from Hacker News

How to measure frequency response of a speaker at home

by philip-b on 12/8/24, 9:49 PM with 57 comments

  • by cluckindan on 12/8/24, 10:34 PM

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

  • by TacticalCoder on 12/8/24, 11:30 PM

    > when Motion+ is connected to my phone via bluetooth, and when it's connected to my laptop via aux-in

    Why not for it's always interesting to experiment but one is lossy (all bluetooth codecs are lossy AFAIK) and the other is analog. Probably on top of an already lossy source too. They "sound" the same the same way a pixelized color print of Mona Lisa next to the real Mona Lisa looks identical if you're far enough. You may or may not be able to tell the difference but lossy Bluetooth and analog aux-in don't sound the same.

    I decided to go for a simple setup: a Yamaha fully integrated amp that does it all, including a network streamer. And I stream from Qobuz (lossless streaming) and from my own collection of CDs I ripped to FLAC (lossless and bit-perfect rips even though you're ripping from an audio CD, verified with an online DB of hashes from other people who did ripped the same CDs).

    So I know that up to amp, it's all lossless. Then the amp does its magic.

    It's simple really: even though I can't tell the difference between a pixelized color print of Mona Lisa and the real thing from far enough, I'd still prefer to know I'm actually looking at the real thing.

    A Qobuz (lossless) subscription doesn't cost more than a Spotify one (lossy although they announced they'd move to lossless IIRC).

    It's 2024: FLAC files are tiny compared to, say, even just a 1080p movie. Bandwith is plenty to stream lossless.

    Why even bother with lossy? Lossy audio is tech from a quarter of a century ago.

  • by mattclarkdotnet on 12/8/24, 11:11 PM

    To do this at home somewhat accurately, see this article 'How to make quasi-anechoic speaker measurements/spinoramas with REW and VituixCAD' https://audiosciencereview.com/forum/index.php?threads/how-t...

  • by mandmandam on 12/8/24, 10:47 PM

    > I eyeballed the two (red) plots and I think they look more or less identical.

    I overlaid those two images [0], and they seem significantly (though not hugely) different to me.

    Wouldn't speculate as to why that is though, without checking the consistency of passes with the same setup.

    0 - https://imgur.com/a/7GUSmPW (with hue shift for comparison)

  • by lanthade on 12/9/24, 1:25 AM

    Oh my. I mean, if this guy is happy with his results then more power to him. However, this write up is a textbook case of the blind leading the blind. I don’t even know where to begin. The classic smiley faced EQ, equating spectograph with transfer function, no discussion of phase or any other time domain considerations. It reminds me of when I was 17 and thought I knew everything about computers. Then I went to college and learned how little it was that I actually knew. The author’s knowledge is me when I was 17. I however own thousands of dollars of measurement mics, audio interfaces, and software, and have experience built on decades of pro audio work using those tools and honing my craft.

    It’s not my desire to slam the author but it’s also important that people don’t take this correct methodology.

  • by FuriouslyAdrift on 12/9/24, 2:49 PM

  • by softgrow on 12/9/24, 12:28 AM

    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.

  • by zkd43 on 12/9/24, 1:18 PM

    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.

  • by IAmGraydon on 12/9/24, 1:56 AM

    >I eyeballed the two (red) plots and I think they look more or less identical. So I guess there is actually no difference in sound and I just imagined it.

    LOL. Why is this even on the front page? He measured it with a phone's mic, then he goes on to "eyeball" the results, which are clearly different even to the eye. He then declares them the same. From top to bottom, everything is wrong with this.

  • by chevman on 12/8/24, 10:26 PM

    Always hear my audiophile friends talking about this company/product:

    https://www.dirac.com/live/

  • by plussed_reader on 12/9/24, 2:09 PM

    Sounds like they described a sub-par preamp on the wired input; something to the quality of BT compression.

    You can still tell that from the coloring of a local reference mic.

  • by harrall on 12/9/24, 2:24 AM

    I own a Soundcore Motion+ and can attest to it to be terribly sounding, even for a Bluetooth speaker.

  • by amelius on 12/9/24, 1:06 PM

    This assumes your amp and speaker are linear systems.

  • by tetnis on 12/8/24, 10:53 PM

    'I tested different EQ presets on "Levitating" by Dua Lipa (Youtube Music, Music video on Youtube). The song is fantastic, and I've been listening to it on repeat these last few days'

    Stopped reading