Which GK to upgrade a GK2 (not A)

Started by vmgk, September 20, 2022, 04:43:56 AM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

vmgk

Hi everyone, I'm new in the forum and I've found a lot of good information. I would like to have your opinions about replacing a GK2 (older one). I'm using it on a les paul to drive an ancient GR50 and lately a VG88 v2, mostly at home to record ideas and input some midi parts. My idea was to turn the VG88 into a backup device in case of amp or pedalboard failure, and using the split pickup to play a few acoustic parts live. What I've found is that the GK2 is very noisy with high gain pathches, for example the Van Halen in 'SOUNDS DER HELDEN' collection. The noise is both background hiss as well as loud noise when touching/scrubbing the pickup itself or even the cable from pickup to control unit. GK cable is ok. For the MIDI use or acoustic models this is not a big issue, unless I hit the pickup. I've read the possibility that GK2 (old) is a single coil pickup, and GK2A is humbucker. Any info on that? Could it be that 'A' stands for audio, since prior to VG units the signal was only used to trigger midi (so hiss/noise was filtered).

Right now I have three more GK pickups I can install (don't ask), any suggestion on which to try first?

Available Pickups:
GK2 
GK2a (needs some fixing to the pickup enclosure)
GK3
AXON PU100 (Seymour duncan designed)

Guitar: Les Paul
Devices: Roland VG88 and GR50

Previous owner says AXON in MIDI application (GR33) was better than Roland (less false triggering octave jump) but has no experience with VG.

Thanks. Marco

admin

#1
Quote from: vmgk on September 20, 2022, 04:43:56 AMHi everyone, I'm new in the forum and I've found a lot of good information. I would like to have your opinions about replacing a GK2 (older one). I'm using it on a les paul to drive an ancient GR50 and lately a VG88 v2, mostly at home to record ideas and input some midi parts. My idea was to turn the VG88 into a backup device in case of amp or pedalboard failure, and using the split pickup to play a few acoustic parts live. What I've found is that the GK2 is very noisy with high gain pathches, for example the Van Halen in 'SOUNDS DER HELDEN' collection. The noise is both background hiss as well as loud noise when touching/scrubbing the pickup itself or even the cable from pickup to control unit. GK cable is ok. For the MIDI use or acoustic models this is not a big issue, unless I hit the pickup. I've read the possibility that GK2 (old) is a single coil pickup, and GK2A is humbucker. Any info on that? Could it be that 'A' stands for audio, since prior to VG units the signal was only used to trigger midi (so hiss/noise was filtered).

Right now I have three more GK pickups I can install (don't ask), any suggestion on which to try first?

Available Pickups:
GK2 
GK2a (needs some fixing to the pickup enclosure)
GK3
AXON PU100 (Seymour duncan designed)

Guitar: Les Paul
Devices: Roland VG88 and GR50

Previous owner says AXON in MIDI application (GR33) was better than Roland (less false triggering octave jump) but has no experience with VG.

Thanks. Marco


To effectively run a GR-50 and VG-88 V2

a Wax Potted GK-2A , or Yahama G1D divided pickup works best

GK-2A has higher ouput vs GK-3

GK-3 Users often complain about weak GK String Level on GR-50 (GK Senstivity) as GK-3 was released much later than the GK-2A.

Wax Pot the GK-2A or Yamaha G1D divided pickup - many are microphonic and may squeal with high pitch feedback when used with the VG-88 V2 VGuitar System high gain settings.
https://www.vguitarforums.com/smf/index.php?topic=43.0

Mount either GK-2A or Yamaha G1D to the guitar - get the divided PU aligned with the strings and height set correctly.

I was told the GK-2A is lower noise vs the older GK-2 - which was Rolands 1st 13 pin pickup intended for the GR-50

The GK-2A is supposed to be  less noise and less hum vs  GK-2 - was told by Roland its becase GK-2A is humbucking 

