Peak Recording Levels – The Basics

Peak Levels, Meter Readings & Loudness

… and why they’re important to the sound quality of your record.

There are many myths and fables regarding the subject of recording levels and what is happening to your audio signal in the digital domain. Most of these myths come from a complete lack of understanding of how digital audio works and most misunderstanding of digital audio stems from a lack of understanding of analog audio (which happens to be very different from digital in terms of workflow and how it is measured).

Here are a few things to help clear some of that up, so you can be best equipped to prepare your mixes for mastering or prepare your audio tracks ready for mixing.

The confusion stems from the fact that many people equate 0VU on an analog VU meter with 0 on a digital peak level meter. They are NOT the same!

Digital is precise. It’s all numbers and there are rules that cannot be broken. For example – 0dBFS (deciBels – Full Scale) is the ceiling and there can be no signal above it. There just isn’t any value to represent it and the result is very audible clipping (and not very pleasing to the ear).

Analog is based on voltages going through copper cables and circuit tracks of which there is theoretically no ceiling. The reason why analog equipment sounds more pleasing to most people is that our ears like (or are familiar with) the distortion that is introduced by the analog equipment as it reaches the limits of what it was designed to sound best at. It’s the reason why most guitarists favour tube guitar amps and why many music lovers still love vinyl records more than CDs. Analog gear will just keep on working over and above it’s designed "zero point" or maximum level until it goes up in smoke, getting more distorted the further it gets. Somewhere above the optimum working range, but before it gets too messed up, the nature of the distortion in the analog circuit sounds very musical and pleasing to most people and is the reason why analog equipment is still very much in demand in the pro-audio world.

Many people who record music on a digital system are still under the impression that the signals should be as close to zero (0dBFS) as possible – a throwback form the analog days, where 0VU was the optimum level for the gear with the best signal to noise ratio combined with minimal distortion and also early 16bit recording gear that had a limited dynamic range (and therefore higher noise floor) than current digital recording systems.

In 24 bit systems this practice is totally unnecessary and in fact can be detrimental to the quality of your record. The key word here is "Headroom". Analog equipment, especially high end stuff like SSL or Neve consoles for example have their optimum performing level. This is where the details get left out because this will go on forever otherwise. Basically this optimum level is 0VU on a VU meter (the one with the needle bouncing about). Above 0VU there is a red area, which if your signal moves the needle into that region during the peaks you won’t hear any distortion, it’ll just seem louder and fatter the higher the peak the higher the voltage of the signal during that peak. The amount over zero that can be tolerated by the equipment before audible (and undesired) distortion occurs is called the headroom and can be as much 20 or 30dB. I.E. quite a lot! But at that point, even if it sounds cool, there will be a lot more noise in the signal created by the electrons in the circuit.

That 0VU level is always calibrated to a specific reference voltage (remember the details are not important in this explanation) and it is this voltage (and always this voltage) that is also used to calibrate the optimum operating level of the analog circuitry in a digital to analog and an analog to digital converter. Therefore, when you record your vocal or guitar or whatever into your mic preamp (analog), into your A/D converter and into your computer you would be best served by using a VU meter as your recording level reference rather than a peak level meter.

All converters are calibrated to reference 0VU to a level below 0dBFS (digital) in order to provide headroom between that level and 0dBFS to avoid clipping your converters and subsequently your plugins and output fader within your recording software. It’s a recreation of the conditions of the analog world, but many people just don’t adhere to that. Many people have no idea about it and record everything so hot that their final mix has all their channel faders pulled right down in order to avoid going into the red on their master fader (another can of worms there).

Lets assume we have a digital system calibrated so that 0VU = -18dBFS.

The best practice is to always leave headroom at every stage of making your record and only bring the level up close to full scale at the mastering stage. DO NOT NORMALIZE – EVER! It is a total waste of time. It is better to spend a little more energy on correct gain staging through your signal chain. Record you sources at the mic preamp’s sweet spot, so as to introduce minimal noise form the preamp. Keep all your audio files at an average level of about -18dBFS, which means they will likely reach peaks (but not consistently) at around -12dBFS. If it sounds quiet, TURN UP THE VOLUME on the speakers! If you take the care to do this, you will be amazed at the clarity of your final mix, the depth and dimension, the stereo separation. You will be running the system the way it was designed (and the way all those plugin manufacturers painstakingly designed) to sound its best.

A lot of what contributes to what people call a harsh, "digital" sound is the fact that most people record in digital in a less than optimum way. A lot of the harshness is in fact their mic preamp being run way too hard, which in the old world of analog using a VU meter on the input, would never be done because it would already be screaming at the engineer (Too HOT!).

Leave the mastering engineer to bring up the level at the end where he/she can do it with quality equipment and experienced ears. Thanks for reading!

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