6dB difference between REW and manual measurement

[chrisp9446]

Hi all,

I'm just starting to get into frequency response measurement, and have started to do some things with REW. I ran a sweep in REW and compared it to a "by-hand" excel response graph, and the REW graph was ~6dB louder at every frequency. To do the "by-hand" graph, I used the REW frequency generator at 1dB increments from 16Hz to 80Hz. It was basically the same as the REW graph, it was just ~6dB lower. I was using the same settings/calibrations/volumes for both measurements.

I have a RS digital SPL meter and a Behringer UCA202 USB sound card hooked up to my laptop.

I was going to start posting about suggestions to correct my frequency response, but I wanted to get this straightened out before I start posting about that.

Thanks for any and all help.

[brucek]

When doing frequency response measurements, you're main concern is the response, not the level.

If everything is set up correctly, the manual and REW method will be within ballpark, but don't get concerned about that. The usual fault people have with the REW method is not running the Calibrate SPL routine after the Check Levels routine.

If you're able to do REW measurements, throw the manual method in the garbage, and be glad about it... it's a pain in the.....................

brucek

[chrisp9446]

Ahhh, yes, that solves the problem, thanks!

No kidding about the manual method...I'm glad to be able to use REW and save some headaches.

Of course, fixing one problem (measuring freq. response) always creates another one (spend more $$ to fix it), but I wouldn't have it any other way.