Newbie learning REW...

[alvinh]

Hi there. I am trying to learn REW so any help from you guys will be greatly appreciated.

I read the first few topics on the REW help files but since I do not consider myself much as a techie, i would feel more confident in taking measurements later on after I verify that my initial set-up of REW is indeed on the right path.

I used a Radio Shack digital spl meter and an Extigy external sound card...tried to follow the guidelines and got this graph for my sound card calibration:



I did what was recommended to check if my calibration is correct...unchecked the c weighted spl meter box and cleared mic/meter calibration file:



With c weighted spl meter box checked and mic/meter cal file loaded:



My first measurement: (at listening position, around 8.5 feet)
50hz - 512hz just to see how my maggies perform on these rhythm notes.



I read here somewhere that the RS digital meters are only accurate to about 3000hz. I have a cardioid Shure Beta58 wireless mic...can I use this to replace the spl meter when measuring higher than 3000hz? Should I use this instead of the spl meter since it is suppose to have a freq response of 50-16kHz?

I just tried another measurement to see how it looks on full range and here is what I got:



Whenever I open REW again to start, my screen shows this graph...



Thanks in advance for any input or suggestions.

[brucek]

got this graph for my sound card calibration:

Looks good.

I used a Radio Shack digital spl meter

The Radio Shack meters are only good to ~3KHz. Don't rely on full range graphs when using this meter. Recommended meter is the Galaxy CM-140 or the Behringer ECM8000 mic with a mic preamp.

I did what was recommended to check if my calibration is correct

Looks good.

My first measurement: (at listening position, around 8.5 feet)
50hz - 512hz just to see how my maggies perform on these rhythm notes.

Please use the accepted vertical scale of 45dB-105dB.

I have a cardioid Shure Beta58 wireless mic...can I use this to replace the spl meter when measuring higher than 3000hz? Should I use this instead of the spl meter since it is suppose to have a freq response of 50-16kHz?

Yes, if you have a calibration file to use with REW.

I just tried another measurement to see how it looks on full range and here is what I got:

Full range graphs should have REW smoothing feature applied (1/6th or 1/3rd) octave. This removes the comb filtering and reveals the underlying signal.
Ignore the erratic response above 3KHz - it's typical of an RS meter.

Whenever I open REW again to start, my screen shows this graph

REW opens with the last attributes used. You are showing the last vertical and horizontal scale used. It also shows the soundcard cal file and meter cal file since you have those checkboxes ticked. You can turn them off to not show on the graph. It also shows the last target line you used. You may select the target line that is associated with your measurement.

For subwoofer plots, always use the standard Vertical graph axis of (45dB - 105dB) and the Horizontal graph axis of (15Hz - 200Hz) using the Graph Limits button in the top right corner of REW. Use a measurement start frequency of 0Hz and an end frequency of 200Hz. Use the appropriate target line that matches your crossover.

For full range plots, use the standard Vertical graph axis of (45dB - 105dB) and the Horizontal graph axis of (15Hz - upper limits you desire, i.e. 15KHz -20KHz. Use a full range target line.

brucek

[alvinh]

Thanks brucek.

I guess i can practice measurements up to 3kHz for now until I get hold of a Behringer mic and mic preamp. Too bad I don't have access to a cal file for my wireless mic.

Got your pointers on the graph settings...looking forward to my next set of measurements.

[Massael]

Looks like you got it figured out pretty fast - I'm hoping I do that well on my end.