Guitar ¼ inch Adapter Cable for Roland GK 13-Pin

Hey all,

I thought I’d share with you that I successfully built a Guitar ¼ inch Adapter Cable for Roland GK 13-Pin connections!  This is a cable that allows you to connect a guitar or other instrument with a ¼ inch output (bass, ukulele, etc.) to the Roland GR-55 guitar synthesizer.  If you are on a gig using the Roland GR-55 the usefulness of this is that if you don’t have another amplifier and effects, you can access the Roland COSM effects and amp models within the GR-55 and use the same sound reinforcement system that the GR is connected to.

Below is a copy of my wiring diagram that was adapted from a similar diagram posted on by “Elantric”.  As the diagram indicates, the normal guitar (or other instrument) signal is transmitted to the GR-55 via pin 7 in the 13 pin plug.  A voltage divider has been added to reduce the GR-55’s +7 vdc to +5 vdc to feed pin 8 which signals the GR-55 that a GK pickup’s volume control is set to 10.  I tested it and, yes, it works!

I hope this information is helpful to you.

Roland GK 13 pin to 1-4 inch guitar adapter cable


Completed Roland GK 13 pin to 1-4 inch guitar adapter cable

Roland GK 13 pin to 1-4 inch guitar adapter cable.pdf

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Michael Jackson – Thriller [Emulating Mini Moog Tutorial with GR-55]

Hi everyone,

I thought I would share my attempt at emulating the synth bass sound in Michael Jackson’s Thriller using the Roland GR-55 guitar synthesizer and my Ibanez bass equipped with a Roland GK-3B bass pickup.

The Pickup

First of all, the pickup and controller installation on my bass is not ideal from a playability standpoint due to the shape and layout of my bass.  I have tried mounting it in various locations and where I have it now seems to be the best compromise.  One of the annoying things about the controller is that the volume knob is very loose and super easy to bump while playing which results in unintended consequences!  To remedy that I pulled the knob off the shaft and added an O-ring around the shaft and put some foam into the inside knob cavity.  That really tightened it up so accidental volume changes are not an issue anymore for me.  The other problem is the S1/S2 switches are also easy to bump, but by being careful during playing I have been able to avoid them.  However, I would like to find a more fool proof solution.  If you have any ideas, let me know!

GR-55 Floorboard Settings

In the video below, the first image is the main page in the GR-55 Floorboard Editor (courtesy of Gumtown on and as it shows, for the Thriller patch I am using two PCM synth sounds, number 241 Synth Bass 2 and 18 Fretless Bass as well as an electric bass COSM model and some of my normal pickups blended in.  I found that having the electric bass blended in added a little more definition which is needed for the staccato parts in Thriller.  

The image for PCM Synth 1 shows the details for that tone.  I believe that a Mini Moog was used in the Jackson recording.  There is a PCM tone in the GR-55 called Big Mini that I thought could be a Moog like tone, but when I used it the sound just wasn’t right.  So I auditioned more PCM tones and finally settled on 241. 

The image for PCM Synth 2 shows the details for that tone which is for tone 218 Fretless Bass 1.  This gave the sound it a little more edge.

The next image is for the electric bass COSM model, which in this case is number 4, Precision Bass.  As you can see I have the volume and tone at 100 %.

And finally, the last screen is for the amp that I chose:  A clean bass amp with middle gain.  Next is a short sample of how the GR-55 Thriller Bass patch sounds.

Here’s the video.


How to Install the Roland GK-3B Bass Pickup for Synth Access

Hi everyone,

I thought I’d share my quick install of the Roland GK-3B divided BASS pickup on my Ibanez 5-string bass.

