REW-Moving Microphone Method Help

[DanGuitarMan]

Ah, ok, I see.

In that case adding a sub is probably the best option left.

Yes, I used to have two SVS SB-1000 subs and integrated them with the mains using Multi-Sub-Optimizer. This was before we remodeled and I sold them. Booooooy do I miss those days. Musical bass I could feel in my nether regions. We are in a condo, so I feel like this is much more appropriate anyhow. We have a really cool neighbor who said she couldn't even hear the bass which shocked me.

 

[Dj7675]

Another fan of MMM here. Just one question - are measurents above of a single speaker or a pair with mono signal?

You are correct. I wasn't sure if it was better to do a single speaker or both at a time. I forgot to save the original measurements, so I remeasured individual speakers with Audyssey both on and off. I tweaked the curve slightly more downward as well. I changed smoothing to 1/12th as well to see it in better detail. Also below is smoothing at 1/3 as well for one speaker to see before/after to see if Audyssey applies the tilt from the app. To my untrained eye it looks like it is doing pretty well.

Left aud on

Left Audyssey Off

Right Audyssey On

Right Audyssey Off

 

[aarons915]

So is the verdict that it doesn't matter if you measure your speakers separate or together as it should be about the same? With sweeps I definitely need separate measurements but the MMM method doesn't seem to make a difference.

 

[tecnogadget]

Hello guys, I've been playing with MMM and I'm having some doubts...Am I missing something ??

I already knew MMM would give a more aggressive tilt from the transition frequency and above, I'm shocked for the extreme tilt down I'm getting.

I measured Pink Noise full range at around 80dB with REW SPL tool "C" Weighting. I don't understand why RTA MMM results are at much lower levels, I did increase the volume and that didn't help. Even ticked the "Adjust RTA Levels" and that didn't help neither.

Here are 3 measurements that show good repeatability on the listening position.

53dB at 45Hz
20dB at 10kHz
12dB at 20kHz

That's a 40/30 dB swing !!! This measurement would only be useful from transition frequency and below. I find it not representative of how the system sound, I highly doubt I'm listening to a 40dB downward slope...

Concerning microphone movement pattern and calibration file, I did follow the example from Echo Bar Studios pointing the mic to one of the sides. Then I tried just for fun doing it with the mic pointing up and doing a circle around listening position.
This is the difference between using 0º and 90º calibration file for Umik-1. 0º shows less high frequency

Then I made some sweep testing pointing the Mic at the center of the 2 speakers. In the absence of a boom mic, I had to hold it with my fingers with extended arms. I used to be super picky doings sweeps only with a mic stand, but even holding it with the hand can get you good repeatability.

This is Sweep vs MMM at the listening position with 1/24 smoothing. Below the transition frequency both correlates incredibly close. I don't get why tho different methods give me such a different Relative SPL.

Sweep has a downward slope of 10/15dB. MMM slope is 40/30dB!!!

Here is isolated Sweep with a better-suited scale.

This are the settings when doing MMM with RTA

 

[Soniclife]

Hello guys, I've been playing with MMM and I'm having some doubts...Am I missing something ??

I already knew MMM would give a more aggressive tilt from the transition frequency and above, I'm shocked for the extreme tilt down I'm getting.

I measured Pink Noise full range at around 80dB with REW SPL tool "C" Weighting. I don't understand why RTA MMM results are at much lower levels, I did increase the volume and that didn't help. Even ticked the "Adjust RTA Levels" and that didn't help neither.

Here are 3 measurements that show good repeatability on the listening position.

View attachment 66598
53dB at 45Hz
20dB at 10kHz
12dB at 20kHz

That's a 40/30 dB swing !!! This measurement would only be useful from transition frequency and below. I find it not representative of how the system sound, I highly doubt I'm listening to a 40dB downward slope...

Concerning microphone movement pattern and calibration file, I did follow the example from Echo Bar Studios pointing the mic to one of the sides. Then I tried just for fun doing it with the mic pointing up and doing a circle around listening position.
This is the difference between using 0º and 90º calibration file for Umik-1. 0º shows less high frequency

View attachment 66600

Then I made some sweep testing pointing the Mic at the center of the 2 speakers. In the absence of a boom mic, I had to hold it with my fingers with extended arms. I used to be super picky doings sweeps only with a mic stand, but even holding it with the hand can get you good repeatability.

This is Sweep vs MMM at the listening position with 1/24 smoothing. Below the transition frequency both correlates incredibly close. I don't get why tho different methods give me such a different Relative SPL.
View attachment 66613
Sweep has a downward slope of 10/15dB. MMM slope is 40/30dB!!!

Here is isolated Sweep with a better-suited scale.
View attachment 66623

This are the settings when doing MMM with RTA
View attachment 66624

Your mode setting is wrong, use RTA, see post 2.

 

[QMuse]

Your mode setting is wrong, use RTA, see post 2.

Yep, mode should be "RTA 1/48 octave" instead of "Spetrum". Adjust RTA levels should be ticked.

 

[whazzup]

Tangential to MMM, but why Pink Periodic instead of Pink Random? Because it's easier to see patterns (with the human eyes) / more accurate / something else?

 

[Blumlein 88]

Tangential to MMM, but why Pink Periodic instead of Pink Random? Because it's easier to see patterns (with the human eyes) / more accurate / something else?

