Rivnedell normalises audio to something like peak -13dBFS if you have it set
to normalise on import etc... The meters in Rivendell are also more like a
real(ish) VU meter, not a peak meter like in Cool Edit/Audition etc... don't
get the two confused. It normalises to this low peak level by default to
protect those using professional sound cards.
Some cards (not sure about the 410 you'd have to check) if balanced still
don't have a decent output level, they are prosumer and not a full +24dBu
output capable card. I have a Terratec Phase 22 with balanced but the output
is +8dBu max so it's not a real professional level card which should be
+24dBu max with a norminal of +4dBu.
But on a pro card, you don't normalise audio to within a few dB of 0dBFS on
a PC. You run a reference tone normally 1KHz at about -20dBFS on your audio
file, to calibrate VU meters (which are an averaging meter not peak) to 0VU
on analogue equipment. You'll then find when you take away the test tone and
apply programme audio you'll get peaks of anywhere from say like -13dBFS
to -6dBFS with some headroom left over. A -20dBFS test tone would give you a
nice +4dBu norminal (average) output on a professional balanced audio card,
with 20dB of headroom for peaks which gives you the full +24dBu output of
the card. (24 - 20 = 4).
If you had an audio file normalised to say -2dBFS on the PC, this would run
a pro card extremely hot (+22dBu out all the time with an average of about
+14dBu output) and doing that can end up cooking some outputs or inputs or
add distortion very easily elsewhere.
On a cheap noisey card however with unbalanced outputs built to drive tiney
sounding speakers an audio file that's peaks are about -9dBFS means turning
up the stereo and also the noise.
I suggest you go through the archives and google what a real VU meter is,
and the SMPTE reference for 0VU is. It's been talked about a lot before in
the past in the mailing list and is one of the hardest things to show and
explain sometimes to budding audio engineers that have grown up on domestic
sound cards with ripped CD's near 0dBFS on their computer (in the consumer
world full of noise).
Cheers,
Gavin.
----- Original Message -----
From: "Keith Thelen" <kthe...@kanabec.net>
To: <rivendell-dev@lists.rivendellaudio.org>
Sent: Thursday, August 07, 2014 1:05 PM
Subject: [RDD] M-Audio Delta 410 low output levels
Hello all!
This probably falls into the category of ‘dumb questions normally asked by
newbies’, but…
Fresh install of RD Appliance. Sound card is a Delta 410 under ALSA
(ice1712/envy24). All the outputs work, but the levels are awkwardly low.
Had to crank everything in alsamixer all the way up to make it even mildly
useful. The VU meter in RDAirplay looks fine, with the peaks occurring right
below 0… but at the console, even with the pot wide open, the peaks are
around -30.
Is there some trick with this card/software setup that I’m missing?
---------------
Keith Thelen
Kanabec Systems
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