DAC output level setting

[jan.didden]

I have a perhaps obvious question, but here goes.
If I set the (digital) output of a DAC to 0dB, can I assume that the analog output signal level is exactly the same
as the signal level encoded in the digital (AES, S/PDIF, USB) input level?

In other words, whatever the specified max output of the DAC may be, at 0dB volume setting there is no signal gain or attenuation from digital in to analog out?

Jan

 

[Davey]

The signal level in your digital signal isn't referenced to any specific analog level the DAC produces.
A digital signal level of 0dbFS should produce the maximum analog output level your DAC is spec'd at.........whatever that might be.
Generally, for consumer gear, in the neighborhood of 2 volts RMS. But, it could be anything.

Dave.

 

[jan.didden]

Hmm, yes that makes sense.
I'm trying to use diferent DACs for different channels in my system and naïvely thought
that when I set all of them to 0dB they all would output the same level (assume same digital input level).
But I guess that's not a valid assumption.

Jan

 

[Davey]

Yep, with disparate DAC's used in the same system, you'd have to actually measure them to characterize the relative differences.

Dave.

 

[rfbrw]

0dBFS on the recording side varies across the board.

 

[jan.didden]

Bit the bullet and dove into the manual.
For the RME you can set different 'reference levels' like +4dBu, +13dBu, etc and that's referred to 0dBFS.
Those levels are then 0dB Vout.
So all info is there to refer back to absolute levels.

Thanks for giving me the hint.

Jan