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[4631] b5 - Summing Grouped Audio Tracks, Peak Meter off
Posted: Tue Feb 03, 2009 5:54 am
by invol
When running a single -6 dBFS test tone through group master, Peak meter reads -6 dBFS. When running the same tone twice, it reads + .02, and shows clipping.
It should not clip and should read 0 dBFS.
Could be my test tones... but worth looking into.
Full Sweep -6.00 db, 44.1 kHz
Test tones were generated with Make A Test Tone by Audio Ease.
-B
Posted: Tue Feb 03, 2009 6:11 am
by Tarekith
Confirmed, master out seems to be 0.02 off in all cases. Not sure how important that is, but worth knowing I guess.
Posted: Tue Feb 03, 2009 6:29 am
by ilia
Ooh, the Pentium bug from '94 is back again...
Posted: Tue Feb 03, 2009 7:03 am
by invol
I know this is not a super big deal, but is worth noting. It could point to something more serious.
Posted: Tue Feb 03, 2009 1:40 pm
by Matthias
hi invol,
we calculate the amplitude from dB by 10^(ValueInDB/20) which results in 0.5012 for -6dB. when added again it sums up to 1.0024 which is then about 0.0208 dB. to get an amplitude of exactly 0.5 you must set the sliders to -6.0206 dB.
as far as I see everything is as it should be...
best wishes,
matthias
Posted: Tue Feb 03, 2009 2:39 pm
by Tarekith
Thanks MR. Wizard (Matthias)!
Posted: Wed Feb 04, 2009 12:55 am
by invol
Great. Thanks for the info.
So you are calculating it as voltage (right?), and I was just assuming the Inverse Square Law, which is dB SPL... Doh!
Thanks!
Brian
Posted: Wed Feb 04, 2009 1:07 am
by ilia
mmm, however you calculate it, -6db comes out to a little over 0.5 in amplitude (or a little over 0.25 in power) ratio. just saying.
Posted: Wed Feb 04, 2009 2:23 am
by invol
Looks like I need to brush up on my physics : )