Need assistance on customizing a 13 pin jack with GK kit GT3

[Verchrona]

I'm building an instrument with onboard effects that use 9V.

I do not plan to use any GK processors. The signal from my custom 13 pin will go straight to the DAW. No switch for Synth/mag, and no buttons.

These are the required pins:

1-6: Hex signal
7: Mag signal
?: 9V+
?: 9V- or GND

If I understand this correctly, the GK preamp needs 7v+/- to operate, which is supplied by the GK Processors. And 5v for synth volume.

Is there any way to power the board internally with 9V that's shared with my other fx, so I don't have to supply a dedicated 7v?

And is there a way to pass the hexaphonic without that 5v pin?

I was also considering just running the pickup straight to the jack, but I don't know if there would be noise issue not using that preamp board.

Any ideas?

[gumtown]

9 volt instead of 7 volt will be fine, but you need a balanced dual supply of +9v 0v -9v, which could be derived from a buck converter module
https://www.digikey.com/en/products/detail/xp-power/IHA0109D09/6220996?s=N4IgTCBcDaIJIAkCCAGAjCgnAESyAugL5A

the 5 volt output from the GK module is only required for volume voltage control of the GK synth unit and not required in your case.
I would use the onboard preamp, as it will help with noise, and the hexaphonic output impedance is quite a bit lower at about 100 ohms.

the GK pins for power are
pin 12 = +7v
pin 13 = -7v
link to GK schematic below
https://www.vguitarforums.com/smf/index.php?action=dlattach;topic=73.0;attach=6662
The GK switch should be left in the 'Mix' position to use both the buffered normal guitar out an the hex signals.

[Verchrona]

9 volt instead of 7 volt will be fine, but you need a balanced dual supply of +9v 0v -9v, which could be derived from a buck converter module
https://www.digikey.com/en/products/detail/xp-power/IHA0109D09/6220996?s=N4IgTCBcDaIJIAkCCAGAjCgnAESyAugL5A

the 5 volt output from the GK module is only required for volume voltage control of the GK synth unit and not required in your case.
I would use the onboard preamp, as it will help with noise, and the hexaphonic output impedance is quite a bit lower at about 100 ohms.

the GK pins for power are
pin 12 = +7v
pin 13 = -7v
link to GK schematic below
https://www.vguitarforums.com/smf/index.php?action=dlattach;topic=73.0;attach=6662
The GK switch should be left in the 'Mix' position to use both the buffered normal guitar out an the hex signals.

Good to know 9V works on the board. The issue is the buffer for the standard mag out. Fuzz is an effect on the instrument, which I need a high impedance signal. Is it ok to have the hex be buffered, while the normal mag completely bypass the GK board, but meet up at the 13 pin jack (pin 7) as an unbuffered signal?

The reason for this is that I also need true bypass for the normal mag sound, that will operate in case no power is present, or dead battery onboard.

[admin]

Good to know 9V works on the board. The issue is the buffer for the standard mag out. Fuzz is an effect on the instrument, which I need a high impedance signal. Is it ok to have the hex be buffered, while the normal mag completely bypass the GK board, but meet up at the 13 pin jack (pin 7) as an unbuffered signal?

The reason for this is that I also need true bypass for the normal mag sound, that will operate in case no power is present, or dead battery onboard.

Need an active high Z to low Z  buffer on guitar for  Normal pickup.

On every GK 13 processor, its pin 7 normal pu input is low Impedance, as it expects a buffered GK-3 output signal

[Verchrona]

Need an active high Z to low Z  buffer on guitar for  Normal pickup.

On every GK 13 processor, its pin 7 normal pu input is low Impedance, as it expects a buffered GK-3 output signal

I actually never intend to use one of the GK processors, because I am running into a daw. Possibly a breakout to pedals first for the normal mag, which is why I was interested in keeping it high impedance. Is it ok to do so if the user is not using one of those GK units?

[admin]

I actually never intend to use one of the GK processors, because I am running into a daw. Possibly a breakout to pedals first for the normal mag, which is why I was interested in keeping it high impedance. Is it ok to do so if the user is not using one of those GK units?

