The Holy Grail – Your Guide To Understanding Reverb

Reverb is not simply "echo", it is actually the result of audio reflecting off the surfaces of the room that you are playing in.

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The first guitar amp I ever owned was a Fender 15R Frontman. The R stood for ‘Reverb’ and it didn’t take me long to realise that the enchanting (and scratchy) reverb dial could make my playing sound magically better.

However just like a serving of baked beans, this is a case where too much of a good thing can eventually turn bad; you jack that dial-up and your musician friends will start to whisper about you behind your back and judge you for your strange and perverse life decisions, meanwhile, all you want to do is sound like you are ripping a mighty solo across the grand canyon – while in actual fact you are doing a Livestream from your bedroom (12 WATCHERS THIS WEEK MUM, NEW RECORD!).

 

I can explain….

In order to understand where people draw the line between Joe Average with his half tin of Heinz on toast and Joe Crazy with his “Bath of Bachelors”, it’s important to understand what reverb actually is. You might have people tell you that reverb is “echo”. I’m going to tell you, here and now, to your face(ish), that those people are wrong (well they aren’t 100% right anyway). Reverb is not simply “echo”, it is actually the result of audio reflecting off the surfaces of the room that you are playing in. The sound made by these reflections are largely due to the shape and construction of the room in which you are playing your instrument.

 

Source: Wikihow. Athlete: Unknown.

 

Here’s an example, imagine you are on one side of a room with a basketball and you throw the ball against the wall opposite to you. Depending on the size of the room, it will take a shorter/longer time for the basketball to hit the wall and bounce back to you. Similarly, if the material of the wall opposite is made of felt as opposed to concrete, the ball might not bounce back as vigorously. If you replace the basketball with an audio wave from a musical instrument or speaker, then you can begin to understand how the room defines the reverb.

Let’s ignore the case of using reverb on individual instruments for now and look at the bigger picture. When we use Reverb in a mix, we are trying to create an auditory landscape for the listener. Good reverb is contextual, it is appropriate for the kind of gig and type of music.

You don’t need to be an acoustic engineer to know that the cavernous reverb on your friends live stream is not a result of the natural reverberations coming from his 2 meters squared shared room in Dublin city centre (a bargain at 900 euros/month). At the same time, we don’t want to have no reverb at all because that gives the impression that the listener is sitting within ear-licking distance of the performer. No thanks.

So how do we work out what does and doesn’t work? And when you are in the studio or talking about Reverb with your mates in your local pub (we all do it guys, right?… RIGHT?),  what words can you use to make people go “Wow, this person really knows their shit about Reverb”?

“Now personally, I prefer to use spring reverb on my guitars, but I then sidechain the output of the reverb to a snare drum, but I’m using plate reverb on that because it’s just so lush you know? It’s like shoegaze on shoegaze.”

 

A Real World Scenario

Before we dive into plugins, let’s talk about the main constituents of reverb. Imagine two friends in a large, tiled bathroom giving each other a high five (We don’t need to know what they are high fiving about).

This is a High Five. Just in case you thought I was talking about something else. Source: WikiHow

The initial slap of the High Five can be heard from both parties immediately, on the graph below this is shown as the red peak labelled ‘Source Signal’. There might then be ‘early reflections,’ perhaps from the sound bouncing off the floor directly under the high-fivers’ feet, this sound reaches the listener’s ear before the “full reverberation” (or Reverb Body on the image), which is what happens when the sound has hit the walls of the bathroom and reverberated back to the listener. Finally, the noise decays as the sound is absorbed into the room.

The two friends cheer because they just pulled off an incredible high five.

Source: LedgerNote

In this case, the character of the reverb is going to be driven by a few factors; the tiled walls, the large size of the bathroom and the other contents of the room. Now that we have seen a disturbing real-life scenario, let’s talk plugins.

 

Deep Dive

I’m going to be talking about TrueVerb by Waves here, it is available for $23 at the time of writing. If you want something similar, but free, I recommend epicVerb by Variety Of Sound.

Source: Waves TrueVerb GUI.

 

Here are what the various buttons/sliders/knobs do:

 

Sliders (Bottom Right)

The sliders act like a mini mixer for the different reverb sounds, you have Direct, Early Ref and Reverb sliders.

Direct

The original input signal.

