PDA

View Full Version : Setting levels for VI (engineering question)


Suke
08-03-2013, 08:20 AM
Hey Guys, I've often wondered whats the best sounding way to set the levels for Virtual Instruments? Set the master level on the VI, set the part level on the VI or adjust the level in DAW mixer?
My bands FOH mixing engineer used to keep all of the board fader's at 0.0 and then adjust the trim/gain of the mics. So I've been experimenting with keeping the PT mixers' faders at 0.0 and adjusting the VI accordingly, even preset to preset in the VI (sometimes they vary quite a bit)
What do you guys do? and what sonic differences have you noticed? just curious.

DonaldM
08-03-2013, 08:54 AM
Hey Guys, I've often wondered whats the best sounding way to set the levels for Virtual Instruments? Set the master level on the VI, set the part level on the VI or adjust the level in DAW mixer?
My bands FOH mixing engineer used to keep all of the board fader's at 0.0 and then adjust the trim/gain of the mics. So I've been experimenting with keeping the PT mixers' faders at 0.0 and adjusting the VI accordingly, even preset to preset in the VI (sometimes they vary quite a bit)
What do you guys do? and what sonic differences have you noticed? just curious.

There's probably no 1 right way to do this. But, I think of it this way. If you were in the studio with a synth and ran the audio out of that to the audio in of the mixing console to then go into the audio interface to record on your DAW, what would you do? Some guys would say, push the volume of the synth up nearly all the way and we'll adjust the input volumes on the mix console, or the input levels on the interface. You'd watch the input meter to get the volume coming in to the right level...avoiding clipping and what not.

Well, in the VI world, I think of it the same way. But instead of adjusting input volumes on interfaces or mixers, you do it on the VI itself. When possible I tend to run the master output a bit hot and then adjust the individual voice controls accordingly, watching the track's input meter. So, for example, on Xpand, I'd set the main output to, say, 80% or so, then adjust the voice output(s) to get the over-all input to the instrument track just right. However, you have to let your ears guide you. Sometimes it's better to run the individual patch's control a bit hotter because there are subtleties in the patch itself that could get lost if its too low, so you have to go back and forth between that fader and the master out.

As our friend Albee here says "The great thing about digital is there's 4 ways to do something; the bad thing about digital is, there's 4 ways to do something!"

nst7
08-03-2013, 10:08 AM
The way your FOH mixer did it was not good, and recommended against by mixer manufacturers. He was simply adjusting the preamp gain on each source for mixing purposes, and in the process was putting some of them at less than ideal settings, allowing noise and signal degradation to happen when he didn't need to.

Regardless, none of these principles are equivalent in the VI world, so you would be better off just using the faders to adjust the volume of the VI's in your mix.

shtik
08-04-2013, 11:25 AM
He was simply adjusting the preamp gain on each source for mixing purposes, and in the process was putting some of them at less than ideal settings, allowing noise and signal degradation to happen when he didn't need to

Can you please explain how this work flow induces noise and degrades the signal?

So I've been experimenting with keeping the PT mixers' faders at 0.0 and adjusting the VI accordingly

As for VI levels, it doesn't really matter sound wise, because there isn't any analog gain stage or any A to D conversion on the way, but this specific workflow and level practice gives you the benefit of higher fader step resolution for more precise level setting and automation when mixing. It is better to have faders close to 0dB than it is to have them in the -20/-30 range for precision reasons.

Suke
08-04-2013, 11:54 AM
Thanks all for the replies guys. @Shtik, thats what I thought too. When my engineer did this is when he got his initial levels. He said it was a bad sign when you saw someones board and it looked like a mouth full of missing teeth (faders too high and too low). All of this stuff is easier and more consistent without analog gain stages etc.

albee1952
08-04-2013, 11:55 AM
Some good stuff already. The basic premiss here is called "gain staging", and its all about having "proper" gain at each stage in the chain. With a mic, that's easy to pin down by looking at the mic output>preamp input>preamp output(if adjustable)>anything in the analog chain post-preamp>Converter input>Pro Tools audio track. That's all about having each stage being driven with a solid level, but not over-driven(usually) so you get the best signal, with the least noise(no worries about tape noise these days, but you still need to pay attention to noise:D) and maximize the bits going thru the converter(any EE types, please correct me if I am off base here).

Now a VI is a bit different as you are already ITB(in the box). I like to start mixing with faders near unity(-0) so I would adjust the VI volume so that its "in the ballpark" and adjust the fader from there, as you would when mixing anything.

Now, live mixing is entirely different, so don't feel compelled to take habits from live, and apply them to recording(trust me as I have done both for a long time:o).

groundcontrol
08-04-2013, 12:57 PM
It is good practice to maintain unity gain in gain staging.

