Whether you're a head-banging guitar player in search of the ultimate stompbox or a big-name producer whose studio boasts a dozen screamin' computers,

Whether you're a head-banging guitar player in search of the ultimate stompbox or a big-name producer whose studio boasts a dozen screamin' computers, you know that having great effects is crucial to any recording. And no matter how packed your hardware or software toy chest may be with effects, chances are that there are times when none of them will do the job. Maybe the distortion isn't thick enough or the chorus isn't wide enough. Or maybe you have a great idea for an effect that no manufacturer has ever come close to building.

For anyone who has faced such a dilemma, db audioware's quantum-fx may be the ideal solution. This Windows program allows you to design and build your own effects using basic DSP building blocks such as filters, delays, and LFOs. (A Mac version should be available by the time you read this.) You can also modify the healthy library of factory-supplied effects in just about any way you can imagine. After creating the effect algorithm, you can build an attractive control panel for it with graphic knobs, buttons, sliders, and meters. Your new effects can then be used as real-time plug-ins in any VST- or DirectX-compatible audio program.

Granted, a little knowledge of basic DSP programming techniques will be helpful. When inserting an LFO, for instance, you need to think about signal routing and the maximum and minimum levels you want the LFO waveform to have. In the quantum-fx user manual, db audioware is careful to warn that when creating new effects, monitoring at a low level is important. Unexpected resonant peaks and feedback loops can toast your speakers or even your eardrums.

That said, quantum-fx makes the process of designing effects as easy as it can be. The program's graphic interface is clean and efficient, and numerous building blocks are supplied to get you started. Anyone who has used a graphical audio programming environment such as Max/MSP or Native Instruments Reaktor will be banging out new effects within a few minutes after installation.


Quantum-fx consists of two components: Plug-in and Workbench. Plug-in is visible to your VST or DX host program and can load any effect it finds in the QFX folder on your hard drive. Workbench is the programming environment in which you design and modify effects.

Workbench is equipped for audio input and output through ASIO and DirectX, which is more than handy when you're designing effects. There's no need to compile the effect to hear it: the effect in Workbench is live at all times. For those who lack a low-latency sound card, quantum-fx will load and play an audio loop instead.

The quantum-fx Plug-in window is simple and effective (see Fig. 1). It has a Bypass button, an Open button for accessing effects, a “?” button that opens up a help text box, and a Presets button for loading presets that were created in Workbench. (You can save additional presets through your host software's save-effect implementation.) Anything else — wet/dry knobs, input and output meters, and so on — is the responsibility of the effects designer.

In the VST version, effects parameters can be automated in the usual way. What's more, LFOs and delay times can be synced to the host's tempo. (Because the algorithms are programmable, you can use the host tempo for other purposes as well, such as forcing a filter cutoff to rise as the tempo increases.)

The Plug-in window is not resizeable in the host application, so after designing the panel layout for your effect it's important to size the panel correctly before saving the file. DirectX effects will always have the same window size, so Workbench lets you specify the largest window dimensions that any of your DX effects will need.

According to the quantum-fx manual, it's supposed to be possible to edit effects algorithms in Workbench without quitting your host application. Cubase is specifically mentioned as the host (see Fig. 2). On my system, Workbench would run concurrently with Cubase SX 2.0 but was unable to share the audio I/O ports with Cubase, which brings an element of guesswork to the editing process.

The factory-supplied effects are varied and useful: even if you never want to design your own effects, you'll find quantum-fx a handy program to have in your system. Audio resolutions up to 24-bit, 192 kHz are supported, and the internal signal path is always at least 32-bit.


Quantum-fx Workbench contains a Library list on the left side of the screen that shows the available modules (see Fig. 3) and a main graphic work area in which effects can be patched together. Objects are dragged and dropped from the Library into the patching area. Modules are connected with graphic patch cords using the mouse — a standard interface, but well implemented with a bit of color coding and automatic cleanup of tangled cord routings.

Pop-up help text is provided for most of the basic modules in the Library, which is good since they aren't described in the documentation. The title bar of the main window gives a figure for CPU usage in percent. Half-a-dozen items, including the control panel that will be displayed when the plug-in is used, can be toggled on or off in the View menu; overall, though, Workbench 1.0 is not exactly a feature-rich environment. Cut, copy, and paste of modules is not yet implemented, for instance, which will slow up the work process if you're building a complex effect.

The simplest modules, such as the phase inverter and the mono-in, stereo-out converter, have only inputs and outputs. Most modules, however, display one or more parameters. These have editable numeric values that can be changed by clicking and dragging up or down with the mouse. All parameters also have control inputs, with which they can be changed dynamically while the plug-in is running.

Double-clicking on a parameter opens its Properties box. (Oddly, you're allowed to right-click on the parameter and select Properties in the Context menu, but when you do this, nothing happens.) In this box you can edit the default value of the parameter, set the upper and lower boundaries of its allowed range, and click a checkbox that will cause it to be shown in the panel. You can also select linear, logarithmic, or inverse logarithmic response to the panel control and give the panel object a name. Parameters that will be shown in the panel are displayed in Workbench with a light-green background. You can also set the amount of smoothing that will be applied to panel controls.

New in version 1.06, which arrived just as I was finishing this review, is the Enable Chaos (randomization) checkbox for each parameter. There's also a chaos module that will work on all parameters for which chaos is enabled. The amount of randomization is just another parameter, so it can be preset or controlled from the effect panel.

