Speaker frequency response (in room)

[Keith_W]

It depends on the design of the microphone. If it's a free field design (designed for reflection free environments), point it at the speakers, if it's a diffuse field design, point it up. Most mic's used for room measurements are free field (they have a built in electric filter to compensate for the rise in HF), but best to read the manual.

This is the correct answer. Most mics that we use are free-field calibrated.

I should point out that even "omnidirectional" mics are not truly omni, they have a polar response:

Here is one example, taken from @SIY review of the Earthworks M23 on AudioXPress. When the mic is at 0deg (pointing straight at the speaker) the frequency response is absolutely flat. But if it is pointing at the ceiling (90deg or 270deg) you can see that it is -5dB at 16kHz.

So: if you are taking a full range measurement of a speaker from 20Hz - 20kHz, point the mic at the speaker. The only time a mic should be pointed up at the ceiling is if (1) you have a calibration file for the 90deg mic orientation, (2) you don't care about measuring high frequencies (e.g. if you are measuring subwoofers), or (3) if you are measuring the timing of multiple speakers in a surround sound system. Otherwise, the mic should be pointed at the speakers ALWAYS.

(EDIT) I see that No. 5 has already given this answer.

 

[staticV3]

If I was to measure the frequency response of the system at the listening position (which of course takes room reflections into account), do I take my measurement mic and point it between the two loudspeakers?

Use the Moving Microphone Method for in-room frequency response measurements.

Here's the paper (PDF download link): https://www.ohl.to/audio/downloads/MMM-moving-mic-measurement.pdf

Additionally, there are multiple guides on YouTube

 

[svtcontour]

This is the correct answer. Most mics that we use are free-field calibrated.

I should point out that even "omnidirectional" mics are not truly omni, they have a polar response:

View attachment 425626

Here is one example, taken from @SIY review of the Earthworks M23 on AudioXPress. When the mic is at 0deg (pointing straight at the speaker) the frequency response is absolutely flat. But if it is pointing at the ceiling (90deg or 270deg) you can see that it is -5dB at 16kHz.

So: if you are taking a full range measurement of a speaker from 20Hz - 20kHz, point the mic at the speaker. The only time a mic should be pointed up at the ceiling is if (1) you have a calibration file for the 90deg mic orientation, (2) you don't care about measuring high frequencies (e.g. if you are measuring subwoofers), or (3) if you are measuring the timing of multiple speakers in a surround sound system. Otherwise, the mic should be pointed at the speakers ALWAYS.

(EDIT) I see that No. 5 has already given this answer.

Awesome thank you Keith! appreciate it.

 

[svtcontour]

Use the Moving Microphone Method for in-room frequency response measurements.

Here's the paper (PDF download link): https://www.ohl.to/audio/downloads/MMM-moving-mic-measurement.pdf

Additionally, there are multiple guides on YouTube

Oh very nice. checking it out now. Thank you.