SPL Meter - Advice? Pics etc. !

Depends on what you want to compare against. At your LP is one measurement so you can determine how close to "reference" you're getting, an in-room close mic is another, outdoor ground plane is another. You have to have the specs of the measurement to make comparisons/judgements as to what the numbers represent....

For instance, what is the definition of max on your meter? Peak? Averaged max of some sort?

Your meter is probably accurate, but it's not telling you anything worthwhile. To do that you need to read each and every frequency within the sub pass band on a chart. That requires a USB measurement mic and measuring software. If you're interested the DIY speaker and sub forum is where to find out about it.

This calculator link for sealed subs will give you a clue as to what your pair of co-located, 15" subs are capable of and go from there as to wanting to know if the reading of your inexpensive sound meter is accurate or not.

Here's what the big boys use if someone is wanting to explore their OCD nature. The cylindrical item on the right of the sample image is a calibration device. This unit is a calibrated unit that has it's very own calibration certificate. Note: accuracy is +/- 1.5 dB and this considering for our purposes, we live in a world where we look to +/-3 dB.

The point, despite added purchase expense, even with the good stuff coming pre-calibrated, with calibration documentation and included calibration device, in my opinion, as highly desirable as good testing gear is, the specifications aren't what I would consider to be the best. The point, at the main listening position, based on what the "Piston Excursion" calculator has to share and the inherent calibrated "inaccuracy" of top of the line measuring gear, it's my opinion that your readings are suspect.

As to measuring methodology, I believe that Bill Fitzmaurice above has suggested, in order to eliminate room caused interference, measuring at one foot gives the most accurate results but then one has to calculate out the fall off or decrease in volume to main listening position with all the foibles taking a reading at the main listening position adds to the mix.

Bill, if you might clear up any hash that I might have made in my above layperson's explanation, that would be kind of you.

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Edited by BeeMan458 - 1/13/13 at 4:31am