YouTube Logo

BX-13-VC 24-to-13 Pin Bus Converter - NEW for 2013!

Features and Specifications:

  • Precision Control for Synth Volume Calibration - Universal compatibility with ALL 13-pin Roland Synths (not just GR-50)
  • Roland EV-5 Type Foot Pedal Output with Precision Calibration (NEW with BX-13-VC!)
  • Combined Synth and Guitar Mute Input for Optional Foot Switch Control (NEW with BX-13-VC!)
  • Hex Fuzz Signal (G-202/303/505/808) sent to 13-pin Synth for Additional Processing (NEW with BX-13-VC!)
  • Vintage GK Mode Switch Automatically Converts to Modern GK Switch
  • Backed by Five-Year Parts and Labor Warranty
  • Size: 120 mm x 100 mm x 53 mm
  • Weight: 15 oz.
  • Ordering Information

Introduction to the BX-13-VC:

BX-13-VX with GR-300
BX-13-VX - Expander 24-to-13 pin Bus Converter, with Roland G-303 vintage guitar synthesizer controller.

For about ten years, Roland Corporation and other manufacturers produced a range of unique, very high quality 24-pin guitar synthesizer controllers. At the transition from the 24-pin format to the 13-pin format, Roland released the rare BC-13, a 24-pin to 13-pin bus converter specifically design to allow 24-pin guitars to play the newly released Roland GR-50 guitar synthesizer.

Since the brief appearance of the BC-13 in late 1989, Roland has continued to developed the 13-pin synthesizer format, with the current GR-55 containing a multiple guitar synthesis technologies, both analog/physical modeling synthesis and pitch-to-MIDI PCM synthesis..

The BX-13 series of bus converters are designed to update the original Roland BC-13. The most notable change is a volume control, which controls the scaling of the GK Synth volume commands to be compatible with any Roland 13-pin guitar synthesizer, from the GR-50 to the newly released GR-55. There have been an entire series of BX-13 units, from the original BX-13, to the BX-13-V2, BX-13-V3, BX-13-VX culminating in the BX-13-VC, the most compact of the BX-13 series of bus converters, with features not found on the original BC-13 like support for Roland EV-5 control and Hex Fuzz Signal access through the attached 13-pin synth.

Expanded Dedicated Foot Switch Control over Synthesizer and Guitar Outputs:

BC-13 Controls

This diagram shows how the Roland BC-13 uses the Resonance knob to switch guitar and synth on and off.

The BC-13 uses the Resonance Knob (CV#2) in a way that is very similar to the Mode switch on the vintage GR-series guitar. But rather than having a three-position switch, the knob has three "zones." The first zone is guitar only, the middle zone is guitar and synth, and last zone is synth only. Confusing? Yes. As you can imagine, it is almost impossible to quickly and accurately turn guitar and synth signals on and off.

The BX-13-VC improves on the BC-13 by adding two dedicated foot switch mutes. Any simple on/off foot switch can be used to independently turn the guitar and synthesizer output on and off. The mute input on the BX-13-VC is a TRS tip-ring-sleeve input. The tip input, when grounded with an external footswitch, mutes the synthesizer (GK Synth Volume) signal. The ring input when grounded mutes the hex fuzz output sent to the 13-pin synth. For my design, I worked with the new Roland FS-6 foot switch in mind. This foot switch is basically two foot switches in one, with LEDS for each switch. Check out the video demo below to see the system in action!

Precision Volume Controls for Synthesizer:

A look at the schematics of various Roland guitar controllers reveals that no two are wired exactly the same. Likewise, the internal circuitry of a Roland GR-55, VG-99, GI-20 and GR-20 differs with each unit. As a result, maximum volume levels can change with different guitars or different synthesizers. The BX-13-VC adds controls to easily fine-tune the synth volume output for maximum sensitivity and maximum output.

BX-13-VX Side View

Compatible with Vintage Bass Guitar Synthesizers:

The BX-13-VC circuitry has also been thoroughly tested with the vintage Roland bass guitar synthesizer controllers like the G-33, G-77, and G-88. Both a Roland G-33 and G-88 were successfully tested with the Roland GR-55 using the BX-13-VX. A G-77 was also tested with the Roland VB-99 and the Roland GI-20 using the BX-13-VX.

Other Roland guitar synths, such as the GR-50 may not work properly, since they were not designed to handle to lower frequencies of a bass guitar.

BX-13-VC with VB-99
BX-13-VC with GI-20

The BX-13-VC is also designed to work with bass controllers and bass synthesizers as well. However, it is important that the connected synthesizer supports bass synthesizer operation. Both the Roland GI-20 and Roland VB-99 work great with the BX-13-VX.

Notes on the BX-13-VC (2013) - Hex Fuzz and EV-5 Output:

The BX-13-VC adds support for the resonance knob on a vintage Roland guitar to be used as a control source with modern Roland guitar synths like the VG-99 or GI-20. This is accomplished by connecting a tip-ring-sleeve cable from the BX-13-VC to a Roland device with a EV-5 input. In addition, the BX-13-VC allows processing of the hex fuzz signal from a vintage Roland G-202/303/505 or 808 guitar synth controller.

Here is a summary of how the BX-13-VC works with the guitar: the Master Volume control on the guitar controls the guitar signal output from the 1/4” jack on the guitar. The Filter Cutoff knob, or CV#1, sends GK S-Vol signals. The Resonance knob, or CV#2, sends EV-5 compatible control signals from the EV-5 jack on the BX-13-VC. The Mode switch on the guitar sends GK S1 and S2 signals.

