RoomFit is very good - my experience and settings

[dominikz]

Quick question: Should the microphone be pointed directly at each speaker, or kept in the sweet spot for both channel measurements?

If you only apply RoomFit at low frequencies (which I'd recommend) mic orientation is basically irrelevant.

If you'd like to EQ higher frequencies as well, or if you just want to be as precise as possible, I'd advise to put the mic in the sweetspot, point it up to the ceiling, and use the 90° mic calibration file. This way the mic response is identical (and correct) for sounds coming from all directions in the horizontal plane.

 

[harkpabst]

At least with the UMIK-1 and UMIK-2 the 90 deg calibration file introduces one more potential source of error, since it's just calculated, not measured.

After reading (I won't call it researching) many arguments of true experts (much more knowledgeable than me) I've settled for pointing the mic straight when doing swipes in 2 channel systems. Even with the moving microphone method (applied over a larger area) I'd prefer varying the microphone angle over vertical.

From my point of view the situation is quite a bit different from the typical multi-channel measuring procedure where most systems try to automatically determine the distance to each speaker from one MLP.

But as always, YMMV.

 

[dominikz]

At least with the UMIK-1 and UMIK-2 the 90 deg calibration file introduces one more potential source of error, since it's just calculated, not measured.

After reading (I won't call it researching) many arguments of true experts (much more knowledgeable than me) I've settled for pointing the mic straight when doing swipes in 2 channel systems. Even with the moving microphone method (applied over a larger area) I'd prefer varying the microphone angle over vertical.

From my point of view the situation is quite a bit different from the typical multi-channel measuring procedure where most systems try to automatically determine the distance to each speaker from one MLP.

But as always, YMMV.

Let me start by repeating that for the purpose of room correction at low frequencies measurement microphone orientation is IMHO irrelevant, so any approach works just as well.

This means that this discussion is largely academic - but perhaps still interesting to some!

Let's first remember that measurement microphones are omnidirectional at low frequencies but become more directional at higher frequencies.

Therefore:

• If we use the 90° calibration curve the mic will capture any sound coming from its sides with a flat spectrum, sound coming at the front will have some HF boost, and sound coming from behind the mic will have some HF attenuation (compared to flat). So if you point the microphone vertically to the ceiling, direct sound, side-, front- and back-wall reflections will all be registered with the correct spectrum by the microphone as the will all hit it at the sides! Ceiling reflection will have some HF boost coming at the front of the mic, and floor reflection will have some HF drop coming from its back, but this is a smaller part of the total captured sound so the total balance of the in-room response should be roughly correct.
• If we use the 0° calibration curve only the sound coming from the front of the mic will be registered with a fully flat spectrum, while sounds coming to the mic from any other direction will exhibit some amount of HF attenuation. So if we point the microphone horizontally between the speakers, most of the horizontal or vertical reflections will be captured with some HF roll-off, resulting in some (relatively minor) HF loss in the total measured in-room response.

This is something I noticed experimentally as well - when doing MMM with vertical mic orientation and 90° cal file I get a slightly higher response at the highest frequencies, compared to pointing the mic horizontally and using a 0° cal file.

In addition, IME MMM measurements with mic in vertical position and 90° cal file track the anechoic PIR very closely at high frequencies, here's one example:

 

[harkpabst]

This degree of correlation between MMM and Klippel PIR is surprisingly good, indeed.

Did you try and compare it to a 0⁰ measurement? Either strictly horizontal or pointing at different angles, as I lightheartedly proposed?

 

[dominikz]

This degree of correlation between MMM and Klippel PIR is surprisingly good, indeed.

Did you try and compare it to a 0⁰ measurement? Either strictly horizontal or pointing at different angles, as I lightheartedly proposed?

Not sure TBH, as it was a while ago since I looked into this.
There's some potentially interesting (though inconclusive) examples in this post, but it's not MMM and there's no comparison with PIR.
Perhaps I'll test this again when I find some time.

 

[Mr Ee]

I don't quite understand the difference.

"Should the microphone be pointed directly at each speaker, or kept in the sweet spot"

Say you are equilateral to each speaker, I'm pretty sure it means should the mic be pointed 30° left then 30° right to point at each speaker or just pointing straight ahead.
Maybe immaterial for those with fancy omnidirectional microphones

 

[harkpabst]

"Should the microphone be pointed directly at each speaker, or kept in the sweet spot"

Say you are equilateral to each speaker, I'm pretty sure it means should the mic be pointed 30° left then 30° right to point at each speaker or just pointing straight ahead.
Maybe immaterial for those with fancy omnidirectional microphones

Yes. That's why I wrote:

When doing independent left and right room correction, pointing the mic to the speaker in question or straight between the speakers will make ~0 difference.

 

[Mr Ee]

@harkpabst
You know I skim read all those long posts on room correction...
But as I'm thinking about adding a subwoofer later this year ( ) maybe I'll have a reason to go back and avail myself of your wisdom, and maybe even get one of those microphone thingies!
Prepare yourself for an onslaught of Rookie questions. Although I'm possibly just as likely to say 'that sounds better, all done here".

 

[Burnside]

@harkpabst
You know I skim read all those long posts on room correction...
But as I'm thinking about adding a subwoofer later this year ( ) maybe I'll have a reason to go back and avail myself of your wisdom, and maybe even get one of those microphone thingies!
Prepare yourself for an onslaught of Rookie questions. Although I'm possibly just as likely to say 'that sounds better, all done here".

Me too…

 

[dominikz]

Did you try and compare it to a 0⁰ measurement? Either strictly horizontal or pointing at different angles, as I lightheartedly proposed?

I tried it today, at two distances - at about 150cm from the loudspeaker and at about 80cm:



In all cases there's virtually no differences below about 6kHz. Which is why IMHO mic orientation is pretty much irrelevant for the purpose of room correction.

At 80cm measurement distance there's practically no difference even above 10Khz - which I suspect is due to the higher direct-to-reflected sound ratio in nearfield.
At 150cm measurement distance there's a bit more difference above 6kHz, presumably due to the higher influence of reflected sound (and IMHO in line with this explanation). Still not very dramatic (it is at most about 1,5 to 2dB >10kHz).

If I find more time I may try a similar test in my other room as well - there I can measure a bit further away.

 

[Machiavelli]

question for the fitters. there are situations with no chance for sitting in the sweet spot in my 'office'. it then has a 2:1 relation. (hope that is understandable). means sitting nearer to the left speaker. until today i use the balance slider. which is fine. the old way. means listening with closed eyes to a mono signal and slide to my inner middle. omm . should i do an extra roomfit for this with this balance applied? no subwoofer in the setup.

 

[dominikz]

question for the fitters. there are situations with no chance for sitting in the sweet spot in my 'office'. it then has a 2:1 relation. (hope that is understandable). means sitting nearer to the left speaker. until today i use the balance slider. which is fine. the old way. means listening with closed eyes to a mono signal and slide to my inner middle. omm . should i do an extra roomfit for this with this balance applied? no subwoofer in the setup.

The channel level difference in this kind of asymmetric listening spot should be fixed with the balance control, regardless whether you use RoomFit or not. This is simply the correct tool to use for this task.

However, even with optimal channel level balance it might still make sense to save separate RoomFit profiles for the sweet spot and for this alternative listening spot.
This is not because of the channel level difference, but because the room will most probably introduce a significantly different pattern of acoustic interference at the two locations.

You can see one example of this in the post above yours - the peak/dip pattern of the same louspeaker is quite different when measuring at 80cm vs 150cm.

By creating a corresponding RoomFit profile for each listening spot you should be able to achieve a much more similar tonal balance at both listening positions.

Hope this helps!

 

[Machiavelli]

The channel level difference in this kind of asymmetric listening spot should be fixed with the balance control, regardless whether you use RoomFit or not. This is simply the correct tool to use for this task.

However, even with optimal channel level balance it might still make sense to save separate RoomFit profiles for the sweet spot and for this alternative listening spot.
This is not because of the channel level difference, but because the room will most probably introduce a significantly different pattern of acoustic interference at the two locations.

You can see one example of this in the post above yours - the peak/dip pattern of the same louspeaker is quite different when measuring at 80cm vs 150cm.

By creating a corresponding RoomFit profile for each listening spot you should be able to achieve a much more similar tonal balance at both listening positions.

Hope this helps!

thank you very much

 

[slartibartfast]

The channel level difference in this kind of asymmetric listening spot should be fixed with the balance control, regardless whether you use RoomFit or not. This is simply the correct tool to use for this task.

However, even with optimal channel level balance it might still make sense to save separate RoomFit profiles for the sweet spot and for this alternative listening spot.
This is not because of the channel level difference, but because the room will most probably introduce a significantly different pattern of acoustic interference at the two locations.

