Re: [LAD] [ANN] Invada Studio LV2 Plugins 1.2.0

Fons Adriaensen wrote:
> On Sun, Aug 23, 2009 at 07:27:18PM +0100, Dan Mills wrote:
>
>
>> Lets say your card is aligned so that 0dbFS = +18dbu (EBU standard),
>> then 0Vu = +4dbu = - 14dbFS, so a software VU calibrated for 0Vu =
>> -14dbFs should read the same as an external Vu calibrated for +4dbu =
>> 0Vu. If it does not then either a calibration setting is off somewhere
>> or one of the meters is faulty.
>>
>
> True.
>
> But even a definition such as 'dB FS' is ambiguous, and
> it's easy to make mistakes as a result of that.
>
> Consider a sine wave that is just below digital clipping.
> This would be called '0 dB FS', but the actual RMS level
> is 3 db lower. I've seen at least one context where this
> same signal would be called -3dB FS. Which somehow makes
> sense as well.
>
> AFAIK the first interpretation is the more common one.
>

'Peak level' vs 'intrinsic level':

    * 'dbFS' refers to 'peak level', 'full-scale square wave'
    * 'dbFS RMS' refers to 'intrinsic level, 'full-scale sine wave'.

This is how is in Germany distinguished and because of the words on
English, it might be an international way to distinguish it.

>> actually fairly common with professional cards.
>>
>
> And it avoids a lot of problems. Semi-pro cards will not
> have the correct levels, but some can be quite consistent
> between channels. For example my Terratec EWS88MT has less
> than +/- 0.1 dB variation between its 8 channels, both
> for input and output. But the actual level is just +3.5dBu
> for a FS sine wave.
>
> The real misery starts when (as reported in a recent post
> on LAU or LAD), a user finds four volume controls between
> his audio file and the physical output (plus of course
> a fifth one on his amplifier), and then of course gets
> confused on how to set all of them.

I guess this is the leading point. Even professional IO amps at times
need calibration.

We should imagine a setup like 'sound card --> tube pre-amps -->
mastering recorder'. For this scenario a VU meter needs to be an
external one.

Ralf
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Received on Mon Aug 24 16:15:02 2009