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Getting To Know REW and GLM

linear diver

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Joined
Mar 6, 2022
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Location
Colorado
Hi everyone! I have been following ASR for a year or two, but this is my first post

ASR has inspired me to get more rigorous about the sound in my workspace. I have done some research, but since ‘I don’t know what I don’t know,’ I’m sure I've got a lots wrong! - Here is a log of my first steps in Improving (?) my acoustics with GLM and REW. I would appreciate any suggestions-corrections to my methodology.

Also, it won't hurt my feelings if folks have suggestions about posting photos and graphical data. :)

This is the REQ part of my story. It ends with graphs of my first measurements. I also include the .mdat file (I had to put it in a zip to attach it to this message). Next I'm going to go through the the same process with GLM. I can't wait to hear what you folks think of my start at acoustic measurement! -- Mike

-------------------
Starting from the beginning ...

I took as much treatment as possible out of my space. It is 19.5 ft x 19.5 ft with a 12.5 foot vaulted ceiling. The floor is Pergo-style flooring with one small rug. 50% of the walls/ceiling is drywall, 50% is pine boards (‘hippie strips’). A significant percentage of the walls is untreated glass. (see photo.)

iMWJMPR_H-A1GsP3G5hWYQEvExkuf-1qgUFK_lj7K__gvnQke7AGItt0D1coIhRSGj2X2E-BnqDLIslkyTnGyA3K3XwDtSXm2GB2P8e7QaC0p__Le_d_K3eh74_jd0Ab6Ys2E6nt



My speakers are Genelec 8340A’s with GLM 4.1.2. I mostly listen through a UAD Apollo solo but I am using a Behringer UMC1820 for this series of tests.

The speakers are on SoundAnchor adjustable stands set at 51” (‘acoustic center midway between drivers’) This is my ear height for serious listening. Measurement mics are set at this level.

The speakers are at two vertices of an 84 inch equilateral triangle. The speakers are rotated 60 degrees.and are approx. 8 in from the front wall.

My Behringer 8000 mic regrettably bit the dust a couple years ago, so I am using an sE 8 small-diaphragm cardioid mic for REW and the Genelec mic for GLM.

For this series of tests, I am measuring the Right Speaker only, from the third apex of the triangle. The mic-speaker distance is 84 in. The cardioid mic is pointed at the Right speaker.

I started by resetting the speakers to their factory defaults. I created a new, blank, SAM file.

NOKGEkTzBTxxXavR8RgBbGqYAKPm3tQku7psjjD7-RpO9HcKWbdWf6CMOh-mTDKqTssJ3NVpHOzB9y-xIkuogzRXzD-If-VuAlLhXT0KXpNAu3BiXcT_fi_L5ofELKw2WLu6A9zT
Xj8hVls2YaL6B_8yEO4F1MYWSg3NeNAn8NSK6Ergf6MAu9HumlnKp2-bI_PEgcAqbC24xm1Fx3Oc9YBZGk4VBosXzQwfQYRCwk5PI7r-c6zEJ7ScQ-9TPlPRc_c0kH2nt-4qCGR5


Now, for REW. I am using the UMC ASIO drive fro my UMC 1820 interface. I am set at 48kHz, CH 1 (sE8) in and CH 2 (REW gen) out.

I’m not calibrating my sound card or SPL meter for now.

So, ready to go with my first measurement!!!!!

bAKW9-d765L-oNGRz3AjBR54rhoGN5atq3va4NEuhelW98bKqyK6dJLiQNx2f1SdYkKLUxugumOKHgCCgBXv_VwtfCEJSVYyGHgY6eTABFeIW6aLLRid32oDp72099UfgGahxZVs
….
3X6g-tQn8A7btJpnzNPojJJHRRTyLynmsFGmAzbRLZvfQkiXbMto8LPwUNTjgUZtJPyQlCIBRk0mvwIvmMVd8yhzFBryKRYuDvSi8dpje9Ya9IVkuDxVDo5CrMoMZaJ-5-JpngV9


ybAQ45eh_Pf1Or-KnZv-oLyx5tfCXBEeECHPaEu0l7TeigRf5MwvDoZzJd85Limbpq1HWXy_RFE-JDbjUkBTZpQyJIqsTTur7F2jCHsbZOFHJqIaBD_NkrNfrEACqauILut8gy4d


To be continued ....
 

