Herding Random Behaviors

After playing Precambrian Resonance for a few people and explaining how the arpeggiator was creating a randomness to the output I was asked how that randomness made it sound different from previous playback. This was easy for me to imagine since I had heard it rendered several different ways, but difficult to explain. Therefore I have re-rendered the piece to illustrate how it changes.

This brings up an issue that I have encountered on several occasions. When audio processing creates some sort of randomness in a mix, how can you get exactly what you want? What if after you export the audio there’s some chunk of randomized audio that just doesn’t quite work?

My solution is to render the track that has the random processing on it several times. For Precambrian Resonance 0.2 I rendered the processing eleven times. After that I’ll listen and compare the renders, or if I hear one that I like during the rendering, I’ll just choose it. Ableton Live makes this easy with the “Freeze Track” option that essentially renders the track while allowing you continue making adjustments.

Sometimes it is not that easy. I have encountered situations where version after version of the randomized processing doesn’t quite fit. At this stage what I do is carefully listen to the audio for phrases that have something interesting going on. The next step is to sequence the selected phrases into a complete track, effectively herding the random behaviors into what I’m after. I suppose that this is similar to using genetic algorithms to hybridize the audio in a semi-manual way.

Precambrian Resonance 0.2

Bit Reduction

This drum loop has been processed by reducing the bit depth and down-sampling the clip until very little of it is reminiscent of it’s original state. As you can see in the image, the waveform has been reduced to a wide pulse that sounds very distorted (you might want to start at low volume). The top of the image represents a short section of the original audio, while the bottom is the processed version.

The bit depth was reduced to two, which allows for four possible positions for the amplitude of the waveform. Two above zero and two below zero. There are no zero crossings that aren’t straight lines, therefore the output sounds very similar to audio that has been badly clipped, but in my ears this sort of distortion has more charm than just clipping the waveform. The only other processing involved is automated pitch shifting from down four octaves up to its original pitch by about seven seconds into the audio. Here is where it sounds closest to it original form. Its stays there until about nine seconds in and then shifts back down minus forty eight semi-tones until it ends after almost twenty seconds.

redux

Tearing Grains

Using the simple granular synth packaged with Pluggo I created this nasty tearing sound. Towards the middle it sounds like it’s causing speaker damage, but don’t worry your speakers are safe. The original waveform was a sawtooth before the grain table algorithms manipulated it as you can see in the image.

Granular synthesis involves separating a waveform into grains that can be rearranged either randomly or with various formulas resulting in dense or scattered clouds of sound particles. For more information about granular synthesis, check out this entry on Wikipedia.

Tearing Grains

Three Story Buildings

How much processing can a voice recording take? I guess it depends on how badly you want to fuck it up. When it’s a recording of Donald Rumsfeld justifying the war on Iraq, I want to fuck it up as much as possible. That said, the recording is pitched and time expanded, run through a noise gate followed by a compressor, automated erosion, stereo delay (feedback at 80%, left at 5ms, right at 12.5ms, mix at 50%), and finally a reverb that creeps in with automated mix and decay. Enjoy!

Rumsfeld

 

Distorted Percussion

In this category I am planning to post a new sound everyday. I may not have created the sound the very same day of the post, but it will be something recent at the very least and more than likely created on the day I submit it. The idea is something like my colleague Tim Armato’s p{365} blog where he is posting a Processing sketch every day for a year.

My goal is to learn more about some of the audio processing that is available to me. It’s not always convenient when working on a project to explore new plugins or new ways to use old ones, especially in the studio or while collaborating. With this exercise I can do that and archive the results here. I’ll briefly describe the process of creating each sound and something about the software and hardware involved.

Today’s sound is a loop of audio that has been heavily processed in Ableton Live with filter taps (Pluggo), distortion, eq, dub delay (MDA), reverb, and more. The loop is an excerpt from a remix of “Some Kind of Adhesive” (One Day to Save All Life) that I produced with Nils Westdal. Believe it or not it started out as a simple shaker pattern. To me it sounds similar to the over driven thumb pianos of Konono N°1, although this was an accident since I was basically tuning the pitches to work in the remix. After I added distortion and a little virtual knob turning on the dub delay, this is what I got.

Distorted Percussion

Kick Drum Hacking

Kick Drum

Of course, in the ideal world, we get to spend a lot of time when mic-ing up the drums and try various tunings, microphones, rooms and signal chain so that the kick drum goes to “tape” with as little processing as possible and sounds great.

Then there is the real world. In the real world, the tuning of the drum is so-so, you have one or maybe two mics to choose from, time is running out and it’s time to hit the record button. So you’ll “fix it in the mix”.

In general, the kick drums needs a shit ton of lower mids pulled out — I usually center around 400Hz and I pull out as little as 5db or as much as 20db or even more! Then you need to put some low end back in, generally around 150Hz. But that pulls the sub-lows up too much so you have to roll off stuff below 50 Hz or so. Then, to add a little click and a little air, you want to jack up 2kHz and perhaps boost up a shelf at like 5kHz and above to bring in a little air.

You also have to make sure you’re not getting a lot of that 400Hz coming through the other mics. It tends to make the kick sound boxy. I usually attenuate 400Hz on the toms and the snare, too, for that reason.

I personally like to put the kick “above” the bass. So the kick will take the frequency space at 150Hz or so and the bass will center more down by 100Hz or so. Letting the kick take over the very low lows can be great for dance stuff. But, in general, the kick should hit you in the chest and the bass should rattle your ass.

Audio Processing

Have you ever put a microphone down the hallway from the studio then cracked the door on the recording booth while recording drums for a bit of natural reverb? Have you ever used the feedback from an open tuned acoustic guitar placed on a stand in front of a speaker? Have you run a vintage mono-synth through a Lesley cabinet? Use the Processing category to tell us what experiments have worked or not worked for you when processing audio in unique ways.

Water Atmosphere

drown thumbRecently I had the pleasure of producing the audio for a short animated piece called “Drown” by Aaron Dabelow. I simply recorded myself blowing bubbles in water with a straw. I captured in it Ableton Live 6 with my AKG c4000b large diaphragm condenser at a distance of about 9 inches, being careful not to splash water on the mic. The processing included down pitching an octave or so, running it through a high pass filter, and then dousing the works with some massive reverb.

Water Atmosphere – From “Drown”

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