# spl meter ?



## erazz (Oct 12, 2012)

anybody ever use a simpson meter model #886-2 seems like a very nice meter... http://www.simpsonelectric.com/uploads/File/datasheets/sound.pdf Any thoughts?


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## Wayne A. Pflughaupt (Apr 13, 2006)

A Forum search shows that you’re the first person to mention this meter. Like Earl said in your cross-posted thread, there’s no reason to use a $800 meter for REW unless you already have one.

Regards, 
Wayne


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## erazz (Oct 12, 2012)

well i definatly would not spend $800 on one i was really just thinking they would have better mics than the rat shack or galaxy meter...and it has it the 890 calibrator.


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## Wayne A. Pflughaupt (Apr 13, 2006)

The Simpson’s mic wouldn’t necessarily be better, as there will be compensation for any deficiencies it has built into the meter itself (just as you have with the mics that come with AVRs for their auto-calibration function). And since a calibration file would be required for using it with REW anyway, that makes the quality the Simpson's mic doubly immaterial. 

The 890-2 merely calibrates the meter for accurate SPL readings. IOW, so that when the SLM (sound level meter) registers 88 dB from a noise source, that’s exactly what the noise source is generating. There are at least a couple of reasons for the dual 94 dB and 114 dB calibration ranges. One would be to insure precise accuracy at extreme differences in noise levels. For instance, if the meter is calibrated for 114 dB, it might not deliver an accurate a reading at 60 dB. Conversely, 94 dB calibration might not give an accurate reading when measuring a 130 dB noise source. The other reason is to ensure the best accuracy for field use at different physical locations or venues, where the meter is typically calibrated before every use to account for the effects of ever-changing temperature and humidity.	

Again, none of this is terrible useful for REW because most people who use the Radio Shack SLM for measurement are concerned with the _frequency content_ of the signal, not pinpointing its exact SPL. 

What you’re getting with a professional grade SLM is a lot of features that the casual user has no use for: A heavy-duty case, tighter tolerances (±0.7 dB for a Class 1 device, vs. ±1 dB for a Class 2 device like the Simpson, vs. ±1.5 dB for a good Class 3 device, vs. ± 2 dB for a lower-grade Class 3 device like the Radio Shack meter), “B” or "Z" weighting capability, XLR connections to accommodate remote mic locating, connections for outboard analyzers, etc.

It’s not an uncommon misconception for people to think that a professional grade SLM will work better with REW. What they overlook is that we’re not using the meter the same way that an acoustics professional or researcher would, whose primary intent is accurately logging absolute noise levels. Certainly, there are pricey pro-grade meters that analyze the frequency content of a noise source (here’s one - scroll down to the bottom of the page), but that’s primarily for the purpose of determining the treatment strategies employed to reduce or eliminate the noise from an auditorium, factory, airplane interior etc. It should be a no-brainer that that’s a far cry from taking accurate frequency response measurements of a room. 

The Radio Shack SLM was never designed for measurement of frequency response. We merely “hijacked” it for that purpose to enable people to economically take measurements of subwoofers, as many hi-fi enthusiasts already owned a meter. For accurate full-range frequency response measurements, you can get a calibrated mic and suitable USB audio interface for a fraction of the thousands of dollars required for a professional-grade meter capable of frequency-content analysis.

Regards, 
Wayne


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## erazz (Oct 12, 2012)

thank you Wayne for your detailed response. Now i understand why there would be no great benefit to using this meter for REW. I am new to trying to measure in room response and just wanted to try to get the most accurate results i can without spending alot of money. I guess it will be better to use one of the meters that already have calibration files available...the mic/preamp route is out of my price range at this time. anyway thanks again for your help/advice.


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## AudiocRaver (Jun 6, 2012)

Wayne P. covered it all nicely. Most SLM use by folks like us is for relative comparison measurements with a broadband source, like pink noise. Doing a quick balance check is a breeze with a pink noise track in your media player and a SLM, no other equipment needed, and the precision of the measurement is irrelevant because of its comparative nature. Or for when you're wondering, "How loud can I play this action sequence on my new Blu-ray before I get called down by you-know-who, 105dBC, maybe 110? "Just for fun" measurements, where accuracy within a couple of db is plenty close.

For detailed frequency response work, a reference mic with its own calibration curve, plus audio interface, is the way to go.


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## alriscove (Nov 18, 2012)

interesting Wayne


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## dachness (Feb 17, 2009)

erazz said:


> thank you Wayne for your detailed response. Now i understand why there would be no great benefit to using this meter for REW. I am new to trying to measure in room response and just wanted to try to get the most accurate results i can without spending alot of money. I guess it will be better to use one of the meters that already have calibration files available...the mic/preamp route is out of my price range at this time. anyway thanks again for your help/advice.


I would urge you to consider the miniDSP Umik-1 measurement mic. I have one on order. It comes out to about $95 shipped and you are good to go just plug in the Mic's usb cord to your computer. With future revisions of REW it can also be used as SLM. 

For any one interested here is my calibration file. FYI you can look at the different calibration files by simply modifying the serial number in the link. I did some comparing to other mics and there are definitely some highly accurate mics out of the box, more so than mine. 

http://www.minidsp.com/images/umik/Umik-1/7000137.txt

If you don't mind spending the time one could consider asking miniDSP for a particular serial number mic. I wasn't aware that all the files were available online when I placed my order...

I will be using the mic to EQ my sub(previously used the Radioshack meter) and to get a baseline EQ for our church PA system.

Daniel


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## erazz (Oct 12, 2012)

Thanks Daniel that looks like a very good option. I think i will have to order one after christmas. It seems like a very cost effective answer to my problem I.E. i won't have to buy a seperate soundcard or phantom power for a mic.


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