Graph comments

[thexder]

Hi,

I've moved my gear to another room and started to do some measuring and been trying to solve issues at the low end.
Not sure yet what is causing them.
Comments are highly appreciated!

Thank you!

 

[John Mulcahy]

Mostly look to be modal resonances/position related, though there are several large reflections which look to be from surfaces near the speakers, particularly the left. Try moving speaker/listening positions (to the extent you can) to see how that helps. A quick way to do that is to set the signal generator to Pink PN and watch the response on the RTA as you move the mic or speakers. You can try placing a speaker in the listening position and moving the mic around to find the best (smoothest) speaker positions, but bear in mind the speaker would need to be elevated so the mid is roughly where your head would be for most representative results, which may not be practical. Use these RTA settings:

 

[thexder]

Okay. Thank you very much. I will sure try that.
Yes, side walls near the speakers are empty, particularly left.
What do you think of other graphs? Waterfall, RT60, ETC?

 

[John Mulcahy]

RT60 looks good, ETC is what highlights the reflections I mentioned. Waterfall also looks reasonably well behaved in the sense the decays are fairly uniform but the likely position-driven LF variability makes it look worse than it is.

 

[thexder]

Thanks, John. How can one see the reflection problem on the ETC curve?
What is interesting is no matter what I put on those empty side walls (wooden diffusors, foam, wool, foam ...) the problems are still there.

Sorry for newbie question. Still learning.

 

[John Mulcahy]

The ETC makes it a little easier to see the spikes corresponding to reflections, though they are similarly visible in the impulse response with the Y axis in dB. Reflections close to the impulse peak can be from surfaces near the source or surfaces near the mic, so need to check both.

 

[thexder]

Could some one please circle the critical spikes?
I read tons of threads but wasn't able to find a perfect ETC graph nor the explanation where to find a reflections on the graph. Are there any specific settings in the REW for analyzing the ETC curve?

Is this it?

 

[John Mulcahy]

This might help: http://www.gikacoustics.com/unpacking-etc-time-domain-measurements-early-reflections/

 

[thexder]

Thank you very much, John, very informative. Much more clear now. I should have focused on easier ones!
What about dips, are they important to? The article doesn't cover that.
This ETC sure looks better.

 

[John Mulcahy]

No, dips in the ETC aren't of concern.

 

[thexder]

Hi!

Happy new year 2020 to all and may the good bass be with y'all!

I'm testing another sub integration approach and have done several measurements of my stereo speakers.
I'm now deciding with measurements should I start with.
I believe setting up one speaker distance (delay) is quite helpful. I'd like to hear an opinion or two about that.

I'm attaching two files:
1. distance test (left speaker distance is set to 1,1 m)
2. open/closed speaker ports and speaker position from the front wall

Thank you!