Calibrating PPM Meters with Final Cut Pro HD
by Kai Whittaker (Kai)
on
Feb 6, 2008 at 8:55:22 pm
Hi,
I have a Final Cut Pro system and I'd like some advice on how to calibrate the audio output. I use a Decklink Multibridge Pro and a Phase3 VP-2 Extended range PPM/VU meter to check levels.
When I lay bars and tone into a timeline in FCP, it's automatically set to -12dB (on FCP's digital scale). If I dump that onto a tape or export a quicktime movie and take it to the sound studio we use for recording/mixing, they say the bars are 8dB too 'hot'. They ask that I set my bars to -20dB in FCP, and adjust my program levels so that they never go above -8 dB (digital).
I'd like to know how I should calibrate my Phase3 PPM/VU meter. My audio engineer guy suggested that I play back a -20dB tone from my timeline and adjust the input volume on my PPM meter (I use my meter in PPM mode) to zero dB.
When I do that, everything in the program seems hot according to the PPM meter.. I'm not very experienced with analog vs. digital sound and I'm wondering if I should adjust my PPM meter to -20dB like the tone in my FCP timeline. But isn't that mixing/matching analogue and digital levels?
Re: Calibrating PPM Meters with Final Cut Pro HD by Chris Borjis on Feb 6, 2008 at 9:18:40 pm
definitely use -20 tone out of final cut.
but turn off ppm and use the VU setting on your peak meter.
-20 out of fcp into the meter with VU using balanced audio should register 1 red bar (equals zero)
I find VU much more helpful for QC standards than digital for sure but I always monitor both. And by the way, digital at -20 is equal to zero on VU.
-8 on digital for the absolute peak (you mentioned) is a little hot, it should be more like -10 so if someone has audio content that is totally slammed at the wall, it will not overload looking at the VU meter.
Re: Calibrating PPM Meters with Final Cut Pro HD by Rob Alexander on Feb 7, 2008 at 9:07:24 am
Hi Kai,
If all you did was change the level of the tone but had previously mixing relative to the -12dB tone then your programme sound would be too hot. So you'd need to drop all the programme sound by 8dB too.
You SHOULD set your reference to -20 and mix relative to that.
PPMs have different ballistics compared to VU meters and in the UK at least are considered more reliable. Here, -18dBFS (digital) = 4PPM = -4dB (analogue). Each mark on the PPM equates to 4dB so peaking at 6PPM gives you a digital peak of -10dBFS. However because PPMs are a little slow to respond a peak of 6PPM may show higher than -10 digitally. You need to check your broadcaster's technical requirements and how they assess the sound levels at QC.
I think that in the US you calibrate with -20 instead of -18 but the analogue remains the same, i.e. -20dBFS = 4PPM etc.
