Nowadays, there are so many ways of ‘seeing’ what is going on with your music. DAW’s are packed with spectrograms, VU meters and most mixing consoles come standard with some form of meter. Should you be looking at pre, post or current levels? What are they used for? How can I use them? I think most of us would be confused by it all. To begin with, one must understand what a decibel is. I found the best way to describe it is by Greg Scarth of Future Music Magazine (UK): “A logarithmic method for measuring the magnitude of a signal relative to a given reference level.” Once you understand the reference level, then the decibel measurement begins to make sense.
 
On most decibel meters, be it digital or analogue, decibels are measured as dBFS or dBVU. The measurements are defined to a maximum level. In digital equipment it is the point just before clipping occurs. Similarly, in analogue equipment, it refers to the highest level just before signal degradation occurs. Digital equipment is calibrated that 0dBFS is the highest possible before the waveform will be squared off at the peaks. Analogue equipment is usually set for 0dBFS at +4dBu. dBu is defined as a signal with a root mean square magnitude of 0.775 Volts.
 
When looking at digital meters, you want to stay as far away from 0dBFS as possible. With analogue equipment, it might be a desired sound to go over 0 as it gives you warm distortion. As a mastering engineer, depending on what the client would like, you want to keep your tracks hovering around 0dBFS. Bob’s Katz’s K-14 method for mastering and metering stresses the importance of monitor calibration. He says: “To set the record straight, the calibration point is 83 dBFS C weighted, slow, ONE speaker at a time.” He continues:  “The test signal is -20 dBFS RMS. This sets up the 0 dB point of the monitor, but that point will be VERY VERY VERY loud for all but some classical music recordings, dynamic home theatre, and some audiophile records.”
 
An engineer will have to attenuate between -6dB and -8dB. The best piece of advice is from legendary producer, Tommy D: “The most important piece of kit in your studio are your eyelids. Close them and just listen.” It doesn’t matter what the meters say, if it sounds good, then leave it.
 
"Pleasure is the object, the duty, and the goal of all rational creatures.” Voltaire