EarlyRef

The early reflections, as talked about above. There is some debate as to whether Early Reflections exist in real life, but that’s a story for another article.

Reverb

The level of the “Full reverberation” signal.

Physical Properties (Under the top image)

The physical properties describe elements of the reverb that arise as a result of the physical space in which the sound occurs. As we are using a plugin, the space is being emulated (ie the plugin is making it sound like we are in a particular kind of room or space).

Dimension
Dimension of the space. Let’s stick with 3 for now, things can get crazy when we go 4D.

Room Size

Controls the size of the room in cubic meters. The larger the room, the more cavernous the reverb.

Distance

Controls the perceived distance of the source. (This is also known as a wet/dry control on some plugins). A larger distance will make the sound more reverb-y as there will be a longer time between the original sound and the sound bounced back from the walls of the room.

Decay Time

The total ‘reverb time’ of the room you create, affecting the early reflections and reverberation.

Damping

Includes HF and LF (high/low frequencies). These parameters change the character of the Reverb itself. I find that changing the damping can make it seem like the room is made from different materials, ie, a cave vs a concert hall vs a bathroom.

 

Waveforms

Ok so now we know what all the dials do, let’s look at some waveforms. I recorded myself saying “DeMars Magazine”. Here is an image of that wave. I’m using a dynamic mic in a relatively well-damped space, so there should be little to no natural reverb on this.

Source: Myself. Saying “deMars Magazine”.

 

I then dialled in a small room reverb preset using a small room size and a short decay time. I got the wave below.

Source: Original signal with light reverb to create the effect of a small empty room.

 

They look pretty similar so let’s run the original waveform and the small reverb waveform through an image diff algorithm:

Source: Image Diff between the two signals.

 

The pink signal is our reverb, we notice that it’s a little louder due to the reflections of the sounds. However, things get very interesting if we zoom in to about ⅓ of the way across. This is when I would have said the “s” in “Mars”.

Source: Image diff on the end of the word “Mars”.

At the end of the word “Mars”, the original signal basically dies down to nothing, whereas the pink reverb signal stays relatively loud. This shows the reflected sound is slightly delayed as a result of travelling across the room and bouncing off the wall before returning to the listener.

Now if we dial up the reverb to a completely different space, like a Cathedral, we get the following:

Source: Original signal put through a Cathedral Reverb preset

 

Here’s the diff on this one. Pink is our reverb signal and black is our original signal

Source: Image diff, original signal and Cathedral Reverb.

The characteristics of the reverb are clear. The repeated reflections and huge space in which they are traversing cause a build-up in volume that basically drowns out the original signal. This is why it can be pretty hard to hear what the priest is saying when you are sitting all the way at the back of the church on Sunday mass. I mean don’t get me wrong, it would be nice to hear what the priest is saying, but you were late for mass again because you wanted pancakes for breakfast and you can’t exactly waltz up the aisle 10 minutes into the sermon or else the whole parish will be talking shite about you.

The signal above also helps explain why our Live Streaming friends who are so trigger happy with reverb can sometimes sound a little more “10,000 Leagues under the sea” than “The Little Mermaid”.

So how much is too much?

Everything in Moderation

Here is what I think,  if you are a musician doing a live stream or mixing your own music at home, have confidence in your own talent. You don’t need to mask your voice with the sound of a million square meters of nothingness for the sake of pleasing that one overly judgemental fan who makes ambient music using modular synthesizers and preys on your Instagram stories.

Here’s a good place to start, find a reverb sound that appeals to you (ie, where do you want to sing? In a cathedral or a smokey jazz bar?), now set the Wet/Dry control to 100% dry (ie no reverb whatsoever). Then turn the dial until you can just about hear a change in the original signal. For live streaming and escaping the ‘I’m singing so close to you I’m going to clean your ears with my tongue’ effect, this should be sufficient.

Having said that, I believe the full saying goes everything in moderation, including moderation. So when the time comes, when the rain is spattering down your window and you just want a pint but Micheál Martin has extended lockdown for 6 weeks and you JUST WANT TO LET IT ALL OUT THROUGH THE MEDIUM OF MOODY MUSIC then grab that Fender Frontman Reverb dial with all your might and turn that shit up to 11.

 

Written by Stephen Brennan

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