DIY ergonomic GK guitar

Started by bea, June 21, 2016, 04:27:26 PM

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bea

Hi everybody,

This project started from the idea of fitting a GK-3 electronics into an already existing ergonomic guitar prototype. Unfortunately the small ergonomic body did not have enough space for the holes of the GK electronics. So i had to modify the guitar massively. The project is still work in progress.

Let me start from the very beginnings, 4 years ago. With the exception of the GK hardware this is a low budget project.
Neck taken from an old cheap guitar, but straight, stiff an nice neck profile.



Body (the wood below the neck): two layers of glued laminated timber (spruce), relatively densely grained and for at least 8 years in my cellar and still straight.

My rough idea on the shape - you might get an idea how the shape morphed between two approaches.


Glueing the body



rough shape of the headstock



rough shape of the body




bea

#1
Let's continue:

cardboard as headstock "veneer"



saddle (the neck has a zero fret):



The guitar was purely passive. Its LoZ pickup played fine through a microphone input. The sound can be modified by a C-switch and a tone control. In the brightest position it has a very nice sound resembling an acoustic guitar.

A few months later i did not like the color anymore - i found the combination of white, red black too aggressive (that's not a heavy metal axe...). And i could not resist when i saw a used GR-20...

Mhmm, where can i install the electronis...
And where the additional connector without losing the positioning comfort - that's possibly a difficulty inherent to any ergonomic design if the GK-stuff is added as an afterthought.



The only way: the body needs to be enlarged.

bea

#2
The only way: enlarge the body.
The final shape develops during the process to fit it to the body. The red dots are blood...





painting - although it would have been possible to repair the white color i chose to use the rest of the gold laquer that was left over from a bass build.



Meanwhile i have clearcoated the golden laquer, and it is time to polish it.

gumbo

Fantastic Beate..  !

Thanks for sharing    ..look forward to seeing more of this as the build progresses.. :D

Regards,
Peter
Read slower!!!   ....I'm typing as fast as I can...

gumtown

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

bea

Hello Peter,

Quote from: gumbo on June 21, 2016, 05:50:56 PM
Fantastic Beate..  !
Mhmm, far too may visible flaws :-(

Quote..look forward to seeing more of this as the build progresses..

coming soon.

Regarding my question on the baritone tuning: i'll put some .013-.056 or .015-.056 flats or halfrounds on it. Maybe take them from another guitar where i want to use lighter strings anyway (two of my archtops / semiacoustics) should prefer from slightly lighter strings...

These would be capable of tunings down to C-C (i am just testing it on another guitar) and still leave me with the possibility to change to standard tuning.

Elantric

#6
Bea, read

GR-55 - Any problem with baritone tuning?
https://www.vguitarforums.com/smf/index.php?topic=3155.msg20337#msg20337


Guitar Scale Length - Does it make an impact on COSM Pickup Modeling ?
https://www.vguitarforums.com/smf/index.php?topic=3200.msg20709#msg20709

whippinpost91850


bea

#8
Two more photos.

Polishing with Micromesh.



And mounting.



The electronics will be pretty minimal: the LoZ-Pickup already a C-Switch and a volume. As it connects nicely to a  microphone input, it will be played directly into the PA. The PU has an almost acoustical sound.
The 2nd pot will become the GK volume. The buttons to switch the sound will be omitted unless i find smaller switches. The signal of the synth will be sent to a 2nd channel of the mixing console or PA.

Amplification: either the PA isntalled in our rehearsal room or one of my old tube PAs - i own 2 Echolette M40, 2 Dynacord Eminent 2, a Dynacord Bassking 1, a set of vintage speakers for the M40 and a small cab with a Fane 12-100CT twin cone speaker. So i have the choice... (the best option on small stages and in sessions is probably the Eminent 2 with the Fane cab)

And the biggest prblem will probably the curvature of the GK3 pickup which is too strong for the close to flat fingerboard.

bea

The guitar itself is finished. The passive LoZ PU works as it should, and the GK part will be tested this night (with fresh and thick strings).

