Frequency response measurement: couple of questions

Dear All,
apologize for the precise questions to which I would like to have just simple answers, if possible, but I am absolutely short of any notion and knowledge in this regard:

  1. Is a frequency response measured at +/- 3dB generally wider than if measured at +/- 2dB, for the same speaker?
  2. Is a frequency response measured on axis generally wider, shorter or simply different than if measured off axis, for the same speaker?

I hope my questions have some sense,
thank you in advance those who will help me.


The difference between +/- 2dB & 3dB is that 2dB will be slightly (1dB) more accurate
On axis & off axis will show different results, it depends on how ‘off axis’ that is, 10 degrees, 30 degree’s or what. Additionally it depends if the measurement is taken in an anechoic chamber or in room; in room will be a variable depending of the size, shape, and its reflective & absorption characteristics & comparing the same speaker in different rooms will show variations, both on & off axis.

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Thank you @Mike-B for the prompt reply.

Therefore, can it be admitted (in a somewhat naïve way) that a frequency response measured at +/- 3dB off axis is generally less precise and wider than that measured at +/- 2dB on axis?

Hi again Airdavid
You are getting into detail & I’m not sure your language
First the difference between 2dB & 3dB is small, maybe not something to be concerned with.
On axis & off axis will always be different. In speaker terms it’s often used as a correct way of measuring a specific speaker design to consider the listening position. Not all brands do this & comparing them is not something I would do.
In speaker terms, a ‘wider’ response normally applies to the speaker design, most/all speakers go to close to the upper end of the range at 20kHz.
Whereas a small bookshelf design might start to roll off at 100Hz compared to a large floorstander will go to 35Hz & a powered sub will go below 20Hz.

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Thank you again, and apologize for my non-native English! :slight_smile:

Non c’e problema

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