DonaldM
08-04-2013, 02:03 PM
The one thing to keep in mind with gain staging VI's is that output of a patch, particularly in a multi-voice VI like Structure or Xpand2 is that it CAN affect the sound of patch. Depending on the the patch was programmed, sometimes too low output and some sonic elements are "lost". So you gotta balance for the sound AND the levels!

nst7
08-04-2013, 02:52 PM
Can you please explain how this work flow induces noise and degrades the signal?

From page 26 of the Allen and Heath GL2800 manual:


"Mixing with faders or gain controls? There is a technique used by some operators where they set all the faders to ‘0’ position and balance the mix using the channel gain controls. We do not advise this method as the signal to noise ratio and control resolution can be severely degraded. In addition, it is impossible to mix monitors from FOH in this way as changes to the gain settings affect the monitors too.
The correct method is to use GAIN to match the source to the operating level of the channel for optimum dynamic range, and then use the FADERS to balance each source into the mix. With correct system gain structure, prime sources such as vocals would have their faders operated around ‘0’ while sources low in the mix such as backing vocals and acoustically loud brass and drums would display their true contribution with their lower fader positions. This is a much more visual and accurate way of mixing."



This would be similar on your audio interface, if you decided you were listening too loud while recording, to turn down the preamp gain, instead of turning down your speakers or headphones. Not an optimal way to do things.

Suke
08-04-2013, 03:31 PM
All of this is great stuff. @nst7 very interesting as it brings up another factor into this. Coming from Cubase (14years) there was a trim control on each channel, and my old Mackie board etc. But there's not one in the PT mixer (at least on nonHD AFAIK).

groundcontrol
08-04-2013, 06:47 PM
From page 26 of the Allen and Heath GL2800 manual:


"Mixing with faders or gain controls? There is a technique used by some operators where they set all the faders to 0 position and balance the mix using the channel gain controls. We do not advise this method as the signal to noise ratio and control resolution can be severely degraded. In addition, it is impossible to mix monitors from FOH in this way as changes to the gain settings affect the monitors too.
The correct method is to use GAIN to match the source to the operating level of the channel for optimum dynamic range, and then use the FADERS to balance each source into the mix. With correct system gain structure, prime sources such as vocals would have their faders operated around 0 while sources low in the mix such as backing vocals and acoustically loud brass and drums would display their true contribution with their lower fader positions. This is a much more visual and accurate way of mixing."



This would be similar on your audio interface, if you decided you were listening too loud while recording, to turn down the preamp gain, instead of turning down your speakers or headphones. Not an optimal way to do things.

Nonsense. If you set your initial balance with faders at 0, you're essentially adding (or taking away) the minimum gain needed to place the instrument in the ballpark of your mix space. You can then use the fader in the region where it has its maximal resolution.

groundcontrol
08-04-2013, 06:50 PM
All of this is great stuff. @nst7 very interesting as it brings up another factor into this. Coming from Cubase (14years) there was a trim control on each channel, and my old Mackie board etc. But there's not one in the PT mixer (at least on nonHD AFAIK).

There's a trim plug-in. There's also an automatable gain for each audio clip pre the channel gain.

It's all in the manual.

nst7
08-04-2013, 08:21 PM
Nonsense. If you set your initial balance with faders at 0, you're essentially adding (or taking away) the minimum gain needed to place the instrument in the ballpark of your mix space. You can then use the fader in the region where it has its maximal resolution.

Are you talking about the Protools software? Or analog mixers? I was responding to the comment about analog mixers, which is why I quoted from an analog mixer manual.

groundcontrol
08-05-2013, 12:14 AM
Same workflow essentially as far as the operation of setting *mixing* levels is concerned.

Setting levels for recording is a bit different. You're trying to match the available dynamic range of your recording chain to the acoustic event (and achieve the highest possible s/nr in so doing).

shtik
08-16-2013, 03:02 AM
"Mixing with faders or gain controls? There is a technique used by some operators where they set all the faders to 0 position and balance the mix using the channel gain controls. We do not advise this method as the signal to noise ratio and control resolution can be severely degraded. In addition, it is impossible to mix monitors from FOH in this way as changes to the gain settings affect the monitors too.
The correct method is to use GAIN to match the source to the operating level of the channel for optimum dynamic range, and then use the FADERS to balance each source into the mix. With correct system gain structure, prime sources such as vocals would have their faders operated around 0 while sources low in the mix such as backing vocals and acoustically loud brass and drums would display their true contribution with their lower fader positions. This is a much more visual and accurate way of mixing."

Few things here are true..

The basic truth is, yes, the signal to noise ratio could get degraded if you find yourself in need to pull the fader up by 15dB on an analog mixer. That's why you make sure that each channel has its gain set so you don't have to do that.

There is also a difference between "setting initial gain structure" and "mixing with gain knobs". It is true that changing gain levels during set will affect stage monitor or IEM balance. That's why you make sure that each channel has its gain set so you don't have to do that.

The whole idea is that you MIX with the faders not with the gain knobs, but it's easier to do real time changes up to 5dB's when the faders are close to 0 then it is when they are close to -20.