GR-55 - Here is how to use all your guitars (until you own a modded US-20)

Started by paults, March 20, 2011, 12:35:23 PM

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paults

I haven't been on the forum for the past several weeks (my music time has been filled with writing, recording and gigs) So, if this has already been suggested, my apologies!

The modded US-20 is the best available solution for this,

ELANTRIC - Roland US-20 "Magic Box Mod"- I/O External FX Loop
https://www.vguitarforums.com/smf/index.php?topic=3664.0


but, if you don't own one, here is a way to do it until you track one down to have modded.  Here is a "free, if you have extra cables and an regular guitar switching box" way to use all your guitars with the GR55, as long as you don't mind having two standard guitar cables running along with your 13 pin cable:

The13 pin cable attaches as you would expect

Ooe 1/4 cable goes from the normal output of your GK guitar to one input of your guitar switch box

The other 1/4 cable goes from the Output of your switch box to the Guitar Input of GK

Your other guitar(s) plug into the other switch box inputs.This will route the selected switch box input into the 13 pin cable.

A couple of programming notes to keep in mind:If you aren't playing your GK guitar, set the switch to "guitar", and/or use "normal guitar" only patches. You want to make sure the hex pickup is not active.

If you prefer to leave the switch in the middle position, you just can turn the GK knob down, as long as it is not assigned to the global output volume in your patches.

tepeti

 i made that today with an old and broken gk cable and input socket jack 6.35 and it works very well:




   pin 7 of the gk  cable ---> + jack
                       ground---> ground jack



banditt11

Quote from: tepeti on March 20, 2011, 03:19:33 PM
i made that today with an old and broken gk cable and input socket jack 6.35 and it works very well:




   pin 7 of the gk  cable ---> + jack
                       ground---> ground jack
Good ol' fashioned ingenuity ;)
Frank Betts
2012 American Strat
Gibson double cut faded guitar
Peavey Classic 30 tube amp
Peavey Bandit Special
ME-70 foot pedal
GR-55 Roland synth
www.frontcentermusician.blogspot.com

Elantric

Very cool

Btw, it might be easy to just make a cable, 13 pin male to 1/4" Phone plug.   

Build a 1/4" Guitar Input > GK 13 pin out adapter cable?
https://www.vguitarforums.com/smf/index.php?topic=5252.0

tepeti

Quote from: Elantric on March 20, 2011, 03:31:21 PM
Very cool

Btw, it might be easy to just make a cable, 13 pin male to 1/4" Phone plug.   

sure, you right, it will work too.

gumtown

How about adding a switch to also select in one of the hex inputs to the guitar signal too, you could have mono PCM synth and modeling.
Free "GR-55 FloorBoard" editor software from https://sourceforge.net/projects/grfloorboard/

fordtaurus


LOL, I am gonna do this. I have a broken cable, broken on one side only, so I should be able to do this. Yeah! Thanks for the idea

Quote from: banditt11 on March 20, 2011, 03:23:59 PM
Good ol' fashioned ingenuity ;)

tepeti

Quote from: fordtaurus on March 20, 2011, 09:50:30 PM
LOL, I am gonna do this. I have a broken cable, broken on one side only, so I should be able to do this. Yeah! Thanks for the idea

You're welcome, in fact I'm glad my idea can be useful to others

paults

If you are building a 13 to 1/4 cable, look at the 1/4 inline jacks and plugs designed for heavy duty speaker cables - they have a larger screw on cover, so you'll have more room for the extra wires inside it than you would with a typical one.


prsrick

I have made a cable with the female connector which has a bigger space also, and I can plug in any standard guitar cable.

MaxTwang

The guitar input on a GK device buffers the guitar signal.  The buffering seems to do some impedance matching and eq's the signal (low end roll off).

I found clean and light break-up sound great without the buffering, but distortion doesn't quite sound right.

Check out the GK-2 schematic in the thread below.  Adding a few resistors, a capacitor and an opamp should solve the problem, the opamp is powered by pins 12 and 13.  I was playing with this a few weeks ago, but have been traveling lately.  The buffer circuit would easily fit in your box.

