PRIMOVA - GKPX-14 a smarter GKP-4 clone/4 channel GK distribution box

Started by CodeSmart, August 06, 2014, 10:50:52 AM

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CodeSmart

Hi there, with a 20-pin microcontroller and a handful components a smarter Roland GKP-4 clone could be made.
As this is a parallel box (not a switcher) GK sound is echoed from GK IN to to all GK A,B,C,D outputs all the time.

The Roland GKP-4 has eight hardware switches to control all the S1/S2 and VOL permutations.
- Switches are expensive
- You have to bend down to toggle them.
- Mounting,drilling,wiring is costly etc.

Instead with just one single foot switch and four double-colored LED's  (GREEN+RED component) the following could be realised:

- When started Guitar VOL is sent to all outputs. S1/S2 switches are sent to GK A. GK A LED is flashing, thats the Cursor.
- When stomping the switch the Cursor cycles through GKB, GKC, GKD and back to GKA etc. shown by flashing LED.
- When Double-Stomping, the GK at Cursor position is toggling the S1/S2 mode. Indicated by RED light ON/OFF.
- When Holding Down the footswitch a short while, the GK at cursor position is toggling the VOL mode shown be GREEN  color ON/OFF.

Notes:
- VOL is either Guitar VOL setting or MAX setting.
- If both RED and GREEN components of LED is lit, the light will be yellowish.
- If both S1/S2 and VOL is OFF the cursor is indicated with a short flash-ON
- If any of S1/S2 and VOL is ON the cursor is indicated with a short flash-OFF

So, do you think it's worth doing? I estimate a sales price around $140 USD



(Edited: 2014-08-07 Moved the foot switch and the LEDS so you can see the LEDS while operating it)
But I got more gear than I need...and I like it!

Elantric

Looks ideal for those who need it, and seek to have more live gig operation flexibility compared to the old Roland GKP-4

Although myself - I typically prefer a box with dedicated  A/B/C/D foot switches

CodeSmart

Quote from: Elantric on August 06, 2014, 10:54:18 AM
Although myself - I typically prefer a box with dedicated  A/B/C/D foot switches

Yes of course it is better and what a full blown stage GK Switcher should have,
but this time I was thinking of something as small and cheapest possible,
foot print 4.7" x 2.5" (120mm x 64mm) replacing a GKP-4 no longer sold with as few mechanical components as possible.

4 foot switches and much larger enclosure adds 40 bucks to it + more cost for shipping.

But perhaps a low end parallel box is a dead end anyhow. Roland stopped making the GKP-4 and now sells a cable instead...for reason.
But I got more gear than I need...and I like it!

CodeSmart

Spent some hours with the PCB for this tiny enclosure today
(sniked away from the boring job of refurbishing the basement for my
upcoming work/music room) and I think I managed to squeeze in
a socket for my subsonic filter in case/if/when it turns out ok. So it looks
it might be possible to have that as an option within this 4.7x2.5 inch
1x4 GKP-4 clone.

Biggest problem is my vacation ends today....less number of quality hours.
But I got more gear than I need...and I like it!

CodeSmart

So now's the question, is there a possible need for a teeny-weeny little microcontrolled GKP-4, should I produce a handful units?

Well, the board is designed...


and it seams to fit...


and also with an optional Subsonic Filter board on top...


...it does seem very brutal to stop now, doesn't it?   ;D



But I got more gear than I need...and I like it!

Rick


"...it does seem very brutal to stop now, doesn't it?   ;D"

Well... I'd like to put my foot in the door for one! My US2 never worked properly but I haven't been unhappy with my GKP4 because there were never any other choices. I've been away in Asia and working in the UK for a few years, with just a Lapaxe and my ipad's garageband, and I'm finally back to my GAS warehouse... that is:  VG8ex, VG88v2, VG99 and GR55, all in need of some loving! I'm on a crap android thing, hard to write on and can't load pix, but if you've got the momentum to make a few and you need a tester, please let me know, I can be more specific and send some pix of my setup. Thanks for now, Rick (Trieste)
axes:
Gibson SG-shaped LP Standard '63
Gibson SG Specially Kahlered Y2K
Lapaxe cocobolo '11
Ibanez RG450AH '99 'rootbeered'
Fender Strat Hitmaker copy
Yamaha 112, GK, fretless & sustainiaked

fx:
VG99, VG8ex, SY300, Philo-Tone Gold, Adrenalinn III, TC VL3, RC202

amps:
GK 206mls + two SR Club

whippinpost91850

Curious about this as missed out on your last larger unit :'(

CodeSmart

Quote from: whippinpost91850 on August 12, 2014, 07:43:37 AM
Curious about this as missed out on your last larger unit :'(

Don't worry Whippingpost, this is just a foreplay to the real act.
This is the small low-cost thing fighting the cable-splitter segment. There will be something greater (more expensive with more hardware) later.
I do this mostly to learn more about the microcontrollers and improve my designing skills.
But I got more gear than I need...and I like it!

