Notes from the Shore

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Free Reverb Roundup

Lately I’ve been experimenting with a variety of the free reverb VSTi’s available on the internet. There are a countless number of them, but some of them, I think, deserve mention. They may find a valuable place in your own virtual studio.


The original reverb was just a large room with flat, hard surfaces. The classic example is the medieval cathedral. Concert halls also have their own reverberant sound, and lots and lots of money and effort goes into refining that natural reverberation. So, what is reverb, anyway?

When a sound is created, we hear not just the sound, but the reflections of that sound as it bounces around and around the space. Generally speaking, reverb is made up of two parts – the initial reflection and the reverb tail, or wash. The initial reflection is made up of the first several echoes off the walls and ceiling. An extreme example is the echo you would hear in a canyon or off a mountainside. Quickly (less than 1 second), the reflections all smear into the familiar wash, or reverb tail. At this point, individual sounds are lost.

Before electronic reverb, there were only two ways to get reverb – record the sound in a large reverberant space, or, if that was unavailable, or more control was needed, use an echo chamber. An echo chamber was a very small, very reverberant space with a speaker at one end and a microphone at the other. There’s a great description of one in use in Sound on Sound’s Classic Tracks article: Be My Baby.

Electromechanical reverberation soon took center stage, creating the reverb effect with a vibrating spring or metal plate. While these didn’t sound exactly like natural reverb, they did have pleasing sounds that became legitimate effects by their own right. Current digital reverbs still emulate popular plate and spring reverbs of the 60’s and 70’s.

The next step was dedicated digital reverb. These units used microprocessors to apply reverberation to a signal. Units were available from the $100 Alesis NanoVerb on up to thousands for Lexicon products. With the advent of personal computers powerful enough to perform multi-track digital recording and editing, software-based reverbs also became popular.

In an interesting turn, reverbs have now come full-circle. Today’s PCs are powerful enough to take a sample of reverb from an actual location (or digital unit), and combine that with an audio signal to make the signal sound as if it was recorded in that space or through that unit – often at a lower processor cost than the digital unit itself. This is called convolution reverb.


So that’s brings us to where we started – a sampling of the best free reverb plug-ins that I’ve come across. We’ll start with digital reverbs.

Classic ReverbKjaerhus Audio makes a whole line of free and pay plug-in effects. One of their most popular is their Classic Reverb. It has a series of straightforward controls, and starting from the presets make dialing in the sound you want easy. This has been my number-one go-to reverb. It sounds great and is very flexible.

DX Reverb LightThe next three are “light” or stripped-down versions of pay reverbs. Usually there are fewer presets or algorithms available. On one end, Anwidasoft’s DX Reverb Light is the ultimate in simplicity to use – one knob and four parameters.

Nebula 3 FreeOn the other end of the spectrum is Acustica Audio’s Nebula 3 Free, which is a full-featured multi-effects with tons of options and programmability.

GraceverbOne more algorithm-based reverb plug-in is DaSample’s Glaceverb. This one leans more towards effects that simple signal processing. The presets that morph and warp your sound pretty seriously.

Now, here’s where things get interesting – the world of convolution reverb. The idea is simple – an unpitched sample of the reverb of a space, called an impulse response (IR), is added to the waveform of the sound, resulting the music (or other sound) sounding as if it actually occurred in that space.

SIRThe big boys include Waves IRL, Tascam Gigapulse, and the original Altiverb. The differences between these and the one I’m about to mention mostly include flexibility, control, and the bundling of really high-quality IR’s. That being said, Christian Knufinke’s SIR is one of the most amazing free plug-ins I’ve ever come across. There are controls for predelay (time between the initial onset of the sound and the beginning of the reverb – useful for increasing clarity), Attack, Envelope, Length, Stretch (lengthen or shorten the actual IR), and a complete parametric EQ. There are numerous free IR’s available on the internet that people have recorded – some for fun, and some to provide a sample of their pay library.

There are samples of both real spaces and IR’s of classic digital units – it can be overwhelming. Here is a list of sites with free, downloadable IR’s. Start with Noisevault, and then move on from there.  I hope to record my own impulse response of a local church with a great natural decay. If I can make that happen, there will be a post on it.

Anyway, speaking of overwhelming, this article is getting overwhelming. All I can say is check out the links, play with the reverbs yourself and see what you like.

4 thoughts on “Free Reverb Roundup

  1. I must agree about SIR. It’s the main reverb plug-in I use. When I compare it to other non-convolution reverbs there is no way I would forsake it, especially when doing important work. Convolution reverb just has more life and sparkle.

  2. Thanks for stopping by, Gary. I have to add a caution about SIR that I just recently learned. According to Sound-on-Sound Magazine (specifically that Mix Rescue series) SIR is not a true stereo reverb.

    While I don’t know precisely what that means, I think it means that the inputs are summed to mono, and then the reverb is applied to it, so the output can be stereo for a stereo impulse.

    Maybe that’s not too important, since a reverb wash needent be too stereo-directional, anyway. But, listen closely to your reverb soloed for phase issues from the mono-sum that happens on the way in.

    For the record, since I picked up Sonar Producer Ed., I’ve been working with their Perfect Space conv plug that comes bundled with the app.

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