I'm doing a subwoofer calibration with the Aperion SPL meter and I was wondering if you guys have a calibration of the actual meter?  That is, how flat is its response down to 32Hz?  I know the meter help section says +7dB at 20 Hz but do you have an actual curve of its low bass response?  Would it be safe to assume say a linear (logrithmically) increase from 0dB to 7dB starting at 32Hz?

Thanks.

Hello and welcome to the forum!

Good question, I believe that our speaker engineer Ken Humphries does indeed have a graph but he is not in his office today so I'll get in touch with him tomorrow and once I get the graph I'll post it here for you.

Thanks!

 

So it turns out Ken doesn't have a graph, but here is a generic graph of an SPL meter that is going to be pretty close.  Really our SPL meter won't have as flat of our frequency response through the midrange frequencies, but the slope of the low frequency roll off should be nearly the same as our meter's response. 

However if you need an actual graph of our meter we can russle one up for you, it may just take a few more days. 

Thanks!

Forgot about this subject for a bit... the whole holiday thing I guess.  Anyways, this graph is a generic representation of the frequency response of just the A/B/C weighting function.  A meter has the ability to track this curve but that would imply that the underlying response of the microphone is flat.  So, if you are saying that the Aperion meter tracks the weighting curve, that's great, but if you have or could get a true response curve that would be even better. 

Thanks for supporting my OCD.

Hi,

There is no shortage of correction maps for the Radio Shack SPL meter which, you may have noticed, looks very similar to our own and, as a matter of fact, behaves similarly as well.

Here's a basic correction sheet:

http://www.danmarx.org/audioinnovation/rsmeter.html

 Here's another sheet, with instructions on the bottom on how to mod your meter to read more accurately in the lower frequencies:

http://forum.audiogon.com/cgi-bin/fr.pl?htech&983682086&openflup&1&4

 I should also point out that the SPL meter is not all that accurate above 10khz so I wouldn't use it to test the linearity of your speaker's response above that level otherwise you might end up thinking you have malfunctioning tweeters.