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

gumtown

Quote from: gumtown on March 20, 2011, 07:43:10 PM
How about adding a switch to also select in one of the hex inputs to the guitar signal too, you could have mono PCM synth and modeling.
Tried this yet?
I could be tempted to do the mod inside my GR-55 and fit a 1/4" jack plug for a normal input, and connect in one modeling input to it as well, so it gives monophonic modeling and PCM tones for a normal guitar.
Free "GR-55 FloorBoard" editor software from https://sourceforge.net/projects/grfloorboard/

paults

A buffered guitar signal into the GR55 makes quite a difference, depending on cable length. The sound of an unbuffered normal guitar into the 55 sounds dark and flat compared to through the buffer in the GK pickup. It makes sense, since Roland designed it to use GK pickups, with no 1/4" input.

I think the editing capabilities of the box are deep enough to put the life back into the normal guitar, but putting a buffer between the guitar and connector to pin 7 instantly takes care of it. I put my VHT Valvulator in line, and it instantly solved the problem. 

If you aren't inclined to build, you could use any gain/EQ/line driver/preamp/etc stompbox with a clean low impedance output.         

HAMERMAN409

I built a buffered version and I am pretty happy with the results. I also included a circuit that set the synth volume signal to full. I also included the circuitry to use S1 and S2 (though I have not fitted switches) in case I ever want to add that.

I wanted the buffer so the sound would be similar to what I get when using a GK-2 or GK-3. That way I am not adding another variable when making patches. I will post pictures once I get around to taking some photos.

jwhitcomb3


HAMERMAN409

Here are a couple of pictures and the schematics.

The circuit is heavily based on the Yamaha G1D. Most parts can be found at Digi-Key. I used an aluminum case I found in the junk pile at work and it turned out it would have been much easier to build if I had used a case. Now that it's done I am glad it's small but I wouldn't do that again. The 13 pin DIN connector is made by CUI. They are complete crap but that's all I had and I didn't want to sacrifice a good hex cable. The hood on the connector is from CUI 5 pin DIN connector since it better matched the thickness of the cable I used. For the cable I used a section of an old serial cable since it was small, had enough conductors and was shielded. The schematic was made to match what I built so feel free to leave out P2 and J2. I just did that so it would be easier to take apart down the road if I ever want to make changes. Ignore the wire colors too, they just reflect how I built it and are only there to make it easier for me to work on it 5 years down the road when I have forgotten what I did. :-)

Potentiometer VR1 is internal. I adjusted it to set the synth volume signal to 5 volts. I used a potentiometer to save space and to give me the option to change the synth volume setting if it turned out that 0V made more sense. It's only buffered through 1C1-B because I had a spare half an op-amp anyway so I figured why not use it (which allowed me to stay closer to the G1D circuit).'

Elantric


gumtown

Quote from: gumtown on March 20, 2011, 07:43:10 PM
How about adding a switch to also select in one of the hex inputs to the guitar signal too, you could have mono PCM synth and modeling.
You could add this option to play monophonic synth from a normal guitar.

BTW: what program do you use for schematic drawing?
Free "GR-55 FloorBoard" editor software from https://sourceforge.net/projects/grfloorboard/

Gastric

Quote from: gumtown on August 09, 2011, 12:49:02 PM
You could add this option to play monophonic synth from a normal guitar.

BTW: what program do you use for schematic drawing?

Gumtown, I've experimented with this by wiring my FX RETURN jack (regular non-GK input) to PIN1/STRING1 for non-GK PCM triggering. My testing thus far as shown it works fair, but depending on what string you map your mono signal to controls the note range of tracking. It appears there's a different range of possible notes for each STRING1/2/3/4/5/6 you map your mono input to - for whatever reason.

https://www.vguitarforums.com/smf/index.php?topic=4218.0

HAMERMAN409

Quote from: gumtown on August 09, 2011, 12:49:02 PM
BTW: what program do you use for schematic drawing?
OrCAD Capture. These days I use Pads at work but I still find OrCAD easier and faster.

Skyze

Sorry to bump an old thread, but im a newb with electronical stuff (and even MIDI) but I am really really considering getting a GR-55, but I want to be able to use some non hex guitars thru it also (plan on having 2 Hex and 2 GK3) - so this interests me greatly.