You can see one example of this in the post above yours - the peak/dip pattern of the same louspeaker is quite different when measuring at 80cm vs 150cm.

By creating a corresponding RoomFit profile for each listening spot you should be able to achieve a much more similar tonal balance at both listening positions.

Hope this helps!

My normal listening position is directly in front of the right speaker despite the fact that if I sat at the other end of the same sofa I would be in the sweet spot between the speakers. I suppose I could make a profile for that position after adjusting the balance but so far I have never felt it necessary. I should really sit at the other end of the sofa more to even out the wear

 

[dominikz]

My normal listening position is directly in front of the right speaker despite the fact that if I sat at the other end of the same sofa I would be in the sweet spot between the speakers. I suppose I could make a profile for that position after adjusting the balance but so far I have never felt it necessary. I should really sit at the other end of the sofa more to even out the wear

IME the difference in response between different seats can be quite large or almost insignificant, depending on the situation.

E.g. in my living room the main peaks in the response are similar across the whole sofa (3 seats). So I just calibrate for the middle seat and accept the minor variation if I sit elsewhere. The distance from middle seat to each speaker is about 2,3m.

But on my desktop system the response changes significantly if I move the mic even just 70cm. The distance from my head to each speaker is about 80cm.

 

[dominikz]

If I find more time I may try a similar test in my other room as well - there I can measure a bit further away.

Managed to do this today, as expected the results again show slightly more high-frequency content with the vertical mic orientation:

This is a different set of speakers so the response is slightly different than before.

 

[Musician]

I always have a problem with this calibration. It's better on the iPad than the iPhone, but it's still weak. It cuts my bass all the time. The sound is made as if I put a blanket on the speakers. Without life.

Some unorthodox trick:
Try using correction settings 100 Hz - 4000Hz . Harman target, 1/6 dB smoothing.
This way , you have nice corrections at the very sensitive 100-600 Hz area ( including SBIR ) but none at all in the bass. This might give you a good result that you like with more bass. The Harman research says that most people want +6 to +9 dB shelving below 100 Hz . The roomgain will give you this ( or even more ) .

Or: …. Correct 20-4000 Hz and save the results, go in manually using PEQ and print only half the dB values of the automatic room correction for frequencies between 20-200 Hz.

I use the very linear Line audio om1 measurement microphone and Audientid14 interface . This gives a better result than my iPhone.

 

[hgo58]

Some unorthodox trick:
Try using correction settings 100 Hz - 4000Hz . Harman target, 1/6 dB smoothing.
This way , you have nice corrections at the very sensitive 100-600 Hz area ( including SBIR ) but none at all in the bass. This might give you a good result that you like with more bass. The Harman research says that most people want +6 to +9 dB shelving below 100 Hz . The roomgain will give you this ( or even more ) .

Or: …. Correct 20-4000 Hz and save the results, go in manually using PEQ and print only half the dB values of the automatic room correction for frequencies between 20-200 Hz.

I use the very linear Line audio om1 measurement microphone and Audientid14 interface . This gives a better result than my iPhone.

RoomFit is not about getting the right sound profile, it's about eliminating room issues and those are primarily in the bass.

The sound profile can be defined by the PEQ/GEQ after the room correction.

 

[Musician]

See a recent Reddit post below - I don’t know exactly how the curves were derived, but they attempt to compare iPhone, iPad and UMIK-1 microphones. I was surprised at the similarity, but UMIK-1 response appears flatter, and the difference is largest below 50Hz. Is the problem that iPhone and iPad mics just aren’t suitable for bass correction?

https://www.reddit.com/r/BudgetAudiophile/comments/1mr2ze1/macbook_iphone_airpods_compare_to_umik1_in_rew

As dominikz already wrote, the scale of those measurement is 300dB . Standard is to use 50dB. If the measurements of the different microphones are done at exactly the same spot ( I doubt it ) , the differences between the different microphones are huge.

Best way to have better sound using the room correction - buy a good microphone.

Regarding the multiple moving mic measurements , one has to decide if you always listen in sweetspot or not. A single measurement exactly at sweetspot is better than using multiple moving mic if you gonna listen at that spot.

Using multiple measurements on different places is compromises supposed to bring a wider useable listening area, and if one are unlucky can bring worse result at sweetspot than a single measurement.