The white knobs trims the output of the GK S-vol signal. The blue knob trims the output of the EV-5 compatible signal. The 1/4” jack with the white ring is a tip-ring-sleeve input to mute either the GK S-vol signal, or the hex fuzz signal. "Tip" mutes the synth volume, "ring" mutes the hex fuzz signal. The 1/4” jack with the blue ring is a tip-ring-sleeve EV-5 type output tied to the resonance control.

With the BX-13-VC, the 13-pin synth direct guitar sound is the output from the hex fuzz circuit in the guitar. The BX-13-VC allows Roland guitar synths like the VG-99 and GR-55 to process with hex fuzz output using internal effects, and COSM guitar amplifiers and speaker enclosures. Use the links below to download the patches used in the BX-13-VC demo video.

VG-99/GR-55 Settings (GK):

1) Go to your GK System settings (System/GK) and set pickup type to GK-2A, scale type to LP for a G-303 or G-808, and ST for the Roland G-202, G-505 G-707, or Ibanez IMG2010. GK Phase, Pickup Direction and S1/S2 position are all Normal.

2) Sensitivity Settings: I designed the BX-13-VC to work with the GK sensitivity settings at "10." That is, "10" on a range of "0" to "100". This is so the VG-99/GR-55 does not have to add additional gain for a solid response. However, this setting of "10" also depends on two other factors: the settings of the internal trimmers in the vintage guitar, and how hard you play. The setting of "10", gives you some room to reduce gain if needed. Adjust the internal trimmers in the vintage guitar to match your playing style. Also, check the pickup height of your vintage guitar pickup.

With proper settings, you should find the vintage Roland guitar is actually quieter than any GK-3 guitar. I have yet to find a GK-3 guitar than can match the signal-to-noise ratio of a vintage Roland guitar. The principle is a bit like the acclaimed EMG pickups. EMG pickups boost the output level of the pickup at the source, the pickup. This makes for a stronger signal sent through the cable. The vintage Roland guitar has output circuitry that works at about twice the level of a newer GK-2A/GK-3 pickup. If you reduce the GK settings in the 13-pin synth to around "10," the 13-pin synth is adding much less gain (noise) at the synthesizer.

3) Hex Fuzz: The hex fuzz output is always active. With the VG-99/GR-55, it is the "direct guitar" signal, so you need to use patches that access the direct guitar signal. I posted the two patches below I used for demonstration purposes in the video online. For GR-55 users, you can use the 3 factory GR-55 patches that use direct guitar input, 30-1, 30-2, and 30-3 (for Normal PU 1, etc.).


BX-13-VC BX-13-VC BX-13-VC
BX-13-VC BX-13-VC BX-13-VC
BX-13-VC BX-13-VC BX-13-VC
Click on any image for larger view.


BX-13-VC Features in Detail:

  • Will the BX-13-VC work with the new Roland GR-55?

  • YES! The BX-13-VC works with all Roland 13-pin guitar synthesizers and guitar processors!

  • Does the BX-13-VC add any latency or delay?

  • No. None of my processors add any delay at all. Like the GR-300 and GR-100, they are purely analog processors that do not suffer from the inevitable latency introduced by digital systems. Many players notice that their guitar synths actually play better, since the gain stages have been especially designed to deliver the best possible signal to the guitar synthesizer.

  • Will the BX-13-VC work with ANY Vintage Roland Guitar Controller or Guitar Synth?

  • YES! I have tested this with the Roland G-202, G-303, G-505, G-707, and G-808 guitar electronics and the Ibanez IMG2010. The BX-13-VC is also designed to work well with the Roland GK-1, and other third party controllers built by Gibson, Steinberger and others. The BX-13-VC has also been tested with the Roland GI-20 and VG-88, VG-99 and Roland VB-99.

  • How do I calibrate the synth volume?

  • First, turn the BX-13-VC synth volume knob fully counterclockwise (zero). Then turn the Filter/CV1 knob on the Guitar to maximum (fully clockwise). While playing your guitar, slowly turn the BX-13-VX synth volume knob clockwise until you reach maximum volume. If you are using a VG-88, VG-99, VB-99 you can monitor the output level by checking what the GK-Vol knob is assigned to. Please consult your manual. The typical position for the BX-13-VX synth volume knob is 3 o’clock, and shown in the photos above.

  • Does this unit require any power?

  • No. The BX-13-VC gets its power from the connection to the guitar synthesizer. This is the same approach Roland used for the BC-13, US-20 and GKP-4.

  • Is there anything like a "reverse" BC-13 or BX-13-VC? I want to use a modern, 13-pin guitar synth controller to control a vintage, 24-pin synth.

  • YES! The RC-1324-VR Bus Converter translates modern, 13-pin signals into 24-pin signals, and provides all the necessary control voltages plus hex fuzz.

  • Where do you get the connectors? I thought they were discontinued by Roland a long time ago.

  • YES! Roland discontinued the connectors from active production about fifteen years ago. So the 24 pin connectors are virtually impossible to find. I bought as many of these connectors as I could from Roland a while back. Depending on availability, I also use connectors refurbished vintage guitars and synths. Either way, there is no new supply of these connectors, so all the processors I build have a very, very limited production run.