A few images of the instrument:






Elantric

#10
QuoteYou may have problems with the guitar modelling with the GK pickup so close to the bridge saddles. 

Agreed

review this thread

Can GK-3 PU be too close to the bridge??
https://www.vguitarforums.com/smf/index.php?topic=13322.0








Be sure you are measuring "GK PU Distance"  from Center of GK PU to the point where the string leaves the Bridge Saddle / or center of Kahler Roller.

For a GK-3 on a Guitar, I would be sure its at least 10mm away. 20mm is probably Optimal.

If the GK PU is set closer than 10mm - it will be sensing a smaller / shorter excursion of any vibrating string, with resulting drop in  the output level of the GK PU .


You can compensate by boosting the "GK Sensitivity" to a higher number - but this results in higher susceptibility to hiss and noise when using DSP COSM Guitar Modeling, with a likely requirement to enable the "COSM N.S. ( Noise Suppressor Gate) to tame the hiss  - but know there will be a resulting loss of picking dynamic range response.


If the GK PU is set too far away from the bridge saddle ( more than  30mm) - it will be sensing a higher / larger excursion of any vibrating string, with higher susceptibility of adjacent string cross-talk anytime you bend strings during Rock/Blues solos - and that creates poor tracking / ghost notes.


bea

Quote from: Elantric on June 28, 2016, 07:42:54 AM
review this thread

I did, and i already wrote about my frustration on Roland's misleading instructions (as close as possible...). It was actually pretty cumbersome to get the pickup that close to the bridge. Anyway, the distance measures from 8 mm to 10mm, dependent on the string. Using thick strings will require a larger compensation and thus a slighlty larger distance. I hope that will be sufficient to improve the situation. I am also going to try to make the gap between the strings and the PU as close as possible.

Elantric

#12
20mm away from bridge saddles is the target "ideal" location for Gk PU   -

Mounting the GK hex PU 10mm (or less) distance from bridge saddles will actually be "too close" and will yield many problems with poor Guitar to MIDI  / Guitar to PCM tracking and  / or weak COSM guitar modeling output on GR-55 / GP-10/ VG-99

read here
https://www.vguitarforums.com/smf/index.php?topic=13322.0

bea

I gave the guitar a few days until the guitar adapted itself to the string tension and did a thorough setup of the neck, the intonation and the distance of the poles of the GK-3 from the strings.

Except of the small distance of the GK-3 from the saddles everything is adjusted thoroughly.
Attached it to the Synth and did a 1st test with the GR-20. Basically it worked more or less out of the box, just needed some fine tuning of the output levels.

First impression:

everything seems to work fine, with the exception of the GK volume which gives a signal in just one position and silence everywhere else.

Tracking of the tones heights seems to be ok, at least mostly. The dynamic range is a bit limited.

I cannot judge wether this is simply a feature of the technologically old synth or indeed a problem with the position of the GK-3. The only way to decide this is to play it side by side to another GK guitar, and maybe through a GR-55.
But at leas spontaneously i do not feel the need to change the placement of the pickup - it seems to play fine.

At present my favorite setting is the double bass emulation.
Real fun to play "Fever", and thanks to the deep tuning this sounds fine.

bea

#14
2nd impression: test in the rehearsal room.

First through the PA. Small Yamaha amp, a pair of 12" fullrange speakers (EVM SX100+)
First impression:
- the GR20 is noisy like a waterfall.
2nd impression: nice sound but something is missing... not only the deep lows.

2nd try. My bass rig. Mywatt 200 (clone of Hiwatt DR201). 115 cab with Oberton 15L400, more or less compatible to a TL606, but neither midrange speaker nor tweeter. Slightly low tuning of the ports.

- way better. I had to turn down the presence pot (high treble). Thanks to the limited treble bandwidth this strongly suppressed the noise. The missing lows were there and the overall sound was a lot more "fresh" and "present".

Again no tracking issues obvious to beginners, but a strongly noticeable dependence on the playing technique (well, actually the damping technique...)


Finally a big thank You: without the information and the hints given by some of the users her i probably would not have brought it to play so effortless.