# Speaker Testing with REW



## 39cord (Mar 6, 2015)

Speakers have been assembled in a 3 way, vertical inline configuration and crossover points are being evaluated. For drivers there's 12", 4" and 1" speakers with XOs at 230 and 2300 Hz.

Input mic for REW is a UMM-6 and the generic calibration file has been downloaded and used.

First test is shown below. I've tried not to be lazy and have watched the YouTube video and read the manual a number of times but I still don't know what I'm looking at. Maybe you can help me get on track with what I should be doing and understanding. Mic is horizontal 40" in front of 1 channel.

My first question is about sound levels used for testing. What is a good level for good results.


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## Wayne A. Pflughaupt (Apr 13, 2006)

For starters, let’s get the graph scaled properly...

Getting Graphs Ready to Post

Regards, 
Wayne


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## AudiocRaver (Jun 6, 2012)

The REW data file indicates there is no sound card calibration file. There should be one.

It also looks like the measurement was taken without calibrating the SPL level in REW. The average SPL is down around 45 dB, which I seriously doubt. You will need to perform the REW SPL calibration.


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## 39cord (Mar 6, 2015)

From what little I understand when using a USB mic there is no sound card so calibration involves only pointing REW to the mic calibration file.

Levels are something I don't get. When 1st loading REW the calibration step required amp volume settings that were close to blowing up the speakers in order to get the VU meters equal. My assumption is to match the colored bars on the VU meters and I don't understand why the red oversaturation bars are in there if there is no control of them and they are proportional to the colored bars. Help is needed here.


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## AudiocRaver (Jun 6, 2012)

Beg pardon, I misread your first post, thought for sure you said EMM-6.

You are correct, no sound card cal file is needed and SPL calibration will be automatic if the Mic sensitivity is included as the first line of the Mic cal file. Edit: I am not sure if the UMM-6 cal file includes mic sensitivity or not.


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## AudiocRaver (Jun 6, 2012)

39cord said:


> match the colored bars on the VU meters and I don't understand why the red oversaturation bars are in there if there is no control of them and they are proportional to the colored bars. Help is needed here.


Are you describing the meters in REW? They should look like this









Typical levels on these meters are -20 to -15 for output and -20 for input. Don't worry about color, look for the dB reading.

But, more importantly, open the mic calibration file with a text editor and see if the first line looks like this:

"Sens Factor =-2.054dB, SERNO: 7003793"

If it does, then you did not need to do that manual calibration, and might have goofed up your levels somehow. Clear the mic cal file and re-load it.

If not then you will have to calibrate sensitivity with an SPL meter. Do you have one? Follow the REW calibration instructions to the letter, they are pretty clear. Your AVR gain should be close to normal and the volume should be prominent but comfortable.

Edit: The narrow red bar indicates peak level, the top of the solid colored bar indicates RMS level, which is the same as the number at the bottom of the bar.


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## 39cord (Mar 6, 2015)

I'll come back and add a p.s. to this after I do some checking on your suggestions but I get what likely has happened by deduction; Scenario: Whether you have a usb mic or not the program capes you into calibrating your mic. You make the adjustment as best you can. Now the levels are all screwed up and you get gored.

Part 2- Calibration file was opened and the 1st line did not contain sensitivity data. Going off to the Dayton site and downloading a new calibration file now shows the sensitivity data. The procedure for downloading the file was a bit different than what I recall doing many months ago.


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## 39cord (Mar 6, 2015)

New tests were run evaluating a 3 way speaker thanks to your help.

Speaker build was completed last week and crossover points are being evaluated.

2nd order XO calculator says the low and high points should be about 230 and 2300 Hz.

REW says otherwise. Without taking up too much of your time maybe you can take a quick look and give me a bit of education based on what you see.

All tests have the current 3 way crossover in place. Only 1 or 2 wires were pulled during the tests so the speaker bypass components making the crossover a 2nd order arrangement are still in the circuit possibly influencing results.

Tweeter only plot has a bunch of noise in the bottom end. What are likely sources that might be fixed.

Mid only looks like a Bell Curve. Not at all like the advertised frequency plot.


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## Wayne A. Pflughaupt (Apr 13, 2006)

Full range graphs are better evaluated with 1/3- or 1/6-octave smoothing to eliminate all the comb filtering and give you a graph that better looks like what response sounds like. :T




39cord said:


> Tweeter only plot has a bunch of noise in the bottom end.


How do you arrive at that conclusion?




> Mid only looks like a Bell Curve. Not at all like the advertised frequency plot.


You can’t reasonably expect an in-room response measurement to duplicate the measurement processor the manufacturer used.

Your questions are better suited for our DIY Speakers area. This area of the Forum is mainly for helping people get REW up and operating properly, and you’re good to go there. Would you to have the thread moved?

Regards, 
Wayne


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## 39cord (Mar 6, 2015)

Yes, please move thread to DIY.


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