[Scott Dorsey]

PStamler wrote:
On Nov 18, 8:39=A0pm, Randy Yates wrote:
=A0 1. If you backtrack to 0 dB from this wikipedia article
=A0 =A0http://en.wikipedia.org/wiki/Line_level
=A0 the reference levels for dBu and dBV are 0.775 VRMS and 1 VRMS,
=A0 respectively. Is this correct? Are the reference levels I've given
=A0 here exact?

No and yes, respectively. The reference level for dBu is actually
0.77459666924148337703585307995648V, according to my calculator --
that's the voltage equivalent of 1mW into a 600 ohm load. The
reference level for dBV is exactly 1V.

=A0 2. Is there a standard for converting from dBFS to dBu? If so, =A0 =
what is it?

No. There's an informal standard used in the film industry and in many
broadcast applications of +4dBu =3D -20dBFS, but it's never been
codified as an official standard. The informal standard, though, is (I
believe) based on an rms scale -- in other words, a tone that would
read 0 VU on a VU meter calibrated to +4dBu would be -20dBFS. Correct
me if I'm wrong on that last bit, but that's what I think is the case.

This is sort of like asking if there is a standard for converting pounds
to feet. They aren't measuring the same thing. If you know something
specific about the item being measured, you can make some good estimates,
but you need to know something more.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."