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December 16, 2006 - 8:03pm
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Othello
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Test CD level

I have a CD player with adjustable balanced outputs and wanted to set them at the proper level. For the rest of my equipment I feed a 0.775V (0dB) tone from an audio oscillator into the board and adjust, if necessary.

I can't use that approach with a turntable or a CD player which is why I bought the test CD 3 to be able to generate a test tone from within the player.

Test tones on the CD have levels given, for example -20dBFS. I don't know what the FS means but i assumed that the recording level was at -20dB, but that seems to be wrong.

Where is my error and what are the recording levels on this CD?

Uwe

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December 16, 2006 - 9:05pm
Jeff Wong
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Re: Test CD level

Decibels (dB) are used to describe relative loudness. In your example, FS refers to full scale (this is not to be confused with dB SPL which represents sound pressure level, where 0 dB SPL would be super quiet and 120 dB SPL would be a deafening airplane engine.) So, -20dB FS would be 20 dB below 0dB FS, which is the loudest digital level.

I think the only way you'll be able to match levels between 2 things is to use the same reference tone, measure the SPL from your listening position, and adjust so that they're the same (and mark each setting on your volume control.) But, this may be pointless since recordings on CDs (and LPs) are going to be mastered at a variety of different levels.

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December 17, 2006 - 6:31am
Othello
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Re: Test CD level


Quote:
But, this may be pointless since recordings on CDs (and LPs) are going to be mastered at a variety of different levels.

Well, I think I have my doubts about this.
My tape machine, for example, has a very much defined output level and if I use another broadcast tape it will have the same level and will not create an unpleasant jump or drop in volume. And you are telling me that is not true for CDs and LPs. So in a studio for the operator each CD is a totally new world and one does not know what to expect, the level could be anything???

So why are the tracks of the test CD at all labeled with levels, what purpose does this serve??

Uwe

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