Waves L1 Weirdness and SR

[PostKID]

Recently we had to do a series of SR laybacks for a show mixed at the studio. The network spec asked the 5.1 be limited at -2 (The mixers didn't know about this spec till after the show was mixed and printed). So we plopped an L1 on the 6 discrete channels in Pro Tools for the layback. Everything looked good. The tapes went out to QC and failed, they were almost 3 db hot....Any ideas what went wrong?

[TVPostSound]

they were almost 3 db hot

If the spec says -2dB, and you were 3dB hot, that makes no sense.

Reread the QC, and tell us what was 3 dB hot. Maybe the dialnorm??

[rhumphries]

That doesn't make sense. I think you are confusing two problems.

You say that QC rejected the shows for being 3dB too hot, but you don't specify what aspect is 3dB too hot. The VU, the Dialnorm, or the peak? I don't think it could be the peak because you stated that the peaks were limited at -2dB (dBFS I'd assume). 3dB above that doesn't exist, so the peak limit is not your problem. If it's the VU or Dialnorm your L1 probably wouldn't affect your VU or dialnorm that much (ymmv) unless you used some makeup gain.

Problem 1) peaks need to be limited to -2dBfs.

Solution: peak limiter with threshold of -2 and no makeup gain.

Problem 2) VU or Dialnorm too hot.

Soluton: Tweak the mix to get it in the pocket based on the spec.



-Richard

[PostKID]

You're right. Its doesn't make sense. I was referring to the peak level and its only sneaking through on the center channel, While the L1 is set with the threshold at -2. Right, there is not 3db over -2. Maybe I wasn't clear, the 3db difference came from adjusting the L1 and checking it on a tektronix meter. The QC report just said "peaking."

[TVPostSound]

Im thinking your electrical calibration on the D/A is off.

[Mundox]

You should set the L1 output to -2, and leave the threshold at -1.
If you do it other way, L1 will add make-up gain.

[UnderTow]

Originally Posted by PostKID

Recently we had to do a series of SR laybacks for a show mixed at the studio. The network spec asked the 5.1 be limited at -2 (The mixers didn't know about this spec till after the show was mixed and printed). So we plopped an L1 on the 6 discrete channels in Pro Tools for the layback. Everything looked good. The tapes went out to QC and failed, they were almost 3 db hot....Any ideas what went wrong?

Besides the issues with failing QC... why do you put a limiter over an already mixed show? If it peaks at 0 dB FS and it needs to peak at -2 dB FS max, just reduce the gain by 2 dB!

You need to learn about all the different types of calibration and metering. If the network ask for -2 it could be -2 dB FS but it could also be -2 PPM or -2 Dialnorm or... If a spec from a network is not clear, call them before starting any work and make sure things are clarified. It will save you work in the long run.

Alistair

[Fabi]

The problem is of different nature.

The HD SR you layed back on probably shows OVERS due to a metering issue Sony didn´t realize

This can happen even when the Mix is limited at -2fs because the over indicator shows an interpolation of a clipped waveform.

And yes still it doesn´t make sense but this is what Sony did there and now we all have to live with it unfortunately.

[apple-q]

Originally Posted by UnderTow

Besides the issues with failing QC... why do you put a limiter over an already mixed show? If it peaks at 0 dB FS and it needs to peak at -2 dB FS max, just reduce the gain by 2 dB!

Well said.