Room/Speaker EQ Approaches: Parametric EQ settings vs Impulse/Convolution

[Wayne A. Pflughaupt]

What you do is open REW. Open RTA and set it to read 1/48th octave instead of spectrum (spectrum is just FFT).

Pull up the Signal Generator and choose pink noise or PN for periodic pink noise. PN is a little better more stable.

In settings for the RTA you can have say 32 averages or forever averaging.

Let it play the pink noise while you move the microphone and record into the RTA. When satisfied you stop the RTA recording and choose Save. It will show up as a measurement in the normal window.

Thanks for that, I appreciate the info.

What happens after the 32 averages are finished? Does the screen freeze with the reading?

Also, what exactly is the "movement?" Are you sitting in the MLP panning the mic from the left speaker to right? All movement in front of one of the speakers? Walking across the room between the two speakers?

I'm an old coot, but I'm willing to learn new tricks!

Regards,
Wayne A. Pflughaupt

 

[Wayne A. Pflughaupt]

In my modest experience, the type of measurement has no effect on the result.

I guess I can see that. If my contention is true (in my room at least) that you can't hear an appreciable difference with program material from one seat on the couch to the next, it stands to reason that there wouldn't be a significant difference it the measurements either.

Regards,
Wayne A. Pflughaupt

 

[hyperplanar]

I guess I can see that. If my contention is true (in my room at least) that you can't hear an appreciable difference with program material from one seat on the couch to the next, it stands to reason that there wouldn't be a significant difference it the measurements either.

Regards,
Wayne A. Pflughaupt

I think the main benefit of MMM is the way that it continuously spatially averages the measurement in a much shorter period of time. It's like taking dozens of sweep measurements and averaging them, except you get the result in a minute or two.

 

[m_g_s_g]

Also, what exactly is the "movement?" Are you sitting in the MLP panning the mic from the left speaker to right? All movement in front of one of the speakers? Walking across the room between the two speakers

This video was recommended before in other threads and worked for me as well.

 

[Blumlein 88]

Thanks for that, I appreciate the info.

What happens after the 32 averages are finished? Does the screen freeze with the reading?

Also, what exactly is the "movement?" Are you sitting in the MLP panning the mic from the left speaker to right? All movement in front of one of the speakers? Walking across the room between the two speakers?

I'm an old coot, but I'm willing to learn new tricks!

Regards,
Wayne A. Pflughaupt

Once you start a signal to the RTA, it counts from 1 up to 32 for the averaging. Then it just keeps adding another average as it drops the oldest one so you have the 32 latest readings. Whenever you stop, the graph freezes. You then select save (little floppy disk emblem), and then it saves either current or peak or both depending upon your choice. I don't know if the old one did this or not, but recent versions of REW work this way.

With forever averaging it keeps a running average until you stop it. Hundreds if you let it go that far.

The video someone posted shows the movement. Research for use in theaters and live sound use either a circular movement rather slow or a figure 8 or a corkscrew pattern. As in they had ideas about what movement was best and tested it. Surprisingly the results are very nearly exactly the same if you cover about the same area with any of those patterns. I kind of like a tilted figure 8 myself.

 

[Blumlein 88]

Intended to post this in regards to MMM. I've seen some concern the movement creates noise.
In this graph you'll see the room noise with no test signal present for both right and left ear position as well as one where I moved the microphone between the two positions continuously. It does induce noise in the microphone, but at a level low enough it can have no effect on test signal results. 1/48th smoothing. Blue is the MMM result.

You'll see some 60 hz and 120 hz noise as the fridge was running. And a 100 hz noise I've never tracked down. It comes and goes at random.

 

[Snarfie]

* Music Playback - Foobar (no Roon or JRiver)
*

Did you ever tried Mathaudio room eq i find it quite comforteble over rew no need for convoltion or any other software to playback. You can change the amount of correction with a slider An use any target curve you want. Did a comparison with room perfect basicly the same only the cost was a big difference incombination with foobar Mathaudio is free of charge. Up & running in minutes without any indepth knoledge regarding room correction.https://mathaudio.com/room-eq.htm

Would be curious about your findings.

 

[Newman]

I assume it is IIR?

 

[patate91]

@mitchco do you plan to test and review mathaudio?

 

[mitchco]

@mitchco do you plan to test and review mathaudio?

Thanks @patate91 I will check it out...

 

[Erici]

Hey Mitch. I did a quick review of MathAudio a while back. I think it's a fast and free way to get somewhat better room EQ without knowing too much about the theory. It would be fun to hear your take on it if you have time!

https://www.audiosciencereview.com/...ar2000-mathaudio-and-the-infinity-r162.14582/

 

[Hipper]

Firstly thanks to everyone who has discussed Moving Mic Measurements (MMM). I'd never heard of the concept before.

I measure for my dedicated listening room with copious amounts of room treatment and I'm the only person listening so I don't mind measuring for one listening position. For that reason it seemed logical to measure using REW's sweep with the mic fixed in the position of the centre of my head. In the past I'd used my exact ear positions doing left and right measurements. The reason I now use the centre of my head and measure both speakers at the same time is that:

• My room is more or less symmetrical.
• I'm mostly concerned with the 0-300Hz range.
• Slight movements in the microphone position can affect the measurements.
• A mic will never exactly detect what my ears /brain hears.
• You can never get ruler flat graphs even if they are desirable. Smooth seems to be the main target.

Real accuracy is therefore impossible to achieve. All we can hope for is to get within one or two dB. As a result my procedure is that once I've implemented the filters for this range I listen with the Real Traps test tone CD (which covers the 10-300Hz range at 1Hz intervals). I then of course listen to music as the final arbiter.

Above 300Hz/400Hz, as Wayne A. Pflughaupt (post 20) and QMuse (post 28) point out, I would only adjust more generally with a wider range of frequencies (lower Q. Does anyone else not like this term Q (quality) and the way it is used when discussing EQ?).

I still get differences if I move my head sideways or forwards, and particularly when I dip my head so the angle of my ears in relation to the speakers is altered. This latter effect is most obvious in the higher frequencies, namely 2kHz and 8kHz. I can't see that any form of measurements will prevent this, particularly as the 2kHz effect is probably to do with speaker crosstalk and their comb filtering (see Toole, Sound Reproduction, p159 onwards).

On the subject of noise when using MMM, presumably the concern is the mic detecting the air movement as it is moved around, like wind on a static mic. I notice on the video linked by m_g_s_g (post 44) they use a foam covering on the end of the mic which is presumably designed to deal with wind effects.

Anyway, next time I do some measuring I'll see what the MMM procedure can bring.

 

[dasdoing]

whenever I take various meassurements a little around my perfect head position the average turns out to be the same as the meassurement at the perfect LP lol.
It makes sense for averaging the sound for 3 LPs, but not for 1.

 

[Pio2001]

Hi,
I always perform an MM Measurement although I only use one listening position, because I have some peaks in the frequency response around 200 Hz and above, and these peaks are very sensitive to the exact microphone position.
With MMM, I can have an average and avoid over-correcting some parts of the frequency response.