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No matter what equipment you use to Produce your
podcast,
audio calibration is one of the most important steps you
take to
produce high quality audio for podcast that sounds
good on any type of
equipment.
 Let's look at this topic from another angle to get you
up
to speed ! Let's say you are driving down the Interstate
and you
think you are doing the speed limit, when you look
in the mirror and you see
Blue Lights (oh, no!). You pull over
and are told that you were going 20 mph
over the speed
limit, but your speedometer said you were driving
the speed
limit. Let's just say in Police terms,
your speedometer was over
modulating.
What we have here is a speedometer that is out of Calibration.
And it just cost you about $1,000. (ugg)
Take that into the Audio Realm. If you wonder
why
your audio is clipping it is because of over modulation.
Your levels are
peaking above 0db. This is know in the
World of audio as "clipping".
Analog audio could slip by
and not be noticed quite as much when pushed over
0db, but Digital
Audio is a different beast. It sounds like glass
being
crunched in your ear.
Your levels are peaking over 0db because of two
things,
You have not calibrated your audio chain, or you just
choose not
to monitor your audio levels. If you are not monitoring
your audio levels,
shame on you. Let's change that habit right now.
Here is a system wide audio VU meter to monitor your
audio chain,
your microphone and other audio equipment you use to create your
podcast.
In reviewing Podcast for listing on The Podcast Bunker, the biggest
mistake
I often hear is the microphone being over driven, distortion ruins
the
audio and the quality of the Podcast.
This tool is free and will be worth its weight in
gold.
Contribute to the author if you continue to use this on a
daily
basis.
Audio Level Meter from Paul Marshall
http://www.darkwood.demon.co.uk/PC/meter.html
Okay you have the Meter, now what the heck
do you do with it ?
Well, lets grab some Podcast Bunker Test Tones. I have
created
4 test tones in mp3 & wav format plus a censorship tone.
You can make an instant download purchase of the tones for
$9.95
The tones included are
0db,-5db,-10db,-15db,-20db
Let's take The 0db test tone and play it on your system.
Now set
your master level so the meter is peaks at 0db.
You may need to turn down the master level of your
Mixer
if your using one, we will get to that in just a second.
Go ahead
and play the 0db tone, I will wait here.
Okay so you are running over peak, so play the 0db tone
again,
and adjust your audio levels to show an output
of 0db. Now take a
Sharpie or piece of tape and place it on
your master gain to mark where peak
is.
Now lets run some audio from any outside source into
your PC or Mac,
and check the levels. If they are showing over 0db, bring the
level
down on the mixer until it peaks on the Audio Meter at 0db.
Check the Microphone level. This can be done by
running
a microphone check by talking into the microphone at your normal
level
that you use when talking in your podcast. Now for a safety
zone,
turn the microphone level down and have it peak at -15db. This
will
insure that you have left yourself some room if you
raise your voice during
your podcast.
One other tip that is very important. Do not try
to talk
over the music if you use an intro for your podcast, bring the
level
of your music down and talk at your normal level. When you are
about
to finish talking or bringing in music when you are near the
point
of finishing your intro slowly bring the music level up to peak at
0db.
This should give you a good idea about audio calibration
and help you
to maintain a good level on your podcast. If you choose to take
your Podcast
into post production, I suggest you find a Compressor plugin or
software.
Set you Compressor to -3b and leave that safety margin. If you
check
your calibration before each podcast, you will have the confidence
that
your are producing a distortion free podcast.
Watch those
levels !
Back to Tips & Tools
© 2008 The Podcast Bunker - http://www.podcastbunker.com
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