Room acoutics issue 300-3000Hz

[ChristianN]

Could be something up with the microphone, especially >8 kHz. Try measure the speakers away from boundaries, reduce gating to 5 ms.

Hi ok,
Moved right speaker to the middle of the room, did three single measure on axis and one left and right +-15 degress, gaited at 5ms and smoothed with 1/6 octave. seems that evened out things, but the dip is still there allthough now 500-2000Hz and a peak still around 4,5Khz

 

[Thomas_A]

Hi ok,
Moved right speaker to the middle of the room, did three single measure on axis and one left and right +-15 degress, gaited at 5ms and smoothed with 1/6 octave. seems that evened out things, but the dip is still there allthough now 500-2000Hz and a peak still around 4,5KhzView attachment 185831

Hm, something is not correct here. I have no good ideas. What happens if you increase microphone distance to 1,5 meter?

 

[ChristianN]

Here are my simple settings from another software; half Hamming, 7 ms duration, speaker at its nominal "position" near wall, about 1 meter from the speaker, 200 Hz-20 kHz, no smoothing. Left and right.

View attachment 185830

That seems like what is to be expected. much more linear

 

[ChristianN]

Hm, something is not correct here. I have no good ideas. What happens if you increase microphone distance to 1,5 meter?

Hi its more or less the same, see graph orange trace. I think I will try to see if there is another source of err. by swiching laptop ( maybee there is some adjustments going on there that Im unaware off) or preamp.

I also tried with/without calibration file, but is has almost no effect.

 

[Thomas_A]

The x-over is 430 Hz and 3500 Hz. I don't know what is going on with your mid driver or x-over at 430 Hz. To see it seems something wrong with the x-over, bass being "broken" that interferes with the mid.

 

[ChristianN]

The x-over is 430 Hz and 3500 Hz. I don't know what is going on with your mid driver or x-over at 430 Hz

Trying to see if there is some errors here. I used a Jabra conference speaker/mic, it cut of at 8Khz, and is not meant for this purpose, but just to see. and it seems to get a much more linear response, which could point to the UMIK. See purple graph.

 

[Thomas_A]

Trying to see if there is some errors here. I used a Jabra conference speaker/mic, it cut of at 8Khz, and is not meant for this purpose, but just to see. and it seems to get a much more linear response, which could point to the UMIK. See purple graph.
View attachment 185834

Looks more reasonable. Something with measurement setup here.

 

[ChristianN]

Looks more reasonable. Something with measurement setup here.

Hmm, yes, the mic is a few years old, maybe it looses calibration. Guess i need to re-calibrate somehow or buy an UMIK-2 which should have individual cal files

 

[Thomas_A]

Hmm, yes, the mic is a few years old, maybe it looses calibration. Guess i need to re-calibrate somehow or buy an UMIK-2 which should have individual cal files

I actually don't have any idea about what is going on, but given your different results with another microphone, it must be something weird in the test setup.

 

[abdo123]

I was just about to comment about the microphone, definitely a setup issue.

There are bad rooms but not this bad.

 

[puppet]

Put loudspeaker on a stool and remeasure.

 

[DJBonoBobo]

Are you sure REW is using the correct device? I once had a very strange FR in REW and worked on it for hours until i noticed it had used the mic of my webcam for the measurement instead of the measurement mic...

 

[ChristianN]

Are you sure REW is using the correct device? I once had a very strange FR in REW and worked on it for hours until i noticed it had used the mic of my webcam for the measurement instead of the measurement mic...

Hi yes, I did check that. Thats how i found out my Jabra conference speaker works as well

 

[ChristianN]

Put loudspeaker on a stool and remeasure.

I could try that, or even lay it down so no drivers are close to the ground. But now im getting worried that the mic is not working as expected, but will give it a shot tomorrow.

 

[puppet]

Just try raising it up ... I'm still curious about the mid range combined floor/ceiling effect here.

 

[DWPress]

Also, verify with a MMM method. It's even easier to do than sweeps.

 

[ChristianN]

Put loudspeaker on a stool and remeasure.

Hi

I did some more measurement, but they show the same phenomenon. I used the Umik1 from before, but also a Sony mic, they agree up until 10Khz, which should verify that they agree that there is an issue 400-2000Hz. Here are the measuresment taken 1m away, with speaker on the floor and elevated 50 cm. just Umik measurement floor and elevated, note the scales are not the same on the graphs.

Then i did the same exact same thing but from another laptop, same mic, same cal file, same REW, same external soundcard. and they agree more or less, but the other laptop see the high frequencies much lower, so not sure what to make of that:

 

[ChristianN]

Also, verify with a MMM method. It's even easier to do than sweeps.

Hi
Im not familiar with MMM, so used this link, which seems to describe it?

REW-Moving Microphone Method Help

Hello. I have used REW some but saw that some people use a moving microphone method to get a quick spacial average. The video I watched made it look quick and easy. I was able to to fumble my way through partially, but the graph doesn’t look like frequency response. Anyone know the steps to get...

www.audiosciencereview.com

The result are as follows and quite different from the sweeps, Taken with UMIK1 1m away, on an single elevated speaker.

So what does that mean, shouldnt sweeps and this method produce the same respons ?

 

[Thomas_A]

Hm, I am back to that this is speaker related. Do you have another speaker measured 1 m with same gating?

What height is the microphone? Tweeter or midrange or between them?

 

[ChristianN]

Hm, I am back to that this is speaker related. Do you have another speaker measured 1 m with same gating?

What height is the microphone? Tweeter or midrange or between them?

Hi
The Mic was placed at the same height at the midrange driver which was 1m when standing on the floor

Here is a measure from a Dali Rubicon LCR, elevated 50 cm, 1m distance, gated at 1-5ms, standing at the same spot. its a much smaller speaker though.