbers listed in the table as multipliers. For example, if you were building a one-octave equalizer, then its frequency centres would use the right-most column of numbers. In Hz, these would be 10 Hz, 20 Hz, 40 Hz, 80 Hz, 100 Hz, 200 Hz, 400 Hz, 800 Hz, 1 kHz, 2 kHz, 4 kHz, 8 kHz, 10 kHz, 20 kHz and so on. If you're really paying attention here, you'll notice that these aren't really octave divisions... because 1 kHz is not one octave above 800 Hz.
Next: Resistor Colour Codes Up: Reference Information Previous: Reference Information Contents Index Geoff Martin 2006-10-15