Tim Kleinert
Joined: Mar 12, 2004 Posts: 1148 Location: Zürich, Switzerland
Audio files: 7
G2 patch files: 236
|
Posted: Sat Nov 03, 2007 10:52 am Post subject:
Brass Ensemble Subject description: "Thinking out of the box" low-budget brass synthesis |
|
|
Here's a quite cheap but effective approach to brass synthesis. Like waveguide-based physical modelling, it is based on an driver-resonator concept, but works entirely with "classic analog" synthesis components. It should be possible to patch this on any real-analog modular synth which has the required modules.
A lowpass filter in self-oscillation acts as a resonator and sound source. Just as it is, it only produces a sine wave when excitated. But if we remove the DC component of its output with a highpass filter and feed the result back into its linear FM input, it starts to produce even harmonics. What actually happens is that the filter phase-modulates itself, as removing the DC component from the FM signal turns it into phase modulation.
This filter is then driven (excitated) by a simple sine oscillator tuned to the same frequency and volume-contoured by a keyboard-gated envelope. The neat thing about this is that it is a cheap dynamic feedback system. So, depending on resonance and linear FM (now PM) input settings of the resonating filter, raising the amplitude of the driving oscillator makes the filter produce brass-like waveforms of increasing brightness. Pushed even further, it starts to break into quite "acoustic" sounding semi-chaotic animations. The trick is now to contour the driver input level in such way that the attack/decay stage is in the more chaotic range and then settles down into a more stable sustain oscillation stage, thus mimicing the typical flatulent (sorry ) brass attack which locks into stability. Tweaking the DC-blocking highpass filter frequency additionally influences frequency content and response of the oscillation.
One word of caution though: It's a dynamic system, and therefore is capable of "locking up" into screeching high-frequency loops which are quite painful to the ears. It only snaps out of them by greatly reducing resonance. Hence, resonance isn't controlled by the reso knob but by the resonance modulation input to which a a max-sustain envelope is fed. So, if the sound locks up, just release the key and the filter snaps out of its resonance and misery. (It wouldn't otherwise.)
I could have added more bells&whistles, eg. adding a scaling to the linFM input do facilitate fine tuning since the linFM input knob has such a wide range, etc.. However, the whole thing was primarily a personal exercise at patch economy. Hence, it's below the 16.6% benchmark both in memory and cycles usage, fitting 6 voices on a DSP and thus giving full 32-voice polyphony on expanded G2s.
4 variations populated, demonstrating how different settings of resonance, linear FM and driver levels determine the overall flavor, from mellow frenchhorns to biting trumpets. The variations all respond well to dynamic keyboard playing. Actually they sound pretty boring without it. I've used a modified version of this patch with a Yamaha breath controller for even better results.
cheers,
tim
Description: |
"Thinking out of the box" low-budget brass synthesis |
|
Download |
Filename: |
BrassEnsemble TK.pch2 |
Filesize: |
1.9 KB |
Downloaded: |
2359 Time(s) |
|
|
blue hell
Site Admin
Joined: Apr 03, 2004 Posts: 24079 Location: The Netherlands, Enschede
Audio files: 278
G2 patch files: 320
|
Posted: Sun Nov 04, 2007 4:49 pm Post subject:
Re: Brass Ensemble Subject description: "Thinking out of the box" low-budget brass synthesis |
|
|
tim wrote: | thus mimicing the typical flatulent (sorry ) brass attack which locks into stability. |
Works pretty good
Nice trick with filters. _________________ Jan
also .. could someone please turn down the thermostat a bit.
|
|
Chet
Joined: Nov 19, 2004 Posts: 231 Location: Lititz,PA,USA
Audio files: 7
G2 patch files: 35
|
Posted: Thu Nov 08, 2007 10:22 am Post subject:
|
|
|
This is a really neat and clever idea, Tim, and it sounds great! Thanks for posting it! |
|