<br><font size=2 face="sans-serif">The radio shack meters are only +/- 3db, but usually perform better, and that is double the volume. The good meters ($250) are +/- 1 or 1.5 db. <br>
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Gray Fowler<br>
Principal Chemical Engineer<br>
Composites Engineering</font>
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<td><font size=1 face="sans-serif"><b>"Tony Stillman" <tony@radiosouthrc.com></b></font>
<br><font size=1 face="sans-serif">Sent by: discussion-request@nsrca.org</font>
<p><font size=1 face="sans-serif">04/26/2004 10:52 AM</font>
<br><font size=1 face="sans-serif">Please respond to discussion</font>
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<td><font size=1 face="Arial"> </font>
<br><font size=1 face="sans-serif"> To: <discussion@nsrca.org></font>
<br><font size=1 face="sans-serif"> cc: </font>
<br><font size=1 face="sans-serif"> Subject: Re: sound meter</font></table>
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<br><font size=2 face="Courier New">Brian:<br>
<br>
Do you realize that 3 DB is DOUBLE the sound level? That's not even<br>
close.....<br>
<br>
Tony Stillman<br>
Radio South<br>
3702 N. Pace Blvd.<br>
Pensacola, FL 32505<br>
1-800-962-7802<br>
www.radiosouthrc.com<br>
----- Original Message ----- <br>
From: "Brian Young" <b4598070@yahoo.com><br>
To: <discussion@nsrca.org><br>
Sent: Monday, April 26, 2004 8:34 AM<br>
Subject: Re: sound meter<br>
<br>
<br>
> Do they calibrate the meter at the NATS?<br>
><br>
> I think the RS meters are within spec if they are +/-<br>
> 3DB.<br>
><br>
><br>
> --- "ed.schummer" <ed.schummer@sbcglobal.net> wrote:<br>
> > Couldn't agree more. Most of these meters work<br>
> > pretty well when measuring<br>
> > relative levels of pink noise, such as in<br>
> > calibrating control room levels to<br>
> > a SMPTE standard, or such. The problem comes up<br>
> > when there is a dominant<br>
> > frequency that is much louder than the others, as<br>
> > often occurs with our<br>
> > planes. We once tested a bunch of these meters, and<br>
> > although on average<br>
> > they were pretty good, I have seen as much as 6 dB<br>
> > difference from one meter<br>
> > to another at single frequencies, both meters<br>
> > calibrated to the same level<br>
> > with pink noise....<br>
> ><br>
> > Ed<br>
> ><br>
> ><br>
> > ----- Original Message ----- <br>
> > From: "Ed White" <edvwhite@yahoo.com><br>
> > To: <discussion@nsrca.org><br>
> > Sent: Sunday, April 25, 2004 5:22 AM<br>
> > Subject: Re: sound meter<br>
> ><br>
> ><br>
> > > At work I have access to a large acoustics test<br>
> > lab<br>
> > > and borrowed a portable calibrator. My RS sound<br>
> > meter<br>
> > > was off up to + AND - 3 dB. It varied<br>
> > considerably<br>
> > > with frequency. At lower frequencies (<1 KHz) it<br>
> > read<br>
> > > low by 2-3 dB, at higher frequencies (>1 KHz) it<br>
> > read<br>
> > > high by 2-3 dB. Pretty much varied all over the<br>
> > > place.<br>
> > ><br>
> > > The message is don't get hung up on 95 dB vs. 96<br>
> > dB.<br>
> > > The RS meter will give you a ballpark absolute<br>
> > value,<br>
> > > and as Earl said will give you decent relative<br>
> > > measurements.<br>
> > ><br>
> > > Ed<br>
> > ><br>
> > > --- "Del K. Rykert" <drykert@localnet.com> wrote:<br>
> > > > My radio shack soundmeter was off by almost 3 dB<br>
> > > > when it was calibrated.<br>
> > > ><br>
> > > > Del<br>
> > > > ----- Original Message ----- <br>
> > > > From: Earl Haury<br>
> > > > To: discussion@nsrca.org<br>
> > > > Sent: Saturday, April 24, 2004 9:05 AM<br>
> > > > Subject: Re: sound meter<br>
> > > ><br>
> > > ><br>
> > > > Steve<br>
> > > ><br>
> > > > It matters a lot. The rules specify dB-A, so<br>
> > use<br>
> > > > the A scale. Without a calibrator most sound<br>
> > meters,<br>
> > > > even the expensive variety, are really only good<br>
> > for<br>
> > > > comparative measurements. So - use it to find<br>
> > what<br>
> > > > makes the airplane quieter but don't get fixated<br>
> > on<br>
> > > > the absolute number without a calibrated<br>
> > reference.<br>
> > > ><br>
> > > > Earl<br>
> > ><br>
> > ><br>
> > ><br>
> > ><br>
> > ><br>
> > > __________________________________<br>
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