I have been using the Roland GR-55 for several years with my guitars.  I am also a bass player, but I just never felt the need up to now to add synth access to the bass.  However I am playing bass on Michael Jackson’s Thriller for Evergreen Community Orchestra’s fall pops concert and I was trying to find some way to emulate the bass sound in Jackson’s recording.  After doing a bit of research it seemed to me that the bass, at least in the studio recording of Thriller, was played through a Moog MiniMoog.  So at first I searched around to see if there is some kind of electric bass effects pedal that could emulate that Moog synth sound and there are.  For example, this or this or this.  But, I stopped in my tracks when the old light bulb turned on in my head when I realized for about the same price as the Boss SYB-5 I could add the GK-3B and have way more flexibility using the GR-55.  The GR-55 includes a HUGE number of synth PCM tones including one named “BigMoog” that I thought might come close to the MiniMoog.  (more on that later!)

Here is a video and a summary of the GK-3B Installation:

About the Roland GK-3B Divided Pickup

The Roland GK-3B Divided Pickup is what you need to add to your bass in order to play through a Roland guitar synth, such as the GR-55.

The GK-3B is easier to install than you would think from first glance at the owner’s manual.  The GK-3 includes an adjustable curve design to keep an even distance between the strings for better response. The shims, pads and double-sided tape lets the GK pickup mount right in front of the bridge. The guitar connection is 1/4 in. to 1/4 in., and the GK pick-up wire retracts for a neat installation.  The Roland GK-3B Divided Pickup sends individual signals from each bass string to GK compatible devices. It is carefully designed for guitar performance by having a large GK knob, and a Select Switch to change from synth, to normal guitar tone, or both of them mixed.

The nice thing is by following Roland’s instructions you can attach the GK-3B without any drilling or modification of your instrument.

Roland GK-3B Divided Pickup Specifications


  • GK Volume
  • DOWN/S1 Switch
  • UP/S2 Switch
  • Select Switch
  • Indicator
  • Power Indicator
  • Connectors
  • GK Connector
  • Normal Pickup Input Jack

Roland GK-3B divided pickup installation

The following diagram of the GK3B appears in the owners manual.

This is the process described in the GK-3B owner’s manual and it should work for other basses.

Make sure you have a clean, cushioned place to work on your guitar. It would be a shame to scratch up your baby.

If you need new strings, this would be a good time to install them!

Adjust the pickup string spacing. As distances between strings vary with the model of the bass, the spacing between each of the coils in the pickup must be   adjusted to match the particular bass.  Unless this adjustment is made accurately, the GK-compatible device will not function at its full potential, or may not operate correctly. Please make this adjustment with care.  See page 8 of the owner’s manual for details on how to measure and adjust the spacing.

Attaching the Pickup with Double-Sided Tape: You decide on the location in which to install the pickup.  For a 5-string bass:Attach the divided pickup so that the center marker is between strings 2 (D) and 3 the 2nd string marker is directly below 1 (G), and the 5th string marker is directly below string 4 (E).

The divided pickup must be installed in the correct orientation. Make sure that the cable from the divided pickup is extending from the bridge side.



Tune each string to its normal tuning.

Adjust the height of the pickup. Use the supplied spacers as needed to achieve a clearance of 1.5 mm between each string and the top of the pickup.  Use the supplied 1.5 mm gauge to check the clearance when the top and bottom strings are depressed at the highest fret.

Remove the strings from the bass.

Attach with double sided tape: Remove the backing from the tapes for the pickup cushion, the pickup spacers, and the pickup, and carefully attach the pickup to the bass.  Be sure to clean the surface of the bass carefully to remove any dust or film before attaching the tape.  Press the assembly firmly to ensure a good bond with the tape.

Restring and tune the bass, then carefully check the height of the divided pickup once more.Adjust if needed.

Attaching the Controller: To maintain a bass-modification-free installation, I installed the GK controller using the supplied bracket.  Due to the shape and configuration of my bass there was not an ideal location, from a usability standpoint, to install the unit.  Ideally, I would like it to be located close to the other controls, but there simply is not room.  Initially, I mounted the controller on the back side of my bass and from an aesthetics standpoint this is a good location because the only thing visible from the front was a small part of the bracket.  However, from a usability standpoint, this location had some problems.  The primary problem with it being rear mounted is that during playing the controller can bump into your body and change the GK volume knob position or the S1/S2 switches.  This is not good!  The volume know turns very easily.  So at first, I wrapped the controller with 3M painters tape to ensure no controls would accidentally get changed.  I control the volume and patch and bank changes outside the controller, so I don’t really need them.  My second placement option is on the front side above the bridge.  This location will be prone to bumping the volume knob and switches too.  So, I am going to try it out here for a while and decide where to go from there after some real life experience.


