w e i v Re Applied Acoustic Systems’ Chromaphone by Jeffrey Powell
Applied Acoustic Systems is one of the champions of physical modeling in the virtual instrument world. Many know about their modeling instruments like Tassman 4, Ultra Analog, String Studio, and a host of instruments for Ableton Live. Outside of their sound bank series, things have been quiet for a while at AAS. But right at the end of 2011, AAS surprised many as they introduced “a synthesizer dedicated to the creation of acoustic instruments” called Chromaphone. Let’s take a look at Chromaphone and see if AAS’s newest instrument really delivers.
sound of a single basic resonator that has been “excited” in some way requires high-powered mathematics to even approach the correct sound that we hear in real life. To complicate matters further, many instruments involve multiple resonators which interact with each other and behave differently than they would in isolation. A classic example of this is an acoustic guitar which has strings and a body which both act as resonators that interact with each other. Needless to say, when the resonators interact, the difficulty of the mathematical modeling required increases.
resonators, you have a quality control (for adjusting the number of modes used), a decay control (which gives the decay time of the partials), a release control (used to simulate dampers on the sound), a material control (used to adjust the decay time of certain partials and is only for certain resonators), and then usually one or two resonator specific controls. For many of these, you can use key tracking, velocity, or even an LFO to modulate them.
As noted above, you can select either one or two resonators. If you choose just one, then you’ll get the response The Concept Despite the computational hurdles, you would get with this resonator in AAS has designed Chromaphone to isolation. If you choose two When playing a physical acoustic model these complex processes resonators, then Chromaphone allows instrument, there are generally two involving resonators in an attempt to you two different options. You can things involved. First of all, you need bring acoustic instruments to your have them behave in parallel and a something that will resonate (i.e. DAW. slider on the GUI simply controls the naturally oscillate at certain mix of the two sounds. Alternately, frequencies with certain amplitudes). The Resonator Module you can choose to couple them, which Examples include the stretched skin of means that energy is transferred a drum head, a string, or the body of Chromaphone consists of three main between the resonators after a wind instrument. Note that every modules that represent the resonators Resonator A is excited. The slider on acoustic instrument has resonators of and the items that cause them to the GUI then acts as a knob which some sort. In order to get them to resonate. The most important module sets how easily each resonator can be resonate, of course, you must do is the Resonator Module. This gives set into motion relative to the other something to them like strike them you a choice of two different resonator. with a stick, pluck them with your resonators which will be used to finger, or blow air into them. produce the sound. The choices for As noted in the well-written manual, resonators are: a string, a beam, a this coupling of resonators allows you In the real world the behavior of marimba beam, a rectangular plate, to make new resonators that contain a resonators and their sound is really an acoustic membrane, an open tube, mixture of the characteristics of the quite complex as there are a number a closed tube, and a manual resonator two original resonators. of factors that interact to produce the (which allows you to adjust the sound you hear. So, modeling the frequency of partials). For most 36
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February 2012