The pink Periodic slots into the bins of an FFT so it is a more stable reading with lower fluctuations of the result. Yet it is still pink in nature.

 

[whazzup]

The pink Periodic slots into the bins of an FFT so it is a more stable reading with lower fluctuations of the result. Yet it is still pink in nature.

Thanks!

 

[whazzup]

Measuring my desktop speakers one by one.
Unfortunately I have my left speaker close to a side wall (limited by table placement). Based on the SPL, my right speaker's pink noise playback is ~1 to 1.5db softer (Left ~75db, Right ~73.5-74). I suppose the left wall's side reflections are to blame.
When measuring the right speaker, should I increase my volume slightly to compensate? Or it doesn't really matter?

On a related note, when I'm doing auto-eq in REW, should I then set target levels to be the same db on both speakers? Or should I bump up the target level on the right speaker by 1db?

 

[renaudrenaud]

The pink Periodic slots into the bins of an FFT so it is a more stable reading with lower fluctuations of the result. Yet it is still pink in nature.

Pink by nature... Wonder if there is a relationship with Floyd or with the panther.

 

[Aerith Gainsborough]

Interesting method. Tried it to see what Dirac does to my system. Seems to have more trouble with the left channel as usual.
Curious question though: how do you guys get values in the 80dB+ range? The volume I used was already pretty loud, I tried to increase it by +10dB but the curve was parallel to the quieter one, so I saw no point in pushing for volume.

Eye candy below. Bright green is the ambient noise. Settings used were the same as in post Nr. 2.
Right Channel

Left channel

 

[QMuse]

Interesting method. Tried it to see what Dirac does to my system. Seems to have more trouble with the left channel as usual.
Curious question though: how do you guys get values in the 80dB+ range? The volume I used was already pretty loud, I tried to increase it by +10dB but the curve was parallel to the quieter one, so I saw no point in pushing for volume.

Eye candy below. Bright green is the ambient noise. Settings used were the same as in post Nr. 2.

Wrong settings, you probably left Mode at Spectrum instead of RTA 1/48 octave or you didn't tick Adjust RTA levels.

 

[Aerith Gainsborough]

Wrong settings, you probably [...] didn't tick Adjust RTA levels.

That's the ticket, thank you. Roughly +27dB difference in volume. Shape of the curve is the same though, I don't need to re-measure.

 

[tecnogadget]

Much has been said about MMM but now that I'm finishing the proper setup of my speakers I'm having some doubts as which movement technique and calibration file combination to use, to generate an EQ filter with REW.

https://imgur.com/GQ29tNL

As in the uploaded video, these are the 2 possible techniques I've been considering but not sure which provides the most accurate response for my purposes. Horizontal Mic as used by Echo Bar Studio guys (they don't specify their calibration file angle), or Vertical Mic pointing ceiling similar to Jean-Luc Ohl diagrams ??

I've been tried both and to be honest, they give pretty much the same results below transition frequency. The real difference comes from using the 0º or 90º calibration file on UMIK-1.

90º is flatter and 0º has a pretty steep downward slope starting at 4kHz, which makes it hard to decide which one to use when you are looking after a specific house curve.

Concerning Max Overlap in RTA settings, I've noticed see most folks use 50%. Would the highest setting be beneficial or detrimental (93.75%)? As for how I see it increasing this number gives you more averages in the same amount of time, which could give you a precise enough result with fewer turns of the mic, but not sure if I'm missing something with this theory...

 

[thewas]

As you say the differences between 0 and degrees orientation are mainly calibration induced even at the higher frequencies (in my case usually only +-1dB) , I tend to use more the 90 degrees one as I find it easier from handling.

 

[Geert]

If you hold the microphone horizontaly I think you need to point it towards the speaker. That's how a free field speaker measurement is done (open space or anechoic).

The microphone upright is normally used for diffuse room measurements (the purpose of MMM measurements) . This measurement has a drop-off in the high end, so it usually requires a calibration file.

A high end measurement microphone comes with detailed specifications regarding the frequency response for both methodes, and corresponding calibration files.

 

[ernestcarl]

Concerning Max Overlap in RTA settings, I've noticed see most folks use 50%. Would the highest setting be beneficial or detrimental (93.75%)?

I have tried different values and it does not seem like it makes that much of a difference. So I’ve kept it at the default.

The more interesting difference I see is in the results when changing the length. This has the consequence of adding more peak transient energy in the lower half of the response. Which will be more stressful to the device under test. I sometimes use this as a ‘peak’ transients stress test. Normally one would see compression in the bass at high very SPL sine sweeps, but with this you will see that your drivers are actually able to play much higher SPL ‘transients‘ beyond that compression line. This can potentially damage the driver so be very cautious if want to test this out.

 

[bigjacko]

When doing the measurement how do we move the microphone? Do we point it towards speaker and draw circle towards speaker? How far to the speaker and how big should the circle be? I saw the video posted here but cant really tell how they did it. Thanks for the help.

 

[thewas]

When doing the measurement how do we move the microphone? Do we point it towards speaker and draw circle towards speaker? How far to the speaker and how big should the circle be? I saw the video posted here but cant really tell how they did it. Thanks for the help.

Below are some nice videos which show it