EMusicTips » Acoustics

Top 10 Reverb Tips and Tricks

bjorgvin — Tue, 31 Mar 2009 17:19:12 +0000

With reverb, you can make or break a space

Imagine listening to a recording and half a minute into a song you notice something wrong. You can’t quite put your finger on it; you just can’t feel the instruments, you feel attacked by the singer’s in-your-face voice and everything is just too…..dry. It’s like listening to music in a vacuum. There’s no space.

Although listening to a reverb-free record is nearly impossible, (unless it was recorded entirely in an anechoic chamber), you can still have a really dry record if you don’t put any reverb on anything.

Reverb can be perceived as a glue that holds everything together, yet retains enough space to maintain a perceived distance between each element. It makes a three dimensional picture of the soundscape you just recorded, causing you to feel that you can hear the room accompanied by the instrument.

Different modes of reverb

There are quite a few different types of reverb. You can call them reverb modes, or room types. Some of the more common types include; Room, Hall, Chamber, Spring, Plate, and Convolution. In our age, we have access to digital reverb simulators which can simulate, quite realistically, all of these programmed room or reverb modes. Let’s take a look.

Room reverb – These types simulate the sound of having recorded something in a room. Whether the parameters are for a big room or a drum room, they usually simulate smaller spaces than their Hall/Chamber counterparts.
Hall reverb – Rich, warm and big are the first adjectives that come to mind when thinking about Hall reverb. These types simulate halls, whether they be medium halls, concert halls, or whatever lush parameter name the hall has.
Plate reverb – Plate reverb is a personal favorite of mine for vocals. Live, I propably use it too much, but I just think it does wonder to the vocals, without taking it too far or drowning it in reverb. Plate reverb is basically sound being sent to a metal plate which vibrates back and forth. These vibrations are picked up and transformed into an audio signal. Plate reverbs are very bright but clean, so they suit vocals especially.
Spring reverb – I was once asked what reverb was when I was fooling around with my guitar. I cranked up the reverb on my small practice amp and then kicked it. “That boing you heard?” “Yeah?” “That’s reverb”. Although true is some form, that boing wasn’t all reverb, it was spring reverb. The reverb found on guitar amps so most usually used for guitar.
Chamber reverb – In the old days, studios had so called echo chambers. In these chambers they had speakers that they routed the audio signal that they wanted to put reverb on. The signal, be it guitar, voice or whatever was produced through the speakers into the chamber and picked up by a microphone that was positioned to capture the reverb in said chambers.
Convolution reverb – This is the type of reverb that allows digital emulation of real three-dimensional spaces. If you’re familiar with the famous reverb plugin Altiverb, then you have heard convolution reverb. In order to capture a room’s reverb characteristics, an “impulse” sound is played in a real space, such as an opera house or a cathedral, then recorded into a computer. The impulse sound allows the computer to simulate that space just from the impulse sound. This is possibly the best kind of digital reverb around

So now you know a little bit about the reverb modes you most commonly work with. Below I have brainstormed a few fun tips you can use whenever you like to spice things up.

