# 1st measurement, questions and interpretation of results



## invenio (Jan 30, 2016)

So I received a miniDSP UMIK-1 for Christmas and wanted to take some measurements in my home theater room. I read through the long manual for REW and I have to admit that about 95% went way over my head. No big deal, I figure I start easy and basic.

I should probably explain my setup. It's a fairly basic 7.1 speaker system with an Onkyo TX-SR875 receiver. I have a home media PC in the room as well and I had REW running on this computer with the 8 channel analog cables running out from the sound card (3.5mm to stereo RCA jack) to the multichannel analog input on my receiver.

So far I have done two things:

1) I calibrated the levels (all 7.1 channels) of my speakers using the SPL meter function in REW and my calibration mic with the "white noise generator signal"/level calibration in my Onkyo TX-SR875 receiver. I was able to calibrate the speakers down to about 0.5 db accuracy. I should note that the subwoofer was above this level but that was purely due to personal preference. I like more low end when watching movies.

2) I also did a full spectrum (20 to 20,000 Hz) level measurement. I posted both the 20-200 Hz and 200-20,000Hz graphs with this post. I also included the actual measurement file (see links below) if that is helpful.

Ok, so I have a bunch of questions.

Software Related:

1) I was not able to test one channel at a time. When using the Java drivers (which is what I used to take the measurement) all channel would play and I could not see a way to select 1 channel testing alone. With the ASIO driver selected, it looked as if each channel can be selected individually for output but then there was no way to use the calibration mic to make measurements. I think I read somewhere that if using an ASIO driver the input/output must be on the same device (ie the soundcard) and not a soundcard and mic? I guess the question is, how do I do single channel measurements (other than unplug the RCA jacks which would be kind of annoying due to the position of the equipment in the room).

2) I have been trying to read some tutorials on multichannel measurements with REW but they all seemed to be focused on using an HDMI output vs regular analog outputs from a desktop computer soundcard. Using regular analog outputs should not be a problem, correct?

3) Since I am using a usb calibration mic (which I have the calibration file), I do not need to calibrate the soundcard output correct?

Measurement Related:

4) As you can see in the measurement graphs, the low end is higher than the higher frequencies. I kind of expected the bass to be significantly louder as that is a personal preference. However, there is significant rolloff through the entire sweep. Is there some good explanation for this? Should I just start to increase those frequencies in the equalizer function in the receiver to try and make the higher 200-20000 Hz graph as linear as possible?

5) Do you think there is significant interference from all the channels being tested at once? What I mean is that when you are watching a movie, not all 7 channels are playing the same frequency vs during the measurement all 7 channels were playing the same signal. Is it possible that the measurement I took does not represent the actual real-life acoustics where dialog is usually isolated to the front center speaker, an explosion in a movie to the front channels, etc?

6) What octave smoothing do you recommend? Obviously the lower you go the more smooth the graph becomes but then you start loosing detail between frequencies.

I'm sure I will have many more questions but this is a start. Thank you so much for your time!

BTW, my home theater room if interested: http://imgur.com/a/GWH2N

20 to 200 Hz Graph:









200 to 20,000 Hz Graph:


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## jtalden (Mar 12, 2009)

Impressive setup!
1-2) Yes, you should use ASIO. Open the ASIO control panel and confirm the correct input and output devices are activated. The others can be deactivated. REW will then allow selection of the channel to be measured.
3) Correct.
4-5) Correct, it is not helpful to measure all channels at the same time. The interference at the higher freqs will cause the downward slope you obtained. Each channel should be measured separately.
6) 1/3, 1/6, Psy, or Var are ones that are most useful to provide a reasonable indication of the SPL response that you will hear (your choice). The others are useful for other purposes.


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## invenio (Jan 30, 2016)

Thanks for the feedback. I am going to go back and try to do the measurements via the ASIO driver with one channel at a time. I'm not sure why I couldn't get the mic to work last time when I tried selecting the ASIO driver but I'll go back and try again. I may not have opened the "ASIO control panel" so I will go ahead and look again.


