Edited ramblings about analogue audio levels
When things are hitting your analogue stages hard there is going to be some loss in sound quality, unless you have VERY good preamp's and converters that are designed with lots of built in headroom well above +4dBu/0VU RMS (their optimum operating level, where they are designed to give good signal to noise ratio and low distortion) and even if they are designed with such good headroom they probably still wont sound their best with levels that high.
Unless you're talking about driving a nice character pre into saturation, which is a different kettle of fish. But even when people drive their fancy preamp's hard they are using in line pads after the preamp in order to NOT SMASH THE SHIT OUT OF THEIR CONVERTERS!
What makes it more frustrating is that instruction manuals for digital recorders and DAWs often tell users to record as hot as possible without clipping, as this is much easier and less confusing than educating people about proper gain staging and the the relationship between analogue and digital audio levels.
I remember first encountering this and having a bit of a wtf moment a few years ago, when using my analogue mixer as external preamps for my pro tools setup, and wondering why the pfl on my desk was giving me a clip warning light but I wasn't getting maximum level in pro tools? The problem is that nowadays we're using the clip indicators in our DAW and often don't have any at all on our pre's, which is where we should have them! The concept of headroom has been pretty much lost with a lot of people who are into recording that have never used much or any analogue equipment.
In the digital world headroom is simple. It's perfect, totally clean, until you clip. At this point you've lost information. Your signal is now fucked, somewhere in there is a square wave. Shit.
In the analogue world it's not the same. As the level gets higher and higher above 0VU your signal will become progressively more distorted, the frequency response can change, and things just generally start sounding pretty dirty, before you get to the point where the wave actually becomes audibly clipped. So long before you're hitting the digital maximum of 0dBfs you're already losing sound quality in your analogue stages. Even though your signal is fine according to your DAW.
There's no real need to ever be running signals this hot. I can't help but feel there are some guys on here who don't seem to grasp quite how much headroom we have available in a modern recording system.
Recording hot is a unfortunate habit, left over from the early days of digital recording when recorders were only 16 bit and the noise floor available was much poorer than we have now. And as a practice it's really not necessary anymore.
Digital audio ramblings
In 24 bit audio we have 16,777,216 amplitude steps available, (yes, nearly 17 million!) giving 144dB dynamic range (greater than that of the human ear, which is only around 130dB) resulting in 116,508 amplitude steps PER DECIBEL. So given a signal that is using all of the headroom available, with one single sample hitting our digital maximum, our sampled signal is accurate down to 1 one hundred and sixteen thousandth of a dB.
Compare this to 16 bit which is only 65,536 steps and 96dB dynamic range. So we have more amplitude steps available PER DECIBEL than people used to have in their entire word length for a digital recording system. We have nearly twice the resolution and detail available PER DECIBEL than a 16bit cd.
Each bit in the word length gives us 6dB better signal to noise ratio. So if you record with your absolute highest peaks at -12dBfs, you can capture a dynamic range of 132dB.
This is nearly double the typical dynamic range of an orchestra (which can be as much as 70dB) And we still have 31,775 amplitude steps per decibel here. Around half of what old 16 bit recorders had for their entire dynamic range!
Also bear in mind we're NOT recording an orchestra here. We don't have lots of low level detail required. It's noisy rock and metal that's going to be compressed and limited within an inch of it's life, dithered down to a 16 bit cd if you're lucky and ripped to a low quality mp3 if you're not.
Hell Chris Lord Alge dumps all his stuff to 16 bit digital tape before mixing. And I don't think anyone can say his sound suffers from not "using all the bits"
Another great advantage of tracking with lower levels is that come mix time you won't have to turn everything down to avoid excessive levels in your aux and master tracks.
Capture things cleanly and stop being a slave to the bits!
After all if you're trying to use as many bits as you can (because digital audio is inferior to analogue right?) then what's the point if you're completely ignoring the signal at the analogue stage in the first place! Get the levels right there and your DAW will capture it cleanly and effectively, even if you're not pegging the top of your meters. There's no point in capturing the highest resolution you can if your signal is compromised before it even hits your DAW!
It's 2011, it's 24 bit, back off your levels and enjoy the headroom!
