# Audio Frequency Response Offset in dB

Say I have some audio device with the following absolute frequency response: I want to shift the curve up, so that the 1kHz point is the 0dB point, and everything else is relative to this point. Am I correct, that I cannot simply add 0.35dB to the entire curve, but need to compute back to Vout from:

dB = 20log(Vout/Vin)

add whatever voltage is necessary to the initial Vout to make the 1kHz point 0dB (we'll call this added voltage "curve offset voltage"), then offset all of the Vout values across the measurement range with that same curve offset voltage to obtain the frequency response relative to 1kHz?

Initially I just added +0.35dB to the entire curve but after thinking about it, I don't think that makes sense, since it would be changing the output magnitudes at each frequency exponentially.

• Just adding to it is perfectly correct. You cannot simply add something to each voltage level. You must multiply them by some factor. Adding logarithms is the same as multiplying. That's how sliderules work. And analog multipliers. – JRE Nov 7 '18 at 7:07