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  • Mar 6 - Factory Defaults.zip
    1.2 MB · Views: 36

ernestcarl

Major Contributor
Joined
Sep 4, 2019
Messages
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1,745
Location
Canada
Hi everyone! I have been following ASR for a year or two, but this is my first post

ASR has inspired me to get more rigorous about the sound in my workspace. I have done some research, but since ‘I don’t know what I don’t know,’ I’m sure I've got a lots wrong! - Here is a log of my first steps in Improving (?) my acoustics with GLM and REW. I would appreciate any suggestions-corrections to my methodology.

Also, it won't hurt my feelings if folks have suggestions about posting photos and graphical data. :)

This is the REQ part of my story. It ends with graphs of my first measurements. I also include the .mdat file (I had to put it in a zip to attach it to this message). Next I'm going to go through the the same process with GLM. I can't wait to hear what you folks think of my start at acoustic measurement! -- Mike

-------------------
Starting from the beginning ...

I took as much treatment as possible out of my space. It is 19.5 ft x 19.5 ft with a 12.5 foot vaulted ceiling. The floor is Pergo-style flooring with one small rug. 50% of the walls/ceiling is drywall, 50% is pine boards (‘hippie strips’). A significant percentage of the walls is untreated glass. (see photo.)

iMWJMPR_H-A1GsP3G5hWYQEvExkuf-1qgUFK_lj7K__gvnQke7AGItt0D1coIhRSGj2X2E-BnqDLIslkyTnGyA3K3XwDtSXm2GB2P8e7QaC0p__Le_d_K3eh74_jd0Ab6Ys2E6nt



My speakers are Genelec 8340A’s with GLM 4.1.2. I mostly listen through a UAD Apollo solo but I am using a Behringer UMC1820 for this series of tests.

The speakers are on SoundAnchor adjustable stands set at 51” (‘acoustic center midway between drivers’) This is my ear height for serious listening. Measurement mics are set at this level.

The speakers are at two vertices of an 84 inch equilateral triangle. The speakers are rotated 60 degrees.and are approx. 8 in from the front wall.

My Behringer 8000 mic regrettably bit the dust a couple years ago, so I am using an sE 8 small-diaphragm cardioid mic for REW and the Genelec mic for GLM.

For this series of tests, I am measuring the Right Speaker only, from the third apex of the triangle. The mic-speaker distance is 84 in. The cardioid mic is pointed at the Right speaker.

I started by resetting the speakers to their factory defaults. I created a new, blank, SAM file.

NOKGEkTzBTxxXavR8RgBbGqYAKPm3tQku7psjjD7-RpO9HcKWbdWf6CMOh-mTDKqTssJ3NVpHOzB9y-xIkuogzRXzD-If-VuAlLhXT0KXpNAu3BiXcT_fi_L5ofELKw2WLu6A9zT
Xj8hVls2YaL6B_8yEO4F1MYWSg3NeNAn8NSK6Ergf6MAu9HumlnKp2-bI_PEgcAqbC24xm1Fx3Oc9YBZGk4VBosXzQwfQYRCwk5PI7r-c6zEJ7ScQ-9TPlPRc_c0kH2nt-4qCGR5


Now, for REW. I am using the UMC ASIO drive fro my UMC 1820 interface. I am set at 48kHz, CH 1 (sE8) in and CH 2 (REW gen) out.

I’m not calibrating my sound card or SPL meter for now.

So, ready to go with my first measurement!!!!!

bAKW9-d765L-oNGRz3AjBR54rhoGN5atq3va4NEuhelW98bKqyK6dJLiQNx2f1SdYkKLUxugumOKHgCCgBXv_VwtfCEJSVYyGHgY6eTABFeIW6aLLRid32oDp72099UfgGahxZVs
….
3X6g-tQn8A7btJpnzNPojJJHRRTyLynmsFGmAzbRLZvfQkiXbMto8LPwUNTjgUZtJPyQlCIBRk0mvwIvmMVd8yhzFBryKRYuDvSi8dpje9Ya9IVkuDxVDo5CrMoMZaJ-5-JpngV9


ybAQ45eh_Pf1Or-KnZv-oLyx5tfCXBEeECHPaEu0l7TeigRf5MwvDoZzJd85Limbpq1HWXy_RFE-JDbjUkBTZpQyJIqsTTur7F2jCHsbZOFHJqIaBD_NkrNfrEACqauILut8gy4d


To be continued ....

Your measurements already looks quite excellent without a sub -- maybe a tad too flat for my taste, but still already better than most. Only thing I might suggest is some acoustic treatment to bring the decay specifically between 200 Hz - 2 or 3 kHz down just down a bit to make it more leveled with the rest.

