Category: DEVICES

Convolution Reverb Pro is a sample based Max For Live device that allows one to digitally simulate the reverberations of a particular space from the real world, referred to as Impulse Responses (IR), to a sound, creating the illusion that the input was recorded in that space. It is essentially the process of filtering a source sound through a digitally stored room sample. The application of this can give a sense of roominess, but also tonal character and width.

The method used to capture the reverberations of a given space involves playing a loud sound, such as a gunshot, into an area, phasing it out and thereby leaving us with a sonic footprint of this space. This makes convolution reverb an invaluable tool compared to other, more standardised versions of digital reverb that typically use algorithms to simulate acoustic reverb.

I experimented with this by convolving a sample using a kick drum as an impulse response. I found I was able to accentuate the low frequencies of the kick within the sound of the sample, while also dampening the frequencies of the sample that aren’t in the kick IR File. This served as a useful tool, allowing me to achieve a clearer bass sound without having to use a low-pass filter which would have cut many of the samples harmonics.

Used creatively, this device allows one to explore various spaces of sound, including unconventional ones such as the kick I used, to introduce a whole new texture to a sound or body of work. Furthermore the same device facilitates the combination of two IRs, in early and late reflections respectively. This hybridisation of multiple space further adds to the versatility of the Convolution Reverb Pro.

Another interesting thing I found was that Ableton’s Hybrid Reverb actually combines both convolution and algorithmic reverbs.

It is often found that artificial reverb effects use some combination of echoes with short delay times to recreate the acoustics of a particular space. By introducing enhanced harmonics of the input signal during the reverberation process we can create a shimmering effect. One such example of this would be to use real-time pitch shifting with feedback delay to acquire said harmonics.

Instead of using the shimmer reverb VSTs downloaded on my computer, I set about trying to recreate it myself, using Ableton’s stock plugins. Drawing up an Audio Effect Rack, I created an effects chain. It consisted of a Reverb, Grain Delay, Ping Pong Delay and another Reverb, in that order, as the distillation of ingredients in a shimmer effect is the combination of a sound diffusing (Reverb) whilst the resulting diffusion shifts in pitch (Grain Delay). I further spread this diffusion out with the following reverb and some slight delay.

Firstly, bypassing the first instance of Reverb, I went about setting the frequency of the Grain Delay to about 5Hz, taking the pitch all the way up to 12, and leaving its random pitch and feedback setting to 0. I altered the dry/wet mix to 75 percent and unchecked the sync box, allowing me to set the delay time all the way up to 128ms.

Turning the first Reverb back on, I increased it’s size and also the decay time to about 10 seconds. After applying some input processing by cutting out a little bit of the lows I brought the modulation speed up to just above 1Hz in early reflections. I then increased the volume of the diffuse slightly, all of which made the Grain Delay’s pitch shifting a little less prominent in the mix. The Ping Pong Delay, just after the Grain Delay also helped spread things out in the stereo field, so that nothing about the resulting shimmer effect was too centred, in order to achieve the appropriate ambience, allowing it to flourish in the background. Using another instance of Reverb at the end of the effects chain, with similar processing to the the one that preceded it, I continued to tweak settings, such as the feedback, in order to explore and apply more characteristics to the shimmer, aiming for a ethereal, cavernous feel.