Author Topic: GK3 Unpowered Mod  (Read 635 times)

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Offline nix808

GK3 Unpowered Mod
« on: January 31, 2017, 05:15:45 AM »
Heya!
I was wondering what you guys thought of getting a GK3 Internal Kit,
and using a soundcard with preamps instead of the Roland amplification circuitry.
This would make it a passive pickup hopefully.
This sounds good to me.
Are there any problems with this idea?
I understand the pickup is 8 leads,-
hmm- are there 2 grounds? or why is there 8, not 7?
I would hopefully use a 7-pin MIDI jack and telephone wire to route to the soundcard.
Cheers!-Rock On
Rock and Rock my boat, as long as you don't rock and rock my boat!hehe

Offline gumtown

Re: GK3 Unpowered Mod
« Reply #1 on: January 31, 2017, 01:37:25 PM »
Signal to noise ratio might be an issue, the GK buffer circuits convert (and amplify) the GK pickup from high impedance to low impedance (about 150 ohms).
You may find your lead will become very noisy, it is worth a try though.

And the reference to a 7 pin MIDI jack?
Do you mean a 7 pin DIN socket? Just to avoid confusion that no midi is involved with the pickup signals.
Free "GR-55 FloorBoard" editor software from http://sourceforge.net/projects/grfloorboard/

Offline Elantric

Re: GK3 Unpowered Mod
« Reply #2 on: January 31, 2017, 01:42:04 PM »



BillBax sells a low noise GK-Buffer  GK Studio Extreme

http://www.separate-strings.co.uk/gk%20studio%20extreme.html




« Last Edit: January 31, 2017, 01:44:51 PM by Elantric »

Offline nix808

Re: GK3 Unpowered Mod
« Reply #3 on: January 31, 2017, 05:10:11 PM »
Thanks mate,
I think I'll try it then.

Yep, I meant a 7-pin MIDI DIN socket and lead to wire the audio, not midi, into the mixer/soundcard,
through a simple breakout into ts patch leads.

Ta for the links to BillBax, I'll keep that unit in mind.

So- could anyone help me as to why there are 8 wires, not 7 coming out of the pu?
Rock and Rock my boat, as long as you don't rock and rock my boat!hehe

Offline Elantric

Re: GK3 Unpowered Mod
« Reply #4 on: January 31, 2017, 05:15:25 PM »
Quote
So- could anyone help me as to why there are 8 wires, not 7 coming out of the pu?


(6) Output from Six Individual pickups

(1 ) Analog Ground Reference

(1) Earth Shield

= 8 total wires

review this thread

Schematics
http://www.vguitarforums.com/smf/index.php?topic=73.0


Offline nix808

Re: GK3 Unpowered Mod
« Reply #5 on: January 31, 2017, 06:00:52 PM »
Thanks, I'll let you know how the snr goes.
I can feel a headless build coming on.

Cheers gumtown and Elantric
Rock and Rock my boat, as long as you don't rock and rock my boat!hehe

Offline nix808

Re: GK3 Unpowered Mod
« Reply #6 on: March 31, 2017, 01:50:53 AM »
I just returned to this thought, as I had a half busted GK3.
Seems like it works OK.
There is no cable noise, but maybe it's half as loud.
Will post a pic tonight!
Cheers 8D
Rock and Rock my boat, as long as you don't rock and rock my boat!hehe

Offline billbax

Re: GK3 Unpowered Mod
« Reply #7 on: March 31, 2017, 06:01:08 AM »
Hi nix808,

A mic input will work best with a GK3 sensor and no buffer preamp. An unbuffered GK sensor's dynamic-range is likely to be in the area of 60-70dB.  If you were to use a line-input and a dedicated GK preamp with optimized component values, the noise-floor will drop to around -105dB.  Separate string output levels are about 1V, and harmonic distortion is around 0.005% THD. A 35dB difference in dynamic-range is quite dramatic, especially when you're recording separate strings.

An unbuffered GK sensor might be fine to plug into a floor pedal like the Boss OC-3, allowing selected individual strings to be pitched down.  In recording however, and unbuffered GK sensor will sound very poor.  Perhaps you want to use a GK sensor for some other purpose?

Good to hear you're having some success, and no intelligence insult intended in my reply.

