Originally Posted by ahmedreda
Would within 1-2 dbs still be hard to achieve? According to cross spectrum they use a small pressure chamber similar to http://www.artalabs.hr/AppNotes/AP5_MikroMeasChamber-Rev03Eng.pdf
and their results is usually within +/- 0.5 db down to 10hz and +/- 1-2 db between 10 and 5hz.
Originally Posted by DonH50
Most SPL meters are not that accurate and unless you spend a lot more than is usual are C-weighted at best (response to 30 Hz). A calibrated (NIST) meter that is broadband will run upwards of a grand ($1k) or more. Unless you are just incredibly anal (can I say that here? as a design engineer that is pretty much my life) all that really matters are relative levels when matching the speakers, so I would just use the mic and REW.
I am curious if the mic is corrected to 5 Hz; that is awfully low. My measurement mic (Earthworks M30, $649 USD on sale now at Sweetwater) is rated 5 Hz to 30 kHz but that is overkill for most of us (me too, actually, but I got it years ago when I was doing this stuff for a living, or at least for the, or perhaps "some", money).
I am not sure what you mean. Measuring 1 - 2 dB's in absolute sound level, or flatness over the band? Most of the time people discuss a calibrated mic, they mean flatness over frequency, not how accurately the measured SPL will be. A typical inexpensive SPL meter is accurate to around +/-2 or 3 dB, at least that is what I saw in my very quick look at a few $20 to $100 meters. Except for some cheaper mics that exhibit some response peaks and valleys at the high and low end, most mics and SPL meters are pretty flat over the mid band. But, most do not reach down to subwoofer frequencies. That said, a couple of dB ripple you are not likely to hear.
If you are asking about the mic itself, as it appears, I would in no way worry about a drop of a couple of dB going from 10 Hz to 5 Hz. That is going to be in the mud as far as real-world room and speakers are concerned.
If you are asking if you can get your room response flat to 1 - 2 dB, probably not, but that is not a requirement.
IIRC my M30 cal report only includes a single-point measurement for output to help ascertain absolute SPL. That has never been one of my goals so I am not sure where it lands. The broadband SPL meter I used for absolute levels ran around $1k a number of years ago, with a NIST cert, and when I last checked was up around $3k now.