The Korg Radias synthesizer was released in 2006, discontinued after a 4-year run, and seems to have polarized all its users. Some dismiss it as "digital crap", others hail it as a "future classic". Who is right? Are these people snobby analog purists? Is the other group Korg's minions, paid to drum up favor for this little silver beast?

I purchased the rack-mount model, the Radias-R, in 2006. I was relatively new to the world of "virtual analog" synthesis, and the sound of the Radias seduced me because it was so different. Think: bright, smooth, icy, crystalline, electrical.

There are many reasons to appreciate this synth. I'll summarize a few, because I want to skip to the heart of this post: The Radias contains 64 sampled waveforms ("SynthPCM"), and they're are a lovely, creative bunch, with lots of rich, cybernetic character. (Someone enjoyed designing these, I bet.) The comb filter is surprisingly useful and rich. Korg's free editing software is a joy to use.

Other features are likable, despite a few flaws: The 39 (!) knobs on the front panel don't rotate endlessly. The insert effects are impressive, but some of the best effects (the amp simulators) are restricted to monoaural output. The unison & stereo spread features are great, but you can't target them via the modulation matrix (yet you can twist those knobs in realtime).

There's also a snappy vocoder, which can vocode live input, or record input as "formant motion" and play it back. Unfortunately, recording is difficult, and must be triggered on the hardware. You can't scrub, or change the formant motion speed. The Radias can store 16 formant motions, but only 8 presets are provided. I hate to admit this, but most of them are tacky... (One of the presets speaks, "Yo! Everybody in the house, say 'Raaaaadias!'")

How Does It Sound?

The most important feature of the Radias -- which you will either love or hate -- is the character of its sound. My opinion is that anyone who describes the Radias as "deep" or "warm" is wrong, just plain wrong. The Radias is the opposite of warm, fuzzy analog. It is deeply cold, in an air-sanitizing sort of way. If iciness can be sexy, this is it.

The sound has a certain sonic distance, as if the phase of one speaker is inverted (but of course, it's not). The basic waveforms seem a bit sterile, even after summoning some analog trickery (detuning the oscillators, etc.) The sound is so smooth that it's practically transparent. This synth sits well in the background. With its bright character, I've been able to drop it into many mixes, and it magically sits well with minimal equalization. But my attempts to feature the Radias as the frontman have never felt satisfactory.

How did Korg craft this particular sound? I ran some experiments to figure this out. Here is my conclusion:

In most cases, the waveforms are not synthesized in realtime. They're pre-sampled.

The Formant provides a clue

The Radias has 9 oscillator types, including a Formant oscillator. (A formant is similar to a bandpassed sawtooth wave.) Here's the spectrum of a formant produced by the Radias, with the narrowest formant width available. (This spectrum was analyzed in Ableton Live.) This looks acceptable, you can see the prominent peak around 800hz:

However, when we increase the formant width, instead of producing a wider hump ... The peak splits into two peaks, with the same narrow widths as before:

By increasing the formant width further, the peaks move even farther apart:

Although the sound is pleasant, this is not a true formant. This behavior indicates that the Radias' "formant" is actually composed of two waveforms. These waveforms have been pre-sampled at various resonant peaks. The Radias produces its "formant" by playing two of these samples simultaneously.

The Sawtooth misbehaves

Another Radias oscillator type is the Sawtooth wave. When played at mid-range and high frequencies, the Radias delivers the expected sound -- a series of overtones marching up to infinity:

But something undesirable happens when we move down the keyboard. When playing lower notes, the high-end treble frequencies roll off:

Further down, it sounds even more muffled:

The Sawtooth waves are not being generated in realtime. They, too, are sampled. This sort of frequency roll-off implies that a sample is being played at a low frequency, and interpolated (a.k.a. "anti-aliased") to smooth the output. I'm not sure which window function Korg chose for the interpolation, but it is the driving force behind the Radias' character, as it filters every sound. Also note that the other fundamental waveforms (Square, Triangle and Sine) are sampled as well.

I suspect that waveform modulations (such as square wave's pulse width modulation) may be pre-sampled as well, since they exhibit the same roll-off. By sweeping the pulse width, the Radias may be interpolating between waveforms (like using wavetables). I can't seem to produce an audio demo to support this claim, so the wavetables may have hundreds of samples in them, too many for the human ear to discern.

