GR-55 -Modification to use as multi effects with any guitar

Started by baratijas, October 04, 2011, 05:08:31 AM

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Toby Krebs

Keep some of your favorites to put in the effect loop.I have patches on usb sticks for different configurations of eq/ dist and overdrives to use in the effect loop of the GR55.

Danno

Ok, I did the mod, ie. soldered a 1/4 in jack with ground to pin 1 and center to pin 7.  The GK guitar continues to work as before but I'm getting nothing from the guitar I plug, via my Boss pedal, into the new jack.  I've tried outputting to the amp from the left (mono), right, and guitar out.

What am I missing?

Elantric

This thread describes modifying the GR-55 for use with normal Guitar Only - without use of the 13 pin cable 

In other words If you expect to have a mod that supports normal guitar 1/4" signal path AND a GK guitar with 13 pin cable  connected via to the 13 pin input simultaneously, you need to use the alternate method at link below - because as soon as you connected a GK-3 to the GR-55, Pin #7 gets loaded down by the GK-3 Normal pickup OpAmp Buffer.   

I suggest read this thread

https://www.vguitarforums.com/smf/index.php?topic=3994.0

Danno

Sorry.  Let me clarify.

I tried the new jack and a non-GK guitar first.  Could not get it to work.  Plugged in my GK Strat to be sure the unit survived my surgery.  No problems there.  So, no, I don't need it to work with both simultaneously.  I just can't get the mod to work.

Elantric

You must use a separate active buffer that has a 1meg Ohm input and a 1K ohm output.

insert any  Boss Pedal (in Bypass or active FX mode) will  accomplish the necessary "Guitar Active Buffer / Driver"  - as this is always needed to feed your new Guitar Input jack on the GR-55.

This is explained in the earlier posts on this thread 


Danno

Yup.  I knew that and that was the original setup:  guitar -> Boss -> new Jack.  Not working.  Which guitar out should I use?  Is there a particular patch I should be on?  This is too straightforward a mod to screw up.   Must be something I'm doing wrong.

You're sure it was pin 7?

Elantric

Once you make the mod - you must follow ALL guidelines to enable the GR-55 to accept the normal Guitar input - Roland made it rather difficult on the GR-55


GR-55 F.A.Q.
https://www.vguitarforums.com/smf/index.php?topic=4006.0



* How to enable "Normal Guitar Pickups" and make the GK-3 Guitar/Mix/Synth three-way switch work with the GR-55:

https://www.vguitarforums.com/smf/index.php?topic=3402.0

gumtown

Quote from: Danno on January 03, 2015, 03:29:39 PM
Ok, I did the mod, ie. soldered a 1/4 in jack with ground to pin 1 and center to pin 7.  The GK guitar continues to work as before but I'm getting nothing from the guitar I plug, via my Boss pedal, into the new jack.  I've tried outputting to the amp from the left (mono), right, and guitar out.

What am I missing?

The numbers don't seem to add up there. "pin 1 and pin 7"?
It should be pin 7 and pin 14 (sheath ground + back shell).
Looking at the previously posted photo of the GR-55 GK connector, if pin 1 is in front and pin 14 is the back closest to the socket and chassis backend.
Double check the connections are correct.

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

Danno


Danno

That was the problem.  I was counting from the 13 pin jack towards the front of the chassis and as a result I had soldered to ground and pin 8 rather than 7.  Correction made.  All is working.

Thanks very much for your patience and persistent effort to help me!!

Regards,

Dan

mahabresq

I made this mod and everything works fine with guitar input connected to Return FX. Unfortunately, a drawback that this approach is that it mute the audio signal from GK pickup. Normally I play without connecting the audio signal to the GK pickup, but I have one instrument which requires it. So every time when I want connect my magnetic pickup directly to GK pickup I must pull off the jack from the FX Return. This is a problem for me because I have a little space in my pedalboard. I thought about adding DPDT switch that would toggle audio signal between the normal pickup signal which is connected to FX return, and normal pickup signal which is connected to GK pickup. This would allow me to stop pull off the jack every time when I want change source my audio signal. Do you have an idea how to mount it ?

gumtown

My GR-55 Mod has two jack sockets on the back of the GR-55, a send and a return.
It can serve two purposes
1) as a preamp and or effects loop for the GK normal pickup (as I use it)
2) connect an A/B foot switch with the GR-55 'Send' into A input, Guitar into the B input and the A/B switched output into the GR-55 'Return'
Free "GR-55 FloorBoard" editor software from https://sourceforge.net/projects/grfloorboard/

mahabresq

Thanx for the hint. Second variant is perfect solution for me. As usual, I wanted to complicate everything :-[

