Help with internal GK-kit, please.

Started by hollowbody, April 13, 2012, 09:07:29 AM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

hollowbody

Hi, I'm almost done with installing an internal GK3 kit into a stratocaster style guitar.

Now I didn't want an extra volume poti for the GK volume (since I never mix the normal PU with the GK one).
I want the normal guitar vol poti to function as a master vol. (When the selector switch is on guitar, it should control the normal PU vol and when in the GK position it should control the GK volume)

Leaving out the three pins for the GK Volume resulted in no sound at all.
When I shortcut the red and white pins on the preamp board, then I hear the GK sound, but it's always 100% volume.

So when I try to connect the three pins for the GK vol poti to the normal guitar volume poti, then it's okay for the GK Vol, but the normal PU sound gets muted.

Is this because they need different ohmic resistance? (the supplied poti for the GK Vol is 50kOhm)

Is there a way I can control both with just one poti?

Many thanks


Elantric

#1
Its not really a good idea to not install the GK Synth Volume pot

Gibson had the same problem with the Dark Fire


See the schematic below and note R7 and R8, as this resistive ladder voltage divider referencing Pin #8 (GK Vol) will enable full synth volume on your GR-55, VG-99. 


R8  = 243 ohm
R7 = 121 ohm

Both are 1% resistors




Although it may be simpler to locate a very small pot to swap for the supplied GK-Vol pot,  and wire it to the internal Gk PC board just as the GK-Kit instruction explain - but place this pot (turned full clockwise ) inside your Strat's  control cavity 

Elantric

Quote
As far as using one pot to control both magnetic pickup volume and gk volume,.. I have no clue. Suggest trial and error.


This can be accomplished with a custom "Stacked" dual pot - but these are very tough to locate.

drjoness2001

#3
Send me a PM, I quite possible have the necessary part. In the older, vintage Roland guitars, there is a dual pot, 50K and 500K. The 500K section is for the normal humbucker, and the 50K is for the synth volume.

Finding a dual or stacked pot is not hard, the tough part is finding a pot with different values. You need 50K for the control (synth) voltage, and 10x that amount, 250K or 500K, for the humbucker side.


highlandsrock

Hi

If you have a problem getting hold of the pot you require have a look at this company - www.warwick-distribution.de - who advertise in the UK Guitarist magazine. Their advert shows dual and triple decker pots and says that they have a branch in New York.

Regards
Ibanez RG870 with GT3 internal kit +
GR-33, VG-99, GR-55, GP-10, SY-1000, Strymon Big Sky

hollowbody

Quote from: highlandsrock on April 13, 2012, 01:07:27 PM
Hi

If you have a problem getting hold of the pot you require have a look at this company - www.warwick-distribution.de - who advertise in the UK Guitarist magazine. Their advert shows dual and triple decker pots and says that they have a branch in New York.

Regards

Thank you all for your help!
Warwick indeed has a dual pot 50K/500K in their catalogue.

But I think I'll go another route.
I'll shape out another little piece of wood to have the space for a separate pot for the GK vol.

My guitar is now almost empty inside... ;)
I had quite a hard time fitting everything inside!

I'll post some pics when (or if...) I'm through.

Elantric

On my Frankenstrat i used a jack plate from an old Alembic StratoBlaster, and painted it to match the guitar  - so I could have more real estate to instal the GK Synth Vol pot.


 

aliensporebomb

Quote from: Elantric on April 13, 2012, 03:47:28 PM
On my Frankenstrat i used a jack plate from an old Alembic StratoBlaster, and painted it to match the guitar  - so I could have more real estate to instal the GK Synth Vol pot.




How does the sustainiac work with the GK pickup?  I read something at the Maniac Music website that said it wouldn't work so great for it due to the proximity of the GK circuitry, but I could think of it working nice for hex guitar stuff if guitar-to-midi might not work so well...
My music projects online at http://www.aliensporebomb.com/

GK Devices:  Roland VG-99, Boss GP-10, Boss SY-1000.

Brent Flash

Quote from: aliensporebomb on April 13, 2012, 05:02:07 PM
How does the sustainiac work with the GK pickup?  I read something at the Maniac Music website that said it wouldn't work so great for it due to the proximity of the GK circuitry, but I could think of it working nice for hex guitar stuff if guitar-to-midi might not work so well...
My Sustainiac works fine (not an internal GK). Is that what you are wondering about the internal GK and the Sustainiac?

Elantric

#9
I installed it myself back in 1999 -

Works fine -

And yes - Alan Hoover (inventor of the sustainiac - at  Maniac Music) said it would not work - but myself and Adrian Belew and Brent Flash know it can be done.

