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TC Electronic FireworX

Signal Processor By Hugh Robjohns
Published June 1998

TC Electronic FireworX

In a world brimming over with multi‑effects units, will TC Electronic's new FireworX cause sparks to fly amongst the competition? Hugh Robjohns lights the blue touch‑paper...

There are probably more effects units on the market today than almost any other type of musical equipment (with the exception of guitar amplifiers perhaps), and with so much competition the leading manufacturers are always looking for that certain something which gives their product the edge over everyone else's. An increasingly popular approach in recent years has been to provide the means to chain multiple effects together, and as affordable digital signal processing has grown ever more powerful, so multi‑effects units have become far more capable. However, sheer processing power is not enough on its own — you need a well thought out user interface to be able to control and make creative use of it.

The FireworX is the latest in an impressive line of signal processors from Danish company, TC Electronic. It offers around 40 different high quality, innovative, and extremely configurable effects algorithms, and the typically intuitive TC user interface. Not only does the FireworX allow enormous flexibility in how the different effects programs can be combined, but it also provides an extraordinary degree of real‑time control opportunities as well, across literally dozens of different effect algorithm parameters. Building that level of functionality into a 1U rackmount box is impressive enough, but to do so whilst retaining a manageable user interface makes the FireworX worthy of further investigation.


TC Electronic FireworX

The FireworX is housed in a standard 1U rackmount box, finished in the traditionally innocuous studio black. The rear panel is quite busy, starting with an IEC mains inlet and power switch on the left, followed by two pairs of XLRs providing balanced stereo analogue inputs and outputs (both software configurable for nominal +4dBu or ‑10dBV signal levels). Digital interfacing is extremely comprehensive too with AES‑EBU and S/PDIF stereo I/Os plus ADAT and/or Toslink optical input and outputs. It makes sense to offer the ADAT interface since it uses the standard Toslink connectors anyway, and TC have provided set‑up menus allowing any two channels to be used within the eight‑channel ADAT format.

Although not fitted on the review model, an optional word clock input (standard TTL signal on a BNC connector) can be installed to allow external synchronisation in the digital domain. The rear panel of the device is rounded off with the usual trio of MIDI connectors and a quarter‑inch jack socket is provided for external hardware controllers, such as a pedal or footswitch (software menus configure the required functionality).

Internally, the FireworX is beautifully engineered, as we have come to expect from these Danish masters. An elegant switched‑mode power supply is carefully screened off to one side of the case, while a large and heavily populated motherboard fills most of the remaining floor area. Surface‑mount components proliferate and a socket on the motherboard accepts PCMCIA memory cards inserted through a slot in the front panel. The analogue I/Os feature delta‑sigma 1‑bit, 128 times oversampling AKM converters, which provide a claimed 24‑bit resolution and an overall dynamic range of around 100dB.


TC Electronic FireworX

The front panel of the machine is clean and tidy to look at, with clearly marked controls and buttons (most with internal LEDs). To the extreme left is a power standby button (the mains isolating switch is on the rear panel), accompanied by input and output level trim controls for the analogue I/Os (from ‑22 to +10dBu). A backlit LCD panel is edged with LED bargraphs — the two on the left showing left and right input level from ‑24 to 0dBFS. The column of LEDs to the right of the display window indicates the amount of gain reduction (up to ‑20dB) being applied when a dynamics effect 'module' is in use. Three status indicators show MIDI activity, digital lock (to an external reference signal), and when a preset program patch has been edited.

The main control functions start with a column of three large black pushbuttons which provide a complete signal bypass through the machine, set the tempo (by tapping) for a given effect's modulation, and allow algorithm control parameters to be allocated to the 'alpha‑mod' control knob at the extreme right‑hand end of the unit (more on this in a moment). A central bank of 12 grey buttons are used to indicate which effects algorithms are in use in the current configuration, as well as allowing them to be individually bypassed and edited. A block of six more black buttons provides access to the preset memory functions, insert effects algorithms in the processing chain, control the 11 internal and nine external effects modifiers (for parameter modulation), configure the audio I/Os, and access the various utility functions.

The last right‑hand quarter of the front panel contains just three encoder knobs (without end‑stops), four more grey buttons, and a horizontal bargraph of LEDs. The first knob is identified as the Parameter wheel and is used to navigate the menu displays in conjunction with the left/right arrow and Enter/Exit buttons immediately above it. The second knob alters the value of a selected parameter and the last control is the previously mentioned 'alpha mod'.

