Guitar Processor



RackVax PerspectiveNow your favorite guitar can sound like an entire collection of guitars, both live and in the studio.

Line 6's Variax guitar, with its collection of 25 unique instruments in one, is without a doubt one of the most amazing advances in guitar technology since the electric guitar itself was invented. But there was always one problem: you can get the great sounds of all those instruments, but isn't the feel of the instrument you are playing just as important?

In the past, enthusiasts have attempted to solve this problem by creating Variax transplants—guitars which have been extensively modified to make room for the Variax electronics by drilling and routing. But who except the bravest among you is willing to do this to their favorite, best-quality, best-playing, best-looking, or most expensive guitar?

With RackVax, you can take your favorite guitar of virtually any brand or model and, without any permanent modifications, access all of the instruments and guitar tones within the Variax. RackVax is a rackmount device with all the familiar controls and I/O you're used to from the Variax line of guitars, but with the addition of five new jacks: GK IN, GK THRU, MIDI IN, MIDI OUT and POWER.

Simply put, RackVax is to the guitar what the Line 6 POD was to the guitar amplifier. Available at your fingertips—or under your feet—is a collection of over 25 unique, digitally-modeled instruments straight from the Variax. It all comes packaged inside of a convenient 19" x 6", 1-space rackmount box, perfect for the stage or recording studio.

For the first time, you can have the tonal flexibility and revolutionary capabilities of the the Variax from any guitar, with absolutely none of the drawbacks. Gone are the days of expensive and labor-intensive Variax transplants. Enter a new world where any guitar you hold in your hands can evoke any tone from vintage to modern, acoustic to electric, and familiar to exotic.

RackVax is a stand-alone, GK-compatible guitar modeling processor in a box. Plug in your guitar and any industry standard, GK-compatible hexaphonic / divided pickup to the 13-pin jack located on the back of the RackVax, then run a standard guitar cable from the RackVax to the rest of your gear and you're on your way to tonal nirvana. Suddenly, a whole new range of tones become available, and yet the same comfortable feel you've grown accustomed to greets you as you play.

All that power would be useless if you couldn't control it. Fortunately, controlling RackVax is easy. On the front panel are controls such as volume, tone, model and pickup select. On the rear panel, MIDI jacks provide for easy integration with MIDI controller pedals for controlling the RackVax during live performance. And within arm's reach, the standard set of GK controls on any GK-equipped guitar allow even more complete control over the Variax.

If you were intrigued by the technology of the Variax but put off by the quality and physical feel of the instrument, RackVax is for you. Play the guitar you really want to play, then choose the guitar you want to hear. Put away the woodworking tools and soldering irons and get back to doing what you love—playing music!


RackVax Electric Frequently Asked Questions

  1. What is a hexaphonic / divided pickup?
  2. What kind of pickup is in a Variax guitar?
  3. What is the difference between magnetic and piezo pickups?
  4. What does GK-compatible, GK-ready, or Roland-ready mean?
  5. How good is RackVax at tracking?
  6. What is MIDI?
  7. What is a MIDI pickup?
  8. What is a MIDI guitar?
  9. What is VDI?
  10. Is RackVax compatible with Variax Workbench?


What is a hexaphonic / divided pickup?

A hexaphonic (or hex for short) pickup is like six separate pickups in one, where each is dedicated to one individual string of the guitar. A divided pickup is any pickup which offers separate output for each string, and therefore a hexaphonic pickup is a divided pickup.

A standard guitar pickup combines all strings into one signal at its output. The purpose of divided pickups is to allow each string to be output as a separate signal, permitting processing capabilities far beyond conventional pickups.

Figure 1) Standard vs. Hexaphonic Pickup
Figure 1) Standard vs. Hexaphonic Pickup
Figure 2) 13-pin GK connector

An industry standard 13-pin connector referred to as "GK" by Roland® (see figure 2) is utilized in order to interface divided pickups with compatible hardware such as the RackVax, Roland® VG-88, VG-99 or other V-Guitar gear, guitar synthesizers like the Roland® GR-20 or GR-33, and guitar-to-MIDI units such as the Roland® GI-20 or Axon AX-100.

