Review – Chromaphone 2 from AAS


Chromaphone is regarded by many as AAS’s jewel in the crown.  Now with version two, there are even more facets in that jewel to dazzle us.


by David Baer, May 2016


This is a review of the Chromaphone 2 instrument from Applied Acoustic Systems (or, more commonly, AAS).  I will be assuming the reader has no experience with the first version.  But before any Chromaphone veterans run off, let me point you to a previous article I wrote about how Chromaphone works its unusual magic in producing sounds in an earlier SoundBytes article.  That can be found here:

In it, we explore how sounds are programmed by deconstructing several of the factory presets.  Although it was written using the earlier Chromaphone version, it’s still 100% relevant.

Here’s one more interesting note for longtime AAS followers.  The story goes that one reason for there being a Chromaphone 2 was so that AAS could convert Chromaphone to their new architecture, something they’ve gradually been doing to most of their other existing instruments.  “But wait”, you say … “wasn’t Chromaphone (1) the first instrument to be mounted on that new platform?”  It turns out that it was, but that “new platform” got some improvements subsequent to the completion of the first Chromaphone.  It being the first software to be taken in the new direction, things were learned along the way.  The new architecture got improved to the point that AAS wanted to make Chromaphone fully compliant with the most advanced version.  Now, back to basics …


Getting Started

Chromaphone 2 (hereafter we’ll drop the “2”) creates sound through mathematical modelling, meaning a lot a hairy calculations are undertaken to produce the data that comprise the output audio waveforms.  Synthesis via modelling is that for which AAS is renowned.  In this case, what is modelled is some configuration of objects that include one or two resonators, a mallet to excite one or both and a noise source to likewise excite one or both.

OK, that’s a bit abstract.  Think of one such configuration: a drum stick (that’s a kind of mallet) hits a stretched circular membrane and creates a “whack” sound.  Even with such a simple scenario, there are a lot of things that can cause the result to sound a certain way.  How hard is the head of the drum stick – is it a small wood head or a fabric-tipped softer type of drum stick?  How tightly stretched is the membrane? 

But the membrane is probably not floating free in space, but rather is stretched over a circular drum body.  Now we have two resonators.  In this case the membrane responds to the mallet and the drum body responds to the excited membrane.  The energy may flow two ways: first from the membrane into the body, exciting the body, and then flowing back from the excited body to further influence the resonance of the membrane.

Now you’re hopefully starting to see what Chromaphone is all about (and don’t worry, we’ll get back to the noise exciter component before this is all over).  But it’s not just about creating un-tuned percussive sounds.  As you’ll see, Chromaphone can create all manner of tuned musical sounds that both mimic real-life instruments and create sounds from imaginary ones.  The breadth of types of sounds is really quite remarkable, as is ably proven by the factory presets.


Sound Production Components


At the top of this article, we see one of Chromaphone’s three UI views, the Play View.  Immediately above, we see the Edit View, in which most of the serious work of sound design is done.

Let’s talk about the resonators first.  We have the following types (this mostly verbatim from the user manual):

  • String: a perfectly elastic string,
  • Beam: a rectangular beam with constant cross-section,
  • Marimba: a beam with variable section allowing one to obtain partials having a quasi-harmonic ratio,
  • Plate: a rectangular plate,
  • Drumhead: circular membrane (this one is new to Chromaphone 2),
  • Membrane: rectangular membrane,
  • Open Tube: a cylindrical tube with both ends open allowing one to obtain the complete harmonic series (even and odd harmonics),
  • Closed Tube: a cylindrical tube with one end closed allowing one to obtain only odd harmonics,
  • Manual: In this mode, one can create a custom resonator by selecting up to four partials; the rank of each partial is fixed using the Partial 1 to Partial 4


A preset can use just one of these resonators or two.  When using two, they can be fully independent, fully coupled (the first resonator being the exciter of the second), or something in between. 

Depending upon which resonator type is selected, certain parameters can be set that include things like Material, the setting for which influences how fast partials decay in relation to one another.  This is at the heart of Chromaphone sound designing and I’m certainly not going to attempt to explain it all.  I’ll leave that to the excellent user manual, which is of the high quality we’ve come to expect from AAS in documentation.  I’ll also suggest once again that the truly curious may wish to check the aforementioned SoundBytes tutorial to learn more on this topic.

The resonator coupling is controlled by a Balance control and the Coupled switch.  When Coupled is not enabled, the two resonators (assuming both are active) just do their thing and the Balance dictates their relative loudness.  When Coupled is on, Balance dictates how easy it is for one resonator to set the other in motion.

If you are finding all of this this a bit baffling (if not downright intimidating), you are certainly not alone.  Little of this is intuitive stuff.  But a little time spent examining the presets will reward you with a lot of insight.  Some experimentation will take you even further.  That said, the one thing I would really like to see added to Chromaphone is a Random button to instantly throw serendipitous variations together.  I truly believe this would be a fascinating way to create some fabulous sounds by building combinations that one would never think of trying.



