Levels Demystified – Gain Staging (Part 3)

Recording Pino Palladino

OK.  Let’s say you get the call to engineer for one of Pino Palladino’s bass sessions.   (Here he is in action.)  Mr Palladino walks in, unpacks his bass, plays a little and you can’t believe your luck when he suggests the exact signal chain you had in mind:  Bass –> Neve 1073 –> 1176 Compressor –> Pultec EQ.  Alright!

Now your goal as the engineer (other than to make it to the end of the session with your reputation still in tact) is to get the best possible level going to tape.  How are you going to do this?  Simple.  You are going to hit each stage in the signal chain at its sweet spot – 0dBVU.  Remember?   (You could also choose to ignore these sweet spots and drive the input stage to bring out the additional characteristics of each device.  But that’s a topic for another day!)

At the end of the session Pino wrestles you to the ground with a bear hug.  He congratulates you for making him sound great and books you for another session on the spot.  Life is sweet!

Back Inside The Box

When setting levels for recording and mixing ITB life works pretty much the same way.  How come?  Well first a little history lesson.

Most plugins began life as an emulation of a piece of analog gear, i.e. a compressor, EQ, etc.  The goal with the plugin was to emulate the sonic characteristics and/or behavior of the analog gear.  To achieve this the plugin had to emulate the analog gear’s sweet spot.  This means plugins also have sweet spots just like their real life 3D counterparts.  And the sweet spot for a modeled plugin is basically the same as the piece of gear it emulates – 0dBVU.  Simple huh?  But wait…there’s a little twist!

The Digital Twist

Most DAWs come equipped with Peak meters not VU Meters.  And guess what?  Peak meters and VU meters do not measure signals in the same way.  Peak meters measure levels in dBFS (decibels Full Scale).  VU meters measure the average level of signal in dBVU (or plain ol’ VU to us simple folk!)

Now here’s the bad news:  there is no relationship between dBVU and dBFS!  (I know.  It upsets me too.)  It is therefore difficult to tell exactly what 0dBVU is equivalent to on your DAW’s Peak meter.  And if we want to know a plugin’s sweet spot we have to know what 0dBVU is in dBFS as DAW meters measure in dBFS not dBVU.  So how are we going to find the sweet spot for recording and working ITB?

The Magic Number!

Fear not my friend!  All is not lost.  I can now reveal that some people much smarter than me figured out a solution.  Through the exercise of levels of genius I will never fully understand they worked out that a signal measuring 0dBVU (or 0VU) on a VU meter is roughly equivalent to (drum roll please….) -18dBFS (RMS not Peak) on your DAW meters.  (Notice the RMS was underlined?  More on than in the next post.)

So there we have it!  -18dBFS (RMS not Peak) or thereabouts is The Magic Number!   Feed your DAW a level of around -18dBFS (RMS) when recording and your convertors will be happy, your plugins will be happy, in fact the whole world will be happy for you too!

Levels Demystified Part 4

For a FULL Course on Gain staging, Click Here


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