[RDD] Meters vs. dBFS(?)

Fred Gleason fredg at paravelsystems.com
Sun Apr 19 10:50:37 EDT 2009

On Friday 17 April 2009 10:38:18 pm Gavin Stephens wrote:
> Anyway, on the
> audioscience cards and with a peak level of -20dB on file, is the output of
> the card +4dBu or does the card need bumped up the 20dB gain switch the ASI
> mixer? Or I should say, what does 0dBFS = in terms of dBu out of the
> Audioscience cards without the 20dB gain switched on and with it switched
> on.

The basic reference gain structure for analog ASI outputs in the default 
configuration is:

	0 VU == -16 dBFS == +4 dBu

So if you had a file with peaks at -20 dBFS, the peak analog output level 
would be 0 dBu.  Twiddling the gain settings in RDAdmin will affect the 
analog output level, but *not* how it appears on the RD meters.

That said, I have virtually never had to tweak those controls in a production 
environment, as +4 dBu has pretty much become the industry standard for line 
level balanced inputs on pro gear.


| Frederick F. Gleason, Jr. |               Chief Developer               |
|                           |               Paravel Systems               |
|      A rock pile ceases to be a rock pile the moment a single man       |
|      contemplates it, bearing within him the image of a cathedral.      |
|                                     -- Antoine de Saint-Exupery         |

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