Left HiZ - it will be prone to crosstalk from active divided pu signals on pins 1-6

And possible  pulse noise injection from S1/S2 switches invading the normal pickup signal path.

[Verchrona]

Left HiZ - it will be prone to crosstalk from active divided pu signals on pins 1-6

And possible  pulse noise injection from S1/S2 switches invading the normal pickup signal path.

Hmm I see, what I'm going to do is actually install a different buffer circuit for the normal mag, taken from a pedal, because it sounds very nice. This means the normal mag sound does not go through the GK board, but will meet up at the 13 pin jack.

Should I bridge the wires from the GK/MAG selector to MIX in this case as well, or bridge it to the GK side only?

[admin]

Hmm I see, what I'm going to do is actually install a different buffer circuit for the normal mag, taken from a pedal, because it sounds very nice. This means the normal mag sound does not go through the GK board, but will meet up at the 13 pin jack.

Should I bridge the wires from the GK/MAG selector to MIX in this case as well, or bridge it to the GK side only?

Review the GK-3 schematic
https://www.vguitarforums.com/smf/index.php?topic=133.0

[Verchrona]

Ok thanks, so from what I gathered, the switch is an ON Off ON DPDT.

To have synth only output, the following are bridged:

Yellow to green.
White to black(shield).
The rest are negated, heat shrink the ends and leave disconnected.

[Verchrona]

9 volt instead of 7 volt will be fine, but you need a balanced dual supply of +9v 0v -9v, which could be derived from a buck converter module
https://www.digikey.com/en/products/detail/xp-power/IHA0109D09/6220996?s=N4IgTCBcDaIJIAkCCAGAjCgnAESyAugL5A

the 5 volt output from the GK module is only required for volume voltage control of the GK synth unit and not required in your case.
I would use the onboard preamp, as it will help with noise, and the hexaphonic output impedance is quite a bit lower at about 100 ohms.

the GK pins for power are
pin 12 = +7v
pin 13 = -7v
link to GK schematic below
https://www.vguitarforums.com/smf/index.php?action=dlattach;topic=73.0;attach=6662
The GK switch should be left in the 'Mix' position to use both the buffered normal guitar out an the hex signals.

Hey that's for referencing the buck converter, i havent used one before. Can you check if this sounds correct? A bit afraid to fry something.

On the XP Power module:
Pin 1: 9V+ that's also powering every other effect(built in overdrive)
Pin 2: GND (negative from 9V supply)

Pin 5: 9V+ that goes to GK Board
Pin 6: 0v, unsure, does this get grounded?
Pin 7: 9V- that goes to GK board

[philjynx]

You connect the +9 0 -9 from the buck to the corresponding +7 0 -7 on the GK board.

BTW the GK board does not, as you said 'need' 5v for synth volume, the only supply to the GK is the +7 0 -7.

It sends a variable voltage to pin 8 which can be assigned on the synth to synth volume or a few other functions.

It uses a small resistor network to vary a voltage OUTPUT on pin 9 to select synth/ mix /guitar mix.

[gumtown]

yes the 0v gets grounded, many (not all) of these converters have the output voltage isolated from the input voltage.

[philjynx]

On the XP Power module:
Pin 1: 9V+ that's also powering every other effect(built in overdrive)
Pin 2: GND (negative from 9V supply)

Pin 5: 9V+ that goes to GK Board
Pin 6: 0v, unsure, does this get grounded?
Pin 7: 9V- that goes to GK board

Strongy recommend that you follow convention and sign your voltages at the front, eg +9V, -9V
Trailing signs can be misinterpretted as gramatical rather than arithmetical, especially if a rogue space finds its way into the text.

[Verchrona]

Ok guys thanks very much for the assistance. Will do with the proper voltage grammar.

[GuitarBuilder]

What do you plan on doing with the string signals in a DAW? Are you going for pitch detection or audio effects?

I ask because GK3 pickups are not known for producing good audio quality.

