Have you ever noticed that audio levels aren’t consistent outputting to Beta?

[Dave Friend]

Ron,

Most of what you are seeing is due to the different metering system in PPro and on the Beta deck. The 1800 is showing you analog VU levels and PPro is showing you digital peak levels. VU is sort of a running average and, as such, simply won’t display the peaks the way that a digital meter does. Those are showing the precise level at any given instant.

There is a SMPTE standard for reference audio from digital sources that specifies a level of -20dB.

Try this:
First, your program material should NOT exceed -9dB on the PPro meters. This is kind of hard (OK, damn near impossible) to do accurately with PPro because of the crude way Adobe chooses to display audio levels. But if you set levels so that someone speaking with a “normal” voice peaks around -12, and that the loudest peaks don’t go more than halfway to -6 on the PPro meters you will be pretty close.

Second, set the tone to -20dB on the PPro meters. Adjust the 1800 record level to 0VU from this tone.

You will find that reference tone and program levels will be pretty much in line. Really, this does work and is standard industry practice.

Hope this helps.

Dave

[Ron Moody]

Dave,

You say that Premiere should NOT exceed -9dB. I accept your statement but where does it come from? Is it part of the industry standard, or your experience, or a page in the manual that I missed? You say it with authority so I know you got if from somewhere but am curious as to its source.

Second, in my experience to date, tone and program within Premiere differ by 7-8dB. Your settings present an 11dB differential. I haven’t tried it yet, but is this what your experience has led you to set as standard levels?

I’m really curious about the peaks at -9dB thing.
rm

PS: To an earlier post, my tone was set at -7dB in Premiere and program at zero (which I now understand is wrong.) Although I haven’t heard any distorition with levels set there.

[Dave Friend]

[Ron Moody] “I accept your statement but where does it come from?”

It comes from a number of sources. First is SMPTE RP155 (a technical document) which specifies the reference level for digital audio as -20dBfs. Every network that I have delivered to (multiple broadcast and cable networks) adheres to that standard. These networks also typically spec that -9dBfs is the maximum peak allowable. Sometimes, they vary by a dB or so. For instance, ABC allows a max peak of -8dBfs if I recall correctly. Send a tape outside these specs, by even a tiny bit, and it will come back in a hurry having failed the tech evaluation. (Europe and some other parts of the world use a slightly different reference level.)

As it turns out (probably not an accident) using these levels as indicated by a digital peak meter will result in a digital to analog (audio) conversion that mostly works perfectly. I say mostly because if your material is highly compressed, say with lots of peaks between -9 and -12 for sustained periods of time, then the analog will be too hot.

There was a thread on this forum some months ago where I went through this with someone else. Read that thread for more details. There is a link in that thread to a website with a lot of technical info on how the different methods of measuring audio levels relate to each other. Unfortunatly, that link now appears to be dead. I will try to find a new link and will post it here if I succeed. Maybe this link or this link will prove useful. They kind of cover the same info the old link did but they are not as easy to read.

[Ron Moody] “I haven’t heard any distorition with levels set there.”
You will not until the level attempts to go beyond 0dBfs which is the absolute max that a digital source will allow. There aren’t any bits left to represent a volume beyond that level. IOW, there is no such thing as +4dBfs in the digital world. As long as your monitoring setup will handle the output sent to it and the meters stay under 0dBfs, there will be no distortion. Not any due to gain settings at any rate.

Hope this helps.

Dave

[Ron Moody]

Wow, that was great! Thanks for the link.

As I suspected, the Beta deck should be set to peak at zero dB on both tone and program. Jumping into Premiere, this means that tone must be about 7 dB below peak program, which everybody seems to agree, should be set to about -20dB within Premiere.

It also appears that somehow Premiere got it wrong in setting tone at -12.

What I still don’t understand is why, when bars and tone are set to a reference level… the same level in Premiere, that the 1800 still reads bars as 7dB louder, even though Premiere says they’re the same level.

I guess I’m willing to leave that as a mystery.

Thanks for the great input though.
rm

[Jan Janowski]

I asked that question (Why -12db?) and was told “It’s the DVD Standard”.
I know for a fact that FCP also uses -12db as it’s reference… I was doing a freelance job at the time,
and set up an automated VHS Dubbing facility, and went through everything and set it for +4db analog….
and then FCP came in 8db hotter…. Tone and Audio…. A mixer in line was the solution…….

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