Measuring speakers using music - FSAF . . .

Steve_Lee

Thanh & Dcibel,

Thanks for your driving contributions to the subject matter over on DIYaudio Forums.
I am following along to see where the dust settles before jumping-in with my own testing but am excited to see how this pans-out.

For reference:

https://www.diyaudio.com/community/threads/measuring-speakers-using-music-michael-tsiroulnikovs-fsaf.418843/page-5#post-7822750

tktran

So far there’s a lot of hand waving from some keyboard warriors. Perhaps some listening, but no actual testing, as far as I can tell.

@dcibel is the only person who gave feedback that one of my 3 audio tracks had clipping in it; and I’ve identified the issue; a fix should be coming.

After that I will post recordings of familiar music, with some familiar (or not so familiar) drivers. Hopefully others might try.

Even if they don’t, that’s OK by me, Someone wiser than me once remarked that the acceptance of new findings goes through stages…

Steve_Lee

It's worse than trying to herd cats over there - drug induced flashbacks from the 80's and 90's galore but no forward motion - you can't even slap them in to consciousness with words on a screen . . . Thread topic destroyed.

https://www.diyaudio.com/community/threads/measuring-speakers-using-music-michael-tsiroulnikovs-fsaf.418843/page-9

dcibel

It's a more interesting thread than this one.

jr@mac

@dcibel said:
It's a more interesting thread than this one.

Harsh

Nicholas_23

We have a MAC user here that builds his my ear. He has brought a couple builds to IDIY. He told me he does his stuff by ear. Sounded pretty legit to me.

Wolf

How is Matt? Haven't seen him around here in a while....

Steve_Lee

@dcibel said:
It's a more interesting thread than this one.

Quoted ^ for its truth/accuracy - let's see if we can remedy this situation . . .

Any comments concerning Kravchenko's ^ post/analysis, Dcibel?

It was a direct response to your distilled distortion audio clip @ post #63 on page 4.

My 1st response to it was that it sounded a lot like cabinet resonance mixed with an over abundance of frequencies around 150 Hz and lower creating a muddy mix.

BTW - thanks for posting it.

Peace.

dcibel

It's just power supply noise, not that interesting really. The low level transformer hum that comes through on most low-mid range amps with linear power supply. Since it's a constant unwanted noise, it comes through very clearly in FSAF.

Keep in mind that the measurement being analyzed here is not acoustic, it's an electrical loopack of the amp output, so it's effectively TD+N of the amp I was using for testing, with no load, so primarily the signal recorded is the residual transformer hum.

Steve_Lee

Can you also test this this with other amps/ClassD/T that you have available?
(time permitting) - Just curious if a SMPS has any effect here . . .

dcibel

A poor SMPS will exhibit hiss rather than hum, very different operation so the 60Hz line noise doesn't really come through. A good SMPS will be completely silent. The amp itself matters as well, some have much better PSRR (power supply rejection ratio) than others. This is easily seen in many of the amp tests at ASR, go ahead and compare a few amps with linear power supplies and SMPS, the spectral content of the power line hum clearly comes through in those 1kHz test tone spectrum analysis charts.

You don't really need FSAF to listen to this, get a relatively sensitive speaker, turn on your amp and put your ear to the woofer. Always remember, your amplifier hums because it doesn't know the words.

tktran

Steve,

I didn’t post any further music clips to compare and contrast after @dcibel notified me of clipped samples in one of the 3 music tracks that was posted:

I hadn’t even listened to this before posting- it was hot off the press, or straight from the acetate!

I had previously thought I had resolved a technical issue in my audio interface, but it was the final straw of intermittent problems that I’ve been wrangling with for months.
So I stopped and paused to find a workaround. To cut a long boring story short, I’ve replaced my audio interface/drivers.

But In the meantime I didn’t tend to the FSAF garden and it’s overgrown with weeds…

dcibel

I don't know that I specifically called out that anomaly as clipping, but it certainly is an odd thing to see in a measurement of loopback noise. Regardless. I know you've had all sorts of issues with your Scarlett interface of what I would describe as "buffer underruns", and nothing you've tried has made any improvement. I hope the new interface serves you well.

Steve_Lee

Hörnli posted some interesting audio residuals today @ post #186, Page 10.

Crackling below 60Hz LPf, not so much above . . . need more info concerning his test parameters.