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Re: Digital clipping; transfer to CD; increased gain

Subject: Re: Digital clipping; transfer to CD; increased gain
From: Dan Dugan <>
Date: Mon, 24 Jan 2005 17:16:15 -0800
Syd Curtis wrote:

>I use Peak LE to copy a digital line out signal from a Tascam DAT to a Audio
>Media III Card in a Mac G3 to make an AIFF file, and then Toast to burn a
>data CD with a writer that uses TEAC technology.  My hope has been that
>after the Tascam has made the initial A/D conversion, I am retaining the
>original digital data unchanged through to the CD.
>
>Question 1.  Is that a justified assumption?

Yes.

>For pleasant listening, a recording below -24dB is too soft.  Peak allows me
>to increase the gain, and for an audio CD I usually aim to increase the gain
>so that the loudest sounds are at about -6dB, with maybe just a few notes
>registering -4dB.

This is conservative and fine. If there are really loud things like 
thunder there's no harm in going all the way.

>Q. 2.   Am I right in thinking that the intrinsic noise produced by my field
>recording equipment is not totally dependent on the recording level, and
>will be relatively worse if I set the R L in the field unnecessarily low?

The noise will be dependent on your mic and preamp combination unless 
you record really low.

>Q. 3.   If I use Peak to increase the gain in the computer AIFF file before
>writing a data CD, am I negating my desire to have the digital data of the
>sounds unchanged from Tascam to CD?

It's changed, but in a benign way.

>Q.4.  Is is possible to explain in terms understandable to a non-technical
>person, what happens to the digital data when I use Peak to change the gain?

Sure. All the data point values get multiplied by a constant.

>I should explain that increasing old-age hearing loss, means that I can no
>longer rely on what I hear as a satisfactory quality assessment of sound,
>and need to rely on what I cam see on computer screen or recorder dials.

Digital is good that way. It would be helpful to have a sorcerer's 
apprentice around to listen. I've been told Isaac Newton was color 
blind and used an assistant to describe the colors of the spectrum. 
And then there was Beethoven.

-Dan Dugan


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