Roland US-20 A/B Selector BUG (Importance of GK-VOL Assignment)

Started by Moonpool, January 28, 2010, 03:16:11 PM

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Moonpool

 


I use a VG8 primarily and have just purchased a US -20  to integrate my VG99  into my live performing rig.  I tried it out using the preset patches and everything worked fine.  Then, I switched to some patches I downloaded from the site and some I modified from the downloaded patches.  When I was using the downloaded patches some very odd things happened.  For starters, the VG99 would play regardless of what I had the US-20 set to.  The VG 8 did not sound at all. So, after switching between A & B, trying one at a time etc, I also noticed something else odd.  When hooked up to the US 20 with both units properly connected, on those user patches that would only feature the VG99 (even when A&B was selected), it also didn't matter what the volume on my GK3 pickup was set to, the VG99 continued to play, even with the volume turned off completely.

When I went to the unmodified presets, everything worked as expected and scrolling back to the user created patches, the problem arose again.    I'm not fluent enough in working with the signal routing on the 99, but I'm guessing somehow that's at the root of the problem.  I can get more detailed information posted this weekend (I won't have time to hook everything up and test till then), but in the meantime I thought someone may have run into this already.  Obviously, I'd love to use some of the downloaded patches live in conjunction with VG8 patches I use primarily, but I have to have silly workarounds to do that which make it difficult if not impossible to play some things the way I want to when switching between units is involved.

If someone has had this before and it's been discussed, I'd appreciate a link to a step by step solution, otherwise, if you have a solution, I'd love to hear it.  I find the complexity of the programming features a bit daunting, largely because I don't have a lot of time to spend programming, which I know I'll have to do eventually.

Thanks for any help and suggestions,
Frank

Elantric

Quotethe VG99 continued to play, even with the volume turned off completely.


Review the US-20 Schematics here:

https://www.vguitarforums.com/smf/index.php/topic,480.0.html

Basically  - if GK-3A's onboard 'GK Vol" pot is NOT mapped to Volume Level on the VG-99 - then the US20 will NOT Work!



Just know that the Roland GK interface design is flawed.

The GK-3 Three way switch and Roland US-20 A/B/Y Selector  / routers ALL rely on the GK-3 "GK-VOL" pot to be assigned to Patch Volume

If you deviate and get creative, and re-assign GK-VOL to control something other than PATCH VOLUME - that's when bugs manifest.

I always put on suitable background music to sing along when creating Control Assignments  - like

The Clash "Know Your Rights"

but I change the lyrics to suit the operation I'm doing:

"You have the Right to Re-assign the GK-VOL pot,  - as long as you're not Dumb enough to actually try it."

paults

You'll find that many of the patches you download will have the knob mapped to something other than volume.  If you modify the downloaded patch, your US-20 will function normally.

big_jan

also check the integrity of the gk cables, i also encounter this issue especially when rushing to setup.

Moonpool

Okay, I'm still baffled.
The integrity of the cables is fine.  I'm not very good at reading schematics, but the bottom line is that the US20 does indeed function correctly on the Roland created patches on the VG99.  The VG8 patches don't seem to be an issue - I can switch between user created ones and factory presets and it works perfectly.  It's just the odd user created patches in the 99 that cause anomalies.

I scrolled through some of the offending patches that I downloaded, like Flute, Oboe.  When I open the Control assign function on the VG 99 I then open the GK Vol screen  According to that screen (Page 1), Source = GK Vol; SW=ON; Target Parameter reads F4 - {A} COSM GUITAR, F5-E GTR, F6-VOL all from Page One.

Page Two MIN=0, MAX=100; Range LOW =1, Range High=127

Page Three Source=GK VOL, SW=ON, Target Parameter- F4={B} Cosm Guitar, F5= E. Gtr, F6= VOL
Page 4 reads exactly as page three.

I randomly checked another patch, one that worked correctly with US20 (that is, it didn't override the GK VOL control functions and did not override the US 20 select functions, and it was set exactly the same.

To clarify again for those who thought the US 20 didn't work, it did work correctly, but on some patches, only the signal from the VG99 would sound, regardless of whether or not  the selector selected the VG99.  These patches all had on thing in common.  They were downloaded from the site and created by a myriad of different users.

As to the GK VOL screens, there wasn't much consistency.  What I noted before, was that on the patches that did the override, I could turn the GK volume all the way off and still have full signal.  I understand that if the GK Volume control was set to another parameter, say Wave Level, then, that might be the case.  I just don't understand why on some patches, only the VG 99 comes through the US 20 even if I have selected the VG8.