[Verchrona]

What do you plan on doing with the string signals in a DAW? Are you going for pitch detection or audio effects?

I ask because GK3 pickups are not known for producing good audio quality.

I am actually trying to use it for audio only, processing individual strings differently with different amp Sims. So far, there is a huge noise issue on the onboard hex fuzz I built.

[Verchrona]

9 volt instead of 7 volt will be fine, but you need a balanced dual supply of +9v 0v -9v, which could be derived from a buck converter module
https://www.digikey.com/en/products/detail/xp-power/IHA0109D09/6220996?s=N4IgTCBcDaIJIAkCCAGAjCgnAESyAugL5A

the 5 volt output from the GK module is only required for volume voltage control of the GK synth unit and not required in your case.
I would use the onboard preamp, as it will help with noise, and the hexaphonic output impedance is quite a bit lower at about 100 ohms.

the GK pins for power are
pin 12 = +7v
pin 13 = -7v
link to GK schematic below
https://www.vguitarforums.com/smf/index.php?action=dlattach;topic=73.0;attach=6662
The GK switch should be left in the 'Mix' position to use both the buffered normal guitar out an the hex signals.

Hey,

I installed the buck converter module and got very strange voltages on my GK board.

Using this diagram here:
https://www.joness.com/gr300/13-pin.htm

The pin that supposed to be ground is reading -7.56v

The pin that supposed to be +7v reads +1.81.

The pin that supposed to read -7v reads -16.94v.

There is a ton of noise on my onboard hex fuzz. (I tested each section by itself with a normal Guitar signal, the hex fuzz is fully operational.

Did I wire something wrong here?

I put:
+9v into pin 1 of the converter.
Gnd pin 2 of the converter.

Pin 5 goes to -7v on GK board.
Pin 6 goes to GND on the GK board.
Pin 7 goes to +7v on the GK board.

On the gk board, it is the RED, WHITE, WHITE, WHITE, WHITE, WHITE, WHITE connector I connected to.

Red and the first 3 whites are not connected.

The last 3 whites are GND, +7, -7.

However that GND point is reading a -7.56v. Very strange because the yellow wire from the other connector is grounded.

Should I ground that white wire that says ground? Right now, connected to it is the 0v pin from the buck converter.

[gumtown]

Hard to say what is going on without knowing what type/brand/specification DC/DC converter you have, does not sound like the output is isolated from the input, and it will make lots of EMF noise unless it is in a shielded can.

As per my previous pst #12

yes the 0v gets grounded, many (not all) of these converters have the output voltage isolated from the input voltage.

[admin]

installed the buck converter module and got very strange voltages on my GK board.

Thats a huge EMI/RF generator

A Mu metal surround might tame its radiated noise.

But a linear power supply will exhibit lower noise near guitar pickups

https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.ti.com/lit/pdf/snva886&ved=2ahUKEwi3nLbM8f_6AhWCLEQIHWCqA-kQFnoECBQQAQ&usg=AOvVaw2ifBCU2uFaZWaMjlpmKMu_

[gumtown]

Thats a huge EMI/RF generator

A Mu metal surround might tame its radiated noise.

But a linear power supply will exhibit lower noise near guitar pickups

https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.ti.com/lit/pdf/snva886&ved=2ahUKEwi3nLbM8f_6AhWCLEQIHWCqA-kQFnoECBQQAQ&usg=AOvVaw2ifBCU2uFaZWaMjlpmKMu_

I think the proposed supply is a single 9 volt pedal type supply.

An alternative would be to use two 9v batteries, they would last a while, and provide easy clean power.

[Verchrona]

I think the proposed supply is a single 9 volt pedal type supply.

An alternative would be to use two 9v batteries, they would last a while, and provide easy clean power.

Thanks for the help, grounding that pin got the correct 0, +9, -9 volts to the board, the noise is still super high, I will look into shielding solutions.

[gumtown]

Your DC/DC buck converter module could possibly not have any output filtering,
 try a 0.01uF capacitor and 10uf electrolytic capacitor (in parallel) across each 9V DC output.