A different take on reverse reverb:
You all know the classic reverse reverb, where the reverse seems to swoosh in before the phrase of the singer or the hit of the drum. A neat trick for something different is to record an infinite reverb on a different track and then reverse it. For example, say you have a slow intermission type middle part and the part before ends on a snare hit. You can record that last snare hit on a different track with a big cathedral like reverb with infinite decay. Then you can reverse the audio part and put it low in the mix, then you have a weird controlled reverbed ambience filling out your slow part.
Gated Reverb on vocals:
Gated-reverb on vocals is something I think is pretty cool. I think this is used on the song On call, by Kings of Leon. His vocal reverb stays on while singing but cuts off abruptly when he stops. You patch your effect processor to a gate and the sound source is side-chained to the gate. That way, the gate opens and lets the reverb out whenever the singer is singing, but cuts off as soon as the sound level dips below the threshold of the gate.
Making things feel bigger and bigger:
Say you have a really spaced out Sigur Ros rock outro(I’m Icelandic, I’ve got to namedrop here) and the drums are going wild in the end. It can be fun experimenting with automating the reverb so the drums, or maybe only the snare, or everything, whatever you choose, gets bigger and bigger. I know for a fact that this can work wonders live to really give that last song a huge impact on the audience.
Pan it:
Use mono reverbs for a mono sound source and pan them to a different location in the mix. It can give an interesting impression.
Put space between source and reverb:
Using a standard room reverb, adjust the pre-delay to give the impression it is a little big bigger without making it linger too long. On vocals for example, it can give space between the singing and the reverb.
Reverb only:
Send your drums to a big reverb and solo-safe the reverb. That way you are only hearing the reverb and not the original sound source. It can make for a cool fade-in intro for a song. Especially if you add reverse reverb for the change into the real drum kit.
Mix it up:
Use different types of reverb on the same source. Mixing a couple of types of reverb can create an interesting effect.
Don’t use any:
Keep some instruments reverb-free. It can add an interesting contrast to the rest of the song. It can put a solo intrument to the forefront in a special way.
Add other effects:
Add other types of effects on the aux channel where you have your reverb. Try distorting it, phasing it or anything else you can think of.
Use REAL reverb:
Try ditching your plugins and use real reverb. Upload your audio clips to Silophone, an old grain silo that has been converted into a do-it-yourself reverb chamber. You upload audio and it is played back in the empty silo, then recorded and sent back to you as a download.

I’ve decided to do an example of tip #7. I’ve taken a small snare sample and put two types of reverbs on it via an aux send. I used the Logic presets “Ambience” in the Platinum Reverb and the “Short Snare Hall” in Space Designer. Although I am using Logic, any DAW with decent reverbs works just as well.

First audio sample has the untreated snare drum.

Second audio sample has the snare with a tiny bit of ambience reverb. Not a huge difference but not as dead.

Third sample has a snare hall preset. The reverb makes the snare much bigger.

Fourth sample has both the ambience and hall reverb patches together. Notice that the predelay on the ambience preset delays the hall reverb so it enters later than the actual snare hit. Could make for an interesting sound.

Reverb is an instrument of endless debate. Everybody has an opinion of what works best(like in everything else regarding audio). But reverb can often make or break a song, too much fills it with too much space and you can’t hear what it’s all about and too little just kills the emotion of it. So you have to take particular care in your appliance of reverb, and also be open to a lot of experimentation. Since it is such a big topic you are sure to find something interesting in your endeavours.

Who knows, maybe you’ll be the next one to invent the next “reverb studio trick”?

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Acoustics Part I: an Introduction to Resonance

admin — Tue, 17 Mar 2009 02:21:38 +0000

Galileo discovered the principles of resonance when experimenting with pendulums

Way back in the old days of the 17th century, a man named Galileo Galilei was fiddling around with a pendulum and discovered that if he gave the weight at the end of the string a tiny push at the right time, it would keep swaying back and forth with minimal energy exertion. He discovered that potential and kinetic energy can be set into motion with just a tiny bit of effort. This phenomenon is what became known as resonance. As it turns out, it’s not just pendulums that resonance is affecting. It’s everything. You could say that everything resonates. This affects us musicians and producers in many ways. For example, your room may have too many resonances in the wrong places, which will mess up audio recordings unless you dampen the sound vibrations with sound paneling or bass traps. But since this an intro, I’m sort of getting ahead of myself, and I will cover the practical side of resonance in Part 2.

Nikola Tesla was the archetype of a mad scientist. He invented alternating current, radio broadcasting, and of course, the tesla coil. He is also the subject of many conspiracy theories.

Several centuries later, another guy named Nikola Tesla had heard of this resonance principal, and dedicated his life to discovering how it could be used. Tesla confirmed that everything resonates when he discovered that a pocket-sized mechanical oscillator can cause buildings to crumble and bridges to tremor through the principles of resonance. All that was needed was a pocket-sized piston-driven oscillator sending tuned vibrations into the steel foundations of a building. The power of resonance lies in its ability to multiply force; Just a little bit input energy results in a lot of output energy.