The mono passive Bridge PU is the crucial part of the sustainiac circuit, as that provides its signal source.

I believe the confusion for Mr Hoover was many Roland VG-8 players back then were building guitars with no other pickups  - only a GK-2A Internal kit PU as the only pickup on the guitar, and requesting a Sustainiac installation too- which can not be done on those type guitars - without Major Mods and great care!

The Sustainiac "Stealth Plus" will not work if the only other pickup on the guitar is a GK-3 , as  it relies on the normal passive magnetic Bridge pickup to obtain the source signal - (same as the  Fernandes Sustainer too BTW.)

That's a Seymour Duncan tapped staggered hot vintage PU in the bridge position - reverse angled to get closer to Hendrix / Dick Dale tone.

Every pot on that guitar is a Yamaha push -push pot - and its been 12 years since I built it - so even I need a refresher course on what each control does.

The guitar has a Fishman piezo Power Bridge, and a LR Baggs Piezo preamp( for acoustic tones) , a Roland GK-2A internal KIT, Fender  / Roland white hex PU, Sustainiac Stealth Plus at the neck, the Duncan Hot Vintage (with coil tap) in the bridge, and real 1961 Fender Strat Middle PU (for SRV stuff)  - a fat '59 Warmoth neck, and reverse left headstock  - which helps keep the tremolo more stable with the shorter E, B, G strings length above the Nut.
 
Thats Robin Trower's autograph above the pickguard.


I admit after doing it, there are many variables at work and the Sustainiac Driver board must be located far far away from the Roland GK-Kit internal PC board -otherwise its a big noise generator - and on mine the metal white painted "load plate" must be carefully located to find the sweet spot with minimum noise.


In hind sight, temporarily removing the load plate might be useful for UFO noises actually! ;)


--

Here's a good site with an overview to wrap your brain around how these sustainers operate:

http://www.fernandesguitars.com/sustainer/sustainer.html





   

hollowbody

#10
Hi, I just wanted to let you know how I did it.

I removed the middle knob and replaced it with the GK volume pot.

So, first know knob is Volume normal PUs
second knob is Volume GK
and third knob is Tone control (now for all three normal PUs).

The three way switch is Normal PU - Mix - GK.

Thanks all for your help!

By the way, a friend commented, my LED looks like an inflamed pimple on the back of the guitar... ;D



datsunrobbie

Nice looking install. On mine I also went with GK volume in place of the first tone knob, then replaced the second tone knob with concentric 250K posts, so I get two tone pots with 1 knob.

Enticing_Scarab

Sorry for reviving a dead thread, but is it possible to replace the stock volume pot that comes with the internal GK kit and use your own? I see the pics on here all have volume pots for the GK's that match the other pots on the guitar.

gumtown

The orginal pot in the guitar won't do as the resistive value is incorrect, but you can just re-use the knob, if the knob doesn't fit the GK volume pot, you can replace the pot with one of the same value as the GK kit one, but with different shaft type/size.
Free "GR-55 FloorBoard" editor software from https://sourceforge.net/projects/grfloorboard/

Enticing_Scarab

Quote from: gumtown on November 03, 2012, 02:32:38 PM
The orginal pot in the guitar won't do as the resistive value is incorrect, but you can just re-use the knob, if the knob doesn't fit the GK volume pot, you can replace the pot with one of the same value as the GK kit one, but with different shaft type/size.

Yeah, I meant just the knob/dial, shouldn't have said 'pot' in retrospect. Is the standard GK volume pot a roughly standard size, as they go? I intend to put some of this style knob on http://www.aliexpress.com/store/product/10x-Genuine-Volume-Tone-Control-Knob-Silver-Dome-Knobs-Steel-Guitar-Push/203288_569370545.html. I thought volume knobs all had a fairly standard size?

gumtown

Yes those knobs will fit, i am not aware the GK-Kit-GT comes with a knob for the pot anyway.

The GK-Kit-GT pot has a splined shaft, where as the GK-3-Wart has a half round shaft.

Free "GR-55 FloorBoard" editor software from https://sourceforge.net/projects/grfloorboard/

Enticing_Scarab

Quote from: gumtown on November 07, 2012, 01:32:32 PM
Yes those knobs will fit, i am not aware the GK-Kit-GT comes with a knob for the pot anyway.

The GK-Kit-GT pot has a splined shaft, where as the GK-3-Wart has a half round shaft.



Yeah I'd looked and couldn't see a volume knob on the internal kit... another thing that made me think a bit! Thanks for your help :)