Any other thoughts?  Am I understanding how to assign the GK Vol parameter correctly?

Obviously what I'd like to do is have the VG8 (for example) be set to a main patch for a song and have the VG99 set to another patch I'd switch to and be able to change from A to B on the US 20 to go between them.  If I have one of the user created patches that creates the override issue, I can't do this, as all I get for sound is from the VG99, despite how I have the US 20 set.


Moonpool

A few further notes.  I just plugged  everything back in for live sound, as opposed to looking it all up on the iMac.  The main offending patches are the Little Wing and Machine Gun patches, the Tin Whistle and the Flute and Oboe, if anyone has downloaded these and is using a US 20 with a VG8, I'd love to hear what happens if you attempt to recreate this situation.

Thanks again.  Oh, and by the way, I really love the patches - when I refer to them as offending  no value judgement is implied.  I simply mean they are the only ones that cause the problem.

Frank

Brent Flash

Quote from: Moonpool on January 31, 2010, 08:43:01 AM
A few further notes.  I just plugged  everything back in for live sound, as opposed to looking it all up on the iMac.  The main offending patches are the Little Wing and Machine Gun patches, the Tin Whistle and the Flute and Oboe, if anyone has downloaded these and is using a US 20 with a VG8, I'd love to hear what happens if you attempt to recreate this situation.

Thanks again.  Oh, and by the way, I really love the patches - when I refer to them as offending  no value judgement is implied.  I simply mean they are the only ones that cause the problem.

Frank
If you give me an example of one that works, I will look at them to see if I can spot anything. I will compare it to LittleWing.mid

admin

The Working Factory patches will have the "GK-Vol" assigned to "Patch Level" - Not COSM Guitar Level.

Your Tin Whistle, Flute, Oboe patches will not work with US-20, because they remain having the GK-VOL assigned to COSM Guitar, which is not even used in those patches. Set your  GK-Vol to control Patch Level, and you you should be golden.

Moonpool

Thanks, I'll try that out first chance I get. Meanwhile for Brent, the two patches I randomly tried that were guitar sounds and worked as expected were 183 (Voxy P90 + strat and 202 Fat LP.  I really appreciate all the assistance and great patches from this site.  I really need more time with this device as it's quite deep and while related. sufficiently different form the VG8 that at times I'm at a total loss wit the programming and tweaking end s of things.

A2theT

So I have my VG-99 and GR-55 A/B/Y'd using a US-20 which I received a few days ago but have been having a weird thing happening.

VG-99 = Output A
GR-55 = Output B

Basically I'd be playing with Both (Y) units selected and enabled and all ok.  Then I'd play with just the VG-99 (A) and everything works fine.  However, once in a while I'd be using GR-55 (B) only with Both switch unselected yet my VG-99 was outputing sound....?
After tons of troubleshooting I found out that the trouble only occured on certain VG-99 patches.  I found this odd as the logic in my head was telling me that when the US-20 is set to B only there'd be no signal sent to the VG-99.  This is NOT the case.

So now it was time to troubleshoot the patches.

What I've determined is that its strictly related to the GK Volume Knob in the Control Assignment.
If the VG-99 Patch has something other than [A]COSM GTR: E.GTR:VOL assigned to the GK Volume Knob then VG-99 sound will output while you are playing even when the US-20 only has the GR-55 selected.

What I found is that I have a pile of patches where the GK Volume Knob is assigned to "Patch Volume".   Basically all these patches output sound when I play and the US-20 is set to (B)GR-55 only.

I'm not sure if this is a bug or if its by design.  I'm guessing its a limitation of the design regarding how the US-20 handles control messages.

I checked the forum to see if anyone else has been experiencing this issue but found nothing. 

Anyway, its a bit of a pain for me as I've had to make modifications to a lot of patches.

I should also make note that once I fix the patch, I can't seem to break it again.  i.e. a patch was set for GK Volume Knob assigned to Patch Volume, so I change it to COSM Guitar Volume and save and it fixes my problem.  I revert back and reprogram as patch level and everything is still fine.  Really, really weird.


