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RMS level and and 3 tips on how to increase it
(RMS = Root Mean Square)
In the context of audio files, the RMS value (Root Mean Square) refers to the measurement of the average power of a signal over time. Specifically, it represents the effective value of the signal’s amplitude, taking into account both positive and negative values.
It is a useful metric in audio processing as it provides an indication of the perceived loudness of the signal. This is done over a specific time and usually it’s 300mS. This is no coincidence that it equals to the VU Meter integration time. The resulting RMS value is expressed in decibels (dB) and is commonly used in audio engineering to set appropriate levels for recording, mixing, and mastering. This is also very useful to ensure that your mixes sound as loud as “commercial” mixes.
Increasing the RMS value of a sound or an instrument can be achieved through a variety of methods. Let’s explore 3 of the most used methods.
The first approach is to apply dynamic range compression to the audio signal. This technique involves reducing the volume of the loudest parts of the audio while simultaneously increasing the volume of the softer parts. This results in a more consistent volume level, which can increase the perceived loudness of the audio and thus increase the RMS value.
The second approach is to use equalization to boost the levels of specific frequency bands, such as the bass or midrange frequencies, which can also contribute to a higher RMS value. However, it is important to use these techniques judiciously and not to over-compress or over-equalize the audio, as this can result in a loss of dynamic range and a less natural-sounding mix. Ultimately, the best approach will depend on the specific goals and characteristics of the audio file in question.
Here is the third and probably most important method to increase the RMS level of your mixes. Parallel compression.
This technique (also Known as New York compression) is commonly used during the mixing stage to increase the RMS value of any track whilst retaining the original Peak and dynamics. It involves sending a duplicate copy of an audio signal (or group of tracks) to a separate processing chain where dynamic range compression and equalisation is applied (this is your wet signal), while leaving the original signal unaffected. The resulting compressed signal is then blended back with the dry, original signal resulting in bigger, fuller and punchier sound.
The benefit of parallel compression is that it can help retain the natural dynamics of a sound while achieving a more consistent and polished result. By blending the compressed and uncompressed signals, the quietest parts of the sound are brought up in level, while the loudest parts are kept under control. This creates a more even sound, without sacrificing the original character of the source material.
Parallel compression is used daily on a wide variety of sources, such as drums, vocals, guitars, and synths, and can be implemented using a dedicated parallel processing bus or a plugin on a DAW. The key to successful parallel compression is finding the right balance between the compressed and uncompressed signals, so as to achieve the desired effect without overdoing it.
All the big engineers use parallel compression to add punch and RMS level to a mix, for example: Andrew Scheps and his signature parallel compression plugin “Scheps 73“, Chris Lorde-Alge on using parallel compression on mixing “Daughtry”, Michael Brauer and his parallel compression for vocals technique.
There are some simple yet very effective tools that you can use to measure, however the easiest of them all is the use of an RMS meter such as the Dorrough one included in one of the Waves bundles
The beauty of these meter types is that they not only tell you the RMS value of the signal but also the Peak value, so they are extremely useful on a mix bus when you are trying to get your mix to sound as loud as the commercial ones while keeping all the peaks under control. Depending on whether you are mastering the mix yourself or not the Peak Vs RMS values vary, so we go from peaking at 0dBFS with RMS as high as -3dBFs for mastered tracks all the way down to -9dBFs Peak and -15dBFs RMS for the unmastered track. If you are sending your mixes out to a mastering engineer we always recommend checking to see what levels she/he expects to receive.
In our next Blog article we’ll talk about Jonny Solway, Head Engineer at Dean Street Studio London and why he likes the Periscope. Stay tuned!
If you are interested in a quick an easy way to increase the RMS value of your mix by adding a solid parallel compressor channel you should check out the Periscope: a unique way to add excitement to your mix.
