GR-55- Creating an external effects loop for the modeling tones

Started by justinmorell, April 30, 2011, 11:26:45 PM

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justinmorell

Quote from: samandlyn on May 02, 2011, 11:50:38 PM
Man , there's your PhD right there, you can stop studying now ;) ;)

Now that the PhD is done, I can get back to my real life's work: trying to figure out how to play three notes in a row on a GR piano patch without a glitch :):):)

:(
justin

GR-55, VG-99

Spider

Hi,
I have plan to build a copy of MR. a2dconverter solution but without functionality of US-20 (I sell my Yamaha G50 so...) I have an idea to put one of the divided PU buffer form GK2 schematics inside this box and use it as a mono synth driven by normal guitar (or more bass) PU. It make sense? Any one try do that?

I worry about:
1. Difference between impedance of the normal vs GK-3 PU (I hope that a buffer will help)
2. Setup inside the GR55 (how to measure distance between "mono PU" and bridge?

fungusgarden

just a thought... Is there a wireless device (similar to a wirless guitar system) that not only sends your guitar signal down to the floor, but then also sends it back up so you can run it into the gk3 ? I guess it would be a wireless send and return. I googled it and came back with nothing. The end on your guitar would obviously have to be small and battery powered for it to make any sense. Wouldnt this provide a FX loop without having to run extra cable or mod your GR-55?

gumtown

You could buy from some electronics supply stores (Digikey has them), a 13 pin plug and a 13 pin panel socket, wire them pin2pin through except the normal pickup, and loop that out to two 6.5mm send/return jack sockets.
No internal GR-55 modes or extra cables to the guitar, just plug it between the 13pin cable and the GR-55.
Free "GR-55 FloorBoard" editor software from https://sourceforge.net/projects/grfloorboard/

fungusgarden


fungusgarden

gumtown,
I did a search on that site and couldnt seem to get 13 pin to come up with any matches... It seems fairly easy to build, but if i wanted to be lazy and buy a pre-built FX loop box, for the 13 pin cable, is there anyone selling these premade.

Also, did i read that you are responsible for creating the GR-55 Floorboard software.... OMG, i cant imagine trying to program the GR-55 without it. I would like to donate to the developer.

Thanks,
RB

Elantric

Digikey is where you get the parts to build your own.

Search for "Magic Box" to learn more about FX loops for 13 pin devices.

https://www.vguitarforums.com/smf/index.php?topic=2940.0


VicLesniak

Tried to connect the gr-55 out left to return on the gt-10 and things get too fat and middy
... however the tip on patching gr-55 guitar out to the GK-3 guitar in really helps the Cosm tones alot ... sounds less digital and more authentic ...
all I need for a restaurant gig. With that setup ... I don't see a use for the gt-10 unless I was to use the guitars pickups to drive my marshall/fender concert stack ... but that would be for a band application ....

PS using a Roland BA-330 for the Gr-55 and send the link out to a little Fender GDec .... sounds full that way ...

WallDemar

So, about "pin 7". Here's my simple scheme:
Using the Footswitch you can select what signal will go to the GR55's NORMAL PICKUP module - NOR PU or External sound

PD FX

Hello,
I like to use analog stuff for distortion with the GR-55, and I use the send/return setup mentioned above for it..
there's 1 little trick for best performance: you should beware of groundloops!!..
1) cable with groundwire cut goes from guitar out into distortion input.
2) normal cable goes from distortion output into GK normal guitar in.
Now, that way you wont get that nasty humming and sizzling...

Here's a demo I made using this setup, It aint a great piece of music but sufficiently shows very high gain usage here..

Elantric

QuoteI like to use analog stuff for distortion with the GR-55, and I use the send/return setup mentioned above for it..
there's 1 little trick for best performance: you should beware of groundloops!!..
1) cable with groundwire cut goes from guitar out into distortion input.
2) normal cable goes from distortion output into GK normal guitar in.
Now, that way you wont get that nasty humming and sizzling...

Good advice!!!

I have built MANY "normal" FX  pedals boards

If the FX were variations on Boss FX , I found for lowest noise, I relied on the DC Power cables to  each FX unit as the ONLY  path for Ground

The short 1/4" patch cords ALL had the ground "cut" at ONE END ONLY  - creating what we call "lifted" or floating ground = no ground connection between FX on the 1/4" Audio jacks.

Because the coax shield was only cut at one end, the cable RF / EMI Shield is still effective.   

