• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

What is the correct method to do room measurement to create Convolution Filter?

Ducnguyen2k10

Member
Joined
Sep 21, 2021
Messages
66
Likes
46
Dear whom knows best about room acoustic measurement,

I’m getting into creating convolution filter by REW to use with Roon. I’ve read few online instruction and I did 2 methods of measurement:
1. To use pink noise to perform 9 measurements/chanel while moving the RTA Mics around listening point. Then do RMS aveage and apply EQ on that FR result.
2. To use full range sine sweep with 3 measurements/per point/chanel with 5 points at and around the listening point. Then do Vector Average and do EQ on that FR result.

I don't know which method is correct. Yet the first method produces the sound I like, and the 2nd method sounds weird to me.

My measurement setup:
- RTA Mic: Behringer EMC8000 with generic calibration applied
- Soundcard: Roland UA-55
- Software: REW

Is any one here knows the best and correct method?
 

ernestcarl

Major Contributor
Joined
Sep 4, 2019
Messages
3,106
Likes
2,313
Location
Canada
Dear whom knows best about room acoustic measurement,

I’m getting into creating convolution filter by REW to use with Roon. I’ve read few online instruction and I did 2 methods of measurement:
1. To use pink noise to perform 9 measurements/chanel while moving the RTA Mics around listening point. Then do RMS aveage and apply EQ on that FR result.
2. To use full range sine sweep with 3 measurements/per point/chanel with 5 points at and around the listening point. Then do Vector Average and do EQ on that FR result.

I don't know which method is correct. Yet the first method produces the sound I like, and the 2nd method sounds weird to me.

My measurement setup:
- RTA Mic: Behringer EMC8000 with generic calibration applied
- Soundcard: Roland UA-55
- Software: REW

Is any one here knows the best and correct method?

If it’s a moving average, why do you even need 9 sets per channel? Seems excessive. A single or two averaged sets would be enough. And with the normal sweeps, you are better off using the rms avg. I use the vector average as well with frequency dependent windowing, but I overlay the rms average on top to see the EQ effect on both.
 

DWPress

Addicted to Fun and Learning
Forum Donor
Joined
May 30, 2018
Messages
964
Likes
1,371
Location
MI
For a quick and easy measurement to get things dialed in close try the MMM method from listening position on your left and right channels inidividually and EQ LR separately. When you create your WAV filter use the EQ result for a stereo filter. See how that compares.

Did you note much difference in your 9 point/channel MMM measurements? Usually mine is consistent between measurements when no other changes are made. MMM will give you amplitude corrections but lacks other information like phase and decay. Creating filters and EQ in REW is a dance between flatness and not losing the dynamics of your listening space. I usually go at making filters from the measured file a few days in a row and apply the results (Roon in your case) randomly afterwards - our subjective impressions change with mood among other things.

Find the sound you like but then bust out the mic again and verify your results.
 
OP
D

Ducnguyen2k10

Member
Joined
Sep 21, 2021
Messages
66
Likes
46
If it’s a moving average, why do you even need 9 sets per channel? Seems excessive. A single or two averaged sets would be enough. And with the normal sweeps, you are better off using the rms avg. I use the vector average as well with frequency dependent windowing, but I overlay the rms average on top to see the EQ effect on both.
thanks for ur respose. So which method should I use? Using pink noise or using the sine sweep?
 

ernestcarl

Major Contributor
Joined
Sep 4, 2019
Messages
3,106
Likes
2,313
Location
Canada
thanks for ur respose. So which method should I use? Using pink noise or using the sine sweep?

Either method works fine. Log sine sweeps matter if one wants to look at the time component. MMM is faster, but it will not have the time information — which is fine if you don’t need it/don’t know what to do with it.
 
OP
D

Ducnguyen2k10

Member
Joined
Sep 21, 2021
Messages
66
Likes
46
For a quick and easy measurement to get things dialed in close try the MMM method from listening position on your left and right channels inidividually and EQ LR separately. When you create your WAV filter use the EQ result for a stereo filter. See how that compares.

Did you note much difference in your 9 point/channel MMM measurements? Usually mine is consistent between measurements when no other changes are made. MMM will give you amplitude corrections but lacks other information like phase and decay. Creating filters and EQ in REW is a dance between flatness and not losing the dynamics of your listening space. I usually go at making filters from the measured file a few days in a row and apply the results (Roon in your case) randomly afterwards - our subjective impressions change with mood among other things.

Find the sound you like but then bust out the mic again and verify your results.
I did the method 1 extensively. After put the Convolution filter into Roon, I did measure again using pink noise for each chanel and found the actual result is very close to the Predicted FR in REW EQ.
There is not much difference in 9 point/channel MMM measurements. So I think 3 points at and around the ears are sufficient.
Today I did the sine sweep method without changing anything in the room.
I do compare subjective listening btw 2 methods and found sine sweep sound really weird to me.
I also compare both methods with Anthem ARC (9 points measured) and the Anthem ARC sounds also very different.
 
OP
D

Ducnguyen2k10

Member
Joined
Sep 21, 2021
Messages
66
Likes
46
Either method works fine. Log sine sweeps matter if one wants to look at the time component. MMM is faster, but it will not have the time information — which is fine if you don’t need it/don’t know what to do with it.
I know with sine sweep, I can look at the waterfall graph to see the decay time.
The one step I skipped when doing the sine sweep method is not doing rephase. Maybe that makes my system sounds weird.
 

ernestcarl

Major Contributor
Joined
Sep 4, 2019
Messages
3,106
Likes
2,313
Location
Canada
I know with sine sweep, I can look at the waterfall graph to see the decay time.
The one step I skipped when doing the sine sweep method is not doing rephase. Maybe that makes my system sounds weird.

You can use rePhase with or without any kind of phase “correction”. You can also drag and drop exported measurements from REW with/out the phase information of either MMM or single sweeps to create your convolution file.

Why it sounds weird is probably because of overcorrection above the room’s transition zone ~150-250Hz
 
OP
D

Ducnguyen2k10

Member
Joined
Sep 21, 2021
Messages
66
Likes
46
You can use rePhase with or without any kind of phase “correction”. You can also drag and drop exported measurements from REW with/out the phase information of either MMM or single sweeps to create your convolution file.

Why it sounds weird is probably because of overcorrection above the room’s transition zone ~150-250Hz
You’re right. Something is really wrong with the sine sweep method. I should do it again!
 

DWPress

Addicted to Fun and Learning
Forum Donor
Joined
May 30, 2018
Messages
964
Likes
1,371
Location
MI
It might help if you showed us your measurements and correction filters so we can see what you're hearing. Like I said, going back and redoing or tweaking the EQ filters is often beneficial to hear the subtlety different approaches.
 
OP
D

Ducnguyen2k10

Member
Joined
Sep 21, 2021
Messages
66
Likes
46
It might help if you showed us your measurements and correction filters so we can see what you're hearing. Like I said, going back and redoing or tweaking the EQ filters is often beneficial to hear the subtlety different approaches.
Thank you! I’ll do the measurement again and post the results for you guys to check!
 
Top Bottom