3

Hi everyone,

I'm working on an art project (http://ll.frey.co.nz) and I'd like to synthesize something that sounds like this. It's a low deep bass thud, as heard on Mark Lanegan's glorious cover of 'Man in the Long Black Coat' from the 'I'm Not There' soundtrack:

[soundcloud]damian/long-black-coat[/soundcloud]

(Four samples of the sound.) I assume it was constructed by passing a lowpass filtered kick drum through a reverb with a long delay.

I need to re-make this in a generative fashion, so I can trigger it with parametric variations. I am currently using Pure Data as a sound engine, with a view to internalising the DSP code using a C/C++ library (TBD). I have been playing around with an Roman Hafaeli's 808 kick drum simulator but i can't get anything that sounds as nice as this.

Any tips about how to synthesize something like this appreciated.

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Keeping it to the basics so that it doesn't involve too much programming, here is what I think might be good starting points:

  • Your main ingredient will probably be some oscillators: sine/triangle wave (or probably a mix), those at a pretty low frequency and playing with different harmonics and volume. Based on your example, I'd say a sine wave will be your main source.

  • Next is an ADSR, this will give you a lot of sound shaping options with just few parameters.

  • You might want to add a low click or a higher frequency at the beginning of the sound to get the thump your example seems to have. This will have to be a very short sound, just a little layer.

  • A pinch of overdrive, this works better on the triangle rather than the sine wave.

  • You can also play with some delay and create a controllable feedback loop, to help give it space and distance. It can sound like a cheap reverb. This is really easy to programme in and might help shape your sound, while again adding some interesting parameters.

  • And of course a good old fashion LFO might be useful.

There's also the noise approach, using a bandpass filter to hone on the right frequency range. Or using subtractive synthesis to create your harmonics.

You might want to check the explosion tutorial in the book Designing Sound. You can download the Pure Data patch here: http://aspress.co.uk/sd/explosions.html The reason I say that is that the fireball subpatch sounds somewhat in the vain of what you're after (just kill the decay and the other stuff). This can at least provide a good base for a generative approach.

I hope this helps a little.

  • hey andrew, thanks -- but the link to the 'explosions' page seems to be broken ..? – damian May 23 '10 at 22:14
  • @damian that's so bizarre... the link works in my Firefox but not Chrome or Safari. The link must have been taken down, but stayed in my cache. Would you like me to email you the patch? Otherwise you can check these tutorials (also by Andy Farnell): obiwannabe.co.uk/tutorials/html/tutorials_main.html there isn't the explosion one, but I'm sure you'll find bits and pieces that will be useful. Maybe checkout the thunder tutorial. ps: you should really get that book, it's awesome! – Andrew Spitz May 24 '10 at 6:26
  • @damian there are also a bunch more obiwannabe.co.uk check out the synth section. – Andrew Spitz May 24 '10 at 6:52
  • @Andrew thanks, i have emailed. Looks like the book is being published by MIT press now, but it's 'forthcoming': mitpress.mit.edu/catalog/item/default.asp?ttype=2&tid=12282 – damian May 24 '10 at 9:07
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A cannon has an intense transient, and then the rest of the sound really is of the echoes from the surrounding environment. If it's a cannon in the distance, you'll need a volume envelope with a fast/immediate attack, short sustain, and a long release, possibly running it through reverb and fairly diffuse delay(s). Design something with a fair amount of frequency content first, then use a low-pass filter to tune that stuff out...starting with an 808 kick or similar isn't going to generate initial bright reflections that'll sound good once filtered.

If it were me, I'd use a resynthesis approach by using something as simple as a firecracker, load it into a software sampler, then layer the effects and envelopes above, and play it back at a lower pitch, and then add a LPF as the final sauce, as opposed to doing direct synthesis from scratch.

But that's just me!

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Going Damiens route, good colourful impulsive sources are a towel snap, leather belt, or just a hand clap. Take them at 192k or at least 96k if you can.

Otherwise, the distancing effect upon a large explosion over several kilometers is due to dispersive and other non-linear propagation effects.

The synthesis trick is to set up a bank of FIR low pass filters, and hit it with an N-Wave.

An N-wave is a bipolar transient, actually a single cycle of a sawtooth, starting and ending on zero. If you're after high quality it might be best to additively composit this into a table first to have a band limted source (the Gibbs effect can actually be desirable and makes the end transients even higher than normal.

The FIR type is more desirable than IIR which will ring too much at the kind of resonance you want, and sound liek a drum.

What you get after several passes is an elongated "Whump" like an overpressure wave that has been spread by distance.

A more direct approach is to wrap up a short line line segment into a chirp by taking its square and then the cosine of that

Try this into a soft, short reverb

[1, 0 50(
|
[vline~]
|\
[*~]
|
[*~ 2]
|
[+~ 0.25]
|
[cos~]
|\
[dac~]

a.

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