I'd appreciate any comments around this subject.
HEAVY on the METAL
Axe-Fx II, Roland VG-99 + FC-300, Roland GR-55, Digitech Jamman Stereo, Ibanez/ESP/Jackson Guitars

Elantric

Review the US-20 GK A/B/Y Selector circuit,





although the US-20 is marketed as an A/B/Y switch box - technically no audio paths are actually switched - instead a Voltage Control (GK-3's  GK-VOL signal) on Pin#8 is employed to effectively "Mute" the undesired connected 13 pin processor (VG-8, VG88, VG-99, GR-55, GR-30, etc)


QuoteWhat I've determined is that its strictly related to the GK Volume Knob in the Control Assignment.
If the VG-99 Patch has something other than [A]COSM GTR: E.GTR:VOL assigned to the GK Volume Knob then VG-99 sound will output while you are playing even when the US-20 only has the GR-55 selected.

It's by design. The production Roland US-20 is full of flaws, since it does not actually switch any audio signals.
https://www.vguitarforums.com/smf/index.php?topic=7423.msg51872#msg51872

Also many non Roland 13 pin guitar have problems with GK Volume not being able to fully turn volume off on the connected 13 pin processor ( VG-8,VG-88,VG-99,GR-30,GR-20,GR-33,GR-55) when guitar mounted GK-VOL pot is fully counter-clockwise. More details on this "bug" here:
https://www.vguitarforums.com/smf/index.php?topic=434.msg1567#msg1567

I would prefer redesigning an improved US-20, using analog switch IC's ( like several Vishay DG-202) - so it actually does switch all the string audio signals and Normal guitar audio signals. 

Here is the stock Roland US-20 - the underlying "A/B", "Both" Foot switch circuits focus on Moving the GK-3's "GK-VOLUME" Control Voltage signal to "0V" (GK13, Pin#8) for the currently non-selected target Roland 13 pin device (GR-55, VG-99, etc)  - effectively making the deselected target device silent (as long as GK Vol is mapped to patch Volume on the connected GK13 processors / Guitar Synth units) . But in practice this method is full of flaws. 



That design decision by Roland might have been fine back in 1996 when the US-20 was designed, but today the Roland US-20 is terribly inadequate for bulk of today's 13 pin gear, where we often have GK-3's "GK-VOL" pot remapped to other non volume related functions.


Manipulating the "A/B" or "Both" foot switches on the US-20 simply re-routes the GK-3 S1 & S2 control lines and the GK-3 Volume control voltage to the target 13 pin processor device selected by the US-20:  Unit A or Unit B or Both.

Observe in the US-20 schematic All 6 string signals (as well as the "normal guitar signal") from the GK-3 are non switched and actually always connected and all GK-3 audio signals are sent to both 13 pin processing units the US20 is feeding. (Unit A & Unit B)

The 20 year old US-20 design relies on the GK-3 Volume control to be assigned to the Master Volume parameter of the connected units (VG-99, GR-55,etc).
When the US-20 "deselects" a connected 13 pin device, it sets the "GK-Vol" control voltage to zero - which essentially "mutes"  the deselected device -therefore: The Roland US-20 A/B box will only work, AS LONG AS you have the GK-3 VOL control set to control Master Volume or PATCH VOLUME (or "GUITAR VOLUME [A&B]") on the connected device! (VG-99,VB-99,GR-55, etc)!!

The problem is in this era of COSM processing, to showcase the new FX parameters for remote GK-3 control, the GK Synth Volume Pot is re-assigned to many other functions / uses besides Volume, (including the factory presets of the recent Roland products) far too many times the US-20 will appear to not be functional and "broken". This is normal.

So the US-20 will not function if you have reassigned the GK-3 Vol control to another parameter, such as Delay level, or EQ control, .

Also note that you MUST connect a 13 pin processor to the US-20's "UNIT A" jack, as this supplies +/-7VDC power to the US-20.


If there were a significant demand, I would redesign the whole US-20 switcher, with actual analog switches on each string signal and market a superior version.

But the truth is there are usually only 50 folks who would want one and only 3 who would actually buy one, and those low numbers dictate the price would have to be large (more than $300) to recoup the production costs. 

Give me an order for 1000 and the price goes way down!

A2theT

Thanks for this insight Elantric!  Wow, so I've now come to realize that when my GR-55 is selected on B I shouldn't hit "WRITE" on my VG-99 or it will store the patch at volume level zero.  I read through the whole US-20 manual (1 page) and it said nothing of the sort.  This is very important info and should almost be a sticky.  I was set to return the US-20 as defective at one point........

Thanks again for your valuable contribution!
HEAVY on the METAL
Axe-Fx II, Roland VG-99 + FC-300, Roland GR-55, Digitech Jamman Stereo, Ibanez/ESP/Jackson Guitars

djidoe

I own a "DIY US-20" made by my brother and I experienced that kind of problem too. Sometimes I have just unit A selected and hearing sounds from unit B. I haven't made any research about the problem but I will surely do.

