By the time Terratec Producer acquired the Axon AX 100 from Blue Chip Music, the formerly cutting-edge guitar-to-MIDI converter needed updating. A new
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FIG. 1: Terratec Producer has updated the Axon AX 100 guitar-to-MIDI converter hardware and developed a software editor for it.

By the time Terratec Producer acquired the Axon AX 100 from Blue Chip Music, the formerly cutting-edge guitar-to-MIDI converter needed updating. A new and improved version featuring numerous cosmetic and functional enhancements was released in 2006. Immediately evident is a redesigned hardware case, and on the front panel, a stereo headphone output with a dedicated level control has replaced the original's monophonic ¼-inch input (see Fig. 1). An internal soundboard has also been added.

Firmware updates accommodate independent tunings for each string, allowing for alternate guitar tunings such as Open G and Drop D, no matter how your guitar is tuned. They also give you the ability to save setup data (including tunings) with each of the 256 presets. Further updates let you specify destinations (the internal soundboard, MIDI Out, or both) and give you the ability to send Program Changes on a MIDI channel separate from the channels that carry note data. Perhaps the most exciting addition, however, is Terratec's fully featured Axon software editor. As a bonus, the Axon AX 100 mkII ships with Steinberg Cubase LE.

Nuts and Bolts

A guitar-to-MIDI converter detects the pitch and dynamics of a guitar performance and uses that information to generate MIDI data. This process requires a guitar that's equipped with a hexaphonic pickup system. Because only a handful of guitars come standard with hexaphonic pickups, aftermarket systems are available from Axon, Roland, RMC Pickups, Graph Tech, and others. Hexaphonic pickups send signals from individual strings to the Axon through a cable with 13-pin connectors. The Axon then translates those signals into a stream of MIDI data for each string. Because hexaphonic systems also send analog audio signals from the magnetic pickups to the Axon, it can simultaneously transmit MIDI and audio signals.

All too often, the process of detecting and converting a guitarist's performance introduces triggering inaccuracies and tracking latency. To combat such problems, according to Terratec, the AX 100 mkII features an early-recognition system that evaluates the initial picking impulses from the string and immediately generates MIDI data defining pitch, dynamics, and note length from those impulses. Terratec claims that this technology makes the AX 100 mkII the fastest and most accurate guitar-to-MIDI converter on the market today.

The AX 100 mkII's internal soundboard offers 500 General MIDI- and XG-compatible sounds, enabling the Axon to function as a true guitar synthesizer. I was unimpressed by the sounds, however; though adequate, they're not much better than a computer's GM-compatible QuickTime sounds. But clearly the Axon's controller and conversion abilities are its real strength.

Ins and Outs

The single-rackspace AX 100 mkII's front panel contains the 13-pin guitar input, the aforementioned headphone output and level knob, a 2 × 16-character LCD, and a Display Contrast knob. The front panel also has a power switch and a complement of buttons for programming the unit.

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FIG. 2: The Axon AX 100 mkII''s rear panel houses all of its audio, MIDI, footswitch, and pedal connections.

The outputs are on the Axon's rear panel (see Fig. 2). It has two unbalanced ¼-inch audio outputs for the internal soundboard and ports for MIDI In, Out, and Thru, as well as jacks for two expression pedals and two footswitches. You can use footswitches to control Hold functions, the internal sequencer, and the arpeggiator. The power connection for the included 12 VAC wall wart is next to those outputs. On the far right is an unbalanced ¼-inch output for routing the guitar's magnetic-pickup signal to a guitar amp or mixer.

I connected my guitar to the AX 100 mkII with a 13-pin cable and then connected the unit's MIDI In and Out to my Mac's audio/MIDI interface, an RME Fireface 800. The Axon communicated flawlessly with Apple Logic Pro 7, but not with the Axon's software editor (which I'll discuss later). When I connected the Axon's MIDI to my Korg Kontrol49 USB keyboard, however, the Axon successfully communicated with the software editor as well as Logic Pro. I dearly wish that the AX 100 mkII had its own USB port, which might eliminate such connectivity issues. Terratec won't comment on future products or updates, but the company is aware that USB is a highly requested feature.

Doing the Splits

One of the Axon's key features is its flexible splitting capability. A String Split lets you divide your guitar's strings into two groups, allowing you to trigger a bass sound with the bottom two strings, for example, and a piano sound with the upper strings. You can place the split between any strings you want. You can also create a Fret Split, which divides the length of your fretboard into two areas. Like String Splits, Fret Splits can be set up anywhere on the fretboard. A Pick Split divides the picking area between the bridge and the highest fret into as many as three sections.