With only One path for Ground between FX on the DC Power connections - I could connect a  large array of unbalanced audio FX and have a few dB less hum than a traditional wired FX board.

I learned this "trick" reading this app note from Rane (suggest read ALL Rane Audio App notes!)

http://www.rane.com/note151.html


PD FX

thats right Elantric!..
Many salespeople/professionals will try to sell you a real DI for groundlift, which is not needed in a closed local system.
ofcourse this kind of hum-removal is only suitable for people who understand electronics. It would be a hazard if people would try this kind of tricks on the wrong place and/or scale..

Magiamusical

I have a US-20, can some tell me how to modify it so I can have a normal switchable guitar into the GR-55.

Tks,
Godin LGXT, Les Paul Studio w/GK3, JTV89F w/GK3, GR-55

Magiamusical

I just received the modified US-20 and I tried it with different effects to get the buffered signal, but then I tried a Line 6 Wireless connected to the Modified US-20 with the ring disconnected and a normal guitar at the other end of the wireless, it works, apparently the Line 6 wireless buffers the signal. Now I can use the a normal guitar wireless and for synths sounds I just switch to the one of the GK3 equipped guitar. 

Super Happy with the setup and thanks to Elantric for the US-20 modification. Still have to work the real state in the pedalboard.
Godin LGXT, Les Paul Studio w/GK3, JTV89F w/GK3, GR-55

Elantric

#39
QuoteSuper Happy with the setup and thanks to Elantric for the US-20 modification


Glad to hear things all worked out! Looks great.
Details on US20 mod is here:
https://www.vguitarforums.com/smf/index.php?topic=7245.0

glennfin

After reading many posts regarding this subject, this one from Elantric explained it well..... but one question remains,

What about the guitar out jack on the GR-55? If this is a low impedance signal, and I plug this output into the input of my guitar amp, it won't be the same as if I plugged the guitar directly into the guitar amp because the mag signal directly from the guitar is a high impedance signal. ???


Quote from: Elantric on May 01, 2011, 06:53:46 PM
As a reference: The Normal Guitar signal flow goes like this:

STEP#1: Normal Guitar pickups on your guitar will feed a guitar mounted GK-13 Preamp driver board (Roland, Ghost, RMC) .

STEP#2: Inside the GK-13 Preamp driver board is an op amp buffer which feeds GK13 cable pin #7. This Opamp buffer also performs a Hi Z to Lo Z impedance conversion. 

STEP#3: The 13 pin GK cable from your guitar feeds the GK IN" jack, and pin #7 has the "low Z" Normal Guitar signal.

STEP#4: Due to the low impedance of the internal "normal guitar signal path" inside the 13 pin cable (as a result of Step # 2) If you modify the signal downstream to create an FX Insert point, you must use a signal buffer between your Guitar and the Pin#7 signal connection.
Using an ordinary Boss pedal works as a HiZ to Low Z signal buffer for this function ( I use a Boss TU-3 Tuner), but many other pedals work too - Ibanez Tube Screamers, Boss  CS-3 Compressor, DS-1 distortion, etc, as used in my US-20 "magic Box" mod. If you use FX which feature "True Bypass" - you will need to add a Hi Z to Low Z buffer circuit to feed the Normal PU path on the target processor (VG-99 / GR-55)

Elantric

#41
QuoteAfter reading many posts regarding this subject, this one from Elantric explained it well..... but one question remains,

What about the guitar out jack on the GR-55? If this is a low impedance signal, and I plug this output into the input of my guitar amp, it won't be the same as if I plugged the guitar directly into the guitar amp because the mag signal directly from the guitar is a high impedance signal. ???

People use Hi to Lo Z buffers all the time to feed Tube guitar amps with HiZ Inputs, (Every boss  / and most Ibanez pedal employs such a buffer - even SRV used a tube screamer for many solos,
If you own a GR-55, don't take my word for it - try the GR-55 Guitar Out first - It works until you enable the COSM Model tones, then most experience too much hiss.

See threads below

GR-55's Guitar Output jack
https://www.vguitarforums.com/smf/index.php?topic=3196.0


GR-55 Guitar Out
https://www.vguitarforums.com/smf/index.php?topic=10610.0

GR-55 Guitar Out into ...?
https://www.vguitarforums.com/smf/index.php?topic=6954.msg48372#msg48372

Guitar output Question?
https://www.vguitarforums.com/smf/index.php?topic=10644.msg77135#msg77135

GR-55 noise in Live Rigs (Guitar Out)
https://www.vguitarforums.com/smf/index.php?topic=5456.0


GR-55 Hum Issues
https://www.vguitarforums.com/smf/index.php?topic=10659.0

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



Advanced Search Tool
https://www.vguitarforums.com/smf/index.php?topic=2978.0

glennfin

Thanks, I will try that in an A/B comparison when my GR-55 arrives. I've owned a VG-99 for a few years now and honestly never tried that test.... I assume the guitar out on the VG99 is similar if not the same circuitry as the GR55.