DjiDoe

aliensporebomb

Devil's advocate:  Add a second GK3 to the guitar?

Ok, ok, I kid!
My music projects online at http://www.aliensporebomb.com/

GK Devices:  Roland VG-99, Boss GP-10, Boss SY-1000.

djidoe

Hi, how do your GK-3 switches (S1 & S2) react when your US-20 BOTH switch is engaged ? Is the S1 & S2 switches operate on unit A AND unit B ?

Thanx

GTRSteven

I used a US-20 with my GR-20 and GR-30 units (see photo from 2009). The way it worked for me is which ever unit was the last one in control (prior to selecting BOTH) is the unit that S1/S2 controlled.
ex. I had GR-20 as Unit A and GR-30 as Unit B. If I was playing Unit B (Piano) and pressed BOTH, Unit A (Sax Section) would sound also and if I used S1/S2 my Piano sound on the GR-30 (Unit B, the last one selected) would change to the next patch.... Hope that's not too confusing... becomes pretty intuitive after a few uses.... GTRSteven

Here's my old set-up, good for a few laughs...

djidoe

How I understand what you mean, is that "BOTH switch" has nothing to do with S1 & S2 switches. The unit that is selected on the A/B switch is controlled by S1 & S2 switches. Is that what you mean ?

Whip

Wow! Am I ever glad I bumped into this thread. I thought my US-20 was mental. I had the same thing happen.
Like, the 'B' channel would be single (only one unit sound), but when you clicked 'A', both units would sound. Then when I reversed the hook-up, (swapped 'A' and 'B' 13 pin cables) the reverse happened.... 'A' would be single and 'B' would be both! Mental!
Now that I know about the settings, I will try that tomorrow and see if it works.

Whip
Roland VG-99 + FC-300,
Roland GR-55, US-20
SG,BC Rich, Lado, Strat, Godin, GK-2a's & GK-3, RMC
Bose L1 M2 & Compact's & T1's
Have Fernandes Sustainers on most guitars. They are a must  ;)

A2theT

Yes, I had to go and change a lot of my patches and reassign the GK-volume and pick-up selection switches in the VG-99.  When I switched between units with the US-20 or used Both I would have no sound when I should have sound or I'd have both sounding when I should only have one etc...
HEAVY on the METAL
Axe-Fx II, Roland VG-99 + FC-300, Roland GR-55, Digitech Jamman Stereo, Ibanez/ESP/Jackson Guitars

Whip

Thanks! Went and changed the setting globally and it works like a charm.
;D ;D ;D 8) 8) 8)

Whip
Roland VG-99 + FC-300,
Roland GR-55, US-20
SG,BC Rich, Lado, Strat, Godin, GK-2a's & GK-3, RMC
Bose L1 M2 & Compact's & T1's
Have Fernandes Sustainers on most guitars. They are a must  ;)

mooncaine

Wow, great detective work and troubleshooting. Great to know.

Bill Ruppert

THANK YOU!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

727lawrence

I'm glad I found this thread also. It simply looked to me as though the standard guitar pickup output was being routed to both outputs regardless of the setting. Great thread. Thanks!

acousticglue

This, to me, is the most difficult thing to wrap myself around. I think we need some step by step how you setup globally the VG99 for use with direct to soundcard output settings or use with pedals and US20. Screenshots show all needed. Any takers?

shawnb

Folks - I've just run into this myself.   I'd like so share one clarification - mainly to make sure I get it right...   

I also couldn't turn off my VG-99 using the US-20 A/B switch, due to some changes I made a while back.    I had a slightly different issue - I had my System-level GK Vol assign to be GUITAR VOLUME [A&B].   In this config, my Normal PU played thru the US-20's A&B  channels on my voices where I had the Normal PU mixed in.   I.e., the US20 properly handled the COSM guitars, but not my Normal PU.   

So one clarification I would add is this:   If you want:
    (a) control over your cosm guitar volumes (A&B), and
    (b) control over your normal PU volume, and 
    (c) a global solution because you always play your VG-99 thru your US-20

...Then you should change your System-level GK Vol Assign to be either PATCH LEVEL 0-100, PATCH LEVEL 0-200, or MIXER [A&B].   

Avoid the GUITAR VOLUMEs, as this will not provide US-20 control over your Normal PU. 

Feedback & confirmation welcome... 

Shawn
Address the process rather than the outcome.  Then, the outcome becomes more likely.   - Fripp