KeldAmpworks

#38
Hi, hope you don't mind me bumping this old thread. I saw a mod like this on an instructables somewhere a year or two ago, which inspired me to make an external box that would do the same trick without drilling the GR55.

https://www.vguitarforums.com/smf/index.php?topic=15383.msg109823 if you're interested.

amus

Sorry, maybe I'm blind but where are the fotos? Any downloadlink?

admin

Another case of original posters deleting their links to third party hosted pics

admin

There are similar topics see
Adding 1/4" Guitar Input / FX Loop to GR-55
https://www.vguitarforums.com/smf/index.php?topic=3994.0

And

GR-55 F.A.Q.
https://www.vguitarforums.com/smf/index.php?topic=3137

GR-55 Mods
*  Add a Normal Guitar Input jack on your GR-55
https://www.vguitarforums.com/smf/index.php?topic=4624.0

* DIY GR-55 guitar pickup input output fx loop Mod with Pictures!
https://www.vguitarforums.com/smf/index.php?topic=3994.0

robwatt


gumtown

Quote from: robwatt on February 14, 2020, 02:04:15 AM
I can't see any photos. How come?

I posted a few GR-55 Send/Return Loop modification images here
https://www.vguitarforums.com/smf/index.php?topic=4624.msg31213#msg31213

As the original post was in 2011 and the user has posted the photos on a 3rd party hosting site, anything could happen.
The site could have ceased, photo links could have changed, or the user could have closed their 3rd party photo hosting account.
This site can't be responsible for photos that others host or share, and link from other sites.
Free "GR-55 FloorBoard" editor software from https://sourceforge.net/projects/grfloorboard/

mahabresq

I would like to come back to the topic because I need a solution other than the one proposed above.

I used to use two GR55s. In both I had an FX loop added. In one, in addition to this loop, I had a DPDT switch mounted so I could route Return or GK Pickup Audio signal to the GR, without having to pull the jack out of socket. Unfortunately, I sold that one a long time ago. I was left with the one with just FX. I don't need that loop anymore. All I need is the extra audio input itself and the ability to choose between the signal from that return input and what possibly flows through the 13 pin jack from my Godin. I'm not good with electronics, but the matter seemed simple to me. I used a 2-pole switch. I connected the tip from the audio jack to one pole of the switch. I connected the ground from the jack to the ground of the Roland board. I connected the audio from the 13 pin input to the other pole of the switch, the signal from the center of the switch was fed to GR. However, something is wrong. I can only hear the audio signal with reverb on as wet. What did I do wrong ? Should I use another switch ?

I would very much appreciate advice with the connection.

billbax

Hi mahabresq,

From your post, which GR-55 signals are you trying to switch, GK Pins string signals 1-6 or just P7 normal guitar input non GK?
Please post a pencil diagram if you can, it beats a language barrier 100%.

Bill

mahabresq

Hi Bill,

Thanks for your interest in my problem. I know that my English is a language barrier;) I think that my drawing can also be such a problem;) What more sensitive electronics asks not to look.



https://zapodaj.net/436a10fa80d8a.jpg.html

I'm thinking of switching between the audio signal from the jack socket (previous return FX) and the audio signal from the 13-pin socket. 7 from edge. I have good wires connected, because before that the FX loop system worked properly. Now, instead of socked send, I installed a switch and have a problem.

gumtown

The pencil diagram looks fine, assumi g the toggle switch center pin is common.
If you have a multimeter set to ohms for continuity testing, it would be a big help.
Free "GR-55 FloorBoard" editor software from https://sourceforge.net/projects/grfloorboard/

billbax

Hi mahabresq,

Gumtown's advice is right with multimeter continuity checks. Apologies for the language barrier comment.

Bill

mahabresq

Hi Gumtown and Bill.

I have some cheap meter. However, I would need advice on how to use it ? Between which points should I test the resistance ? With jack and PIN13 cable inserted ? GR should be on or off ? I opened it up. Some pictures.


https://zapodaj.net/89a9de401fe04.jpg.html


https://zapodaj.net/4102bd17919b5.jpg.html

With GR off, meter set to 200M and no jack inserted it generally shows me a value of 00.8 everywhere

Ps. I forgot to add that there is still an RMC OPT and it is through it that I connect to GR. IMHO for switch operation it shouldn't make any difference.