[AG-TECH] Audio Question

[Osland, CD (Chris)]

Naturally many things can cause crackling and pops, but IMHO
by far the most common is not getting the levels right through
the whole audio chain.  With a Gentner AP800 there are the
following variable gain points (from memory - I may have missed
one out!):
 
    mic gain - coarse and fine together - aim for post-gain level
        that only exceeds 0 dB occasionally and by no more than
        say 6 dB
 
    output channel gain - ditto
 
    RAT 'send' gain - normally I aim for 70% - 80%, into the
        yellow but not the red
 
If any of these are higher or lower and then compensated for
by another gain, the chances of cracking, popping, distorting
and general nastiness are high.  Always get these right before
attacking any other parameters; e.g. using a limiter to correct
too high a post-gain mic level adds a second possible form of
distortion - it doesn't remove the first!
 
In these days of all (or at least most) signal processing being
in the digital domain, errors are punished much harder than
in analogue days.
 
Cheers
 
Chris
 

____________________________________________________________________ 
Chris Osland                                               Office tel: +44
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-----Original Message-----
From: Nolan, Kevin [NCSUS] [mailto:knolan at ncsus.jnj.com]
Sent: 14 October 2002 16:48
To: 'Robert Olson'; Nolan, Kevin [NCSUS]; 'ag-tech at mcs.anl.gov'
Subject: RE: [AG-TECH] Audio Question



We are at 16khz - it could be that we are too hot - just thinking of other
options.  thanks 

-----Original Message----- 
From: Robert Olson [ mailto:olson at mcs.anl.gov <mailto:olson at mcs.anl.gov> ] 
Sent: Monday, October 14, 2002 11:04 AM 
To: Nolan, Kevin [NCSUS]; 'ag-tech at mcs.anl.gov' 
Subject: Re: [AG-TECH] Audio Question 


You're not at 8khz, are you? the audiopci cards at 8khz can introduce 
distortion. 

have you carefully balanced mic & system levels? perhaps you are 
overdriving a level at some point in the audio chain. Hard to tell for sure 
what it is without hearing it. 

--bob 

At 10:39 AM 10/14/2002 -0400, Nolan, Kevin [NCSUS] wrote: 
>At Johnson & Johnson, we are having some audio issues with slight 
>crackling as we communicate with other sites.  Has anyone seen this in the 
>past?  These are room to room systems. 
> 

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