You can combine the three different split types into as many as 12 possible combinations. Each split can have its own instrument assignment, MIDI program, volume, transposition, Pitch Bend quantization, attack time, and even MIDI Control Change (CC) values. Each string can also be transposed separately; unlike the alternate MIDI tuning feature, which allows different transpose values per string, each split's transposition parameter affects all six strings.

Such flexible splitting allows you to create some amazing fretboard setups, in which three picking zones can control various synth parameters using MIDI CC messages, different strings and fret positions can play different presets, and so on. You can transpose or quantize certain instruments without transposing or quantizing others, which allows natural pitch bending.

The AX 100 mkII provides four modes for quantizing Pitch Bend data. On and Off modes enable and disable quantizing for a given split; On mode quantizes in semitone steps, and Off mode continuously responds to bends. Trigger mode works like Off mode but affects only the current split zone. My favorite quantization mode was Auto, which quantizes Pitch Bend when you play chords but has no effect when you play monophonically.

I really love the Axon's advanced split and quantization capabilities. Unfortunately, you can't set the Axon to quantize only note attacks, which would have allowed bends to occur after a specified attack time. That feature would have been great for catching errant fingering and still allowing natural bends. Nevertheless, quantization was especially useful with instruments for which string bends sound unnatural.

Pedal to the Metal

The AX 100 mkII delivers far more than just MIDI conversion and splits. By attaching a momentary switch (which is included), you can trigger the Axon's arpeggiator, step sequencer, and various Hold modes. For example, when you press the switch, play a chord, and release the switch, the Axon will hold that chord on its own MIDI channel so you can accompany yourself on other channels. You can also use the switch to activate a sequencer pattern or to layer two presets.

The unit's full-featured arpeggiator responds to whatever notes you play for as long as you press the Hold switch. You can select from 7 arpeggiator modes (Assign, Reverse, Recycle, Up, Down, Up/Down, and Random) and 32 rhythms. Half the rhythms are factory presets, and half are user definable. You can also select each arpeggio's number of notes, number of repeats, octave limits, and tempo — either fixed or synchronized to MIDI.

The Axon's sequencer can store a maximum 32 patterns and 8 tracks. As soon as you trigger a sequence with the Hold switch, the Axon plays a preprogrammed pattern or an entire track's worth of patterns on a separate MIDI channel. Trying to program the sequencer from the front panel alone would be extremely tedious, but using the editing software makes it fairly straightforward.

Virtual Fretboard

The Axon divides its functions, parameters, and settings into separate modes, menus, and submenus, all of which you can reach using the front-panel buttons. The unit does its best to make every mode and submenu as accessible as possible, but editing such a deep device using 12 buttons and a rather small LCD screen is never ideal.

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FIG. 3: AX 100 Editor gives you complete access to all the hardware''s parameters and provides a GUI that''s much more intuitive than the unit''s front panel.

Fortunately, Terratec has developed AX 100 Editor, an application that ships with the device and runs under Windows XP and Mac OS X on PowerPC and Intel Macs (see Fig. 3). It furnishes tabs for each of the Axon's modes, and each tab places all of that mode's submenus onscreen at the same time. The editor also features very handy graphical user interface elements such as virtual fretboards, graphs, and pull-down menus.

After using the Axon for several months, I couldn't imagine using it without the editing software. Its intuitive layout makes editing the unit a breeze. I only wish that the sensitivity control on the editor offered metering like the LCD does.

Get Your Ax On

The Axon AX 100 mkII is a very compelling product. Its guitar-to-MIDI conversion is as fast and accurate as anything available. Whenever I use it with my custom Koll Tornado guitar equipped with Graph Tech's Ghost Modular Pickup System, the AX 100 mkII accurately converts my performances into MIDI data (see Web Clip 1). Its amazing breadth of features makes it ideal for live performance.

Along with the Axon's power comes complexity, but the excellent editing software helps to minimize the learning curve. Some guitar-to-MIDI converters offer simpler operation but fewer features, and others offer better built-in sounds but less flexibility. If you want a guitar-to-MIDI converter with impressive performance and a ton of features, the AX 100 mkII is the one for you.

Orren Merton is the author of Guitar Rig 2 Power! (2006) and other books for Thomson Course Technology.


Axon AX 100 mkII

guitar-to-MIDI converter



PROS: Fast and accurate. Flexible splitting capability. Onboard arpeggiator and step sequencer. Excellent software editor.

CONS: No USB. Disappointing onboard sounds.


Terratec Producer/Synthax (distributor)