Reverb and Mixing

Reverb is a necessity when it comes to mixing. It is an effect that every producer and mixer use to add dimension and space to a track. In this blog I will discuss the science behind reverb and how to utilise the effect by understanding helpful techniques and statistics, and when to apply them.

Everybody loves reverb. It gives audio more interest, space and colour and makes a song more pleasant to listen to (in moderation of course). From a mixers point-of-view however, “Reverb is one of the two principle ways that we can add artificial ambience to a track in a mix, but there’s a lot more to it than just dialing up a pre-set. While sometimes that may work, more often than not, a reverb’s settings are as carefully crafted as the mix itself” (Owsinski, 2017). While exploring the area of psychoacoustics, I learned that by nature, our ears use reverb to determine our environment. If the level of reverberation following a sound is increased, the sound can be made to seem more distant. Higher frequencies are absorbed by air so distant sounds are less bright. This can be applied to mixing by thinking of reverb as a way of creating the front-to-back dimension of a mix: To make a sound further back in the mix, apply a high-cut filter and use a long reverb with a high wet:dry ratio. Alternatively, closer sounds contain more of the direct sound and less reflections so it will sound brighter and dryer, which is why highly reverberated lead vocals need a high-level mix.

So, what makes up reverb? Pre-delay is the amount of time between the source sound and the subsequent reverb; it helps to keep audio clarity, and a longer pre-delay will increase the impression of the room size. Decay time is the time it takes for the sound to fully die away. Dry/ Wet is the blend of the original sound and the reverb. Diffusion determines the density of the reverb reflections; low diffusion sounds smoother which is good for vocals, while a higher diffusion is better for drums and percussion.

The early reflections of reverb can help us to understand the main difference between real and artificial reverbs. The early reflections are closely spaced and can help the listener to localise the sound. In a real room, every instrument in an ensemble produces different early reflection patterns as they are situated differently in the space in relation to the room boundaries. This means the reflections blend creating a more complex and denser pattern. With artificial reverb however, a fixed pattern is used, so all instruments in our imaginary room are in the same position. Consequently, it is important to turn down early reflections and use the same reverb type when mixing an ensemble. On the contrary, in more popular music, we are under less constraint. A more natural sounding reverb could take away from the track, so it is important to experiment with different types and parameters.

Figure 1: Graph showing the order of events from an impulse

response to create reverb. (Buffoni, 2020)

Here are a few typical reverb set-ups to help you get the most out of your mixes:

1. One singular reverb – This makes everything sound as though it is in the same space so is best for ensemble work.

2. Two reverbs – One room (short) and one plate (long).

3. Three reverbs – Plate (short), Chamber (medium) and Hall (long).

The longest reverb is usually used in moderation and as a glue to bring the mix together and provide added cohesion by making it seem as if it is in the same environment. Another trick that makes a track smoother and more polished is timing reverb to the track. This adds depth without the reverb sticking out. This is done by adjusting the decay time, so it dies out before the next snare hit for example, this allows it to ‘breathe’. Also, add pre-delay to give the source space and clarity.

I do believe reverb can ‘make-or-break’ a track, however beyond the science and reasoning of this effect, it is still a creative tool to which we can use however we like. There are no boundaries to creativity. Still, with that being said, we all still want our tracks to sound good, right? Understanding and utilising reverb well will definitely aid this. Afterall, “Reverberation is undoubtedly the most important studio effect at our disposal” (White, 2002).

References

BUFFONI, L. (2020) A wise approach to Spatial Audio – Part 3 – Beyond Early Reflections. Part 3. [Online] Available at: https://catoolkit.herts.ac.uk/toolkit/referencing-websites/. [Accessed: 26th October 2021]

OUTPUT. (2021) Spring vs Plate Reverb: When To Use Each. [Online] Available at: https://output.com/blog/spring-plate-reverb. [Accessed: 26th October 2021]

OWSINSKI, B. (2017) The Mixing Engineer’s Handbook. Fourth Edition. West Burbank: Bobby Owsinski Media Group Publishing.

PRO AUDIO FILES. (2017) 5 Different Types of Reverb Explained. [Online] Available at: https://theproaudiofiles.com/5-different-reverb-types-explained/. [Accessed: 26th October 2021]

WHITE, P. (2002) Recording And Production Techniques. Second Edition.: SMT