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How to measure frequency response of a speaker at home

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Re: How to measure frequency response of a speaker at home

#41

Post by semitones »

lanthade wrote: post #38
aljgz wrote: post #36

Earlier quoted context omitted.

`When disagreeing, please reply to the argument instead of calling names. "That is idiotic; 1 + 1 is 2, not 3" can be shortened to "1 + 1 is 2, not 3".` `Please don't fulminate. Please don't sneer, including at the rest of the community.` As a curious person with a degree in Electrical Engineering, and one in Computer Science, very interested in quality audio, etc, I know what you mean. But please, don't be the perso…

I find it interesting that you chose to respond to my comment like this as opposed to others which are more egregious on the issues you bring up. That aside though, I did mention a number of issues with the write up. Anyone interested is welcome to dig into them and come back with questions if they desire. This is not however an introductory level topic and I elected to not try to thumb tap out a distillation of a ve…

He responded to you because he thinks you can still be saved

Re: How to measure frequency response of a speaker at home

#42

Post by radicality »

cluckindan wrote: post #3

You need a calibrated measurement microphone to do this for real. Otherwise the microphone’s frequency response will skew the results.

I have Lyngdorf amplifier at home, and it came with a calibration microphone. You move it to different locations while the speakers play different tones and measure how the sound interacts with your environment, and creates a listening profile for it.

Re: How to measure frequency response of a speaker at home

#43

Post by hulitu »

garyfirestorm wrote: post #16
cluckindan wrote: post #3

You need a calibrated measurement microphone to do this for real. Otherwise the microphone’s frequency response will skew the results.

Not just that but the FRF calculation is slightly complex. You need to take into account windowing function, amplitude correction factor, sampling rate and block size of each measurement and %overlap… leakage is a very important thing in signal processing and spectral analysis. Also you need an anechoic environment to capture this, because you would be also capturing room reflections and characteristics of room acous…

> Also you need an anechoic environment to capture this,

They were talking about a home. /s

Re: How to measure frequency response of a speaker at home

#44

Post by jampekka »

garyfirestorm wrote: post #16
cluckindan wrote: post #3

You need a calibrated measurement microphone to do this for real. Otherwise the microphone’s frequency response will skew the results.

Not just that but the FRF calculation is slightly complex. You need to take into account windowing function, amplitude correction factor, sampling rate and block size of each measurement and %overlap… leakage is a very important thing in signal processing and spectral analysis. Also you need an anechoic environment to capture this, because you would be also capturing room reflections and characteristics of room acous…

For the logarithmic sine sweeps (confunsigly also known as exponential sine sweeps) used here the standard method is to use an inverse filter to (de)convolve the sweep recording into an impulse response. No worries about windowing or leakage when using that.

This is sadly not very well documented process, but some open source implementations exist. E.g. https://github.com/maj4e/pyrirtool

Re: How to measure frequency response of a speaker at home

#45

Post by unethical_ban »

lanthade wrote: post #38
aljgz wrote: post #36

Earlier quoted context omitted.

`When disagreeing, please reply to the argument instead of calling names. "That is idiotic; 1 + 1 is 2, not 3" can be shortened to "1 + 1 is 2, not 3".` `Please don't fulminate. Please don't sneer, including at the rest of the community.` As a curious person with a degree in Electrical Engineering, and one in Computer Science, very interested in quality audio, etc, I know what you mean. But please, don't be the perso…

I find it interesting that you chose to respond to my comment like this as opposed to others which are more egregious on the issues you bring up. That aside though, I did mention a number of issues with the write up. Anyone interested is welcome to dig into them and come back with questions if they desire. This is not however an introductory level topic and I elected to not try to thumb tap out a distillation of a ve…

Your last sentence is exactly what the best of HN is: wonderful distillation of complex topics.

Re: How to measure frequency response of a speaker at home

#46

Post by fatnoah »

softgrow wrote: post #25

Years ago at uni, one group chose as their control systems term project to take a known bad speaker (2 inch from transistor radio), measure its response, then build an inverse function to make it perfect using an analog computer. Don't know what the result was but they did have fun.

Probably even more years ago at Uni, my senior project group built an automated analysis system for a large (literally large,club to stadium sized) speaker company.

It was a very cool project that spanned multiple disciplines as we built a phased microphone array, a system to tilt and rotate the speaker, and programmable logic and software to generate and analyze signals.

It was proof-of-concept quality, but was later made real and reduced analysis time from dozens of hours to about 45 minutes. Two of the project members were even hired by the company.

Re: How to measure frequency response of a speaker at home

#48

Post by zkd43 »

I just want to point out that it's a pretty big leap to go from "I observed the same frequency response curve with two different inputs" to "there is no audible difference between the two inputs". There are many other measurements you would need to take to prove or disprove the hypothesis, such as signal to noise ratio and dynamic range. And even then you couldn't really prove it definitively due to the complexity of how humans interpret the sound.

When you use Bluetooth, your speaker is functioning as the DAC (digital to analog converter), but when you use the aux, your computer is functioning as the DAC and also amplifying the signal, so it's reasonable to expect them to sound different.

Re: How to measure frequency response of a speaker at home

#49

Post by atVelocet »

mattclarkdotnet wrote: post #13
cluckindan wrote: post #3

You need a calibrated measurement microphone to do this for real. Otherwise the microphone’s frequency response will skew the results.

iPhone mics are consistent enough to be used for most purposes. Apple provides the correction curves and they are used by apps like Audiotools

This! So many people don't take advantage of this fact.

Re: How to measure frequency response of a speaker at home

#50

Post by wl »

amelius wrote: post #47

This assumes your amp and speaker are linear systems.

Linearity is an excellent assumption for virtually any non-overdriven modern amplifier. THD measurements make sense for speakers, but that's not getting in the way of what the author is attempting to do here.

I don't even know where to begin addressing everything that's wrong with this article, but assuming linearity isn't one of those errors.

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