Understanding FFT in Audio Measurements

Frequency analysis in audio is a common technique (called "FFT"). How it works though is key to understanding its benefits and limitations. Importantly, without knowing how it works, you will have an impossible time comparing one frequency spectrum analysis to another. In this video I explain what an FFT is, and show in real time the effect of various parameters.

[ReTr]

Thanks for the educational content Amir. Signal processing and basic electrical theory are knowledge which most audiophiles lack, even though they are so very essential for understanding our equipment. You could make a whole video series about basic math, electrical theory, physics and psychoacoustics for audio applications. I'd watch every last video and try to spread the knowledge, I'm sure many others would as well.

[plcamp]

It is refreshing to see knowledgeable folks spend their time to advance the general knowledge of folks...it enables their choice to follow a productive path for audio performance vs the myth based nonsense ( audiophoolery ) that so often yells for attention from the sidelines.

Great stuff, keep it up!

[Tueftel-k]

Glad we have people like you to cut through all the marketing bullshit and actually educate people.
I study computer engineering and find myself learning something new almost every new "debunking" video.
Thank you Amir, keep up the amazing content!

[JesusMartinez-mkfc]

Great introductory video on FFT analysis Amir. I feel like I'm back in college. :) This video shows viewers that you really master electronics engineering and the testing of electronic systems. Some people that have called you a hack in dark basement with some cheap testing equipment, because they didn't like the outcome of the gear you reviewed, must now be feeling real small in their shoes and revising their opinions of your qualifications and honest intentions. Keep up the great work Amir! To those who still don't trust this empirical measurement path, knowledge will set you free... not blind faith in some glorified reviewer's seductive words.

[jblesser]

This is clearly a labor of love. I knew about your website but this has focused your efforts and mission for me. I donated through your website but clearly should increase my donation to support this work and your wonderful community. Thank you again. This is wonderful.

[DiegoooTech]

This is the best kind of video imho. Snake Oil win where there's no knowledge. Helping people understand basics is the best currency.

[BadGuyGoodAudioReviews]

So, damn, glad..you started this channel. Great vid

[ronalcasid]

This video gave me flashbacks to my EE digital signals processing class.

[jsfotografie]

wow now i have a headace :D keep up those great videos Amir! love the mix of reviews debunking and tutorials :) in interessting one would be SND+Noise is that calculated with fixed parameters so all have the same result? cheers janosch

[aaaaaaaaaa]

The best thing to come out of your work is how manufacturers are taking measurements seriously and building better products and we can also see a trend in many reviewers leaning towards measurements too :). Had it not been for your website, I would have saved up a quite a bit of money and spent it buying things which got very positive reviews but performed horribly in measurements, will not name them here. Thanks for preventing us from wasting our money :)

[sonickiller]

I feel like I’m back in advanced engineering math.

[TheNaboen]

Thanks! This was helpful. I find these types of videos far more constructive than those that appear as battles in the war between subjectivists and objectivists. Knowledge that is conveyed for the value it has in itself is far more valuable than the one that is used as a club to prove somebody wrong.

[Elektronik-]

Great video, but unfortunately you forgot to say when distortion is audible.

[doctorbo]

Trust is good, control is better.
It's unbelievable how much money is invested in useless high-end equipment these days.
Well, it probably secures jobs and fills the pockets with money. Anyway I also belive in good cables and high quality Hifi components and speakers, but I do not follow every new hype.

Music is what we want to enjoy at the end of the day! To many people are more and more focusing only on equipment and forgot to enjoy the music.


Your videos are excellent.

[gsus]

Amir, I have a video idea for you. Could you show how we at home could use something like an Oscilloscope to do some of our own measurements? It's a FAR cry from your audio precision analyzer, but do you think we could still derive some ideas about the performance of our DACs/Amps with an oscilloscope?

[tomas_m]

You mentioned perhaps the most common argument against the value of measuring audio gear - that good performance with 1kHz sine wave doesn't guarantee good music reproduction.
I'm intrigued myself whether the circuits might behave differently with a complex music signal than a one-frequency-component signal. Whether that might even show some design flaws.
Could you demonstrate this with a segment of a real music file in a future video? Is it as simple as running evaluated DAC -> analyser's ADC and comparing the result digital file with the original? Or analyser's DAC -> evaluated AMP -> analyser's ADC.

[anishnair]

Great video Amir (nostalgic memories of my career 20 years back as DSP engineer in audio codecs - not in HiFi but GSM)

[bizkac]

hi, could you make a video about gaming motherboard that advertise good audio?

[evaduk]

Enjoying all of your videos, Thank you.

[itsik_]

For folks that want to jump into this on their own, all you need is a sound card and software such as ARTA. For measuring higher power devices, there are interfaces out there that can normalize the voltage so that it is friendly to your soundcard, e.g Pete Millett's Sound Card Interface or Jan Didden's Autoranger