“Although Tesla was not the first to discover resonance he was obsessed with it and created some of the most incredible demonstrations of it ever seen. He studied both mechanical and electrical versions. In the process he created an artificial earthquake, numerous artificial lightning storms, knocked an entire power plant off line in Colorado, and nearly caused the steel frame of a sky scraper under construction in Manhattan to collapse. Tesla realized that the principles of resonance could be used to transmit and receive radio messages well before Marconi.” link

Everything has resonance. Resonance is the principle behind the rattles and vibrations of idle objects caused by the subwoofer hitting a certain note. It is why you can shatter a wine glass with the right audio frequency and a loudspeaker. When the loudspeaker is oscillating at the frequency of the wine glass’ natural resonance frequency, it shatters. Sound waves are pushing the glass at regular intervals, just like you would be pushing the swing, and that regular interval is the same rate that the glass is vibrating. This causes the vibrations in the glass to keep amplifying until the glass can no longer stand the intense shearing action and it breaks into pieces.

Sound waves propagating through a field of air molecules and reflecting off of square walls

In space, electromagnetic waves are exploding out of stars, propagating infinitely outwards. Once on earth, we can detect these vibrations through our eyes, which are like windows through which a certain band of frequencies can pass through. (Interestingly, our eyes are actually tuned to the atmosphere, because the visible spectrum of light corresponds to the spectrum of frequencies which which pass through the filter of Earth’s atmosphere) We can think of all of our senses simply as vibration sensors that are tuned to different frequency ranges. Our ears sense vibration by directing sound waves towards the ear drums, which are compressed and rarefacted by waves of compressed air molecules. Those little drums in your ears are connected to a bone that wiggles some fluid in the inner ear, which excites even tinier little hairs that send signals to the brain, where that information is finally interpreted into what we know as sound. So, next time somebody asks you “if a tree falls in a forest and nobody is around to hear it, does it make a sound?” you can say that it doesn’t make a sound! It only causes compression waves through the air. If there are no ears to convert compression waves into sound, you could argue that the sound does not exist at that point in time and space.

Figure 1: A graph of a fundamental frequency along with the second harmonic

Each and every system in the universe naturally vibrates at certain frequencies. Theoretically, there is an infinite amount of resonances in any system. Think about it, your body is made of cells, all which have their own resonance frequencies. Your body, which is composed of many smaller sub-systems, has a resonance frequency, just as an organ pipe or a flute or the body of a guitar has a collective resonance frequency. All objects (also known as systems) have a primary, fundamental frequency, as well as many overtone resonance frequencies. The fundamental is the one frequency at which the system sympathetically vibrates the most. The other frequencies at which the system vibrates are comprised of a series of progressively “quieter” overtone frequencies that also vibrate in resonance, but at a lower amplitudes. These are also known as harmonics. Almost all sounds are composed of a series of frequencies all “riding” on top of one another In Figure 1, you can see that when two or more frequencies add up, they produce a new waveform (the resultant waveform in Figure 1). You can produce almost any sort of sound by adding sine waves of different frequencies together (this is the principle behind additive synthesis.

How to find an object’s resonance frequency

“The easiest way to find the resonant frequencies is to place the object next to a speaker and also place a microphone attached to an oscilloscope next to the object. Have the speaker play a tone at a given volume, and then without changing the volume slowly change the pitch (or frequency). If you watch the oscilloscope you will notice that at certain frequencies the amplitude of the wave, which is proportional to the volume of the sound being picked up by the microphone, will be greater than at surrounding frequencies. These are the resonant frequencies, and are detectable as the sound energy absorbed by the object is re-emitted more efficiently at these pitches. Note that you can perform the same procedure, albeit less precisely, in a low-tech way: try holding a large bowl, or coffee can, or some other object that you are hoping to make resonate, in front of your face. Slowly sing a tone with increasing pitch. If there is a resonant frequency in the audible range, you should be able to hear the tone emitted back to your ears at that pitch. Or if you have a piano available to you, try singing into the piano and you’ll see the strings vibrate when you sing their resonant frequencies. ” link

Well, that just about wraps up what I’ve got to say about resonance. In part two of this article, I will explore how resonance principles can help us make informed decisions about recording audio. Do you have anything to say about resonance? Let me know in the comments!