Quote from: Elantric on March 31, 2014, 07:33:35 AM
People use Hi to Lo Z buffers all the time to feed Tube guitar amps with HiZ Inputs, (Every boss  / and most Ibanez pedal employs such a buffer - even SRV used a tube screamer for many solos,
If you own a GR-55, don't take my word for it - try the GR-55 Guitar Out first - It works until you enable the COSM Model tones, then most experience too much hiss.

See threads below

GR-55's Guitar Output jack
https://www.vguitarforums.com/smf/index.php?topic=3196.0


GR-55 Guitar Out
https://www.vguitarforums.com/smf/index.php?topic=10610.0

GR-55 Guitar Out into ...?
https://www.vguitarforums.com/smf/index.php?topic=6954.msg48372#msg48372

Guitar output Question?
https://www.vguitarforums.com/smf/index.php?topic=10644.msg77135#msg77135

GR-55 noise in Live Rigs (Guitar Out)
https://www.vguitarforums.com/smf/index.php?topic=5456.0


GR-55 Hum Issues
https://www.vguitarforums.com/smf/index.php?topic=10659.0

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



Advanced Search Tool
https://www.vguitarforums.com/smf/index.php?topic=2978.0

Elantric

Quote. I assume the guitar out on the VG99 is similar if not the same circuitry as the GR55.

Read the GR-55 Manuals and VG-99 Manual - the "Guitar Out" jack on each is unique - only the GR-55 can be set to output COSM Modeled Guitar tones - but who cares since its rather noisy filled with too much hiss for most folks rigs. Read the "GR-55 Guitar OUT" threads I linked above.

glennfin

Yes, I did read the links you posted, (thank you) and of course I've read the VG99 manual.... I wasn't refering to the function of the guitar out jack, just the raw circuitry that drives the output.

Quote from: Elantric on March 31, 2014, 09:13:22 AM
Read the GR-55 Manuals and VG-99 Manual - the "Guitar Out" jack on each is unique - only the GR-55 can be set to output COSM Modeled Guitar tones - but who cares since its rather noisy filled with too much hiss for most folks rigs. Read the "GR-55 Guitar OUT" threads I linked above.

Elantric

#45
QuoteI wasn't refering to the function of the guitar out jack, just the raw circuitry that drives the output.

They are very different - VG-99 is much cleaner - mostly because unlike the GR-55,  there are fewer parts and no programmable routing switch upstream and no DAC output on the VG-99 Guitar Out jack.

glennfin

I see..... Most likely the guitar out on the VG99 is simply a buffered out from the 13 pin cable

Quote from: Elantric on March 31, 2014, 10:03:50 AM
They are very different - VG-99 is much cleaner - mostly because there are fewer parts and no routing switch upstream and no DAC output

Elantric

#47
QuoteI see..... Most likely the guitar out on the VG99 is simply a buffered out from the 13 pin cable

Correct! - as shown in the Block Diagram in the V-99 Owners Manual

The only switch on the VG-99 "Guitar Out signal is the switching Jack on the VG-99's "Guitar IN jack  If you insert a 1/4" plug into the VG-99 Guitar Input jack, the 13pin pin #7 Normal Guitar input feed is disabled form the the VG-99 Guitar Output Jack.

glennfin

Not exactly, if you look closely you'll see the guitar out signal at the common of that switching jack is also connected to the "C" section of the 3 section switchblock which is probably some sort of analog switch IC. It's also connected to that USB A/D function block.

Quote from: Elantric on March 31, 2014, 10:26:26 AM
The only switch on the VG-99 "Guitar Out signal is the switching Jack on the VG-99's "Guitar IN jack


glennfin

I just looked at the GR-55 block diagram and with "Modeling tone" switched off, it appears to be the same setup/signal path/switching arrangement as the VG99
Again, that's with the Modeling tone turned off.... The guitar mag signal goes into the same "line select" switching block just like in the VG99.

That being said, for me, modeling tone off would only be useful for straight guitar (mag pickups only) patches but that may be ok since I believe that can be selected per patch.  :D

Very interesting......