1646618483594.png


Say, down to 400ms would be enough. Again, I do not believe it's a necessary intervention to be done, but just something I personally would prefer if it were my own room.

FDW 15 cycles (edit: some people may think I'm too generous, so I changed it to a 50dB vertical scale)
1646620305135.png


Other than the room-induced phase rotation and bass dip around 150 Hz, this looks great!


1646618752481.png


By improving the decay time in the range mentioned, you would have increased the C50 just above 10 dB -- bringing it to par with the rest of the response.

*You might want to try comparing your sweeps to a moving microphone measurement (MMM) average.
 

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    1646618605532.png
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Last edited:
OP
L

linear diver

Member
Joined
Mar 6, 2022
Messages
20
Likes
20
Location
Colorado
Your measurements already looks quite excellent without a sub -- maybe a tad too flat for my taste, but still already better than most. Only thing I might suggest is some acoustic treatment to bring the decay specifically between 200 Hz - 2 or 3 kHz down just down a bit to make it more leveled with the rest.

View attachment 190888

Say, down to 400ms would be enough. Again, I do not believe it's a necessary intervention to be done, but just something I personally would prefer if it were my own room.

FDW 15 cycles (edit: some people may think I'm too generous, so I changed it to a 50dB vertical scale)
View attachment 190895

Other than the room-induced phase rotation and bass dip around 150 Hz, this looks great!


View attachment 190890

By improving the decay time in the range mentioned, you would have increased the C50 just above 10 dB -- bringing it to par with the rest of the response.

*You might want to try comparing your sweeps to a moving microphone measurement (MMM) average.
Thanks so much, ernestcarl. I'm not sure how to properly credit you ... I'm new to this internet stuff :)

It is great to know that I’m starting out on the right foot! Your feedback and the REW manual have taken me much further down the line to understanding what the data say about my speakers and room. Onward …

I “treated” the room with patio cushions and moving blankets at the side wall 1st reflection points, and the lower back wall.

I have not yet done anything to the front wall (behind the speakers).

I measured my treated room using GLM 4.12. Here is the graph ...

NOTE: My understanding is that GLM does not re-measure the system after calibration, so I interpret this graph as showing the measurement before this calibration

03-18 GLM Small.png



Then I applied the calibration and took a measurement from the same position with the sE8 and REW ...


03-18 REW - quick ping 8.png


Here are the untreated vs. treated result from the RT60 overlay display....

03-18 RT60 Comparison Small.png


And finely, the clarity graph:


3-18 Clarity Comparison Small.png


CONCLUSIONS?

So … My interpretation is that we achieved our design goals of lowering RT60 between 200-2K Hz, and raised the Clarity metric above 10 dB.

To my naive ‘eye’ the data look pretty consistent between REW and GLM. And the measurements (except MMM) make some sense to me.

BTW: I’m investigating schemes to scrape that raw csv data and plot everything with a common tool - any suggestions? :)

My big questions at this point are:
What is the best aesthetic/acoustic mix for the room treatment, and, and what to do about sub woofers; zero, one, or two!

Thanks so much for the input! -- Mike
 

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  • 03-18-22 T2 and GLM 3.zip
    2.5 MB · Views: 17

ernestcarl

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Location
Canada
BTW: I’m investigating schemes to scrape that raw csv data and plot everything with a common tool - any suggestions? :)

My big questions at this point are:
What is the best aesthetic/acoustic mix for the room treatment, and, and what to do about sub woofers; zero, one, or two!

I'm presuming you mean the csv data from GLM... where I really have no idea what to do with -- given I don't use GLM -- sorry!

But you could digitize the plotted traces using just an image capture along with something like VituixCAD's 'SPL Trace' tool.

Many would probably say you do not need that much more treatment given you're pretty much already between the often cited 300-500 ms (RT) reflection-decay time range. And your modes aren't really ringing much... T60M is also good. If you added a sub for bass extension, you might see an increase in your low end decay which could benefit from additional very thick broadband absorbers / slightly thinner (2-4"), but rigid or semi-rigid acoustic panels like owens corning 705 and rockwool's rockboard/comfortboard 60/80. But, at the moment, I think you are already doing pretty good.

For dedicated studios and multichannel home-theaters it is sometimes recommended to go lower down to 150-250 ms. Not really an expert in room treatment, per se, but you might get some inspiration looking at videos by Jesco (home studios) and Anthony Grimani (home theater/audiophile listening room designs).
 
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