Put a Hex On Your Guitar™

How to Connect Your Guitar to a RackVax Guitar Modeling Processor

Voodoo Doll

Not to worry, we're not really going to put a curse on your guitar. At least we hope not! In this article, we'll discuss hexaphonic pickups and what you need to do in order to plug your guitar into that strange-looking GK 13-pin input on a RackVax guitar modeling processor.  

Hex Pickups

A divided pickup, more commonly known as a hex pickup in guitar parlance, is required in order to successfully connect your guitar to a RackVax guitar modeling processor. If you do not already own a guitar with a hex pickup system, there are a number of retrofit options for you to consider as well as guitars with hex pickups built in from the factory.

You may be wondering why a hex pickup is required in the first place. The answer is that as in the original Variax, the DSP (Digital Signal Processing) technology within RackVax takes advantage of divided pickup technology to work its magic and serve up stunningly accurate guitar models, digital alternate tunings and 12-string simulations. It is the polyphonic processing capabilities made possible by the hex pickup's individual outputs for each string that make this a reality.

Figure 1: Roland GK-3 external hex pickup
Figure 1) Roland GK-3 external magnetic hex pickup

Hex pickups can also be used in many other ways, both practical and creative. With a hex pickup, you are free of the limitations of a monophonic, summed guitar signal and can enter the world of polyphonic processing, where signals from each string of the guitar are processed separately and in parallel. Completely new possibilities are opened up, such as connecting your guitar to compatible guitar processors like Roland's VG or GR series and interfacing with guitar-to-MIDI converters such as the Axon AX-100 for driving your favorite synths and software samples or recording a score of what you play in real-time using a MIDI sequencer. If you happened to own six different amps, you could even route each string of your guitar to a different amp using a suitable 6-way splitter box!

Divided pickups are very flexible. When a hex pickup system is installed on your guitar, you can easily switch between the output of your guitar's onboard magnetic pickups, the hex pickup, or a blend of the two. The 13-pin cable which is used to connect hex pickups to compatible devices carries more than just the six individual string signals from the hex pickup—it also carries the signal from your guitar's onboard magnetic guitar pickups, phantom power, up/down patch change signals and a signal corresponding to the position of a potentiometer for controlling the parameters of compatible devices from your guitar.

Roland makes the most popular line of divided pickup systems, which are part of a line of products marketed as "GK." Internal and external retrofit kits are available for guitar and bass. The external kits such as the GK-2A and GK-3 (Figure 1) require no permanent modifications to your guitar and can be installed in minutes without any specialized tools or expertise.

Internal or External? That is the Question

Internal kits require slight modifications to your guitar, but the advantage is that your guitar comes out looking cleaner. Roland's internal pickup kit is the GK-KIT-GT3. It is equivalent to the GK-3 except that it is installed internally. Other manufacturers which offer internal divided pickup systems include Graph Tech, the makers of the Ghost pickup system and RMC, makers of the PolyDrive pickup system. RackVax guitar modeling processors are compatible with and sound great using any of the aforementioned.


Roland GK-KIT-GT3 GR-Synth Driver Kit Standard
Roland GK-KIT-GT3 Internal Kit
Graph Tech Hexpander MIDI Interface Kit Standard
Graph Tech Hexpander MIDI Interface Kit


RMC PolyDrive I
RMC PolyDrive I
RMC Piezos
RMC Piezos


An external kit can be installed very easily, and we encourage you to do so if this is your first experience with divided pickups. If you choose to go with an internal kit, we recommend that you have a capable guitar technician or luthier perform the modification unless you have the experience necessary to do it yourself.

Magnetic vs. Piezo

There is one other choice to consider before selecting your divided pickup system: magnetic or piezo? The difference, in the end, is up to taste. There are pros and cons for each type of pickup. Both are compatible with RackVax, and you will only notice a slight difference in tone. One property of piezos is that they will de-emphasize the body resonance of your guitar, thus providing more of a blank slate for modeling, but the real advantage of piezos is that they are impervious to electromagnetic interference. However, they are susceptible to handling noise. For instance, when using a whammy bar, piezos tend to pick up extra, unwanted mechanical noises. The advantage of magnetic pickups is that they are impervious to these types of mechanical noises. However, they are susceptible to electromagnetic interference. As they say, you can't have your cake and eat it too. We encourage you to experiment with both types to see what is right for you.

Graph Tech offers an incredibly extensive selection of quality piezo pickups for retrofitting any guitar. RMC Pickup also offers a line of piezo pickups for many popular guitar bridges. Roland is the main manufacturer of magnetic GK pickups.

GK-equipped & Roland-ready Guitars

GK 13-pin 

If retrofitting a guitar is not to your liking, there are also several guitars on the market with GK-compatible hex pickup systems built in from the factory. Almost every type of guitar and many of the major brands are represented so there are options for everyone. Many of these guitars utilize the same electronics found in the aftermarket retrofit kits discussed earlier.


Fender Standard Roland-Ready Stratocaster Electric Guitar Brown Sunburst
  •  Gibson Dark Fire Les Paul w/ RIP interface & RIP-to-GK13 cable
Gibson Dark Fire Les Paul
Gibson Les Paul Standard 2010 Limited
  • Gibson Dusk Tiger w/ RIP interface & RIP-to-GK13 cable
Gibson Dusk Tiger
  • Ibanez RG1520GK
Ibanez RG1520GK
Parker Guitars Fly Mojo MIDI Electric Guitar P0904054

Godin Freeway SA Electric Guitar (Black Pearl) Godin XTSA Solid Body 3-Voice Electric Guitar (Light Burst)

Godin LGXT Solid Body 3-Voice Electric Guitar (Cognac Burst)

  •  Carvin Synth Access guitars
Carvin HF2SCarvin SH475
  •  Brian Moore iGuitar
Brian Moore i113CSBrian Moore i213TS
Moog Model E1-M


Plug & Play


Once you have a guitar with a GK-compatible hex pickup ready to go, you'll need a cable to connect it to RackVax guitar modeling processors and other compatible devices. The cable you will need is a 13-pin guitar cable, marketed as a "GKC 13-pin Cable for GK-Compatible Gear" by Roland/Boss, which technically is a DIN-13 male-to-male cable.

From there, with the cable and your gear in hand, it's as simple as plugging in and turning everything on. Connect the 13-pin cable to your divided pickup's output jack and plug the other end into the jack labeled GK IN on the back of the RackVax guitar modeling processor. Finally, get ready to rack-and-roll!

Once you've put a hex on your guitar, we'd love it if you share some photos with us in our Flickr group, Hexed Guitars.