As stated earlier, there are two mechanisms that introduce energy into the resonators: the mallet and the noise generator.  They can be used singly or concurrently.  Some portion of either can be routed directly to the output mix.  The mixer controls can be seen to the right.  The two controls labelled Direct govern the output level that goes directly to the output mix.





The mallet parameters are simple: Stiffness, Noise and Color.  Stiffness is self-explanatory.  Noise is not to be confused with the Noise exciter; it is just a noise component of the mallet strike.  Color influences the frequency content of the mallet noise.

This is a good time to mention modulation.  In the image to the right, the preset has the Stiffness lightly modulated by key position and semi-lightly modulated by velocity.  Modulation is set by clicking and dragging on the little colored dot.  Rings of corresponding color appear around the control.  This scheme is consistent throughout Chromaphone; it’s simple, elegant and effective.




The Noise exciter is simple on the surface but actually a bit deeper than the Mallet exciter.  With it, we can have a sustained exciter influence that can be modulated by an envelope and/or an LFO.  There’s a filter which can be one of a variety of pass types.  In the image to the right, an LP filter has been selected.  The Frequency control does what you’d expect and the middle control dictates the Q of the resonance.  For other filter types this control will vary.  For example, for an HP/LP pair, the middle control will be width (i.e., the distance between HP and LP cutoff frequencies).

Density is also what you’d expect.  Think of impulses arriving at a rate defined by density.  The output is something like a Geiger counter: a few occasional randomly timed impulse clicks when the level is low  to full-on continuous noise for a nuclear reactor core.

It’s worth pointing out that Noise is used in unexpected ways in many of the factory presets.  In some cases, it achieves a bowed quality and in others it becomes like a stream of air exciting pipes to produce an organ-like sound.

There is just one envelope and one LFO in Chromaphone, which for veteran sound designers may sound inadequate, although the vibrato module does have an internal dedicated LFO.  For everything else, it’s rare that one envelope and one LFO cannot get the job done, given the types of sounds Chromaphone excels at creating.


Effects and More


We’ll just touch briefly on FX in this review.  They are quite serviceable and entirely adequate for the job at hand.  The FX View is seen above.  There is an EQ and a compressor always available as well as a reverb module at the end of the FX chain.  The two modules with the little white inverted triangle can each be set to one of a list of FX module types: delay, distortion, chorus, flanger, phaser, wah-wah, auto-wah and a notch filter.  I’m not going to spend time on these.  They are all fine and just what you’d expect.  Download and dip into the user manual if you need to find out more prior to purchase.

Another thing I haven’t mentioned is the arpeggiator, new to version 2.  It is supplemented by a rhythm-pattern engine to give a groove to the arpeggiation.  This is seen in the Play View, the UI of which appears at the top of this article.  If you are an arpeggiator curmudgeon like me and normally avoid using them, let down your defenses and give a few of the factory arp presets an audition.  I’d be willing to bet several will bring a smile to your face.  There’s just something about Chromaphone that arpeggiation enhances in novel ways.

Finally, in the Play View, you can also see modules for controlling Vibrato, Unison (two or four voices) and Clock for specifying “host tempo” when running standalone.


The Sounds

If the proof of the pudding is in the eating, the proof of the instrument is definitely in the listening – and Chromaphone proves itself to be nothing less than brilliant.  Even though many users may be intimidated by the notion of doing sound design for this unusual form of synthesis, the 600 factory presets, supplemented by a superb bonus sound set of 128 presets give you more than enough to keep one happily creating music.

As stated earlier, Chromaphone naturally excels at creating percussive-type sounds.  What else would you expect when the primary exciter is a mallet?  But if we want to get technical, it must be acknowledged that instruments like the piano and the xylophone are also percussive instruments, ones that happen to produce precisely-pitched sounds.  So it will come as no surprise that Chromaphone also has presets for a brilliant glockenspiel, and enchanting celeste and oh-so-cool vibraphone and many more mallet-struck real-world instruments.

But there’s so very much more.  Presets are organized into categories.  The browser is nothing fancy, but the organization is straightforward and it’s very easy to find what you might be looking for.  On the right you will see the categories of the factory content.  There are 600 or so presets that range from strikingly realistic simulations of real-world instruments to wondrous flights of fancy.

For existing owners, any version 1 preset content can seamlessly be migrated simply by moving some files into the new preset area on your hard drive.


Is Chromaphone for You?

I cannot envision any owner of version one wanting to pass on the upgrade for a mere $39 (assuming the initial $29 upgrade price is no longer in effect by the time you read this).  It’s worth that money just to acquire the marvelous 128-preset add-on library called Synbiosis which is part of the deal.  The full version is priced at $199.  But AAS does routinely have sales with very good discounts.  You know the drill: get on their mailing list or be a regular lurker on any music forum that carries news about current bargains.

Chromaphone can be installed as 32-bit or 64-bit VST, RTAS, and AAX Native plug-ins for Windows and AU, VST, RTAS, and AAX Native plug-ins for Mac OS X.  It also can be run as a standalone application.  Authorization is painless and permits use on two computers concurrently.

What’s not to like?  Highly recommended!


For more information, to check out a very nice demo video, or to purchase Chromaphone, go here:

The software is also available from a variety of independent music software dealers.



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