Roland GK pickup history
https://web.archive.org/web/20160309133620/http://wiki.csisdmz.ul.ie/wiki/Guitar_Synths_%26_the_GK-2_pick-up

admin

#2
I have not experienced Axon AX-100 (Seymour Duncan) GK pickup  - Europe has the highest population of these
- Roland Corp legal department effectivly blocked its release in USA as the Radius Adjust screw violated Rolands GK-3 Patent  - this lawsuit as well as global lead free WEE/RoHS initiative and slow sales effectively forced Teratech to cease production of the Axon products   

vmgk

Thanks for your answer. I'll try to fix all of them in a removable way and compare the results. I've made my own GK2 metal support, but hole spacing is different from other pickups, so before crafting a new one I have to decide what's best. Also my GK2 pickup is now half open and I'll try to understand if it's really a single coil (I suppose it is). If anybody is interested in the subject I'll try to photo the differences between the pickups guts. I realize I have all the GK family on my bench plus this rather unknown Axon/Duncan PU100. If it has GK2A output level, I bet it's going to be the winner (I was also told it was more expensive than Roland GK at the time)

whippinpost91850


vmgk

#5
Meet the family. The open pickups are GK2 (leff) and GK2A (right). Main difference is that GK2 has a rigid PCB and the coils are glued to the top plastic panel of the pickup, so removing the PCB means destroying the winding connection, unless desoldered or unglued. Lifting just a little pcb shows the coils that seem single. The stepped design of top panel makes the radius of the individual coils. On the right the dual coils of GK2A mounted on a flexible pcb that allows for radius.

Below is a comparison between PU100 (left) and GK3 pickup. Since this are in working condition, I'd rather not open them.

Some quick masures I took (millimeters)

Mounting hole distances: GK2 85.7  Axon PU100 96.5 GK3 95.1

Pole distances (innner-outer)

GK2 47.4 56.6
GK2a 47.5 55.6
GK3 48.5 59.1
PU100 49.7 57.9

Pole spacing

GK2 6.5
GK2a 5.5
GK3 4.8
PU100 5.5

GK3 has the widest coils (closer one tho the other), old Gk2 the most separate.

Resistance per coil (ohm)

GK2    83
GK2A   59

admin

Quote from: vmgk on September 21, 2022, 01:52:27 AMMeet the family. The open pickups are GK2 (leff) and GK2A (right). Main difference is that GK2 has a rigid PCB and the coils are glued to the top plastic panel of the pickup, so removing the PCB means destroying the winding connection, unless desoldered or unglued. Lifting just a little pcb shows the coils that seem single. The stepped design of top panel makes the radius of the individual coils. On the right the dual coils of GK2A mounted on a flexible pcb that allows for radius.

Below is a comparison between PU100 (left) and GK3 pickup. Since this are in working condition, I'd rather not open them.

Some quick masures I took (millimeters)

Mounting hole distances: GK2 85.7  Axon PU100 96.5 GK3 95.1

Pole distances (innner-outer)

GK2 47.4 56.6
GK2a 47.5 55.6
GK3 48.5 59.1
PU100 49.7 57.9

Pole spacing

GK2 6.5
GK2a 5.5
GK3 4.8
PU100 5.5

GK3 has the widest coils (closer one tho the other), old Gk2 the most separate.

Resistance per coil (ohm)

GK2    83
GK2A  59

Confirms the GK-2A is humbucking,
while GK-2 is not.

Review the Divided Pickup physical dimension comparison

https://www.vguitarforums.com/smf/index.php?topic=41.0#msg61785

vmgk

Quote from: admin on September 21, 2022, 07:51:53 AMConfirms the GK-2A is humbucking, while GK-2 is not.

By looking in the holes of GK2 PCB, it seems like there are two coils... so maybe it's not single coil. I'll have to look closer.

vmgk

Confirm that the GK2 seems to be humbucking as well upon closer inspection.
Spent a few time to resolder the wire on the GK2A and 3d printed a new lower plate for the pickup.
So the pickup is not 100% stock, but seems fully functional.

Unfortunately the background noise level seems almost the same as the old GK2.
Gk3 and PU 100 noise level is much lower, so that should rule out cable issues.

The test is like this:

- VG88 firmware updated to v2.
- preset: Van Halen from 'SOUNDS DER HELDEN' collection.
- output type: line / headphone
- output level potentiometer: max
- Driver setup : type Gk2A or GK2, string sensistivity between 76 and 86
- Expression pedal position: max
- Gk connected to VG 88 with 5m cable, not mounted on the guitar, headphone, no other unit connected to VG88

Result is a constant hiss/whoosh with GK2 and GK2A. With GK3 and PU100 it's much lower.
Of course rising the noise gate migth tame the noise, but at the cost of loosing dynamics.

I'll try to connect an oscilloscope to give 'numbers' about the noise level.

admin

#9
We know the GK-2A has higher output vs GK-3

Higher output levels presents potential for higher noise.

Thats wby VG-88 is equipped with a "N.S. (Noise Supressor)- to minimize noise and mute when not playing -enable the N.S.

There are third party solution to address higher signal to noise ratio - using an improved GK preamp from Bill Bax

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