Elantric

QuoteWhen started Guitar VOL is sent to all outputs. S1/S2 switches are sent to GK A. GK A LED is flashing, thats the Cursor.
- When stomping the switch the Cursor cycles through GKB, GKC, GKD and back to GKA etc. shown by flashing LED.
- When Double-Stomping, the GK at Cursor position is toggling the S1/S2 mode. Indicated by RED light ON/OFF.
- When Holding Down the footswitch a short while, the GK at cursor position is toggling the VOL mode shown be GREEN  color ON/OFF.

Notes:
- VOL is either Guitar VOL setting or MAX setting.
- If both RED and GREEN components of LED is lit, the light will be yellowish.
- If both S1/S2 and VOL is OFF the cursor is indicated with a short flash-ON
- If any of S1/S2 and VOL is ON the cursor is indicated with a short flash-OFF

* I assume "Guitar VOL"  = GK VOL (Pin #8 ). How does the user turn Off one of the outputs? (GK-A, GK-B, GK-C, GK-D) or make selections to  "enable or disable" a specific output ?
* Does it still work if the user has reassigned  GK VOL parameter away from volume, to something else on VG-8, VG-88, GR-55, GP-10 like "Delay time or Reverb Depth?

CodeSmart

Ordered 10 PCB and components for 5 GKPX-14 units  :)

News:
I did a last minute change to the circuit so this tiny unit with only one footswitch may now operate in two modes:
- Poor mans 4 channel US-20 SWITCHER
- or a GKP-4 (4 channel parallel unit).

Right now I think the software will do the following:
- Single-stomp -> Iterate to next channel (A, B, C, D, A, B ... etc)
- Double-stomp -> Toggle S1/S2 ON/OFF for the selected synth
- Long stomp (2s) -> Toggle VOL mode for the selected synth

Advanced:
- Triple-stomp -> Exclusively enable S1/S2 only for the selected synth, i.e. turning off S1/S2 to other synths.
- Very loooooongg stomp (10s) Toggle between 4 channel US-20 and GKP-4 operating mode.

I tried and imagined thumping my foot to the floor with the patterns and I actually think it will be workable.
Musicians I hope have good muscular control. Think of what a drummer can do with his feet working the bass drum  8)
But I got more gear than I need...and I like it!

CodeSmart

Quote from: Elantric on August 12, 2014, 07:59:01 AM
* I assume "Guitar VOL"  = GK VOL (Pin #8 ). How does the user turn Off one of the outputs? (GK-A, GK-B, GK-C, GK-D) or make selections to  "enable or disable" a specific output ?
* Does it still work if the user has reassigned  GK VOL parameter away from volume, to something else on VG-8, VG-88, GR-55, GP-10 like "Delay time or Reverb Depth?

GKP-4 does not have a mute function. It is 5V or GK VOL. As I just wrote I did a last minute change so the 5V can be replaced with 0V by the Microcontroller.
Yes, it's a poor mans switcher/parallel unit. Components are very cheap and few. And it is NOT a full switcher.

The GKMX-33 (or whatever my next multiple input/multiple output project will be called) will have full hexaphonic switching using high-grade switching components on all inputs and outputs. This is a low cost unit, but yet it might be a little more flexible than a GKP-4 or a splitted GK-cable.

But I got more gear than I need...and I like it!

whippinpost91850

Excellent news. I'm not in a huge hurry, so will keep following along. 8)

Bill Ruppert


CodeSmart

Quote from: Bill Ruppert on August 12, 2014, 05:42:47 PM
Holy Smokes you did it..
Count me in!!

Bill

Yes I did, shame on you Bill, planting the seed ;D
Target price in the region of a Roland GKP-2 cable.
But I got more gear than I need...and I like it!

mateomasfeo

Dances with Sheep on SoundCLoud

https://soundcloud.com/dances-with-sheep

pappywatts

Yeah I got one of those Smart phones, trouble is it's smarter than the owner....

Variax Kit:JTV69 +GK3,JTV59P +GK2a.
Carvin SH575, Fender Strat USA Roland Ready, Godin ACSA Multiac Nylon usb model.
GR55,GR30,GP-10, VGA7,Baggs Acoustic Reference, Zinky Green Velveteen 18w,JTM45 Head.Yamaha DXR10

CodeSmart

Quote from: pappywatts on August 18, 2014, 01:28:16 AM
Yoh Robert, I'm up for one as well
regards

Hi Paul. Just got the components from Germany.
Hope I can get the PCB boards soon so I can start to physically work with this project.
I don't wire up a prototype board anymore, don't have time for it.

If things work out as planned I just have to mount a board to do a enclosure drilling mask.
Play around with the drilling machine a little while and send the enclosures for painting/printing.
Meanwhile, I throw together a software that can be downloaded and operate the board with the imagined functionality.
Should not be much more difficult than that...ehhh I think :P

But I got more gear than I need...and I like it!

CodeSmart

Ha-ha amazing, this must be the "GKP-4 Clone-Day-Of-The-Year" :D
"Thanks" to Bill Ruppert we both rushed ahead at the same time and did something similar but yet different in our own way.