Bill

www.separate-string.co.uk

Offline nix808

Re: GK3 Unpowered Mod
« Reply #8 on: March 31, 2017, 06:20:56 AM »
oh none taken, and thanks so much for the technical information!
Yeah, I'm just looking at the level now,
but my soundcard meters don't have db.
It seems I need 7 X as much digital amplification multiplier,
but I only have the soundcard preamps up half way atm.
My other soundcard which is now slightly incompatible is disconnected, but will give me db when I return to Win7.
It does track fine though, also the luthering on the guitar is terrible action-wise atm-
so I can't play as quickly.

I just jacked the preamps all the way up to +20db and now it is about 3x quieter than the active GK3 on 0db preamp.

I'm happy- I don't model, so any tone loss is fine, as long the pups communicate pitch perfectly, so yeah my purpose is to use a VST to do MIDI conversion.

Cheers Bill!
Rock and Rock my boat, as long as you don't rock and rock my boat!hehe

Offline nix808

Re: GK3 Unpowered Mod
« Reply #9 on: April 28, 2017, 12:36:28 PM »
Here is the pickup before I put the adapter in the control cavity->


Rock and Rock my boat, as long as you don't rock and rock my boat!hehe

Offline Elantric

Re: GK3 Unpowered Mod
« Reply #10 on: April 28, 2017, 12:40:27 PM »
IMHO - installing  a non buffered magnetic hex PU will be prone to noise and signal loss of cable capacitance.


Most folks use a stock GK-3, then feed the 13 pin cable to a remote 6 channel break out box 

find them here:

Gk Accessories
http://www.vguitarforums.com/smf/index.php?board=13.0


* Bill Bax's mini GK13 Breakout Cable
http://www.vguitarforums.com/smf/index.php?topic=11851.0



Ricky Graham's Septar Kit for Hex Guitar to PC processing with Pure Data (PD)
http://www.vguitarforums.com/smf/index.php?topic=4222.0



RMC Fanout box
http://www.vguitarforums.com/smf/index.php?topic=2062.0




SpiceTone 6Appeal
http://www.vguitarforums.com/smf/index.php?topic=12104.0

« Last Edit: April 28, 2017, 12:49:01 PM by Elantric »

Offline GuitarBuilder

Re: GK3 Unpowered Mod
« Reply #11 on: April 28, 2017, 01:01:08 PM »
I'm building a next-generation hex guitar, using the Cycfi Research Nu Multi pickup instead of the Roland approach (full build thread planned in future):

http://www.cycfi.com/projects/nu-series/

I like the idea of being able to get 6, 7, 8 string pickups with built-in buffers, or even make your own with any number of individual pickups.  The 6-string cost is higher than an internal GK kit (not by that much), but one gets state-of-the-art low-power consumption pre-amp circuitry and full customization ability (it's all open source!).  Since this hex pickup has a flat response from 20 - 20,000 Hz, it is far more capable than the Roland GK-3 and can double as a regular bridge pickup.  When you consider that feature, the price difference is pretty much nullified.  Check out the posts on virtual pickup processing on their site!

This is what Roland should have built as the replacement for the GK-3.

Offline nix808

Re: GK3 Unpowered Mod
« Reply #12 on: April 28, 2017, 01:16:28 PM »
Thanks for all the links, and advice Elantric!
Here's high E finger picked, with all preamps at 20db gain->


I actually use the powered GK3 in strap button housing in 2 guitars also,
here is my mains breakout->


I'm going to construct 4 breakouts, 2 of which will be powered 13 pin, and 2 passive 7-pin DIN

edit- just saw your post Guitar Builder. I am so interested in the 6-pack, Elantric put me onto it I think.
I have experience with single-coil form factor pups, you will really have to watch out for cross-string interference.
It makes the high notes difficult to read for MIDI, when an adjacent string is ringing over them.
If you post a build thread, I would check it keenly.
Rock and Rock my boat, as long as you don't rock and rock my boat!hehe

Offline Elantric

Re: GK3 Unpowered Mod
« Reply #13 on: April 28, 2017, 01:18:35 PM »
I'm building a next-generation hex guitar, using the Cycfi Research Nu Multi pickup instead of the Roland approach (full build thread planned in future):

http://www.cycfi.com/projects/nu-series/

I like the idea of being able to get 6, 7, 8 string pickups with built-in buffers, or even make your own with any number of individual pickups.  The 6-string cost is higher than an internal GK kit (not by that much), but one gets state-of-the-art low-power consumption pre-amp circuitry and full customization ability (it's all open source!).  Since this hex pickup has a flat response from 20 - 20,000 Hz, it is far more capable than the Roland GK-3 and can double as a regular bridge pickup.  When you consider that feature, the price difference is pretty much nullified.  Check out the posts on virtual pickup processing on their site!

