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<TITLE>RE: [AG-TECH] Audio Question</TITLE>
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<DIV><SPAN class=763110509-15102002><FONT face=Georgia color=#0000ff>Naturally
many things can cause crackling and pops, but IMHO</FONT></SPAN></DIV>
<DIV><SPAN class=763110509-15102002><FONT face=Georgia color=#0000ff>by far the
most common is not getting the levels right through</FONT></SPAN></DIV>
<DIV><SPAN class=763110509-15102002><FONT face=Georgia color=#0000ff>the whole
audio chain. With a Gentner AP800 there are the</FONT></SPAN></DIV>
<DIV><SPAN class=763110509-15102002><FONT face=Georgia color=#0000ff>following
variable gain points (from memory - I may have missed</FONT></SPAN></DIV>
<DIV><SPAN class=763110509-15102002><FONT face=Georgia color=#0000ff>one
out!):</FONT></SPAN></DIV>
<DIV><SPAN class=763110509-15102002><FONT face=Georgia
color=#0000ff></FONT></SPAN> </DIV>
<DIV><SPAN class=763110509-15102002> <FONT face=Georgia
color=#0000ff>mic gain - coarse and fine together - aim for post-gain
level</FONT></SPAN></DIV>
<DIV><SPAN class=763110509-15102002>
<FONT face=Georgia color=#0000ff>that only exceeds 0 dB occasionally and by no
more than</FONT></SPAN></DIV>
<DIV><SPAN class=763110509-15102002>
<FONT face=Georgia color=#0000ff>say 6 dB</FONT></SPAN></DIV>
<DIV><SPAN class=763110509-15102002><FONT face=Georgia
color=#0000ff></FONT></SPAN> </DIV>
<DIV><SPAN class=763110509-15102002> <FONT face=Georgia
color=#0000ff>output channel gain - ditto</FONT></SPAN></DIV>
<DIV><SPAN class=763110509-15102002><FONT face=Georgia
color=#0000ff></FONT></SPAN> </DIV>
<DIV><SPAN class=763110509-15102002> <FONT face=Georgia
color=#0000ff>RAT 'send' gain - normally I aim for 70% - 80%, into
the</FONT></SPAN></DIV>
<DIV><SPAN class=763110509-15102002>
<FONT face=Georgia color=#0000ff>yellow but not the red</FONT></SPAN></DIV>
<DIV><SPAN class=763110509-15102002><FONT face=Georgia
color=#0000ff></FONT></SPAN> </DIV>
<DIV><SPAN class=763110509-15102002><FONT face=Georgia color=#0000ff>If any of
these are higher or lower and then compensated for</FONT></SPAN></DIV>
<DIV><SPAN class=763110509-15102002><FONT face=Georgia color=#0000ff>by another
gain, the chances of cracking, popping, distorting</FONT></SPAN></DIV>
<DIV><SPAN class=763110509-15102002><FONT face=Georgia color=#0000ff>and general
nastiness are high. Always get these right before</FONT></SPAN></DIV>
<DIV><SPAN class=763110509-15102002><FONT face=Georgia color=#0000ff>attacking
any other parameters; e.g. using a limiter to correct</FONT></SPAN></DIV>
<DIV><SPAN class=763110509-15102002><FONT face=Georgia color=#0000ff>too high a
post-gain mic level adds a second possible form of</FONT></SPAN></DIV>
<DIV><SPAN class=763110509-15102002><FONT face=Georgia color=#0000ff>distortion
- it doesn't remove the first!</FONT></SPAN></DIV>
<DIV><SPAN class=763110509-15102002><FONT face=Georgia
color=#0000ff></FONT></SPAN> </DIV>
<DIV><SPAN class=763110509-15102002><FONT face=Georgia color=#0000ff>In these
days of all (or at least most) signal processing being</FONT></SPAN></DIV>
<DIV><SPAN class=763110509-15102002><FONT face=Georgia color=#0000ff>in the
digital domain, errors are punished much harder than</FONT></SPAN></DIV>
<DIV><SPAN class=763110509-15102002><FONT face=Georgia color=#0000ff>in analogue
days.</FONT></SPAN></DIV>
<DIV><SPAN class=763110509-15102002><FONT face=Georgia
color=#0000ff></FONT></SPAN> </DIV>
<DIV><SPAN class=763110509-15102002><FONT face=Georgia
color=#0000ff>Cheers</FONT></SPAN></DIV>
<DIV><SPAN class=763110509-15102002><FONT face=Georgia
color=#0000ff></FONT></SPAN> </DIV>
<DIV><SPAN class=763110509-15102002><FONT face=Georgia
color=#0000ff>Chris</FONT></SPAN></DIV>
<DIV> </DIV>
<P><FONT face=Arial
size=2>____________________________________________________________________</FONT>
<BR><I><FONT face="Comic Sans MS" color=#ff0000 size=4>Chris
Osland</FONT><B></B></I><B></B><B></B><B><FONT face=Arial size=2></FONT></B>
<FONT face=Arial
size=2> </FONT><I>
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<BLOCKQUOTE dir=ltr style="MARGIN-RIGHT: 0px">
<DIV class=OutlookMessageHeader dir=ltr align=left><FONT face=Tahoma
size=2>-----Original Message-----<BR><B>From:</B> Nolan, Kevin [NCSUS]
[mailto:knolan@ncsus.jnj.com]<BR><B>Sent:</B> 14 October 2002
16:48<BR><B>To:</B> 'Robert Olson'; Nolan, Kevin [NCSUS];
'ag-tech@mcs.anl.gov'<BR><B>Subject:</B> RE: [AG-TECH] Audio
Question<BR><BR></FONT></DIV>
<P><FONT size=2>We are at 16khz - it could be that we are too hot - just
thinking of other options. thanks</FONT> </P>
<P><FONT size=2>-----Original Message-----</FONT> <BR><FONT size=2>From:
Robert Olson [<A href="mailto:olson@mcs.anl.gov">mailto:olson@mcs.anl.gov</A>]
</FONT><BR><FONT size=2>Sent: Monday, October 14, 2002 11:04 AM</FONT>
<BR><FONT size=2>To: Nolan, Kevin [NCSUS]; 'ag-tech@mcs.anl.gov'</FONT>
<BR><FONT size=2>Subject: Re: [AG-TECH] Audio Question</FONT> </P><BR>
<P><FONT size=2>You're not at 8khz, are you? the audiopci cards at 8khz can
introduce </FONT><BR><FONT size=2>distortion.</FONT> </P>
<P><FONT size=2>have you carefully balanced mic & system levels? perhaps
you are </FONT><BR><FONT size=2>overdriving a level at some point in the audio
chain. Hard to tell for sure </FONT><BR><FONT size=2>what it is without
hearing it.</FONT> </P>
<P><FONT size=2>--bob</FONT> </P>
<P><FONT size=2>At 10:39 AM 10/14/2002 -0400, Nolan, Kevin [NCSUS]
wrote:</FONT> <BR><FONT size=2>>At Johnson & Johnson, we are having
some audio issues with slight</FONT> <BR><FONT size=2>>crackling as we
communicate with other sites. Has anyone seen this in the
</FONT><BR><FONT size=2>>past? These are room to room systems.</FONT>
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