# Measurement issues



## n0m0ney (Jul 23, 2009)

Hi guys!

Sorry for the title, but i couldn't think of anything else.

I'm fairly new to REW and just started using it. I think it's great!

First i used my cheap large diaphram condenser microphone to do the measurements. It went great, even though the measurement wasn't really reliable. So a few weeks later i got the Behringer ECM8000 microphone(which most people here use i guess?), but now i get the message "Impulse peak is not where it should be, the measurement may have been corrupted. Check the impulse respone and the captured data plots.".

The measurement starts, everything looks good. But the 1M measurement takes about 8-10 seconds and only gets about 50-70% into the test. Then i get this message.

I searched this forum, but the problem seems to be a Mac issiue, and i use PC Windows XP.

Any solutions anywhere? I've spent the entire night yesterday to figure out the problem. But got nowhere.

Argh, i wish i could post the links to the pics and vid i got, but i'm a new member. :foottap:

/ Daniel


----------



## brucek (Apr 11, 2006)

> Behringer ECM8000 microphone


What mic preamp are you using?

brucek


----------



## n0m0ney (Jul 23, 2009)

Hi Brucek!

I use the internal in the Mackie Onyx Satellite. I haven't had any issues with it earlier.

/ Daniel


----------



## brucek (Apr 11, 2006)

When you run the Check Levels routine, are you able to set a correct level on the input VU meter in REW?

brucek


----------



## n0m0ney (Jul 23, 2009)

Yes, i start of by setting my speakers at a good level. I've heard that 75 db is every day normal level, not too loud and not too low. So i did, and then i set my input level until i have about -18dbfs in the input, like it says in the help box.

Thank!
/Daniel


----------



## brucek (Apr 11, 2006)

Mmmm, I was going to suggest that you do have to be using WDM drivers. I don't know what drivers your firewire 1394 interface uses. Java (which REW uses) only supports WDM drivers for audio under Windows, not ASIO. So you have to ensure the card uses WDM drivers (if available).

But, if you're able to set up the input and output levels, the drivers probably OK, so I'm a bit confused why your levels return a poor impulse response.

Be sure that you're using the appropriate test signal in the Check Levels setup. i.e. subwoofer test signal for 0-200Hz measurement, and Mains test signal for full range measure.

Does the sanity check Check Levels in the Measure screen popup return a proper level?

BTW, try -12dB rather than -18dB for your input level in REW.

Also be sure all your monitoring capabilities are shut off.

Were you able to perform the soundcard calibration without any problems and get a good cal file?

brucek


----------



## n0m0ney (Jul 23, 2009)

But i used this card before(a couple of weeks ago) with the other ldc mice and that worked fine? 

I just tried the subwoofer test signal, but still the same result.

Yes, the sanity check says "Level Ok -15,9db".

I will try that.

Thanks for your help!

Edit: Nope, still the same result with -12dbfs.

This is the vid i made:





no sound because i couldn't record the sound meanwhile i measured.

/ Daniel


----------



## brucek (Apr 11, 2006)

For the majority of the sweep, the input signal is very low. Only near the end is the signal acceptable. What are your measure screen limits (i.e. 200 - 2000Hz)?

You never answered, "Were you able to perform the soundcard calibration without any problems and get a good cal file?" If so, may I see the graph of the file.

BTW, are you using the ECM8000 cal file from our download site?

brucek


----------



## n0m0ney (Jul 23, 2009)

Hi again!

EDIT: That test in the vid was between 20 and 300 hz, that explains the start with the low output in the beginning.

I'm doing a test between 50 hz to 300 hz. I'm using Adam a5, and those speakers are not very good at producing low end, so i started at 50 hz. My measure screen limits are 20 hz to 300 hz.

Yeah, here it is:
http://img39.imageshack.us/img39/1111/mackieonyxsatellitecali.jpg

No problems what so ever.

Yes, i am using the ECM8000 calibration file.

I'm starting to think that this is a bug or some sort. Maybe colliding with another process that is making the program to act wierd. I've tried to reinstall REW and my soundcards latest drivers, but with no luck. I'm starting to think that i may have to format my computer, since the tests worked perfectly a couple of weeks ago.

/ Daniel


----------



## brucek (Apr 11, 2006)

Yeah, the soundcard cal is fine.... Too weird.

I guess you've tried shorter sweeps rather than the 1 M.

Did you try the REW pulldown Settings and select "Delete Settings and Shutdown". That can often remove something stuck in its brain......

brucek


----------



## n0m0ney (Jul 23, 2009)

Yeah, but that calibration was made before this happened, and i just tried to make another calibration. But the same thing happens here as with the mic calibration! :foottap: 
"Impulse peak is not where it should be, the measurement may have been corrupted. Check the impulse respone and the captured data plots."
Now i'm really angry :yay:

Yeah, i've tried every length there is.

I tried to do the delete settings and shutdown, but the same thing happens.

I've tried to install REW in another map, but i have the same issue there. 
Another thing might worth mentioning, is that recording in Cubase and other programs works fine! 

/ Daniel


----------



## brucek (Apr 11, 2006)

Do you perhaps have some sample rate conversion being carried out somewhere. Try the opposite of what you have selected now. i.e set it to 44.1K if you have 48K selected now.

I would also check that java is up to date. Click on update in the java app located in the control panel.

You might also look in the REW error log located in your home directory. Usually it will be in c:\Documents and Settings\yourusername\

The error files are stored there and are called roomeq_wizard0.txt, roomeq_wizard1.txt, etc.....

You can open them with Notepad. There's a rotating list, so choose the one with the newest date.



brucek


----------



## n0m0ney (Jul 23, 2009)

Hi again!