The alpha mod wheel provides instant real‑time control over the key parameter(s) of the effects processing and the bargraph meter above the knob indicates its current value. The alpha mod controller (or 'modifier' as TC Electronic prefer to call it) can be allocated to change an enormous variety of elements within the signal processing algorithms — and can operate several different aspects of one or more programs at the same time. When using the standard factory presets, the alpha mod function is generally predefined to be the most useful or most often used parameter(s), allowing very fast customisation and tuning of the preset effect. However, the precise function of the control can be reconfigured by the user for any purpose through the 'modifier' menu pages.

Building FX Blocks

The basic signal processing structure of the FireworX is very straightforward. The input signal can be selected from either the 24‑bit converted analogue input, 24‑bit AES‑EBU, 20‑bit S/PDIF or Toslink, or any pair of channels from the 16‑bit ADAT interface. The relevant signal is routed through the 'digital engine' for effects processing before being re‑dithered at a user selected resolution between 8 and 22 bits, or off, as required. The processed signal is then presented on all outputs simultaneously.

The only caveat to my last statement is that since the Toslink and ADAT interfaces share the same physical ports, the user must select the desired operating mode. In the case of the ADAT mode, the processed output can be dispatched to any two desired channels — not necessarily in adjacent pairs either.

TC Electronic have produced a superb‑sounding and extraordinarily capable machine in the FireworX.

As with some other TC Electronic processors, if the main programme inputs and outputs are analogue, the digital I/Os can be reallocated as an insert point (or vice‑versa), allowing an external processor to be incorporated into the signal path. The insert send and return points can be freely allocated within the FireworX processing chain.

In terms of the FireworX's signal processing algorithms, there are 12 basic effect processes (or 'blocks' as TC call them), many of which also have additional sub‑categories of effects. To build up an effects chain, these blocks are allocated to a position (or positions) within a virtual routing matrix and interconnected in series or parallel according to which positions they occupy. Placing processors in the same row of the grid means the signal flows from one to the other serially. Processes placed in the same column mean that the input signal is processed by them at the same time but independently, ie. in parallel.

The grid allows enormously complex effects patches to be constructed, since it may be any size up to eight rows by eight columns, although this would be rather extreme! Fortunately, rows and columns can be added or deleted as desired such that the matrix is actually very manageable.

The FireworX allocates its DSP resources dynamically so that additional effects processors can continue to be added until the total DSP resource of the machine has been exhausted — there are no rules about which blocks can be used in combination and the machine gives warnings about the remaining DSP resources as you progress.

As already mentioned, there are 12 basic effects blocks and many of these provide sub‑categories. The full listing is given in the sidebox (see 'Effects Blocks'). Most of these signal blocks may only be used once in any one patch. However, some may be used simultaneously in different positions within the matrix. For example, the dynamics block may be used up to three times in a single patch and each of the chorus, delay, pan, and synth modules twice.

In addition to the fundamental effects blocks mentioned above, there are also a number of 'house‑keeping' blocks, such as the insert send and receive modules which determine the send and return points for external signal processing. There are also feedback send and return modules which allow the signal from one part of the processing chain to be returned to a different part. There is also a 'pipeline' module which simply passes the signal straight through a matrix position and allows multiple processing paths to contain different numbers of processing elements.

Processor Power

The Dynamics processing block is available in three sub‑flavours (all stereo in/out) and requires around 12% of the DSP power. The options are Expander/Gate, Compressor, and Compressor/Limiter, and each one features all the expected controls. The amount of gain reduction applied by the processing is shown on the bargraph meter on the front panel, and if more than one dynamics function is employed at a time, the user can select which one drives the meter display.

The various Filter and EQ options require around 25% of the DSP's power. Filters are available in no less than five forms: Resonance, Bandpass (both stereo in/out functions), Phaser, Resonator and Resochord (mono in/stereo out); and the two EQ sub‑algorithms offer either fixed or controllable parametric sections. This is where things really start to get complicated by the wealth of options and parameters available, particularly since many of them can be controlled by internal or external operators, such as the internal low frequency oscillators (LFOs) or external footpedals. For example, the sweep rate of the Phaser can be set as multiple bars or subdivisions of a tempo tapped in on the front panel button (ie. 1/16ths etc), and the centre of the bandpass filter could be controlled from a pedal.

The Resonator and Resochord algorithm names probably don't mean much but the programs are actually based around rather elaborate flangers, incorporating four separate delays and feedback paths to create very complex resonant peaks and comb filtering effects. The Resochord version has been configured so that these resonances are tuned and scaled according to musical chords, and there are comprehensive options allowing the user to determine the key and the type of chord (major, minor, 6ths and 7ths etc).