However, the two effects based on frequency modulation ("Cross" and "VPM") do modulate in realtime. They produce appropriate spectrums, even when the oscillators run at low frequencies.

The Radias features a "morphing" filter, which can move between two filter shapes (for example, a lowpass and a highpass). This is probably achieved by processing the incoming signal with two "cardinal" filters (LPF24, LPF12, HPF, or BPF), and mixing their results together. I can't prove this, but the spaces between the cardinal points seem a little dull, as if phase artifacts are creeping into the treble, or the anti-aliasing artifacts are doubled.

These experiments helped me understand how the Radias acquired its sound. Short, single-cycle waveforms are looped and anti-aliased, resulting in smooth, hygenic timbres. Some of the longer samples (in the "SynthPCM" group) have more density, but they're still filtered by the anti-aliasing algorithm, which makes them sound airy and hollow. The Unison and Analog Detune features can add density, but in my experience, they don't add much thickness or richness, as it's merely playing multiple copies of the same smoothed waveform.

Hopefully this post doesn't read like Radias-bashing. I was more interested to discover Korg's tricks than anything else. The Radias is suited to some very specific genres and roles, and I wouldn't recommend it to everyone. Still, the sweet GUI editor makes this the most "fun", accessible synth in my collection, and I keep returning to the Radias for this reason alone.

To hear some creative Radias patches, check out Jexus' great YouTube demos: part 1, part 2.

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Filtered Noise Sequencer

Drag and resize the blue blocks to change the filter frequency and width.

This sequencer is not using expensive bandpass filters. The oscillators are sine waves, which are frequency modulated with white noise. It may not sound inherently musical, but you can produce great hihats, bass thuds, and airy pitched noises.

Here's the source code. (Requires Flash CS5 to compile.) Have fun!

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A Curious Lack of Light by tooManyMoths

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The Braindead Monkeys: Space Donut

After a 4-year hiatus, Space Donut arrives! It's their strongest album to date. Lots of head-nodding jams, and lots of smiles.

Recommended tracks:

• #3: Parody of a popular 80's cartoon
• #4: TERRORISM! "The United States is currently at war with everything..."
• #7: Nintendo (NES) + marching band
• #5, #13, #18: Delicious electro jamstep

Grab a banana and an electric drill, and enjoy!

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There are many ways to disable Spotlight. I don't remember which combination worked for me, but the end result is that mdutil doesn't run on this machine anymore, and my menu bar is devoid of a Spotlight icon. (Also I disabled Quick Look, since its indexing also caused problems.)

But I still want to search my files. My solution was to create an automated job that runs once a day, and saves the path of every file into a big text document. Then I created a little command-line alias called search, which prints any file paths that match a search term. Here's how to do it:

First things first... We need a script that will traverse the file system, and save the path of every file into a massive text document. This is pretty easy, the find utility can do the heavy lifting. Here's the script I wrote:

#!/bin/bash
rm /Users/chaz/dev/search/tree.txt
find / > /Users/chaz/dev/search/tree.txt

I saved this script as /Users/chaz/dev/search/build_tree.sh . Make sure it's executable, then run it:

$ chmod a+x build_tree.sh
$ ./build_tree.sh

The first time through, the rm command will complain that it has no tree.txt to delete, but that's okay. find will throw some other warnings at you: it can't traverse every directory because it doesn't have permission. Again, that's okay -- I probably won't be hunting for files in such places.

Grab a beverage, this process takes a few minutes. When it's done, you'll have a (rather large) tree.txt file in the directory. How large, exactly?

$ wc tree.txt
1719365 5761267 196118611 tree.txt

1,719,365 lines, so I just indexed 1,719,365 files. Awesome.