First this morning drJoness published his nice GK QuadBoard product suitable for rack or your own enclosure
https://www.vguitarforums.com/smf/index.php?topic=12164.0

And now today I got my boards and assembled my first miniature microcontroller based "1-button" version of GKP-4 / 2xUS-20.
I haven't got much to show until I do some programming, so meanwhile enjoy drJoness video of his product.
(Must be great for you other guys just playing guitar or something, while we do the hard work for you  ;)

We both spend lot's of time and some investment to do these things so I hope we both sell a handfull.

I'll put up a video as soon as I can get the controller running, assuming the board works.




But I got more gear than I need...and I like it!

billbax

CodeSmart,

Funny how things come in threes, as my GKP4 re-amping breakout box is nearly ready. Perhaps we could do a GKP4 clone robot wars. How the mind boggles!

Bill

CodeSmart

Quote from: billbax on August 25, 2014, 08:15:18 AM
Perhaps we could do a GKP4 clone robot wars. How the mind boggles!
Bill

Yes, that would be awesome!!!
I'll be using my GR-55 Darth Vader breath patch and the GP-10 laser guns.
But I got more gear than I need...and I like it!

billbax

QuoteI'll be using my GR-55 Darth Vader breath patch and the GP-10 laser guns.

OK fair enough...I'll be using my active separate-strings taser sword device with its 50,000 volt IC frying capabilities.

Back to more serious matters.  Your GKP4 clone looks very nice and compact.  I noticed how Wayne's board is 15.3cm  and plenty of space between each 13-pin socket.  Mine is 13cm and will have three PCBs. 1. GKP4 Clone. 2. LED VOL and PATCH switches. 3. Seven TRS Jacks / PCB. Three PCBs is the only way to stack and fit this into a relatively small diecast stomp case.

Bill

CodeSmart

Quote from: billbax on August 25, 2014, 09:24:55 AM
Your GKP4 clone looks very nice and compact.
It's compact because the microcontroller controls every switch setting in software. My board may also host a second board (subsonic filter), but it's veeeery tight in there. Also I don't know if there will be noise radiating from the controller. In that case I'm dead meat.

Unfortunately my programmer was not compatible with the device I elected for this board so I've given up right now. Have to order a new better programmer/burner. More $$$... :P
But I got more gear than I need...and I like it!

CodeSmart

Well, had a play with the drill to make the first rough enclosure.
The two-colored LED's will be prolonged to stick out 2 mm. Holes are 0.5 mm wider than required to cope with two layers of paint.
The soft "no-click" foot switch is easy to operate and will allow you to program:
- What unit(s) to be muted (US-40 mode) or kept at full volume (GKP-4 mode) while the other unit(s) are controlled by the guitar volume knob.
- What unit(s) getting the guitar S1/S2 commands.

The unit can also host an optional GKFX-11 Subsonic Filter if you have piezo instruments. In that case the foot switch will have to stick out a little bit more.

The pedal is powered by Unit A and contains protection diodes for the other units.
Unit B,C,D draws a small amount of current so GR/VG/GP can detect the presence of GK input.

Waiting desperately for the new programmer to arrive so I can start downloading C-code into this tiny little thing.

My hesitations right now:
- Will the microcontroller work, and is it accessible from the PC using PICKit3 connected to the six pin connector of the board?
- Even if board is designed with very much ground shields, will the microcontroller radiate audible noise located so close to analog circuitry and connectors?

Well we'll soon find out...



But I got more gear than I need...and I like it!

Elantric

Quote- Even if board is designed with very much ground shields, will the microcontroller radiate audible noise located so close to analog circuitry and connectors?

You must employ separate "Analog Ground" for Op amps and GK13 jacks  and separate "Digital Ground" for CPU. - and then tie them together at one location for a "star ground" arrangement.

Some will employ  a 10 ohm resistor between AGND and DGND, to decouple any RF Current noise that is rampant in the Digital Ground from the Analog Ground

CodeSmart

Quote from: Elantric on August 26, 2014, 02:51:08 PM
You must employ separate "Analog Ground" for Op amps and GK13 jacks  and separate "Digital Ground" for CPU. - and then tie them together at one location for a "star ground" arrangement.

Some will employ  a 10 ohm resistor between AGND and DGND, to decouple any RF Current noise that is rampant in the Digital Ground from the Analog Ground

Completed the coding. Learnt a whole lot. Even got the in-circuit debugger working. The PCB works great from a logical standpoint but yes, as I was afraid of it's noisy  :(

I got myself into a not so trivial topic. The computer itself induces audible background digital noise as it executes instructions and the current inrush when flashing LED's on/off causes "clicks" to the hex audio lines. My idea is now to cut some traces on the board, rewire digital ground and see if it cures the problem. Will also test with external power to the digital circuitry for comparison. Also may need more/different capacitors and inductive filters.

Not as easy as I imagined adding a computer powered by the 13-pin connector, but yet very interesting...
But I got more gear than I need...and I like it!