If the complexities and sophistication of the Resonator and Resochord effects are too much, there is also a simpler Chorus/Flanger program module. This provides all the classic sounds and still offers a very wide range of controllability and flexibility.

Distortion effects are available in two forms — a fairly conventional but extremely flexible analogue tube‑style effect (called Drive), plus a system which deliberately introduces horrible digital distortions in the form of aliasing and quantising errors (Cruncher). Both versions have comprehensive sets of parameters to allow fine‑tuning to suit almost any circumstance. I'm not sure about the practical applications for the Cruncher algorithm, but it could help you to recognise the characteristic sound signatures of faulty digital equipment!

Next up are two unusual, but powerful and creative processing blocks: the Formant generator, which requires about 22% of the processing power and creates pseudo‑human vowel type sounds; and the Vocoder, which needs a massive 55% or so of the DSP's attention. The Vocoder can also be used to create Ring Modulator effects with external or internally generated carrier signals. As might be expected, these effects can be controlled and modulated in a variety of ways to make extraordinarily expressive noises and/or weird effects.

Useful as an internal signal source for the Vocoder and Ring Modulator, the Synth processor generates tones and musical notes (controllable over MIDI, of course) in sine, triangle, square and sawtooth shapes, plus various flavours of noise and a 'chaos' generator.

The FireworX also offers pitch‑shifting algorithms; mono, stereo, reverse and multi‑tap delays; elaborate reverberation programs (with the choice of all‑encompassing or simplified set‑up parameters); automated panners (including a version which provides pseudo‑surround sound effects); tremolo effects; and a simple stereo width enhancer. If there are any effect processes TC Electronic have left off this machine, I can't think of them — and I can't recall a more comprehensive effects unit on the market either.

An Easy Life?

For many, one of the strengths of the FireworX is going to be its enormous breadth of customisation options and the ability to fine‑tune every element of every program algorithm. However, for many users, all these effects, parameters, control options and matrix patching is simply too much like hard work and would just get in the way of making music. Fortunately, there is no real requirement to have 'a brain the size of a planet' as the FireworX comes with 199 factory preset effects chains, all available at the touch of a button or two.

In fact, between them the factory presets did pretty much everything I could have wanted, plus a whole bunch more besides, and provided excellent starting points on the occasions when I wanted something slightly different. It probably says more about my life than I should admit, but the most fun I have had in weeks was in trying to guess what kind of effect I would find from each preset, as their program names are even more inventive than the algorithms themselves (how's about trying 'Grut Gut', 'Smart Face', and 'Broadcasting Sick'!). Despite these elusive names, the majority of pre‑programmed effects are actually very useful and usable, and the parameter values are well chosen. The alpha mod wheel function for each factory program is also well selected in the majority of cases, providing instant control of some key parameter of the effects chain. Of course, everything can be edited and tweaked to suit any requirements and modified programs stored in the user memories (internally or on external PCMCIA card). An effects machine wouldn't be right without the positively weird and wacky program patches though, and you'll be pleased to learn that the guys at TC have designed a few of the very strangest to amuse and entertain!

Fireworx Display

TC Electronic have always managed to provide pretty intuitive user interfaces on their equipment, and if you are familiar with any of their other processors, driving the FireworX will feel quite familiar. The large LCD provides concise and understandable information in a semi‑graphic form, with clear sub‑menu pages listed across the top of each display and status boxes listing the current settings.

At an 'introductory level', navigating the menus is not too scary at all and a novice operator should have no problem configuring the machine and performing basic effects processing tasks. The detailed adjustment of some of the more intricate processing parameters is perhaps not for the faint‑hearted — many of the algorithms have huge lists of parameters — but the handbook is very helpful, providing plenty of clear information plus handy hints and tips.

Similarly, configuring which 'modifiers' control which parameters can be a daunting task. The internal modifiers include two low frequency oscillators (with a variety of wave shapes and output configurations), two triggerable ADSRs, two envelope followers, a pitch detector, a control value sequencer, and two function modules which combine a pair of control modifier signals in various ways and output the result.

The external modifiers include the alpha mod wheel plus eight others which may be configured from the pedal/footswitch input and a host of MIDI functions — aftertouch, note on/off, pitch‑bend and program change information can all be used as modifiers.

To determine which modifiers affect which parameters, another matrix system is used, although because of the sheer scale of controllers and controllees, it is often rather cluttered and less than perfectly clear. I would not imagine many users fighting their way through this kind of set‑up too often, but it does provide a huge resource of possibilities and creativity for the willing enthusiast.

