I came to something a little confusing while learning EQ techniques... this might be quite simple to some of you...
20 Hz – 20 kHz (+0, -1 dB)
i read that this means the level 1kHz (1000 Hz) is taken as a reference and the response that other frequencies are determined from in terms of equalization. No frequency has a response greater than that at 1 kHz; likewise the maximum downward deviation is 1 dB – no frequency is more than 1 dB down with respect to 1 kHz.
What part of this specification indicates that the reference level is 1kHz? For example, if I go in-store and start looking at equipment what indicates this reference level?