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Old October 31st, 2012, 11:10 AM   #1
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Gain structure with a computer---what do people do?

I've been puzzled for a while over how best to establish a reliable, repeatable gain structure with desktop video. By "gain structure" I mean a system that can be duplicated across many desktops in a production facility.

When you work in an all-hardware environment, I think this becomes a bit easier (because you can set the appropriate gain for each piece of hardware, then forget about it). But when you work on a personal computer that you also use for listening to music recreationally and/or surfing YouTube...you're likely to tweak your computer's audio output in a variety of places.

For example, most DAW's and NLE's have their own software mixers and output level controls...but these can also be adjusted (or overridden) by the main computer volume slider at the OS level. If you're trying to set up professional, accurate monitoring levels, for example, how do you know where to set that "fuzzy OS volume" slider?

Then things become a bit more confusing when you have a mix of Macs and PC's being used for editing. (Which is the case in our shop...along with a mix of Avid and Premiere Pro.)

So I'm just curious to know how many people here who are in a predominantly desktop-computer-driven editing environment (e.g. you don't have outboard mixers, monitor/headphone amps, outboard meter bridges, etc.) pay attention to repeatable gain structure?

My question comes from a need (in our shop) to get all my editors on the exact same page in terms of audio monitoring and mixing. I'm in the process now of standardizing everyone on the same headphones and near-field monitors...but now I'm wondering about how best to establish a process for structuring gain that can be repeated across Macs and PC's on both Avid and Premiere Pro?

Thanks,
Scott
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Old October 31st, 2012, 11:34 AM   #2
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Re: Gain structure with a computer---what do people do?

Try this setup procedure: Blue Sky Blog Archive Blue Sky Calibration Test Files
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Old October 31st, 2012, 12:41 PM   #3
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Re: Gain structure with a computer---what do people do?

If there are appropriate API (application program interface) "hooks", a little software utility could be written which goes through and presets all the audio-related settings to some baseline standard. You could have it run when a user logs into the system so that everybody always starts from the same point.
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Old October 31st, 2012, 09:10 PM   #4
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Re: Gain structure with a computer---what do people do?

I have been frustrated for years because the Windoze audio sliders aren't calibrated in any way.

IMHO a computer (or at least a good internal/external sound card) should have fixed gain on the output side, calibrated so that 0dBFS (for example on any editing program) produces a known and unchangeable output voltage. Life would be much simpler if someone had implemented this by now.

PCs are being sold as serious workstations, yet we still have a "Pong-oriented" approach to the entire sound mixing scheme.
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Old November 1st, 2012, 09:00 AM   #5
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Re: Gain structure with a computer---what do people do?

@Greg---yes! I agree with you 100%. Or at a minimum, if there were accommodations at the OS-level for a DAW or NLE to take over 100% of audio controls, e.g. once you open Premiere Pro, the OS's volume slider is deactivated (or ganged to Premiere's master output faders). At least then you'd have one less variable.

@Steve---thanks for the link. At a glance, it looks very similar to the K-System for audio mixing (created by Bob Katz). I've tried using the K-System...but even that is difficult on a computer, because using the K-System correctly is dependent on having a monitor amp with output knobs marked in decibels (so you know where 0dB is...and can set the amp at a fixed, known number of decibels below 0). And of course I can't do that on a MacBook!

But at a minimum, I'm thinking what I could do is go around to each editor's workstation with an SPL meter and the pink noise file, and let everyone set their listening environment (however they want to) so that they're listening at a peak of 85dB...which corresponds to (say) -14dB on Premiere's (or Avid's) master output meters. Then ask everyone to take notes on their EXACT settings for all volume sliders everywhere. (That's basically how the K-System works.)

Scott
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Old November 2nd, 2012, 11:02 AM   #6
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Re: Gain structure with a computer---what do people do?

I guess I'd really like the PC (or sound card) to have two distinct outputs:

"Line output" which is related only to the absolute value of the file. i.e. 0 dBFS always produces a given voltage level at this output jack. When you see 0 dBFS in your application, you know you will always have a given analog output level. Then you just need to run the power amp for your monitor speakers at a given setting and the SPL results will be consistent every time.

"Monitor output" whose output could be affected by an OS or Application control (e.g. the Windoze "Volume" slider). This would be similar to the present variable output level, useful for "consumer" applications, games, Windoze internal sounds (mine are always disabled, of course), etc.

Even given all of the above, every audio "slider" in the system should be calibrated with a numerical scale, preferably in dB (but God knows the average consumer would be boggled beyond belief with negative scales on everything).
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Old November 2nd, 2012, 12:35 PM   #7
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Re: Gain structure with a computer---what do people do?

Quote:
Originally Posted by Greg Miller View Post
,,,Even given all of the above, every audio "slider" in the system should be calibrated with a numerical scale, preferably in dB (but God knows the average consumer would be boggled beyond belief with negative scales on everything).
My external Firewire audio interface (Echo Audiofire) output levels are independent of the Windows volume control settings and its own control console sliders are indeed calibrated in dB below full scale.
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Old November 10th, 2012, 12:50 AM   #8
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Re: Gain structure with a computer---what do people do?

Pro-Tools audio interfaces such as my Mbox mini have their own analog outputs which seem to be independent of the PC volume. They typically have analog output faders which could be taped down.
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Old November 10th, 2012, 12:51 AM   #9
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Re: Gain structure with a computer---what do people do?

I'm not sure if it's possible in all cases, but I have seen someone route the Mac system audio (e.g. media player) to a Pro Tools interface.
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Old November 10th, 2012, 03:30 PM   #10
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Re: Gain structure with a computer---what do people do?

If you are doing professional work, then you need professional equipment. Our studio is pretty much 100% in the box. The only exception is the VO room where we use an analog mixer for talkback and monitoring.

As far as I know, any professional audio interface will bypass the OS volume controller and any ugliness that the OS might cause in your audio.

I keep every thing at 0db, the software and the sound card mixer. I use an analog device to adjust the volume. At work I use a very expensive surround controller from dangerous audio, and at home I use a simple $75 volume knob from TC Electronic.

Another thing that is very important is how you measure the levels. The peak meters in most software will only tell the actual digital level, it won't tell you how, subjectively loud the signal is.

To solve that problem I use RME audio interfaces exclusively. RME has among the best sound, and more importantly to me, the most stable drivers. They also include a little app that is essential, a really nice meter that shows both peak, as well as loudness. That will really help you dial in your compression and limiting to get a nice loud and even volume.

Another nice thing about RME is that there who two brothers who write the drivers- one is a windows guy, the other is a mac guy. In the end, the sibling rivalry leads to great drivers on both platforms.

When you use a professional sound card on windows it will bypass the OS. There is a special driver called ASIO the allows the software to communicate directly with the sound card. On the mac side, apple went ahead and made core audio work nearly as well.

So to answer the question- what I do is keep everything in the computer at 0db, and use an analog volume knob to adjust the listening level.

~Jay
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