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## invenio (Jan 30, 2016)

So I went back to try and do measurements using the ASIO driver instead but I had the same issue.

When I use the ASIO driver, I can select which output channel (speaker) to use for the test signals, but the calibration mic does not seem to get any input. REW's SPL metter just gives me pretty much a silent reading.

Likewise, if I select the Java drivers, the mic can get a signal reading, but there is no way (that I can see) to select which channel to test.

I tried opening the "ASIO control panel" but it only had two settings there (latency, set to 10 ms) and something else I can't remember off the top of my head, but nothing to do with channel or mic selection. On the same preferences page, there are two input selections with the ASIO driver selected, labled IN-00 and IN-01. Again, neither of these actual give me any reading when I open the SPL meter and make some noise. I could be wrong but it almost seems like when I switch to the ASIO driver, REW is trying to get the input signal from the soundcard instead of the usb calibration mic. Likewise, when using the Java driver, I can get the input to the calibration mic, but can't select the output signal channel.

Any ideas on what I am doing wrong?

EDIT: I'm using the soundcard's default ASIO driver, do I need to install ASIO4ALL for REW to work correctly?


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## jtalden (Mar 12, 2009)

I'm not sure.
I believe you need ASIO4All for this to work. I may be wrong. I don't use this type of setup so have no personal experience to rely on. 

Try loading ASIO4All.exe and then check the inputs offered on in the ASIO panel. You should see something related to USB or Umik-1 as an input for the mic.

If this does not work then someone with experience with this setup should jump in and help.


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## invenio (Jan 30, 2016)

Went back and got some more measurements. Unfortunately, I did not have success with getting the ASIO drivers to work with the usb calibration mic. I even tried installing ASIO4ALL but no matter what I do it will not take the usb mic as an input for measurements and defaults to the IN-00 and IN-01 inputs which it thinks is on the sound card. So pretty much I have to use the Java drivers to utilize the usb mic. That's kind of annoying and I hope I find a solution to this in the future.

I was able to get single channel readings by an alternative method. I opened up the mixer software that came with the soundcard (Asus Xonar_D2PM). I was then able to mute each speaker level individually. I would essentially mute all the channels except the one particular channel I was doing measurements on at that that particular instance. This worked for all the channels except the subwoofer. I have no idea why the sub channel had no output. I kept all measurements to 200-20k Hz so that's fine for now.

So here are the measurements:









It seems like the center channel is louder than the rest. Not sure why this is the case as I had all the channels balanced before I even started taking readings.









Center









Left









Right









Left Surround









Right Surround









Left Back









Right Back


So now I have these readings, what's next. I don't see an exact pattern emerging? I can't seem to upload the .mdat file as I get an error saying something along the lines of a "security token" error. Not sure why this is the case, maybe a file size limit, it's 17 mb's?


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## jtalden (Mar 12, 2009)

Yes, the file is probably too large. 3-4 sweeps is often the max that can be posted in one file. The file size probably varies depending on the measurements settings so there is no firm number.

I think its may be helpful to have the mic plugged in a few seconds before REW is launched for it to be detected. Assuming you did that then it may be helpful to post a screen shot of the ASIO control panel. Maybe using a different USB port when the PC is booted will help. Someone here that uses USB mics can probably provide more helpful thoughts. The MiniDSP site has lots of good info and forum support also.

Next steps depends on whether you finalized speaker locations, acoustic treatments and SW and Mains delays/distances. If those steps are concluded then choosing a house curve and setting EQ is the final step. REW 'Help' has good info on the automated EQ filter selection feature. We can answer EQ questions after you experimented with that feature and have specific questions.

I forgot to mention above that for SW EQ 'no smoothing' or 'var' is the best choice. Do not use others for EQ of the SW range. I have no thoughts on why the SW channel signal did not sweep for you, assuming you remembered to change the sweep range for that measurement. 