The most popular divided pickup systems are the Roland® GK series, which come in both external versions (GK-2A, GK-3) that can be easily attached without any modifications to your guitar and an internal version (GK-KIT-GT3) requiring a little modification.

There are also several other manufacturers with their own take on divided pickup systems, including Graph Tech, which makes the ghost pickup system and RMC Pickup, makers of the PolyDrive system. Both magnetic and piezo divided pickups are available, and retrofit kits compatible with every major brand and type of guitar are easily obtained in the aftermarket.

If retrofitting an existing guitar is not to your liking, guitars with GK-compatible divided pickup systems and 13-pin outputs are on the market, such as the Fender Roland-ready Stratocaster, Gibson Dark Fire Les Paul (w/ RIP-to-GK13 cable), Ibanez RG1520GK, Parker Fly Mojo MIDI, Brian Moore iGuitar, Godin Synth Access & Multiac lines, Carvin Synth Access guitars, and Moog Model E1-M. These guitars are commonly referred to as "Roland-ready," "GK-compatible," or "synth access" and are also sometimes incorrectly referred to as "MIDI guitars."

See our article entitled Put a Hex On Your Guitar for more information on retrofitting guitars with GK 13-pin pickups.

What kind of pickup is in a Variax guitar?

Variax guitars utilize a divided pickup system consisting of one piezo pickup per string within the bridge saddles of the guitar. These piezo pickups are connected to the Variax electronics via short wires. It is this divided pickup system which allows the Variax electronics to so accurately model the vast collection of instruments using DSP (Digital Signal Processing). Algorithms within the Variax electronics process the raw signal from each separate string in real-time to reshape the sound and/or alter the tuning.

What is the difference between magnetic and piezo pickups?

Pickups and divided pickups come in two major types: magnetic and piezo. Magnetic pickups operate using the familiar principle of a steel guitar string inducing an electronic signal in a coil of wire as it vibrates within the magnetic field of a permanent magnet. Piezo pickups operate by taking advantage of a property of piezoelectric crystals which allows them to convert mechanical energy such as the vibration of a guitar string into an electronic signal.

What does GK-compatible, GK-ready, or Roland-ready mean?

First, a little history: Roland® was first to market with divided pickup systems and compatible hardware. "GK" was the term they used for naming the various models of pickups in this line. Since then, the 13-pin interconnect used by Roland GK devices has become industry standard and is now used by other manufacturers. Therefore, GK-compatible, GK-ready or Roland-ready are today used to refer to devices compatible with this standard, meaning the devices can be successfully connected and used together.

How good is RackVax at tracking?

The term "tracking" is generally used to describe pitch detection and tracking changes in pitch. RackVax does not perform pitch detection. Variax technology processes the signals from your guitar strings using DSP (Digital Signal Processing) and reshapes the waveforms in real time to reproduce the sound of a whole collection of guitars or alters the pitches to produce alternate tunings.

What is MIDI?

MIDI (which stands for Musical Instruments Digital Interface) is a digital communication protocol. It is a standard which enables the communication of data between MIDI-compatible devices. For instance, a MIDI keyboard can transmit MIDI data to control an external synthesizer, sampler or sound module by triggering note-on events to cause the external unit to play a sound. As a very simple example, if one presses the C4 (middle C) key on a MIDI keyboard, the note-on event C4 will be sent to any external devices it is connected to via MIDI. A guitar with GK 13-pin divided pickup is not capable of doing this on its own. A seperate guitar-to-MIDI converter device such as the Roland GI-20 or Axon AX-100 is needed to generate this type of MIDI note data. Guitar-to-MIDI devices typically have a GK-compatible 13-pin input jack and a MIDI output jack for connection to other MIDI-compatible devices. These devices typically operate by performing pitch recognition algorithms on the audio signals from each individual string and coverting the recognized pitch value to MIDI events which are then sent to the MIDI output.

