weighting?

Spectralissime, High Precision Spectrum Analyzer.
mjgraves
Posts: 18
Joined: Tue Oct 14, 2014 6:32 pm

weighting?

Postby mjgraves » Mon May 01, 2017 7:23 pm

This past weekend Spectralissime to monitor an outdoor concert. I had it set for ISO mode so it was displaying RMS SPL. It worked splendidly. I recorded it's output, overlaying it on a video stream of the stage.

I also used a standard logging SPL meter (3M) to keep track of the simple loudness, expressed as db(A).

The RMS SPL shown by Spectralissime doesn't match the 3M meter, presumably because one is A weighted and the other unweighted. Technically that's known as Z-weighted.

Given that I have a recording of the Spectralissime screen, so I can see levels of the 60 RTA bands, is there any formula by which I could derive an A-weighted SPL measurement?

Would you consider adding weighting to Spectralissime?

Vincent Burel
Site Admin
Posts: 417
Joined: Sun Jan 17, 2010 12:01 pm

Re: weighting?

Postby Vincent Burel » Tue May 02, 2017 8:03 am

thanks for your feedback, we will add A-Weighting soon i guess...
(BTW: for SPL measure, you have to calibrate your microphone - see user manual use case #1)

Feel free to report the SPL difference between our analysis (without weighting ) and normalized tools. we firstly did it for that
because we would like to encourage sound engineers to watch true level and appreciate the sound quality/balance with their ears.

We think that A-weighting is leading sound engineers to setup P.A. system with something around +20dB in bass/sub and +6 to +10db in the range 1k -5kHz...

mjgraves
Posts: 18
Joined: Tue Oct 14, 2014 6:32 pm

Re: weighting?

Postby mjgraves » Tue May 02, 2017 1:37 pm

Yes, I used a MiniDSP UMIK-1 microphone and a calibrator. The calibrator exactly fits the mic head. It generates a 1kHz tone at 114 db and 94 db. I was able to calibrate the software to within 0.1 db.

mjgraves
Posts: 18
Joined: Tue Oct 14, 2014 6:32 pm

Re: weighting?

Postby mjgraves » Tue May 02, 2017 5:01 pm

I appreciate that production work (broadcast, PA, recording) demands unweighted measurement. Actually, the standard is now called "Z-weighted," which specifies flat from 10 Hz - 20 KHz (+/- 1.5 db)

Environmental noise analysis is quite different. A-weighted measure is the norm.

Is it correct to think that the A-weighted filter might be applied to the overall SPL measurement, separate from the RTA measure?

That is, the meter on the extreme right could be set to display A-weighted, independent of multi-band display? If so then perhaps mere adding an optionl a-weighted meter would be an approach?

mjgraves
Posts: 18
Joined: Tue Oct 14, 2014 6:32 pm

Re: weighting?

Postby mjgraves » Wed May 03, 2017 9:25 pm

Having considered it further, both displays should read the same; A, C or Z-weighted. To do otherwise would be silly.

mjgraves
Posts: 18
Joined: Tue Oct 14, 2014 6:32 pm

Re: weighting?

Postby mjgraves » Mon May 08, 2017 3:51 pm

My project is ongoing over the next few months. Leads to the question of when A-weighted measure might be available?

Vincent Burel
Site Admin
Posts: 417
Joined: Sun Jan 17, 2010 12:01 pm

Re: weighting?

Postby Vincent Burel » Tue May 09, 2017 4:05 pm

should be done before end of May...

mjgraves
Posts: 18
Joined: Tue Oct 14, 2014 6:32 pm

Re: weighting?

Postby mjgraves » Wed May 24, 2017 4:54 pm

Any news on this? I have another day of monitoring scheduling this coming weekend.

Incidentally, there are three of us with Board Spectralissime licenses engaged in this project. The other two have followed my lead.

Vincent Burel
Site Admin
Posts: 417
Joined: Sun Jan 17, 2010 12:01 pm

Re: weighting?

Postby Vincent Burel » Sat May 27, 2017 10:38 am

i should do this in the next week...
see download link on our facebook/g+


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