REW problem. High frequencies are cut no mather what I do

[valtra103]

Hi.
I have problem with REW, but only on laptops. I want basic 20-20Khz sweep. So I set it up, run it, I clearly hear it going to the high frequencies.
Then I look at results and for some reason one laptop rolls off everything over 6Khz (lets call it i7), and very old laptop rolls of at 7khz.


Desktop PC works fine to 20-20khz, no problems.
TWO laptops only go to 6 and 7khz.
I used that i7 laptop for measurements some time ago. And it was fine.
Mic is WM61A S.L. recipe. But i cant imagine how it would decide to perfectly destroy high frequencies ONLY on two laptops I tried, but still work fine on desktop. So I am sure that mic is fine.

Since I can hear sweep going way above 7khz (my ears are capable of almost 18Khz), then it must be something with inputs on those laptops. But i7 was fine all the time. Old one I dont know, I just tried it only because this isue.
i7 - Win10
old one - WinXP

This is extremely anoying and ruins everything, since i cant just carry 15kg desktop PC around

I tried to describe the problem as good as I can. Sorry if I reapeated myself
Photos for ilustration:


IMG-20200528-173541 — ImgBB
IMG-20200528-173831 — ImgBB
IMG-20200528-173915 — ImgBB
IMG-20200528-173929 — ImgBB
Desktop PC works fine:
[url]https://ibb.co/YjsZNWY
[/URL]

 

[Boden]

What soundcard are you using with the laptops?

 

[wgh52]

@ valtra103

Please consider the fact that NotebookPC's internal sound solutions are often not very wide band and not very linear. My suspicion is that the Notebook's internal sound solution "quality" is insufficient for measurements, while it is still OK for a Skype Call . This has led me over the yewars to only use external sound solutions (USB) which are known good and linear together with a calibrated measurement microphone. Yes: This approach is not cheap! But "garbage" is avoided this way.

Have you performed a closed loop calibration of your complete measurement set up and are the resulting data used in REW?
Is the Microphone calibrated and are the calibration data used in REW?

Greetings,
Winfried

 

[Pano]

Also, can you do a loop back into the line input? Or at least run line level from on laptop to the other? That might tell you if it's the mic input doing something strange. Line level might give you a flat response.

And FWIW, I have gotten strange results before only to discover that the internal mic was active! Worth a check.

 

[valtra103]

What soundcard are you using with the laptops?

None, just Mic / Line in jack

Also, can you do a loop back into the line input? Or .

And FWIW, I have gotten strange results before only to discover that the internal mic was active! Worth a check.

I will try loopback. My laptops have no internal micss.

@ valtra103

Please consider the fact that NotebookPC's internal sound solutions are often not very wide band and not very linear. My suspicion is that the Notebook's internal sound solution "quality" is insufficient for measurements, while it is still OK for a Skype Call . This has led me over the yewars to only use external sound solutions (USB) which are known good and linear together with a calibrated measurement microphone. Yes: This approach is not cheap! But "garbage" is avoided this way.

Have you performed a closed loop calibration of your complete measurement set up and are the resulting data used in REW?
Is the Microphone calibrated and are the calibration data used in REW?

Greetings,
Winfried

But like i said, it was fine before. It was working 20-20khz fine with laptop. And some time ago i did loopback it was flat like ruler and less than 0.05thd. I wasn't measuring anything for like half year. And now have this. MIC is not calibrated, but they are quite good without it. Good enough for S.Linkwitz. So plenty for me. I don't care about 1-3dB iregularities over 15khz, they tend to have. And no calibration would fix this, it is just nothing over 7khz, I dont believe that calibration could be 50+dB gain which would rise top end. That just sound unreal.
And my desktop pc works fine for measuring so theres nothing wrong with mic.

I forgot about loop back. I will do it again, and post an update.
Thanks for help guys.

 

[valtra103]

Yeah. Loopback shows the problem. I wonder what messed it up. It was like ruller in 2019. Now response looks like this
Still -90dB noise floor though.

Imgur: The magic of the Internet


EDIT:
Found 2euro usb sound card lying around. Did loopback and card calibration. Will try measuring like this. Distortion is now is 0.2% which is quite bad. But I can always buy better card.
I still wonder why laptop decided to do that thing. It was fine all the time. Almost feels like something to do with drivers or windows 10 crap. Would not be the first time when "features" cause problems.

4 — ImgBB

 

[Boden]

Is there a sound panel/mixer of sorts in your laptop? Maybe you changed settings and have some hi cut applied now.

 

[valtra103]

Is there a sound panel/mixer of sorts in your laptop? Maybe you changed settings and have some hi cut applied now.

No just basic realtek stuff with few settings. Couldn't find anything suspiciuos. Last time after update windows just decided to disable my mic. And it is in privacy section not in anything to do with audio. Maybe some random crap again in some random settings and I cant find it because it is not logical.

 

[42476]

@ valtra103

Please consider the fact that NotebookPC's internal sound solutions are often not very wide band and not very linear. My suspicion is that the Notebook's internal sound solution "quality" is insufficient for measurements, while it is still OK for a Skype Call . This has led me over the yewars to only use external sound solutions (USB) which are known good and linear together with a calibrated measurement microphone. Yes: This approach is not cheap! But "garbage" is avoided this way.

Have you performed a closed loop calibration of your complete measurement set up and are the resulting data used in REW?
Is the Microphone calibrated and are the calibration data used in REW?

Greetings,
Winfried

Hi all; I am looking to get a microphone for use with REW (I have never used it before). Some people say the USB microphones are not all that good.

Are there specific recommendations?

I am looking into these:

PRM1 | PreSonus

connected to this:

UR12 | Steinberg

I understand that having a microphone with phantom power would most likely be of a higher quality than USB alone.

EXPERIENCES???

RECOMMENDATIONS???

I want something fairly low noise and fairly accurate; I am willing to spend up to about $250 US or so for a mic, decent stand, pre-amp/power supply, etc.

Or; would I be better off getting the PE Dayton kit:

Dayton Audio OmniMic V2 Acoustic Measurement System

Thanks!

 

[Lojzek]

Dayton emm-6 is being offered with a calibration file, which is a fair deal. Usb microphones come with their own electronics. I have built once a measurement microphone out of a Panasonic wm 61 cartridge, used a metal pencil body as enclosure, worked flawlessly and I know that because I compared it to a Clio mic that I bought as a kit. There is still cartridges from Monacor for the job, but I have not tested any of them yet.

 

[chris661]

My argument against USB microphones is entirely practical: USB cables tend to be relatively short. XLR cables can be a few hundred metres long with no ill effects and while the average DIYer won't need to have the mic that far away, 3-10m is entirely feasible.

A USB audio interface also allows the user to perform impedance measurements, which is very useful.

Chris

 

[42476]

Dayton emm-6 is being offered with a calibration file, which is a fair deal. Usb microphones come with their own electronics. I have built once a measurement microphone out of a Panasonic wm 61 cartridge, used a metal pencil body as enclosure, worked flawlessly and I know that because I compared it to a Clio mic that I bought as a kit. There is still cartridges from Monacor for the job, but I have not tested any of them yet.

I have the EMM-6 on order; I'll be using it with a M-Audio interface; also on order.

Some others got back to me elsewhere; thanks for the inputs and advice!