Everything was great and then after the second chorus he decided to lay into the guitar with some percussive strums. So much for not getting any louder. Now at this point many engineers would be sweating, biting their nails and possibly thinking of ways they could cover up their tracks: “I could use my de-clipping plug-in . . . or maybe I could suggest using a tape simulator plug-in and say it’s the ‘tape saturation’ you’re hearing . . . ummm, no, maybe I should just tell him it’s the tube mic, oh wait there’s no tube in it! . . . ahhh . . . oh #%$^&!!!”
when you set the proper recording levels . . .
The common understanding of recording levels goes something like this, “I need to record as ‘hot’ as possible to use all 24 bits and so there’s no noise.” And so the common practice is to get the levels as close to the red without clipping the signal. Now this is pretty easy to do if you’re working with a super saturated, compressed sound, but impossible when dealing with a sound source that is very dynamic.
However, not only is this a misunderstanding of proper recording levels as it relates to bits, signal reference and sound quality, but it’s also a recipe for disaster both during the session and afterward.
Signal Reference: line level and meters
Your audio interface (AD/DA convertor) was calibrated and designed at what is called “line level”. The tricky part is knowing exactly what that calibration level is. My Digidesign 002r, for instance, was calibrated for - 20 dBFS. So if I ran a steady signal into the 002r so that it held at -20 dBFS on the channel meter in Pro Tools, that would be the line level calibration. But before your eyes glaze over and I lose you in the boring spec stuff, let’s just assume that the interface you’re using was calibrated at the standard -18dBFS.
The bottom line is this, your audio interface was designed to operate most optimally at line level. That means that when you send signal into your interface (snare drum, electric guitar, keyboards, etc.) you want to aim for the signal level peaking around -20 to -12 dBFS.
Since your audio interface was calibrated at line level, it’s very important to be sending signal that is around that level. Sending signal to the AD converter that averages around the line level calibration ensures a good signal strength and signal to noise ratio, the lowest distortion, and plenty of headroom. And by pushing the ADC higher we may be exceeding its design limits even before reaching 0 dBFS resulting in a dirtier, noisier signal with possible distortion of the waveform reproduction. Imagine tracking an entire song with hot levels versus at the line level reference. Based on the information so far, which do you think would sound better? If you said the one with lower recording levels, “jugotitmang”. (Say it with Izzy’s inimitable accent for all you Miami Vice fans out there.)
A Recipe for Disaster:
Let’s say you decide to record everything hot. When you look at the meters they’re all averaging in the yellow with peaks into the orange. This is actually quite common. I’ve had to tell other engineers to record at a lower level and have had to work with tracks recorded too hot.
And everything just heats up even further when you...
- Create a buss or a master fader and see what happens to the sum of all those hot tracks. Red and clipped? Yep!
- Try inserting some plug-ins and see what happens. Red and clipped? Yep!
- On the EQ plug-in, try boosting a frequency. Ouch! The plug-in’s output is clipping now.
Right off the bat mixing becomes a complete mess because all those tracks have been recorded too hot. And not only would this be difficult during mix time, but also during an overdub session. If you ever work with a band or artist where they’ve done some of their own recording you will see this problem a lot. During the overdub session they figure you just have to set up a mic, maybe some ‘verb and the recording can begin. Nope, you’re scrambling to bring all those faders down, maybe adjust the inputs and outputs on the plug-ins, and figure out how you can come up with a suitable rough mix for the overdub. It’s a disaster and on top of that they start asking, “Hey man, what’s taking so long?” All that could have been avoided if they just . . .
set the proper recording levels.