It would be nice if the indexing ran automatically, preferably when I'm asleep. Since cron is being phased out of OS X Leopard, we'll use launchd instead. I created this file, called rebuild_search_tree.plist:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http://ww w.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>Label</key>
<string>chaz.search.tree.rebuild</string>
<key>ProgramArguments</key>
<array>
<string>/Users/chaz/dev/search/build_tree.sh</string>
<string>daily</string>
</array>
<key>LowPriorityIO</key>
<true/>
<key>Nice</key>
<integer>1</integer>
<key>StartCalendarInterval</key>
<dict>
<key>Hour</key>
<integer>6</integer>
<key>Minute</key>
<integer>15</integer>
</dict>
</dict>
</plist>

Save this into ~/Library/LaunchAgents . You may have to create that directory, and there's an added wrinkle: for both the LaunchAgents directory and the .plist file, the owner has to be root.

$ sudo chown -R root ~/Library/LaunchAgents

Register this script with launchctl:

$ sudo launchctl load -w ~/Library/LaunchAgents/rebuild_search_tree.plist

Now this launch agent will run automatically at 6:15 every morning.

Finally, we need a command-line tool to search the tree. I added this line to my .profile:

function search() { clear; cat /Users/chaz/dev/search/tree.txt | grep "$@" | more; }

And here's how you use it:

$ search test
/Applications/Adobe Photoshop CS3/MATLAB/tests/teststats.m
/Applications/Audacity folder/nyquist/test.lsp
/Applications/iTunes.app/Contents/Resources/da.lproj/iTunes Help/gfx/gfx_test.gif
...

For each file that matches your query, it displays the full path of the file. This could be made fancier, but for now this is all I need!

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OpenMoko Train Wreck from Dave Fayram on Vimeo.

More OpenMoko Train Wrecking (Now with Qt!) from Dave Fayram on Vimeo.

There's a ton of literature describing best development practices out there. But I think case studies of failure, or good intentions gone horribly awry, are just as important. It's essential to recognize what not to do. I still regard The Daily WTF as a learning resource, full of cautionary (and hilarious) case studies.

Also, there are no "________-killers," but that's a subject for a different day.

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Click to play! It's not polished, but it lets you explore different flocking behaviors. Here's what the controls do:

• count The number of "birds" in the simulation.
• alignmentRadius Birds rotate to match the direction of their neighbors. This parameter changes how far away they can "see". Larger values tend to align the entire flock; small values let the flock break apart.
• separationRadius Birds try to avoid colliding with nearby walls and other birds. They will turn and simultaneously hit the brakes. This number controls their stopping distance.
• peripheralVision Birds have a blind spot behind them. When this slider is maximized, the birds will have no blind spot, and will see 360 degrees.
• turnSpeed The speed at which birds turn.
• brakePedal Birds will slow down to avoid colliding. When this slider is minimized, the birds will never use their brakes.
• travelSpeed The top speed of the birds.
• Scatter and Randomize: Try them and see...

If you want access to the code, the SubVersion repository is open: http://dev.zacharcher.com/svn/flocking_test/

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I borrowed the font used in Major Havoc and created several new classes to support this. First, here's how it looks:

Play with the .swf . Click the screen to set the keyboard focus (I'll debug Selection.setFocus() later.) Type letters. Press backspace to clear the screen.

Each letter is placed randomly, and has a GlowFilter applied (an attempt to simulate the look of old CRTs) with random colors and settings therein.

Here are the classes being used:

• vector.ShapeSegment (either a single line segment, or a bezier curve)
• vector.Shape (a continuous path of several ShapeSegments)
• vector.Symbol (a collection of Shapes)
• vector.font.Havoc defines the Symbols for each letter of the Havoc font, using delimited strings. Here's the string for the "A" character: "0,1; 0,0.5; 0.5,0; 1,0; 1,1 / 0,0.5; 1,0.5 ". Note that each letter is drawn on a coordinate space ranging from (0,0) to (1,1). The "/" character divides the coordinates into two Shapes (a separate Shape is needed to draw the bar through the center of the "A").
• vector.font.BaseVectorFont parses the strings contained in Havoc, and returns Symbols.

Symbol, Shape, and ShapeSegment each have a draw() method that requires a MovieClip (to draw in), and a flash.geom.Matrix (to govern the position/size of each vector entity).

Currently this code is all locked down, not for any malicious reason... But I'd let my framework & libraries mature a bit before I start accepting feedback. If you'd like to poke through my code, then I can open up my SubVersion repository; let me know if there's interest.

Up next: 3D

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I just switched from Typo (Rails) to WordPress. Come and get me, spambots!!!!

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