An extra mouse-click (or a tap of the Escape key) is required to close the Properties box. Pressing the Return key is equivalent to clicking on the Save Changes button, but that doesn't close the box in the expected way. There's a reason for this design: the Properties box can be left open, and it will update to reflect new parameters as you click on them. That makes it easy to fiddle with the ranges of various parameters so that they work well together.

Individual audio modules can be bypassed while editing — a highly desirable feature, as it lets you isolate one part of a complex effect while building or troubleshooting it.


The Basic Modules folder has subfolders labeled Signal Routing, Switches, Volume, EQ, Filters, Mixers, Delays, Dynamics, Fancy Stuff, Generators, Controllers, and Graphical Modules (see Web Clip 1 for an example that uses some of these modules). Some folders contain only a few items, others a couple of dozen. In the Filters folder, for instance, there are ten items each in the Mono and Stereo subfolders, plus four items in the Crossovers folder. The EQ folder, by contrast, contains two subfolders (Mono and Stereo) with only three items each: low shelf, high shelf, and parametric.

In version 1.06, three step sequencers have been added to the Generators folder. While not complex, they're cool for setting up rhythmic filtering effects, as illustrated in the factory beatslicer effect. The sequencers sync to the host sequencer's tempo, and even better, to its downbeat. Also new in 1.06 are single modules containing allpass and comb-filter banks, making it easier (and more DSP-efficient) to create reverbs.

One item I'd like to see added to the Generators folder would be a multisegment envelope generator with an adjustable trigger threshold. Such a module would be useful for building more complex rhythmic effects. Quantum-fx has an envelope follower, but there's no way to trigger free-running processes from transient peaks.

All of the modules are useful, but one of the key elements for creating complex effects is likely to be the crossover, with which various frequency bands can be isolated for different types of processing. Quantum-fx provides two crossovers (both of them in mono and stereo versions) — a two-way linear-phase crossover with variable rolloff slope and a three-way “vintage” crossover with a fixed 6 dB-per-octave slope. The former module is more surgical but also more DSP-intensive.

You can build your own macro modules out of smaller components and include them in any effect that you're building. This essential feature will greatly speed up your workflow if you're developing a significant number of complex effects. Your new macros will show up in the Library browser pane, where they can be dragged and dropped into the effect-editing window just the way the factory modules and macros can be. Double-clicking on a macro opens its edit window for further tweaking.

Parameters that are highlighted on the individual modules within a macro's edit window (by selecting “Show in plugin” in the Properties box for the parameter) are made available as editable parameters in the higher-level module. That eliminates the need for control input and output modules, which are required in macros in Reaktor and other modular software.


It is fairly easy and very instructive to modify some of the simpler plug-ins in the QFX factory set. When I loaded the overdrive-doubler effect, for instance, I noticed that turning its Width knob produced a momentary chorusing effect that was quite pleasing. The Width knob controls the number of milliseconds of delay applied to the right output. In the factory algorithm, this is a static delay amount (although you could always modulate the knob from the plug-in's host application). I added an LFO to change the amount of delay dynamically and an Animation knob to control the depth and (very slightly) the rate of the LFO.

The overdrive doubler adds distortion only to the midrange frequencies of the signal. I added a separate distortion process to the lows. I also noticed that background noise was bleeding through to the output with certain parameter settings, so I added a stereo-expander section just before the output to lower the level of quiet signals. I haven't had the courage yet to try modifying the QFX reverb, but it was instructive to open the reverb in Workbench and examine how the allpass and comb filters are patched together.

You can share your new effects with other QFX owners. Effects can be saved in “public” or “private” format, and if you choose private, other QFX owners will be able to use your effects but won't be allowed to open and edit them. That will give you some protection for your intellectual property in the event you're developing an algorithm that you hope to market commercially. Doing so will require a different development environment, however, as QFX plug-ins can't be exported in a free-standing form that can be used by non-QFX owners.

While working with version 1.04 of quantum-fx Workbench, I ran into a few bugs — none of which were serious. All of these were fixed in 1.06. Version 1.04 crashed only once while I was testing it, probably because I was banging on it by entering impossible values for parameters (such as -2000 for delay time). The flanger-delay effect in version 1.06 has a bug that renders one of its sliders unusable, but thanks to the programmability of the program, you can fix this particular bug pretty easily.


Even if quantum-fx didn't allow you to create your own effects, it would be a reasonable purchase as a collection of plug-in effects for DAWs. The real power of the program, though, is that it allows you to modify the factory effects and create entirely new ones. While the process of creating your own effects is not entirely painless, quantum-fx makes it pretty darn easy.

A couple of other programs also let you create new effects plug-ins, but they're a good deal more expensive (and have numerous uses other than creating effects), so it's great that db audioware has created an all-effects application. Although there is room for some refinements in the next version, there is no need to wait to buy the program: producers and sound designers will likely find quantum-fx 1.06 a great addition to their effects plug-in lineup.

When he isn't playing the cello, Jim Aikinwrites about music technology and composes avant-pop synth music in his PC-based home studio. His latest book is Power Tools for Synthesizer Programming (Backbeat Books, 2004).

Minimum System Requirements

quantum-fx 1.06

Pentium III/800 MHz; 256 MB RAM; Windows 98/2000/XP


db audioware

modular effects software



PROS: Compatible with VST and DirectX hosts. Good suite of factory plug-ins supplied. Numerous useful modules, including filters and step sequencers. A great way to learn about effects design.

CONS: There is no cut, copy, or paste in Workbench.


db audioware limited
email: info@db-audioware.com
Web: www.quantum-fx.com