Performance Quality

From my first audition, the sonic quality of the signal processing within the FireworX is quite stunning. I was extremely impressed with its remarkably quiet and clean backgrounds — in fact, it is almost eerily silent most of the time, even with a fully loaded matrix of effects and analogue interfacing. No doubt the use of 24‑bit resolution in both the converters and the DSP number‑crunching is the key to this performance success.

Although it obviously depends on the selection of effects in use, my overall impression of the FireworX's sound character is of a bright, sparkly, clean and transparent nature, although the machine can also make very usable 'grunge' effects too. Most of the 199 factory presets are surprisingly usable, although the program names are far from obvious in many cases and the description of the alpha mod function is often a complete mystery! This can make finding a suitable program rather tedious for anyone who is not familiar with the machine, but at least the front panel effects selector buttons illuminate to show which blocks are in use within a chosen patch.

Individual effect algorithms are almost impossible to fault, and they all sound extremely good even when used in isolation. All have comprehensive parameters to adjust so that the sound can be precisely tailored in the finest detail and I couldn't detect any degradation of any kind when combining different effects together. In fact, the only slightly weak element I could find was the pitch‑shifting which, like so many other multi‑effects machines, tends to sound glitchy and mechanical with larger shift settings. It is hardly surprising though, since this is such a difficult process to achieve anyway — only a very few specialist machines are capable of truly good results — and within typical uses, FireworX's pitch‑shifting will be perfectly adequate.

Another very hard effect to get right is reverberation, and although reverbs are hardly the raison d'etre of this machine, they actually sound extremely good and realistic. The algorithm also offers extraordinary flexibility for fine‑tuning.

Where I must level a more serious complaint, however, is that there does not appear to be a global setting for the effect wet/dry signal mix. If the FireworX is used as an outboard processor to a mixing desk, it would be usual to control the wet/dry balance at the desk by altering the relative levels of direct signal (channel fader) and wet signal (effects return level). On the other hand, as an in‑line processor for a guitarist or keyboard player, the output would have to carry the direct signal as well as the effects.

Unfortunately, the wet/dry mix seems to change with every recalled factory preset, which can be extremely frustrating when recalling and comparing a number of different presets. Indeed, in some cases, recalling a factory preset doesn't produce any 'wet' signal at all until some modifier is activated (typically the alpha mod wheel)! It is possible, of course, to alter the wet/dry balance as required, but that involves diving into the parameter editing pages for every program preset, and re‑saving the settings. It seems a great shame in an otherwise excellent machine, that there isn't some kind of global override of the dry/wet mixture.

TC Electronic have produced a superb‑sounding and extraordinarily capable machine in the FireworX. I'm not sure how many users would actually make full use of its flexibility and customisation facilities, simply because of the time and complexity involved in setting it all up. Designing and configuring effects patches is made relatively simple thanks to TC's graphical menu pages, but the vast number of parameters, options, and modifiers available make it a time‑consuming process. Having said that, if there is something specific that you want to achieve, the FireworX will certainly allow you to achieve it, and the results will sound crystal clear and noise‑free.

However, if you just want to dive into a particular algorithm's parameter menu page to tweak some element of its operation, that remains very quick and easy to do. Best of all, when effects need to be synchronised with the music, just tapping out a rhythm on the Tempo button instantly sets the perfect sweep rate or delay time. Superb!

Effects Blocks

  • Dynamics (compressor, compressor/limiter, gate/expander)
  • Formant Filters
  • Distortion (analogue and digital effects)
  • Filters (resonance, bandpass, phasor, resonator, and resochord)
  • Vocoder (vocoding and ring modulation)
  • Pitch‑shifter (single and dual shifts)
  • Delay (stereo, dual, multi‑taps, and reverse)
  • EQ (parametrics)
  • Chorus/Flanger
  • Panner (stereo, surround, tremolo, and stereo width enhancer)
  • Synth (sine/square/triangle waveform, noise and random signal generator)


  • Extraordinary flexibility and customisation possibilities.
  • Wide choice of effect processor types.
  • Inumerable parameter modifiers for expressive control.
  • Flexible interfacing.
  • Graphical menu displays.


  • No global dry/wet mixture control.
  • Flexibility can be seen as complexity by some users and could be offputting.


A superbly flexible and highly usable multi‑effects processor that provides a wealth of effects algorithms with extraordinary degrees of controllability. Even long chains of effects remain noise‑free and sparklingly clear, and the host of analogue and digital interface options make connectivity very easy.