A humorous look at resonance:

More Resources

Interactive applet demonstrating a point source wave reflecting off of a wall
Pythagoras, string vibration, and standing waves
AbsoluteAstronomy.com on Resonance
Bio on Nikola Tesla

Quick Home Studio Monitor Tests

admin — Sun, 20 Jul 2008 21:25:36 +0000

via HomeTracked.com

I keep a collection of audio samples designed to help check my monitor setup. Test tones, essentially, that I use after I’ve moved my speakers or desk, to ensure the speakers still behave as they should.

I’ve included 4 of the samples below, and I hope you find them useful – and possibly enlightening. Each tests a facet of the two most common monitoring problems in home studios: Uneven bass response, and poor stereo imaging.

Sine wave sweep

Contents: A sine wave sweeping from 40Hz to 300Hz.
Use this to test for: Bass response, sympathetic vibrations.

[download MP3]

Unless you’re outdoors, or listening on headphones, you’ll notice the volume rising and falling as the audio plays. That’s normal, although the level doesn’t actually change. (Open the MP3 in your DAW to confirm this.) Rather, you’re exposing the acoustic response of your room.

Use this test as a rough gauge of how extreme the acoustic issues are in your space. (You can flatten the response somewhat, but acoustic treatment is a topic unto itself. For some more information, check the quick backgrounder on home studio acoustics.)

Additionally, the sweep can expose low-frequency dependent rattles, buzzes, or other sympathetic vibrations happening in the area around you. With this test, I once discovered the casing on an overhead light shook at exactly 140Hz, after puzzling with a mix for 15 minutes, unable to isolate the odd rattling sound.

Two octave walk-up

Contents: Consecutive semitones from G1 (46.2Hz) to F3 (174.6Hz)
Use this to test for: Bass response, specific problem notes.

[download MP3]

Here, the tone ascends through a chromatic scale. Certain notes will jump out or disappear, for the same reasons as above. Remember these notes, as they’re important to the character of your mixing space. Specifically, when you know that, for example, the B at 61Hz drops in volume in your space, you can reconsider when you find yourself reaching for the fader every time the bass guitar plays B.

5-point pan check

Contents: 5 bursts of white noise at different pan positions.
Use this to test for: Coarse panning issues.

[download MP3]

This file plays sound at the center, hard left, hard right, half left, and half right. If you don’t hear 5 separate panning locations, you’ve got stereo issues!

Most stereo imaging problems are caused by incorrect speaker configuration (i.e. the speaker aren’t equal distances from your ears,) and poor room acoustics.

Short-pan test

Contents: White noise at 3 different pan positions.
Use this to test for: Fine panning issues.

[download MP3]

This file plays a sound at 50% left, then hard right, then 25% left. (The jump to the right distracts your ear so it can’t track the sound moving from 50% to 25%) The 3 sounds then repeat on the other side.

Most listeners can reliably distinguish 5 or 7 distinct pan positions. So if your stereo imaging is clear across 9 points, i.e. 25% increments, you’re in good shape (for mixing in a home studio, at any rate.)

On the other hand, if the difference from 50% to 25% isn’t clear in your monitors, or is more defined on one side, you might want to consider using headphones to verify your important panning decisions.

Note: Since these test don’t require high fidelity, MP3s should be fine for checking your setup. However, here are links for WAV versions of the test:

Sine Wave Sweep – 40Hz – 300Hz
Consecutive semitones from G1 (46.2Hz) to F3 (174.6Hz)
White noise at 5 pan positions
White noise at 3 pan positions