I would suggest full range measurements for all channels. The SW XO should be active. That way we can see the XO range roll-off. That is necessary anyway if you want to confirm the delay/distance setting for the SW.


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## invenio (Jan 30, 2016)

jtalden said:


> Yes, the file is probably too large. 3-4 sweeps is often the max that can be posted in one file. The file size probably varies depending on the measurements settings so there is no firm number.


That's probably it.



> I think its may be helpful to have the mic plugged in a few seconds before REW is launched for it to be detected. Assuming you did that then it may be helpful to post a screen shot of the ASIO control panel. Maybe using a different USB port when the PC is booted will help. Someone here that uses USB mics can probably provide more helpful thoughts. The MiniDSP site has lots of good info and forum support also.


The USB mic was plugged in during boot up so it had been connected well before REW was started. REW also asked me for the calibration file for the mic so I'm pretty sure it recognized it properly, especially considering that it worked fine with the Java sound driver. I'll take a look at the miniDSP site as well.



> Next steps depends on whether you finalized speaker locations, acoustic treatments and SW and Mains delays/distances. If those steps are concluded then choosing a house curve and setting EQ is the final step. REW 'Help' has good info on the automated EQ filter selection feature. We can answer EQ questions after you experimented with that feature and have specific questions.


I set the speaker distance in the receiver setting (as well as the initial speaker volume levels as well). I think that should have taken care of delay issues.



> I forgot to mention above that for SW EQ 'no smoothing' or 'var' is the best choice. Do not use others for EQ of the SW range. I have no thoughts on why the SW channel signal did not sweep for you, assuming you remembered to change the sweep range for that measurement.


Yeah, me neither. It was really weird. I did indeed reset the sweep to low frequency. For some reason it was just the subwoofer channel that was completely silent on output. 



> I would suggest full range measurements for all channels. The SW XO should be active. That way we can see the XO range roll-off. That is necessary anyway if you want to confirm the delay/distance setting for the SW.


I'll have to try and get the sub channel working. Not sure why I am having so much difficulty with the setup/software.


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## FargateOne (Mar 3, 2015)

invenio said:


> So I went back to try and do measurements using the ASIO driver instead but I had the same issue.
> 
> When I use the ASIO driver, I can select which output channel (speaker) to use for the test signals, but the calibration mic does not seem to get any input. REW's SPL metter just gives me pretty much a silent reading.
> 
> ...


You must read this carefully:

REW 101 Step By Step Setup Guide, by AustinJerry and others at AVS Forum, Rev 4.4 Dec 31, 2015.

You must (Windows sound preferences of input) select the UMIK as the default mic and activate it in Asio4all advance settings (click on the wrench to open the window ). Please, deactivate your antivirus and firewall before downloading rew or Asio4all. Plug your mic and hdmi from computor to receiver before to open Rew and Asio.
Hope that will help


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## dandiele (Aug 30, 2014)

I have also had this issue when trying to use ASIO4ALL for the first time, Java works fine but REW detects nothing from the mic when I choose ASIO. Also, windows didnt detect anything from the mic until I clicked "configure" which had me set it up for voice dictation and then it actually showed that is was picking up sound but it would not work in REW. I was using HDMI output to my AVR and a umm6 mic.

a few times when I would click check levels, the sound would play from the output channel I selected however there was no reading from the mic, and in most cases the ASIO4ALL driver would crash.

Did you OP come up with a fix for this? I am running Windows 10 if that matters.

Thanks everyone!


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## invenio (Jan 30, 2016)

I have not had a chance to work on it but plan to do so in the very near future. I downloaded and printed out the step by step guide suggested above. I saw that there is a significant windows configuration procedure even before starting up REW. I did not do any of this initially so I plan to go back and go through these steps one by one and try again. I will definitely report back on the results but it may be a few weeks as I am leaving for a trip today and the next two weekends I will be unavailable. I'll report back on my findings.


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