There should be a pdf file on the included mini CD disc titled “Read me” that has instructions.
Typically you will want to use the narrow band response files. Files are provided for orienting the mic at 0, 45 or 90 degrees in relation to the speakers. I.e., 0 degrees would be used for pointing the mic directly at the speaker, etc.
Save the files to your REW folder, then open the folder and change the extensions to .CAL. In REW, click the “Settings” icon, then the “Mic/Meter” tab. From there the “Browse” icon will let you select the calibration file you want to use.
is it really necessary to use only right output of the soundcard and split that into 2 identical signals, or can the L R output of sound card go into my receiver? I couldn't find my RCA mono splitter right now.
Hard to say, knowing nothing about your sound card or system, or what you intend to measure. If you're only going to measure the sub, it's a mono output from your receiver, so only one input is needed. If your sound card has a pan control that takes the input and sends it to both outputs, then no splitter is needed.
By the way, the ECM is an omnidirectional mic, so for measuring subwoofers, the mic orientation or calibration for 0, 40, or 90 degees doesn't matter. That only comes into play above ~4khz. IOW, for subwoofers any mic orientation is fine with any calibration file.
I did a sweep up to 2000hz, it has a lot of null down to 0 db on frequency above 200. Is that expected from an untreated room or is there some problem with my measureing gear? The whole thing got really jagged after the subwoofer measurements.
Yes, that sounds like it could be the phenomenon called comb filtering... do the dips start out every X Hz or so, and then as you get up in frequency because each frequency is displayed closer and closer togther the dips combine into a mis-mash? That's absolutely typical of an untreated room, and even many treated rooms too (you don't want to know what the room will have to look like to eliminate that altogether). With full range scans, we're looking mainly to see the overall trend of the line, so you can apply 1/3octave smoothing to the plot to eliminate some of that "noise" and get a better idea of what's going on.
Also, on the mixer only the first green LED light lit during sweep and maybe the 2nd one. Does it need to be adjusted to get more LEDs (3?) lit?
Everything is too loud as it is and I am have to turn the soundcard line in about 1/2 way down.
I think I need to calibrate the db levels, how to get the signal down to around 75db? Do you turn down the receiver? or turn down the input gain on the soundcard?
I don't remember what LEDs on my mixer ever looked like. I don't think I paid much attention to them.
You run the Calibrate SPL routine in REW... while the noise is playing, adjust the volume on the AVR so the noise reads 75dB at your listening/mic position, and tell REW the signal it's getting is 75dB.
Also, on the mixer only the first green LED light lit during sweep and maybe the 2nd one. Does it need to be adjusted to get more LEDs (3?) lit?
Everything is too loud as it is and I am have to turn the soundcard line in about 1/2 way down.
I think I need to calibrate the db levels, how to get the signal down to around 75db? Do you turn down the receiver? or turn down the input gain on the soundcard?
So I ended up turning the receiver down, from -22db to -30db, so that it says 75db on the radio shack SPL, and hit the calibrate button.
Then the graph is a bit different than the one I have taken up there at 85db.
The test is rather quiet now.. but maybe that is the way it should be?
Is that normal?
Here is the sweep to 10k with filter applied, I have no idea why the volume from the mains is rather low on average. With individual test tone I calibrated each speaker level to about the same db with my RS SPL.
I wasnt trying to EQ a house curve or anything here yet, this is my default receiver setting I have been watching movies with.
Try reposting that with a vertical scale from 45 to 105dB. I don't really think it's all that different, the level is a bit lower, that's to be expected, and it covers a much wider frequency range.
Do you have a soundcard calibration loaded?
When you calibrated each speaker, was that with the SPL meter or with REW? Were you using the internal test tones on your AVR?
I tilted the mic about 10 degrees forward from vertical something I read from another thread
tilted = purple
vertical = green
Yikes, that affects reading a little bit.. I guess I can't really rely on any graph an absolute reference I am probably not going to EQ the mains, but might do some treatment to see how it affects the graph
What level of smoothing are you applying?
These graphs do show your sub running hotter than the mains... whether or not you want them better balanced is a matter of preference, so do, some want the sub running hotter.
I'm more curious about the variations in the midrange. Scan each main speaker by itself. I find it interesting that I think there's another thread by another person with a problem in a similar range.
I tilted the mic about 10 degrees forward from vertical something I read from another thread
tilted = purple
vertical = green
Yikes, that affects reading a little bit.. I guess I can't really rely on any graph an absolute reference I am probably not going to EQ the mains, but might do some treatment to see how it affects the graph
The mic is omnidirectional below ~4 kHz and exhibits increasing directivity or directionality (or whichever word is technically correct) above 4 kHz. As Greg alludes, there must be some explanation for the variations you’re seeing below 4 kHz.
Also, why are you stopping your measurements at 10 kHz?
Smoothing is 1/3 octave from the menu, based on your recommendation, I saw someone do 1/6 octave smooth but I don't see this option.
Now that I have a db number (in the record button) in REW with ECM8000,
should I have the receiver play test tone again and adjust each speaker's volume based on the reading in REW? That should be better than using the RS SPL which jumps around.
I suppose since I adjusted the sub level based on my RS meter, it made the meter heavily jumping around and I took a guess, I could have set it too hot to begin with, however this level may be useful when I set the house curve.
I have tried up to 12k but after the sweep, I heard a funny blip of sound each time I wonder what that is.
The high pitch was getting uncomfortable for me so I stopped at 10k. I can go up to 20k without worrying about anything?
Is the peak at 600hz some kind of room mode, I think it could be EQ'd out and maybe the dips next to it might go away also.. I have adjustable PEQ on each speaker in the receiver setting, all presets band they are available, 500, 630, 794hz. Testing the left and right alone would be a good idea.
Now that I have a db number (in the record button) in REW with ECM8000,
should I have the receiver play test tone again and adjust each speaker's volume based on the reading in REW? That should be better than using the RS SPL which jumps around.
You may find REWs meter moves also. Did you have the RS set to "slow?" If you wanted to achieve as good as you can get balance between the two, consider running a series of scans and tweaking the level between each one based on what you see, untill you can't tell the difference...
Is the peak at 600hz some kind of room mode, I think it could be EQ'd out and maybe the dips next to it might go away also.. I have adjustable PEQ on each speaker in the receiver setting, all presets band they are available, 500, 630, 794hz. Testing the left and right alone would be a good idea.
I doubt you would see a mode that high up without seeing evidence of it lower down, but I suppose it's possible. Where are those PEQs set? Can they be defeated?
If it was my system, I'd rather see the individual scans first.
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