Note that MIDI can also be used to communicate many types of data other than pitch, such as patch changes or CC (continuous controller) messages to control device settings. This makes MIDI quite useful to guitarists. A well-designed guitar rig can be controlled via a MIDI foot pedal with little to no "tap dancing" on footswitches, as tends to happen when MIDI is not being utilized. MIDI offers the advantage that a single toggle of a footswitch can control more than one device at once. Contrast that with an array of standard guitar effect pedals which must be toggled individually during performance and you will begin to see just how useful MIDI control can be.

What is a MIDI pickup?

This is a misnomer commonly and mistakenly used to refer to GK 13-pin pickups. GK pickups do not produce, carry or output MIDI data. The audio signals output from GK pickups are purely analog. The only way to produce MIDI events from the output of a GK pickup is to use a GK-compatible guitar-to-MIDI processor.

What is a MIDI guitar?

In most cases, this is a misnomer that is used to incorrectly refer to guitars which have a divided pickup and GK-compatible 13-pin output.

What is VDI?

VDI stands for Variax Digital Interface, which is a special digital connection proprietary to Line 6 that is present on all Variax guitars and, by extension, RackVax. Line 6 devices compatible with VDI currently include Variax Workbench USB interface, POD XT Live, POD X3 Live, POD X3 Pro, POD HD500 and Vetta II. VDI is used as an alternative means of connecting a Variax or RackVax to these devices.

Connecting RackVax to Line 6 equipment with VDI offers the following advantages:

  • 100% pristine digital audio signal transfer.
  • Bi-directional digital control. Patches stored on the device to which you have connected via VDI can store and automatically recall Variax settings for you. Every available control can be stored and recalled with patch changes: volume, tone, model, and pickup selection.
  • Power is provided over the VDI connection, removing the need for an external power source such as a wall wart, batteries or the XPS power supply.

In addition, the VDI connection is the conduit through which the Variax Workbench software can be used to edit and customize the Variax models. By plugging into a suitable interface such as the Variax Workbench USB interface, POD XT Live, POD X3 Live, POD X3 Pro, POD HD500 or Vetta II, RackVax may be connected to a PC or Mac running the Variax Workbench software via USB or MIDI and customized to your heart's content.

As a side note, you might have noticed the physical similarity of the VDI jack and plug compared to the ethernet connectors on your computers and networking devices. That is because they are in fact the same 8P8C/RJ-45 connectors. A standard CAT 5 networking cable can even be used in place of the specialized Line 6 VDI cable, if needed in a pinch!

Is RackVax compatible with Variax Workbench?

Absolutely! You can edit the guitar models to your heart's content using your PC or Mac and the Line 6 Variax Workbench software by connecting to RackVax via MIDI. USB connectivity is also possible by pairing RackVax with a USB-to-MIDI interface or VDI-capable Line 6 device such as Variax Workbench USB interface, POD XT Live, POD X3 Live, POD X3 Pro, or POD HD500. See our guide here.


If your question was not answered here, feel free to ask on our support site or post on our forum.


RackVax Electric Specifications

RackVax Electric RVX-100E

RackVax Electric RVX-100E

  • Powered by included power adapter**, Vetta II, PODxt Live, POD X3 Live, POD X3 Pro or POD HD500
  • GK-compatible 13-pin input with ±7V phantom power
  • GK thru allows simultaneous connections to additional GK devices
  • Full live control over volume, tone, pickup and model select and more via GK controls or with a MIDI foot controller
  • Digital I/O jack for POD® XT Live, POD X3 Live, POD X3 Pro, POD HD500, Vetta™ II, and Variax Workbench connectivity
  • Standard 1/4" guitar output jack
  • Analog bypass for your guitar signal
  • MIDI in/out
  • Over 25 unique instrument models

Instrument Models*:

Technical Specifications:

Nominal Output Impedance (Analog Out): 100 ohm
Power Requirements: 9V DC, 800mA
Dimensions: 19" x 1.75" x 6" (1U rack)
Weight: 4.75 lbs

* All product names used in this webpage are trademarks of their respective owners, which are in no way associated or affiliated with RackVax LLC. These trademarks of other manufacturers are used solely to identify the products that were studied to create the instrument models within the underlying technology of RackVax.

** Appropriate AC-DC power supply for your country of origin included.


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