The latest drivers to my sound card is very special, cause it automaticly detects the sample rate required. This has driven me insane and chose to use a older driver normally. But this driver does not send any audio signals to REW, so i have to use the latest driver. I can not turn the sample rate detection off.

I've just updated java, but still the same problem. 

I can only find the "roomeq_wizard0.log.txt", and it says:

"2009-aug-20 01:47:27 roomeqwizard.RoomEQ_Wizard main
INFO: Room EQ Wizard started", which is not very usefull information.

I've also tried to use both 44.1k and 48k but the same thing applies. To manually change the sample rate, i have to get into cubase and change the sample rate in a project.(It's a pain, right?!). Also stuff like some windows sounds and stuff changes the sample rate. I don't know if this only applies on my Mackie Firewire interface, but i've asked some qualified people on how to fix it, but i got no answer.

/ Daniel


----------



## brucek (Apr 11, 2006)

> Room EQ Wizard started", which is not very usefull information.


Well, that's the output when you have no faults. So, in that context, I guess it's useful.

I have to say I'm now officially stumped. 

Funny thing, we find we have the most problems when someone has one of these sophisticated high end cards, and the least problems come from the el-cheapo run-of-the-mill soundcard. 

If you just want to run REW to do a measure, the internal on-board cards work just fine.... but I do realize it's kind of a challenge thing to find out why your card isn't working..... 

brucek


----------



## n0m0ney (Jul 23, 2009)

Yeah, i've asked this question on two forums, and nobody except you has provided me with a few "checks". Thanks alot Brucek!

Since i really don't know what to do next, i might try to format the computer. I can't really use the inboard computer interface either, cause i don't own an external preamp.  

I'm thinking about changing the card, but the hardware is so excellent, but the software is really .

Haha, yeah, i guess in this situation you might want a regular in board card, but i can't get mine to work  I have never used it 

If you think of something, please, do tell me! 

/ Daniel


----------



## brucek (Apr 11, 2006)

Yeah, I'm going to ask John (author of REW) to look at this thread and see if he can help me.

brucek


----------



## n0m0ney (Jul 23, 2009)

That would be much appreciated =)


----------



## JohnM (Apr 11, 2006)

So you do hear the sweep OK? If you go to the Scope tab after a sweep does the captured signal look correct? A screenshot of that may help, worth zooming in on the plot also to make sure it looks correct. What do the Windows mixer settings show for record and replay?


----------



## n0m0ney (Jul 23, 2009)

Hi JohnM, thanks for your time!

Yes, the sweep sounds good in the speakers.

But i do not think the scope is correct. It doesn't look normal.










Zoomed in:










Does this indicate sample rate issues or buffer size? What i can understand is that the Sweep and the captured sound should be somewhat on the same position? Right?

I can not access the Windows Mixer window with my soundcard. All is controled via the interface knobs. But my sound and audio devices are set to the Mackie Onyx Satellite.

/ Daniel


----------



## brucek (Apr 11, 2006)

> What i can understand is that the Sweep and the captured sound should be somewhat on the same position? Right?


Yeah, for sure the input should start when the output starts . You have some sort of latency there?

Here's a quick pic of a short sweep on my system and also an expanded view of the start. You can see the input starting just as the output starts.
















brucek


----------



## n0m0ney (Jul 23, 2009)

Oh my gash! ;D We have found the problem. 

But i have no idea what's causing this problem. My buffer size is at 128, and my latency in cubase is not even noticeable. 

So i guess there is nothing wrong with my computer, but my soundcard is ?  Well, i already knew that, but any ideas on how i can fix this? Like i said, i had no problems with latency in cubase.

/ Daniel


----------



## brucek (Apr 11, 2006)

I have no idea. We'll see what John thinks........


----------



## JohnM (Apr 11, 2006)

Some of what looks like delay may just be the lack of output at the beginning of the sweep. The first thing to sort out is your mic preamp, which is clipping heavily (hence the flat portion of the captured sweep). You need to back off the mic gain so that it doesn't clip, you may then find the measurement is OK.


----------



## brucek (Apr 11, 2006)

> lack of output at the beginning of the sweep.


Perhaps, but why does the input signal extend so far past after the output signal is finished? Is this not abnormal?

brucek


----------



## JohnM (Apr 11, 2006)

It is certainly unusual, but not necessarily a problem.


----------



## brucek (Apr 11, 2006)

OK, assuming it's not causing a problem, then he should expand the horizontal scale on the end portion of the input (red) signal and look for evidence of clipping. If it is clipping, then the input level should be reduced to remove it. Seems strange to get clipping though, since he originally was using a -18dB signal level... But then I suppose the band limited pink noise in the Check Levels may not have been covering that clipping area. I suspect he must have been using the subwoofer test signal (band 30Hz-80Hz). His measure was from 50Hz-300Hz.

brucek


----------



## JohnM (Apr 11, 2006)

The clipping is in the mic input, not the soundcard, hence the lengthy flat portion at the end of the captured trace. The mic preamp is clipping before the soundcard input, so the soundcard levels will never look excessive but the signal is heavily clipped nonetheless.


----------



## n0m0ney (Jul 23, 2009)

Well, i do not have any clipping in my mic pre. I monitor it very closely to make sure it was not clipping. The clipping must come from some elsewhere.

Yes brucek, i was using the subwoofer test signal, but i've also tried the full range speaker test signal, but with the same problem.

I am going to format my computer tomorrow, since i now can't even install the proper drivers for my sound card, which makes the card pretty useless at the momemt. I am pretty sure that the fault is in my sound card and not the program anymore. I'm also strongly thinking about buying a new sound card, since Mackies drivers are extremely unstable and unreliable. 

I will get back to you with the results if the format worked or not!

Sorry for bad english at the moment, but i'm a little drunk. 

Have a great evening(or whereever you come from  )

/ Daniel


----------