Finally, be sure to attach the 1/4″short cable to the GK-3B and bass 1/4 inch output jack.

Completed Installation

This is the Roland GK-3B divided bass pickup on my Ibanez SR405EQM 5 string bass.

I hope this is helpful to you and that you thoroughly enjoy your Roland GK-3B Divided Bass Pickup.


Roland GK-3 Pickup Settings

I have been asked what my setup is for the Roland GK-3 divided pickup on my Fender Modern Player Marauder.  Well, here they are!  In an earlier post I documented my process for installing the Roland internal kit for the GK-3 pickup in my Roland Marauder guitar.

Per Roland’s product description:

This kit includes all parts for permanent installation of a GK-3 Divided Pickup into an electric guitar: a GK-3 Divided Pickup, circuit board, switches, power indicator LED, 13-pin connector, wiring and hardware. Professional installation is required.

  • Divided guitar pickup for use with Roland V-Guitar System, GR-20 Guitar Synthesizer, or BOSS GK Effect Pedals
  • 3-position switching between divided pickup, natural bass pickup, or mix of both
  • Mounts on any electric or steel-stringed acoustic guitar

Roland GR-55 pickup settings for Roland GK-3

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RMC Hex Pickup and Poly-Drive Install for Roland GR-55 Synth Access

Here’s my recap of my process of upgrading my Ibanez Artcore Expressionist AM93 semihollowbody guitar with new RMC Pow’r Bridge ‘G’ pickups in the bridge along with the Poly-Drive 1 electronics module and all new control wiring.

Watch The Video


The synth access equipped guitars on the market, for example such as those available from Godin (LGX-SA and LGXT-SA) or Carvin (Frank Gambale FG1) were very attractive to me but cost more than I wanted to spend on a guitar. Besides I love working on things so I decided to do this upgrade myself and document what I did in case anyone else wants to give it a try too. I had already had a few years experience using the Roland GK-3 external mount pickup on my Epiphone “dot”, which worked great, but it was big and ugly. Sure, beauty is in the eye of the beholder, buy in my beholder eyes I decided I didn’t like it. Also, I had moved on to the smaller body (ES-339 style) Artcore AM93 and I wanted to keep it as stock looking as possible while still being able to enjoy synth access.

Perhaps the biggest challenge was the bridge.  The RMC “PBG pickup saddles” retro-fit the Schaller GTM (Nashville) bridge as well as the TonePros TP-6 bridge, but they don’t fit in the Gotoh tune-o-matic bridges because the intonation screws are too high in the Gotohs.  The bridge in the Artcore is called by Ibanez the Art-1 bridge and I don’t know who makes it, but I took measurements and determined that the RMC pickups would not fit.  In the end, I decided to buy a Schaller GTM bridge, but the main problem was that the Schaller bridge posts/bushings were smaller than the Artcore bridge posts.  I fashioned wood plugs for the holes and drilled them out to fit the new Schaller posts.  This required very careful measuring and rechecking.  Once it was verified I glued them in with Titebond hide glue.  Be careful to wipe up any excess glue from the guitar finish!

Before beginning any work, I carefully planned what I would do. Below is a copy of my proposed control layout diagram. I couldn’t find graphic of a blank Artcore body online, so I went with this one and about the only major difference is the extra hole on the top for the ¼ inch output jack which is on the side on the Artcore.

I also did my own wiring diagram that would be specific to my particular guitar. My install included what RMC calls the “Cool Circuit” which provides a master tone, guitar volume, synth volume and RMC/Mag pickup blend control.

