Metering - VU LUFS LU K-Ref....

I remember when I first started in this crazy ass industry. One of the most appealing things about mixing was looking at VU Meters. I have to confess, a VU meter can tell you far more about your mixes than a full-on PPM Meter. Because our ears are logarithmic it makes sense, at least to me, to use a meter that reflects exactly how we hear. But we have come a long way since the good old days of VU meters.

Nowadays loudness meters are the rage and rightly so.

But let us start with the gentle old school VU meter.

VU meter

VU meters are the closest meters that behave like our logarithmic hearing. They show only relative levels and have a slow response time which makes then a little restricted in terms of the information given to the user. Additionally, vu meters have to be calibrated to the system known reference level. In most digital systems when using a vu meter we tend to calibrate to -18 dBFS (decibels full scale). We use dBvu as the units of measurement for vu meters.

PPM – Program Peak Meter

We have them in all DAWs and I have to say I hate them with a passion. Yes, they are more advanced that vu meters as they can display instant peak activity. However, they cannot find intersample peaks due to the very slow release time for the meter which can be as much as 1.5 seconds and because they are not calibrated to a reference they cannot provide accurate loudness levels therefore their representation is not very accurate. We use dBFSas the units of measurement for PPM meters.

LUFS meter – Loudness Units Full Scale

Loudness meters are the rage nowadays and rightly so. They measure perceived loudness which is a huge step forward from measuring average or peak levels. Loudness Units (LU) are denoted in decibels, so 1 LU is equivalent to 1 dB. We also have a variant of LUFS called LKFS which adopts weighting to account for differences in frequency response. Additionally loudness measurement requires integration over time, whether that be in the long term — the entire duration of the programme — or over just a few seconds.

LUFS meters give us all manner of information and over specific times. These include the following:

Momentary – which measures loudness over 400 ms (milliseconds). This is extremely useful as we can gauge what is happening to the programme material over the last 400 ms. This allows us to view transients as they move by in the meter’s display.

Short Term – measures loudness over 1-3 seconds. This is very useful in that you can visually see what is happening to transients over this time period.

Long Term – also known as Integrated Loudness – measures the whole programme material. This is the most important value as we can see what the perceived loudness of our music is. This allows us to make mix critical edits.

True Peak – this measures inter-sample peaks (ISP) and is everything that the PPM wasn’t.

My suggestion is to watch the 25 minute video. In the video I go through each and every type of meter explaining how they work and how to read them.

For mixing music nothing is more important than seeing and hearing exactly what you expect to see from start to finish and for that we need detailed metering.

Topics covered in this video are: