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<DIV><FONT color=#0000ff face=Arial size=2><SPAN
class=210220201-17022005>Tony,</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN
class=210220201-17022005> This is all very interesting. Even in the short
time I've spent looking at these meters I noticed some questionable areas.
That's why I asked if there was a more specific set of test criteria /
procedures. It seems to me, that even under controlled conditions, a GOOD meter
might not produce repeatable results. It is of course very important to
calibrate to a reference (i.e. 94dB / 1KHz), then measure. Without doing that
you can't take accurate absolute measurements. Also, Unless the spec. is written
to allow for tolerance of the meter (most of the ones I've seen are +/- 1.5dB),
sometimes you'll read (too) high and sometimes you'll read low, even with the
same source and a calibrated meter. It's probably more important to have an
accurate means of re-calibrating the meter rather than having a meter that has a
tighter tolerance. Taking reasonably accurate measurements relative to a known
reference should be acceptable, I would think. That's why a band tunes to
the keyboard if they don't have an electronic tuner handy. A modern electronic
keyboard can be considered an accurate reference for pitch.
</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN class=210220201-17022005>
<P><FONT size=2>John Pavlick<BR><A href="http://www.idseng.com/"
target=_blank>http://www.idseng.com</A><BR> </FONT>
</P></SPAN></FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=Tahoma><FONT size=2><SPAN
class=210220201-17022005> </SPAN>-----Original Message-----<BR><B>From:</B>
discussion-request@nsrca.org [mailto:discussion-request@nsrca.org]<B>On Behalf
Of </B>tony@radiosouthrc.com<BR><B>Sent:</B> Wednesday, February 16, 2005 7:25
PM<BR><B>To:</B> discussion@nsrca.org<BR><B>Subject:</B> Re: Sound Level meter
requirements<BR><BR></DIV></FONT>
<BLOCKQUOTE dir=ltr
style="BORDER-LEFT: #0000ff 2px solid; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px; PADDING-LEFT: 5px"></FONT>
<DIV><FONT face=Arial size=2>Del:<BR>The problem with all meters I know of is
that they all change! I was the first one in the USA to work with the
FAI in establishing how a db check would actually be done in the field.
I did the first ones at the 1983 US Team Selections in Rough River, KY right
before the 1983 World Champs. As I was the assistant CD for the WC, AMA
wanted me to gather the data and learn how the system the FAI had designed
would really work in the field. We found that even expensive db meters
developed drift.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>The expensive versions used by AMA have to be
adjusted about every 4 hours, as they can drift 1/2 to 1 1/2 db in that period
of time due to temperature changes. That is the problem with any
meter. Unless you have a calibrator to adjust the meter, it is really
pretty worthless in getting an accurate measurement. As long as + or - 5
db is OK, you don't need to worry. However, if you are trying to meet
any model noise requirement out there, your really spinning your wheels.
</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV>Tony Stillman<BR>Radio South<BR>3702 N. Pace Blvd.<BR>Pensacola, FL
32505<BR>1-800-962-7802<BR><A
href="http://www.radiosouthrc.com">www.radiosouthrc.com</A></DIV></BLOCKQUOTE></BODY></HTML>