RMC Poly-Drive 1 Controls Layout for Ibanez Artcore AM93 Rev. 2

RMC Poly-Drive 1 Wiring for Ibanez Artcore AM93 Rev. 2



1  Bridge Post Hole Retrofit For Schaller Gtm Bridge

  1. Remove guitar strings. I discarded the factory strings as I had new D’Addario NYXL strings that I wanted to install when I was done.
  2. Remove stop bar. (It will actually slide off its posts as soon as you remove the strings.)
  3. Remove stock bridge. Set it aside until you are ready to replace the saddles with the RMC pickups.
  4. Extract stock bridge bushings. Place a short screw or bolt in the bushing hole and then tighten the bushing against the screw until the bushing lifts out of the hole.
  5. Measure bridge post hole diameter and depth.
    • ID:
    • Depth:
  6. Fabricate post hole plugs:
    • OD: 17/64”
    • Length:
    • ID of Schaller bushing:
  7. Verify Schaller bushings fit in the fabricated post hole plugs.
  8. Re-verify post hole depth and plug length:
    • Depth:
    • Plug Length:
    • Hole spacing:
  9. Install plugs and glue in place.
  10. Press in Schaller bushings.

2   Bridge Saddle Replacement

  1. Remove and replace bridge saddles with RMC saddles per RMC instructions.
  2. Remove bridge pickup and move it out of the way.
  3. Install Schaller bridge.
  4. Route pickup cables into guitar body.



3   RMC Wiring connections

  1. Remove the volume and tone knobs. Tip of the hat to Sweetwater’s Insync for the helpful suggestion to employ the tip of a spoon as a lever to pry the knob up. Be sure to protect the finish with a cloth or napkin and pry gently.
  2. Remove the nuts and washers from the volume and tone pot stems, the pickup switch and the ¼ inch jack. (Save them in case you need an extra nut or washer later.)
  3. Remove all stock wiring through bottom F-hole:
    • Volume and tone pots. (Label the pickup wires)
    • ¼” guitar jack
    • Pickup selector switch
    • Discard pots and ¼” jack.
  4. Mark and drill holes for S1 and S2.
    • Drill size:
  5. Mark and cut opening for the battery box. (Note:  it is not shown here, but I applied masking tape first over the areas where I needed to cut into the guitar to avoid chipping the nearby finish.)
  6. Mark side for jackplate opening.
  7. Make template for jackplate opening cutting/routing.
  8. Cut/route side opening for jackplate.
  9. Connect mag pickups to selector switch.
  10. Connect all Poly-Drive wires per RMC drawing.
  11. Connect mag pickup ground wires to Poly-Drive module per RMC drawing.
  12. Connect pickup selector switch to Poly-Drive module.
  13. Connect RMC pickup wires to Poly-Drive module per RMC drawing.
    • Add cable tie down to secure inside guitar.
  14. Route battery wires to battery box.


4   RMC Wiring Harness Installation

  1. Insert Poly-Drive module and ¼” jack through F-hole.
  2. Attach module with two screws and ¼” jack with nut to dual jackplate.
  3. Attach jackplate to guitar with screws.
  4. Attach all pots and switches.
  5. Connect battery wires to battery box.
  6. Secure internal wires to guitar interior.
  7. Reinstall bridge pickup.
  8. Install strings.
  9. Tune and check string action and intonation.
  10. Install 9V battery.
  11. Test all functionality:
    • S1: Changes GR-55 programs?
    • S2 = Gtr + connect ¼” to amp: Mag pickups work?
    • S2 = Synth + 13 pin to GR-55: RMC pickups work?
    • S2 = Mix: Both pickups work?
    • Guitar volume works?
    • Master tone works?
    • Mag/RMC blend works?
  12. Polish guitar.
  13. Create GK Set in GR-55 with setting applicable to RMC piezo pickups.
  14. Go play your guitar!






Ibanez Artcore with RMC synth Access1




Ibanez Artcore with RMC synth Access2







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