How much would it cost for someone to make me something like this? Or at least, how much do the parts cost?

drjoness2001

I realize this post is somewhat old, but rather than modifying something you have, and perhaps reducing its value should you one day sell it, and alternative might be the Filter/Buffer, which works really well for using any guitar with the GR-55:


augie1

Quote from: tepeti on March 20, 2011, 03:19:33 PM
i made that today with an old and broken gk cable and input socket jack 6.35 and it works very well:




   pin 7 of the gk  cable ---> + jack
                       ground---> ground jack

hello again, was reading your posts on the forum, I am a total newbie with my gr55. would love to ask a couple questions please? first off, with my gk3 installed, and switching it to  guitar, with my guitar plugged into the gk3, are all or most of the amp modeling, and effects available, as if using the gr55 for a normal guitar processor? and I am very interested in using my other guitars without the gk3 if the amp models and effects are available?? I read there is a buffer issue, and see the 13 pin to 1/4 cords can be made up, then just plugging this new cable into to output of a buffered effects pedal output should take care of most buffer issues? like my overdrive pedal, etc...  would like to know for sure that this works? and I realize it is limited, no s1/s2 switching etc... and... if all this works, does this mean that the small gk3 unit which includes its own guitar input to use through the 13 pin cable, takes care of all the buffering issues, as well as forwards the natural guitar pickup to the gr55 to use the amp sims, and effects? And if so, would there be any reason that I could not just use one of my extra gk3 pickups, mounted on my guitar strap that has straplocks, and plug in any of my guitars into the strap mounted gk3. the of course use the bulkier 13 pin cable to connect to my gr55, and obviously the small cable from the guitar of choice into the gk3 guitar in. and If I were worried about astetics and bulk, I could even remove the midi-pickup section of the gk3 so it is not dangling into space... I am just trying to get a grasp on the capabilities of my gr55, aside from the synth sounds, and the awesome cosm guitar sounds, I have a dozen sexy guitars, and dont want them just hanging on the wall getting lonesome, because they dont each have a gk3 mounted on them, and.... another important thing, as much as I love my gr55, I kinda miss the live feel of regular pickups, palm muting, etc... there is no doubt some feel, and nuances that are missed when I am playing strictly midi.. I see the options of buying the modded US20 clone called a UX20 online, and seems full featured, as well as the RMC opt-01 buffer options. not sure if I want to take that plunge yet. and besides is my gr55 really going to be that supe great of a standalone guitar processor to spend all the money on these units, just to use as a non midi rig, with some extra options? surely a boss gt10 or 100 would seem to be money better spent for just effects? with the harmonizers, dual pitch shift, dual tone, etc... I have the feeling that my gr55 can sound great, but never will have those abilities.. so I am hoping when you have time you will be kind enough to try to help, and answer some, or most of my questions about using the gr55 without midi, and if my gk3 mounted on a strap=13 pin out to unit would work? and what I can expect as far as amp or cab sims, and or affects I will be able to use with my regular magnetic pickup guitars. and after that is there a fairly inexpesive mod I could do, to add a 1/4 buffered jack to my actual gr55 unit. like a physical mod? dont plan on ever selling, so not worried about drilling a hole in my unit. thanks in advance... Augie.

Elantric



or


Roland US-20 "Magic Box Mod"- I/O External FX Loop, and Remote S1/S2
https://www.vguitarforums.com/smf/index.php?topic=3664.0




Build a 1/4" Guitar Input > GK 13 pin out adapter cable?
https://www.vguitarforums.com/smf/index.php?topic=5252.0

GR-55 FAQ: TOP THINGS TO KNOW
https://www.vguitarforums.com/smf/index.php?topic=4006.0


https://www.vguitarforums.com/smf/index.php?topic=13405.msg131406#msg131406
Gumtown wrote>

A centre mounted GK-3B pickup for a 4 string bass would normally use the 4 inner pickup poles, and exclude the 2 outer pickup poles,
so it would use GK 13 DIN pins 2,3,4,5 and common ground on the outer shell.

If you wanted to include a GK Volume control, you could use this simple arrangement in the schematic below, with only a 390 ohm resistor and a 1K ohm potentiometer.
The schematic is for a simple "regular bass jack to GK", but the GK Volume part can be used.



Toby Krebs

I went back to tube amps and regular guitar pickups for a few weeks and recently started using my modded GR55 again. It sounds so good it's ridiculous. And a hell of a lot of fun. You can get the GR55 to sound pretty close to anything you want . It takes time,patience and persistence but man is ever worth it!