This is what Roland should have built as the replacement for the GK-3.
Quote
I have experience with single-coil form factor pups, you will really have to watch out for cross-string interference.
It makes the high notes difficult to read for MIDI, when an adjacent string is ringing over them.
If you post a build thread, I would check it keenly.



I look forward to adjacent string crosstalk comparison of  Cycfi Nu Hex PU vs a GK-3

just based upon looking at the pics of  Cycfi Nu- I predict this will be a battle

(but the rest of the design looks great)

http://www.cycfi.com/projects/nu-series/



The Cycfi Research developer used to have a thread here at VGuitarforums a few years ago, but i see he deleted it. 

I admit I inquired if he had taken minimum Adjacent string crosstalk  as a design goal but he admitted I was the only person who asked and it it was not part of   his goals for Cycfi pickups
« Last Edit: April 28, 2017, 02:03:53 PM by Elantric »

Offline nix808

Re: GK3 Unpowered Mod
« Reply #14 on: April 28, 2017, 02:18:08 PM »
Oh hmm, well we can hope they aren't too bad-
last time I battled with Paul Rubenstein ones I came off second best.

Here are pictures of the finished mod:-




Don't worry, it's not a real mx 220 hehe
Rock and Rock my boat, as long as you don't rock and rock my boat!hehe

Offline GuitarBuilder

Re: GK3 Unpowered Mod
« Reply #15 on: April 28, 2017, 10:04:19 PM »


I look forward to adjacent string crosstalk comparison of  Cycfi Nu Hex PU vs a GK-3

just based upon looking at the pics of  Cycfi Nu- I predict this will be a battle

(but the rest of the design looks great)

http://www.cycfi.com/projects/nu-series/
(Image removed from quote.)


The Cycfi Research developer used to have a thread here at VGuitarforums a few years ago, but i see he deleted it. 

I admit I inquired if he had taken minimum Adjacent string crosstalk  as a design goal but he admitted I was the only person who asked and it it was not part of   his goals for Cycfi pickups

Forum member @chlorinemist has a working system using the Nu Multi and 6APPEAL; perhaps he could answer the crosstalk question.  I'll be able to provide my input in about a month, since mine is a scratch build instead of a retrofit.

Offline chlorinemist

Re: GK3 Unpowered Mod
« Reply #16 on: May 16, 2017, 07:43:29 PM »
Forum member @chlorinemist has a working system using the Nu Multi and 6APPEAL; perhaps he could answer the crosstalk question.  I'll be able to provide my input in about a month, since mine is a scratch build instead of a retrofit.

Joel from Cycfi reports -49dB crosstalk at 1mm and -54dB with active cancellation (i assume this is a forthcoming tech). I'm not well versed in the specs of other hex PUs but according to him -54dB is nearly 3x better performance than a GK-3.

I have not used to the Nus specifically for pitch to midi (i use a fishman tripleplay for that) but i have heard from other users that it performs very well. With regards to polyphonic effects like string panning, poly envelope modulation, etc., i have had absolutely no issues whatsoever with crosstalk. String seperation behaves exactly as expected. Only time i eved noticed crosstalk at all was when i muted some strings on the 6appeal by accident and started plucking them extra hard, wondering why they were so much quieter than all the other strings.

This topic reminds me of a recent development I've see n from the Cycfi guys. Theyre doing a collab with Strandberg on a 9 string with Nus in the bridge AND neck positions! I asked Joel how he could do that without excessive crosstalk. He didnt give me stats for the neck position crosstalk but he said for poly fx purposes it seemed more than usable during testing, though he did note that string bends can cause the strings to "travel" between channels on the neck pickup. He gave the example of string panning: if you bend a string, the note will pan back and forth as you bend. Kinda cool.

« Last Edit: May 16, 2017, 08:44:25 PM by chlorinemist »

Offline nix808

Re: GK3 Unpowered Mod
« Reply #17 on: May 17, 2017, 11:27:37 PM »
Oh, that's great news ChlorineMist,
I will build one of these Nus for MIDI sometime in the next few years.
Rock and Rock my boat, as long as you don't rock and rock my boat!hehe

 

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