GK-3's unique Pin 9 functionality explained

Started by Elantric, January 26, 2012, 11:32:54 PM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

Elantric

Trivia - Prior GK-2A pickups had a no connection on Pin #9

With the 2003 GK-3 hex PU, Roland introduced Pin#9 to be used as a Control voltage  - with specific control voltage ranges for Guitar (GK-3)  and separate control voltage ranges for Bass ( GK-3B )

GK-3/GK-3B are the only 13 pin hex preamps that transmit a Control voltage on pin 9, based upon the current position of the 3 way switch. The VB-99/VG-99/GR-55/GP-10 all react to the Pin9 Control Voltage by transmitting appropriate  MIDI CC#7 ( MIDI Volume or CC#7 =0 =mute) message to enable/disable external MIDI Synth from the guitar.

And its worth revisiting your Synth's MIDI Implementation sheet to see is it supports MIDI CC#7 as Global Volume control - most do but some don't.
and review the official MIDI Spec too

MIDI TUTORIALS
https://www.vguitarforums.com/smf/index.php?topic=2977.0


Connect a MIDI Monitor to the  VB-99 MIDI Out jack and verify you see this activity as the three way "Bass/Mix/GK Synth" switch on the GK-3B  is moved to a new position.


Prior to the GK-3  / GK-3B hex pickup , Pin 9 on the 13 pin cable was always free and not connected. and labled "N.C." on schematics. This is true for GK-2A, Ghost, Axon, Yamaha, RMC. L.R. Baggs ,Sound Garage hex pickups with 13 pin output.

But starting with the GK-3 hex pickup , Roland introduced a new output control voltage transmitted on pin 9 of the 13 pin cable, based upon the current position of the 3 way "Guitar/Mix/Synth[GK]" switch


Guitar GK-3 (Pin#9) Voltage Range:
GK  = 1.56V
Mix =  1.04V
Guitar =  0.52V



Bass GK-3B (Pin#9) Voltage Range:
GK  = 4.48V
Mix = 3.96V
Bass = 3.44V




The VG-99 interprets the GK-3's voltage change on  Pin 9 of the 13 pin cable:

When you switch the three way switch from Mix to Guitar, the VG-99 sends out MIDI CC#7, value 0.  When you switch from Guitar to Mix, it sends out CC#7, value 127.

The VG-99 is using these CC messages to switch the COSM guitar off (when you select Guitar) and on (when you select Mix), but if you have other MIDI gear attached that also respond to MIDI CC messages  you may encounter some interesting conflicts, so be advised


The GR-55 and GP-10 operate in the identical manner.

thanks to erikbojerik for this discovery
https://www.vguitarforums.com/smf/index.php?topic=419.msg35936#msg35936


More details about the GK-3 is here:
https://www.vguitarforums.com/smf/index.php?topic=4729.0


KeldAmpworks

Quote from: Elantric on January 26, 2012, 11:32:54 PM

The VG-99 is using these CC messages to switch the COSM guitar off (when you select Guitar) and on (when you select Mix), but if you have other MIDI gear attached that also respond to MIDI CC messages  you may encounter some interesting conflicts, so be advised


I suspect the GR-55 operates in the identical manner.


In the light of the 'set GK vol to tone volume' bodge that you have to do to get the GK/mag switch to work, would you agree that the GR55 has actually turned out not to be using the DC level in this manner? Or is that bodge only necessary on GK2a guitars

Elantric

#2
Its confirmed that when moving the three way "Guitar/Mix/Synth(GK) switch that:

GK-3 (Pin#9) Voltage Range:
(Synth(GK)  = 1.56V
Mix =  1.04V
Guitar =  0.52V

GK-3B (Pin#9) Voltage Range:
(Synth(GK)  = 4.48V
Mix = 3.96V
Bass = 3.44V


GR-55, VG-99, and VB-99 interprets the voltage change on GK-3's Pin #9 in the following manner:

When you switch the GK-3 three way switch from Mix to Guitar, the VG-99 or GR-55 transmits MIDI CC#7, value 0.  When you switch from Guitar to Mix or Synth), it sends out CC#7, value 127.


QuoteIn the light of the 'set GK vol to tone volume' bodge that you have to do to get the GK/mag switch to work, would you agree that the GR55 has actually turned out not to be using the DC level in this manner? Or is that bodge only necessary on GK2a guitars

If you want the GK-3  "Guitar/Mix/Synth(GK) switch to actually work when using the GR-55, then all User patches must incorporate the "GK VOL" parameter assignment is set to Patch Volume.

More details here:


* How to enable "Normal Guitar Pickups" and make the GK-3 Guitar/Mix/Synth three-way switch work with the GR-55:
https://www.vguitarforums.com/smf/index.php?topic=3402.0
Next post is related to the above,
* Roland US-20 A/B Selector BUG (Importance of GK-VOL Assignment)
https://www.vguitarforums.com/smf/index.php?topic=3494.0


jim-analog



  Greetings,

  Regarding the "Pin-9" issue............for those of us with GK2/a (and prior) pickup electronics, it would seem that an unused pin could be put to great use as an enhanced ground connection. Provided it was bonded at one or both ends of the shell to eliminate any possible differential voltage issues of course. Any thoughts?  Thanks for reading!

Regards, Jim

admin

#4
Quote from: jim-analog on April 12, 2020, 06:25:39 PM

  Greetings,

  Regarding the "Pin-9" issue............for those of us with GK2/a (and prior) pickup electronics, it would seem that an unused pin could be put to great use as an enhanced ground connection. Provided it was bonded at one or both ends of the shell to eliminate any possible differential voltage issues of course. Any thoughts?  Thanks for reading!

Regards, Jim

Yes, using Pin #9 as a redundant GROUND works well with the early GK-2A, but typically you must use a custom cable or feed a modified US-20 A/B/Y Switcher which has Pin#9 tied to Ground 

And be aware adding additional ground return on Pin 9 may introduce a new source of ground loop noise .