Level measuring in use: The VU Meter
In recording, mixing and mastering, ears are the most important instruments. But they are not enough on their own! Level meters are essential for checking and evaluating a recording, a mixdown or a master as well as individual signals. They can be used to check levels that are sometimes not perceived by the ear. Finally, we also have to adhere to level standards and regulations that we could not check with our ears alone. Level meters help us to keep an eye on these standards.
The simplest level meter is the VU-Meter (here the VU-Meter from Studio One).
A VU meter roughly indicates the perceived volume. The VU meter measures the rectified value with a slight tendency towards the RMS value. The display is based on the logarithmic labelling of the scale. The louder the signal, the more accurate the display. Typically, levels between -20 and + 6 VU are displayed. VU meters react more slowly than peak meters, which are better at displaying short or fast signal peaks. However, many VU meter plug-ins today have the option of changing the sensitivity or response time.
Why is this interesting for us?
The loudness dynamics of a song or signal can be visualised using a VU meter. The dynamic range is the fluctuation between the lowest and highest (measured) volume – i.e. the perceived programme dynamic range. Classical pieces, jazz etc. are often very dynamic. Film music is also characterised by a wide dynamic range. Current pop or EDM productions are less dynamic.
If the needle remains in a small range during playback, i.e. does not make any large jumps, the signal is not very dynamic. However, if the needle jumps back and forth wildly, dancing between small and large values, the signal is highly dynamic. By switching the VU meter behind a compressor, for example, you can check the extent to which it limits the dynamics. Ratios between signals can also be easily determined with a VU meter: For example, the volume ratio between a bass drum and a bass guitar can be set quite well with a VU meter: The bass drum signal is levelled so that it shows a maximum level of -3 VU. By adding the bass signal, you try to achieve a value around 0 VU when both signals sound at the same time. This often results in a very good output ratio for both signals.
When creating a song sequence, the VU meter can help you to determine large differences in volume or jumps between songs. You want to prevent songs from being perceived at different volumes during mastering at the latest. The endings and beginnings of tracks can be levelled to each other. DJ mixes can also benefit from using the VU meter 😉 When crossfading between two tracks, the level should not suddenly jump or become significantly louder.
In mastering, the VU meter can be used in conjunction with a peak meter to get a song as loud as possible on a medium (limited by the dynamics of the medium or by the standards addressed). To do this, you can use limiting and compression to try to bring the value of the VU meter closer to that of the peak meter.
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