Speakers distortion

[Krunok]

To remove the display of the currently selected measurement just untick the check box for it in the legend. These kinds of questions probably belong in one of the dedicated REW forums though.

I'm trying to find out how to clear this. I pressed Save and now I want to take another measurement in that RTA window.



Ok, I just realised that after I press Reset averaging I can start a new measurement from fresh. I find it a little confusing that old graph stays in place when I press Reset averaging. IMO it would be logical to clear the graph when Reset averaging is pressed, eventually asking if the measurement should be saved if it already hasn't been.

 

[Liberal Democracy]

Do we need a REW Q&A thread? Inquiries like these are best posted in a place where the answers would help the greatest number of people .

 

[Krunok]

Do we need a REW Q&A thread? Inquiries like these are best posted in a place where the answers would help the greatest number of people .

Although this thread is about discussing and measuring speakers distortion (primarily with REW) it does seem like a good idea.
Assuming of course @JohnPM is willing to support it.

 

[Liberal Democracy]

Although this thread is about discussing and measuring speakers distortion (primarily with REW) it does seem like a good idea.
Assuming of course @JohnPM is willing to support it.

Tbh the best place is REW forum least poor john get pulled all over the internet answering the same questions.

 

[Krunok]

Tbh the best place is REW forum least poor john get pulled all over the internet answering the same questions.

Probably so. But then, he may as well be feeling that this forum is not just another audio forum but is instead unique, so he may as well decide to support REW directly here.

 

[Krunok]

I have measured that my comfortable SPL while listening is app 75 dB of average SPL, so I have made distortion measurements on that level with sine tones using RTA method with REW with settings as @JohnPM suggested, and this is what I've got:



I have found RTA method to be quite consistent between multiple measurements with the same tone so I decided to use that one.
I took measurements at istening position which is app 4m from the speakers.

I will try to repeat the measurements closer to the speakers to see what difference does it make.

 

[RayDunzl]

Tbh the best place is REW forum least poor john get pulled all over the internet answering the same questions.

Looking at the "Last Post" dates, he may have come here looking for something to do...

 

[Krunok]

App 1m from the speakers. Due to length of my mic cable I cannot make it closer:

 

[andreasmaaan]

App 1m from the speakers. Due to length of my mic cable I cannot make it closer:

Are the "left" and "right" columns showing percentage measured THD?

 

[Blumlein 88]

App 1m from the speakers. Due to length of my mic cable I cannot make it closer:

So no big difference in the two distances.

 

[RayDunzl]

do you have an idea why log sine sweep measreuments show app 9db higher than RTA?
Also, can you please help with clearing the RTA window question?

Simplistic answer (as I perhaps incorrectly understand it).

The analysis calculator (FFT) has many buckets to fill covering small frequncy ranges.

The steady tone fills one bucket.

The sweep tone partially fills many buckets as the tone slides past them.

 

[Krunok]

Are the "left" and "right" columns showing percentage measured THD?

Yes, with all harmonics in audible band included.

 

[Krunok]

So no big difference in the two distances.

Yes, i would say it's quite close.

 

[Krunok]

Simplistic answer (as I perhaps incorrectly understand it).

The analysis calculator (FFT) has many buckets to fill covering small frequncy ranges.

The steady tone fills one bucket.

The sweep tone partially fills many buckets as the tone slides past them.

Would the same logic explain why RTA method for measuring distortion with single tone is giving more consistent results than sweep?

 

[RayDunzl]

I'm trying to find out how to clear this. I pressed Save and now I want to take another measurement in that RTA window.



Ok, I just realised that after I press Reset averaging I can start a new measurement from fresh. I find it a little confusing that old graph stays in place when I press Reset averaging. IMO it would be logical to clear the graph when Reset averaging is pressed, eventually asking if the measurement should be saved if it already hasn't been.

Looks like you stopped the measurement - red button not so red. RTA remains so you can see it. Reset Averaging doesn't do anything to stopped RTA, because, it is stopped (?).

When you start it again (red button) the RTA and Peak is new.

 

[RayDunzl]

Would the same logic explain why RTA method for measuring distortion with single tone is giving more consistent results than sweep?

Maybe. I am mathematically inept, so can't really say.

 

[Krunok]

Looks like you stopped the measurement - red button not so red. RTA remains so you can see it. Reset Averaging doesn't do anything to stopped RTA, because, it is stopped (?).

When you start it again (red button) the RTA and Peak is new.

Yep, in the meantime I figured how it works. Not the way I expected but it still makes excellent value for the money!

 

[Krunok]

Maybe. I am mathematically inept, so can't really say.

Don't say that. Your avatar is so not beautiful you have no option but to be good in math!

 

[Krunok]

Let me add specs of my mic. It's cheap but I believe it can do the job well.

 

[Krunok]

So no big difference in the two distances.

One more thing - I will repeat the same measurements in a couple of days. If I get similar results only then I would be willing to trust them.