Great post from Paul Frindle on ITB mixing

[admin]

Next time you're wanting some analog stuff to make your mixes better just think of these words, this is the kind of thinking that really got my digital mixing skills much better:


Paul Frindle / Gearslutz:

"I have been part of many discussion about this and posted several explanations of why digital mixing needs to be done with care and how it can mess up without you really being aware.

I have a lot of sympathy with the emotions people have about ITB mixing. But having designed stuff on both sides of the camp (and in between, like large digital consoles) I have become convinced that this is caused by a mixture of insufficient apps (both mixers and plug-ins), misrepresentation of what's going on in your mix from metering - and the biggest and most crucial of all, loss of immediacy during the artistic mixing process. It's just dramatically more tedious and less involving to be fiddling around with a mouse and a screen (or with loosely coupled add on controllers) than it is to have the whole thing right in front of you, responding immediately to the minute adjustments you make almost subconsciously to get your sound. Overcoming this lack of immediacy takes time, effort and the wrong kind of concentration - and the dividends in digital of more integration, better accuracy and predictability - and all the other stuff you can do more easily - does not fully compensate for the artistic 'disconnection' we feel?

But some myths still prevail that may confuse people even more? For instance none of the analogue stuff I have ever designed for SSL or others had significant distortion or saturation. Saturating these would require running at least at +24dB above operating levels!!

The analogue summing stages were just like somewhat noisier versions of a digital summing process - there is no obvious technical difference as far as the sound goes. Adding signals together is something that digital processors can do essentially perfectly.

It is a fallacy that outboard effects are necessarily of a higher quality than plug-ins (even reverbs). In fact it may be the reverse, as (even host) plugs may have access to more processing power than many expensive boxes - and may be running on more highly developed processors.

If you are avoiding inter sample overs by running at -6dB or less and using good quality plug-ins, the performance you are getting is way beyond any analogue system is capable of.

But the inconvenience of the interface might be undoing all that good, as far as user involvement is concerned."

[pk1]

If you are avoiding inter sample overs by running at -6dB or less

just clarify what this means and why you should do this plz Jesse...

Paul

[Bitfiend]

nice post, couldn't agree more. Yet one more reason i've gone off GS, they just won't let the argument die.....

[admin]

just clarify what this means and why you should do this plz Jesse...

Paul

It's a bit tricky to explain but here goes.. Essentially what you see in the DAW when viewing the sample display or digital meter is not correct. This is because signals are reconstructed when passing through a filter, like the one in a converter. This is what takes the blocky looking stair steps and turns them into continuous analog audio. When this process happens the signal level can rise, up to 6db above what the meter/sample display shows.

You can test this by taking some noise, then throw a filter over it at 20k and when you do you'll see the level increase.

According to Paul this is the main reason people get a choked sound in digital.

This is why clipping can be a bad idea, especially if you are looking for increased level. As once that clipped signal is sent through a filter or DA then the level jumps up and you can distort.

It really depends on where the signal is going though. Some processes won't do any harm. I always master with the Sonnox limiter to take care of intersample peaks. But even in the mixing chain you have to be wary. The trick is that unless you analyze every plugin you have you won't really know which ones could cause problems.

So Paul's advice is to just mix low so that nothing is hitting more than -6 just to be safe. In practice I don't do this too often as in my experience the plugs I used often don't have adverse effects in this area. But his point is that by mixing low you don't have to worry about levels and you can just mix and get the balance right without having to constantly worry about clipping. So it's more of a be safe than sorry type of method.

[admin]

Here's a pic of what I'm talking about with the noise.

This is a white noise sample. I've normalized it to -6db. You can see in the first pic the meter is showing the signal as -6db with the Sonnox eq bypassed. This is what where digital meters fall down as when that signal comes out the DA it's not actually -6db.

In the second pic I have the HiCut filter on. It's set to 36db so very sharp and at 20k, highest it will go. This basically emulates what happens in your DA converter when the sound is reconstructed and represents the acutal signal level that's being output. If you look at the level meter you'll see that same -6db noise is now showing about -0.9db. So we have the same sound and same apparant level but much higher actual signal.

[admin]

Here's a pic I made of what happens to samples that pass through a reconstruction filter on their way out the DA. You can see that although the sample level is right at 0db inside the DAW when it goes through the filter the level exceeds 0db.

[sven hauck]

Very cool, good to know. Can you mention a few plugs in addition to the Sonnox EQ that don't exhibit this feature where the reconstructed signal is higher?

[admin]

Sorry not sure what you mean as the Sonnox EQ does make the signal go higher as should any Lowpass filter.

[sven hauck]

Sorry, rephrase, I didn't quite understand what you meant by this:

"It really depends on where the signal is going though. Some processes won't do any harm. I always master with the Sonnox limiter to take care of intersample peaks. But even in the mixing chain you have to be wary. The trick is that unless you analyze every plugin you have you won't really know which ones could cause problems."

I guess the question could be what processes don't do any harm?

[admin]

Well anything that's 32bit should generally be ok but you never know. Stuff that upsamples and downsamples can recontstruct internally, you wont hear it but youll see more level.

That was part of Paul's point about keeping levels low just so you can concentrate on the mix and not worry about this stuff.

Other than that you'd just have to test whatever plugs you're using to see how they react. Obviously the Sonnox stuff doesn't have any issues but other than that I don't really have a list.