However, with more complex musical or speech signals the meter will typically under-read, and a sustained sound will produce a significantly higher indication than a brief transient signal, even if both have the same peak voltage. With a steady sine-wave signal applied to the input, a VU meter gives an accurate reading of the RMS (root-mean-square, or average) signal voltage.
#MIXER VU METER FULL#
The needle fall-back time is roughly the same, and the full meter specification is enshrined in the IEC 60268-17 (1990) standard.Ī VU meter's display is influenced by both the amplitude and duration of the applied signal.
It was developed as a collaborative project by CBS, NBC and Bell Labs in America and, since the meter scale was calibrated in 'volume units', that's the name that stuck! The SVI/VU meter is amongst the simplest of all audio meter designs and essentially behaves as a simple averaging voltmeter, with a moderate attack (or 'integration') time of about 300ms. However, for historians, the VU (or Volume Unit) meter was conceived in 1939 and originally called the SVI or Standard Volume Indicator. I urge everyone to use these meters in preference to everything else! This is an excellent metering system that provides a new and very accurate Loudness Meter scaled in LUFS - which does a much better job than the VU - along with an oversampled True Peak Meter scaled in dBTP, which does a much better job than the PPM. However, in our modern digital world, neither meter really performs adequately, and the current state of the art is enshrined in the new ITU-R BS1770 standard, which is being adopted very rapidly around the world in the broadcast sector and elsewhere. SOS Technical Editor Hugh Robjohns replies: These are both, strictly speaking, obsolete analogue metering formats! In short, the VU meter shows an averaged signal level and gives an impression of perceived loudness, while a PPM indicates something closer to the peak amplitude of the input signal.
I recently came across a plug-in that incorporates both VU and PPM metering, and it got me thinking: what exactly is the difference between the two?
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