Some 4klang notes on Alcatrazes' Equilibrium soundtrack

category: music [glöplog]
Virgill did a really good job with Equilibirium's soundtrack and also generously published the music source files. Maybe it makes sense to study these for a bit instead of just spending another evening mucking around in 4klang. So let's jump right in and examine three instruments of the patch.

The wind chimes

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Chimes unit stack

This really blew my mind. We have an AM modulated high frequency bleep (slots 5 and 8) whose pitch is automated with a slow noise LFO (slot 15-17).
Add some reverb and that's it! The reverb is very important here, compare: chimes_dry.mp3 vs. chimes_wet.mp3.

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Chimes spectrogram

The staccato violin

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The staccato violin uses reverb to make the melodic bowing sound.


A Karplus-Strong string instrument. First we synthesize a burst of noise, filter it (slots 5-7), and shape with a distortion unit. The key is the delay unit with Note sync enabled. This makes the delay line length match the note pitch wavelength (I think?) and therefore introduces a melodic echo. That echo is the actual bowing sound. So the original noise burst acts both as the aharmonic impact sound of the bow hitting the string and as the exciter for the melodic note feedback loop.

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Dual role of the noise burst

The bass

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The bass is synthesized from a single Pulse-LFO in slot 3.


There's three tricks going on here. First, the repetitive bass pattern is not programmed as MIDI but as a looping pulse wave LFO (slot 3). Second, we don't have the main oscillator here at all! Instead, the pulse LFO in slot 3 produces just a click that's spread out on the time axis with the DelayLine unit in slot 9. So, some kind of Karplus-Strong synthesis again. Third, we put in some stereo expansion with the Store unit in slot 10 that maps the raw mono audio signal directly to channel panning. Dirty but good enough.

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We get some ambient echos for cheap by adding noise to the initial click signal in slots 5 and 6.

Other instruments
There's still the choir, trumpet, and other stuff left to cover but I'll leave those for someone else :)
I hope you learned something new and remember: friends don't let friends to use 4klang presets!
added on the 2018-03-04 22:27:27 by cce cce
thanks for the writeup!
added on the 2018-03-05 00:06:59 by psenough psenough
neat :)
added on the 2018-03-05 12:29:57 by ferris ferris
Can we have more like this please?
added on the 2018-03-06 09:27:27 by ton ton
Sure, just follow the orders in the second-to last line in the original post! ;)
¨ber metallic reverbs 2018 :)
added on the 2018-03-06 14:21:11 by leGend leGend