Tech Tuesday: Deep Dive into Room Correction

I wanted to share my experience in room correction so far- objective being to tame my shouty and bright b & w 706 s2 . I have the Wiim only for a week and tinkered with it on the weekend using iPads Mic from my listening position . When I give the frequency range quite wide , e.g., say 20 hz to 20 kHz, the Wiim is having only 10 parameters available and it gave mainly fixes on the bass via room correction. Since my problem is coming from higher frequencies it didn’t really solve my problem . So i clicked pics of the frequency curves Wiim room correction generated and also independently got a frequency curve from a reviewer who had uploaded it online . I uploaded all these curves into ChatGPT and got it to give peq for shouty and bright speakers . Post that it was listening and giving feedback to ChatGPT for further tinkering which gave me workable peq parameters . Will evaluate this over a week and see how it sounds .
 
I don't see any more the option to save the PEQ settings under a different name...
Is it me?
 
If you choose a frequency range for room correction of for example 20-300Hz and a target curve, then the algorithm needs to be able to match the level of the corrected range to the uncorrected level of the response above 300Hz so the overall result fits the target curve. I wonder how the target level is chosen by the WiiM algorithm. Presumably microphone inaccuracies outside the chosen correction range will affect overall result.

With REW you can choose the target level by manually moving the target curve until the high frequencies match the curve as closely as possible. REW can also calculate what it thinks is the best target level but it doesn't often get it right.
 
IMHO, another issue to consider arises in the independent correction of the left and right channels and concerns the presence of an imbalance in the level of the two channels.

Let’s assume that the frequency response of both channels is perfectly identical, but the right channel is two decibels lower in level.

In this case, if the levels of the two channels are balanced using the balance control before performing equalization, the equalization process will be identical for both channels. As a result, the equalized frequency response will remain perfectly identical.

However, if the imbalance is not corrected beforehand, the equalization algorithm will attempt to compensate for the level difference between the two channels. Since it can only use the ten available filters, this will lead to an unnecessarily different frequency response between the two channels.

How does the WiiM room correction algorithm prevent this issue (if it does…)?
 
slartibartfast said:
If you choose a frequency range for room correction of for example 20-300Hz and a target curve, then the algorithm needs to be able to match the level of the corrected range to the uncorrected level of the response above 300Hz so the overall result fits the target curve. I wonder how the target level is chosen by the WiiM algorithm. Presumably microphone inaccuracies outside the chosen correction range will affect overall result.
Click to expand...
That's exactly what I think is one core problem at the moment and the reason that we see things like e.g. this:

IMG_20250216_122342.jpg

A +4 dB "Peak" filter with a Q of just 0.1! What this really does is simply boosting almost the entire frequency range chosen for correction (33 Hz to 3300 Hz in this case). Let's watch this isolated from the other filters:

IMG_20250216_122410.jpg

This is from a stereo "calibration". I'm pretty sure that an incorrectly determined average SPL is the root cause. In particular it looks like the typical silly peak between 8 kHz and 16 kHz found with most smartphone measurements might have been taken into account, although it is far outside the correction range.

I still have to think about how independent L/R "calibration" can be affected under different conditions. How likely is a full range channel imbalance of e.g. 2 dB? I agree that this should be taken care of first, but how should automaiRC approach this? A sort of imbalance over a wide frequency range (but not necessarily the full range) is probably more likely.
 
harkpabst said:
That's exactly what I think is one core problem at the moment and the reason that we see things like e.g. this:

View attachment 17318

A +4 dB "Peak" filter with a Q of just 0.1! What this really does is simply boosting almost the entire frequency range chosen for correction (33 Hz to 3300 Hz in this case). Let's watch this isolated from the other filters:

View attachment 17319

This is from a stereo "calibration". I'm pretty sure that an incorrectly determined average SPL is the root cause. In particular it looks like the typical silly peak between 8 kHz and 16 kHz found with most smartphone measurements might have been taken into account, although it is far outside the correction range.

I still have to think about how independent L/R "calibration" can be affected under different conditions. How likely is a full range channel imbalance of e.g. 2 dB? I agree that this should be taken care of first, but how should automaiRC approach this? A sort of imbalance over a wide frequency range (but not necessarily the full range) is probably more likely.
Click to expand...
WiiM's way of using shelf filters without using shelf filters 😂
 
harkpabst said:
I still have to think about how independent L/R "calibration" can be affected under different conditions. How likely is a full range channel imbalance of e.g. 2 dB? I agree that this should be taken care of first, but how should automaiRC approach this? A sort of imbalance over a wide frequency range (but not necessarily the full range) is probably more likely.
Click to expand...
Two approaches come to my mind:
  1. Calculating the room correction after the balance control.
  2. Allowing the "zero level" to be set independently for each channel.
That said, aside from this specific case, I’d be curious to know, more generally, at what frequency the algorithm sets the "zero level," both in the case of stereo correction and in the case of independent correction for the two channels.
 
Just got a updated WiiM Home App. In the release notes I see this!

"External Microphone Calibration File: Import calibration files for improved Room Correction accuracy."

But no further instructions seems to be available.1000004129.jpg
 
hgo58 said:
Just got a updated WiiM Home App. In the release notes I see this!

"External Microphone Calibration File: Import calibration files for improved Room Correction accuracy."

But no further instructions seems to be available.View attachment 17324
Click to expand...


I believe that version might also be a rushed release to provide a workaround for a beta firmware version for the ultra for the Spotify Connect issue some are facing, as I posted earlier
 
hgo58 said:
Just got a updated WiiM Home App. In the release notes I see this!

"External Microphone Calibration File: Import calibration files for improved Room Correction accuracy."

But no further instructions seems to be available.View attachment 17324
Click to expand...
It didn't show up in an update check but when I searched for the WiiM app it was available.
 
hgo58 said:
Just got a updated WiiM Home App. In the release notes I see this!

"External Microphone Calibration File: Import calibration files for improved Room Correction accuracy."

But no further instructions seems to be available.View attachment 17324
Click to expand...
If you plug a mic in then some new settings appear in "Room Correction" settings 😃
Screenshot_20250216-153833.png
 
I compared the WiiM room correction with the Room Perfect function of my Lyngdorf amp… the result was not surprising for me as you may guess… using a phone and doing one measurement from one position simply is not satisfying.
 
Suntoucher said:
I compared the WiiM room correction with the Room Perfect function of my Lyngdorf amp… the result was not surprising for me as you may guess… using a phone and doing one measurement from one position simply is not satisfying.
Click to expand...
Were you using the phone mic? If so I am not surprised at all.
 
Suntoucher said:
I compared the WiiM room correction with the Room Perfect function of my Lyngdorf amp… the result was not surprising for me as you may guess… using a phone and doing one measurement from one position simply is not satisfying.
Click to expand...
RoomPerfect is on an entirely different level, but that doesn't make WiiM room correction useless. Good to see some progress regarding the cal file import. (y)

Bismarck said:
BTW, what does "Gain: 18db" mean
Click to expand...
That should simply be a part of the device name.
 
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